BIBLIOGRAPHY MAPANAO, JULIET D. APRIL ...
BIBLIOGRAPHY
MAPANAO, JULIET D. APRIL 2013. Yield and Chip Quality of potato var
Igorota Applied with different Volumes of Water under La Trinidad, Benguet Condition.
Benguet State University, La Trinidad, Benguet.
Adviser: Janet P. Pablo, MSc.
ABSTRACT
The study aimed to determine the growth and yield of potato applied with different
volumes of water, to determine the chip quality of potato applied with different volumes
of water, and to determine the best water volume for maximum yield and chip quality of
potato var Igorota.
Generally, no significant differences were observed in all the data gathered except
for percent survival and dry matter content. The application of 200, 400 and 800ml
significantly produced high percent survival comparable to the control of 600ml. The
heaviest marketable yield was obtained from the application of 600ml (control) while the
heaviest total yield was obtained from the application of 800ml water.
The lowest sugar and dry matter contents were obtained from the potato plants
applied with 1000ml water. Whereas, 600 ml application gave the highest dry matter
content.
The application of 200, 400, and 600 ml resulted in a crispy, slightly oily to not
oily, perceptible, and liked much potato chips by the panelists.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
INTRODUCTION
Potato (Solanum tuberosum L.) is one of mankind’s valuable foods and is produced
in 130 countries where three-fourths of the world’s populations live. In addition, the best
quality and largest yields are produced under cool climate and high altitude with elevations
higher than 2000 meters such as Benguet and Mountain Province (HARRDEC,
1996).Thus, Benguet and Mountain Province are producing 74% of the Philippine potato
production while the remaining percentage is produced from Mindanao.
Consumption of potato and potato by-products is growing rapidly in the
Philippines. This scenario alone projects the increase in the demand of processing varieties
considering the rising number of fast food chains and snack house like Jollibee and
McDonalds coupled with the increasing population.
However, most of the potatoes grown like granola variety are not suitable for
processing due to their inherent excessive moisture and sugar content. To address this
problem, the Philippine government imported 61,699 metric tons of a wide range of
processed potato products (PCARRD, 2008). The importation cannot compensate all the
demands and needs of the country and it is just a short-term solution to the problem leading
to the evaluations of different potato cultivars by researchers of the different agencies and
institutions. These evaluations led to selection of several processing varieties and Igorota
variety is one. The Igorota variety is one of the varieties developed at Benguet State
University possessing a high dry matter content of 18-21% suitable for processing.
On the other hand, with the arising problem in climate change, FAO (2002) reported
that agriculture is one of the most vulnerable sectors. Thus, food production and security
will be most affected. It is stated that most agricultural regions experience periods of
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
deficient moisture. It is reported that the prolonged drought of five to six months is common
in the northern highlands of the Philippines like Benguet and Mountain Province. In these
areas, potato as one of the major crops planted with a total 10, 960 hectares cultivated with
potato annually (DA-CAR, 2005). Further, Jose (2008) stated that Benguet alone is
planting 10,240 hectares planted yearly with crop often suffers from lack of irrigation
during dry season.
To alleviate this problem, researchers have been working on the development of
high yielding varieties with resistance to abiotic stresses such as drought or the
development of drought tolerant genotypes.
Increased production of processing varieties is greatly needed due to the rising demand of
the processing companies and the ever-increasing population. In fact, fast food chains
particularly McDonalds and Jollibee, serving French fries in Baguio and La Trinidad alone
need at least 2,000 to 6,000 kilos a week of potato suitable for French fries (Palangchao,
2009).
This demand however, cannot be attained because of some abiotic factors particularly
drought or scarce water supply during summer in the rain-fed areas that contribute to low
production. In addition to this, the poor and scarce water is a problem of vegetable farmers
in the region, particularly Benguet. The scarcity of water in Benguet during the dry season
results to less extensive production of food crops. On the other hand, with climate change,
continuous rainfall is also being experienced in the growing area that causes flooding or
above the saturation of the soil affects the growth and development of the potato. It is
therefore necessary to determine the water use efficiency of potato for processing. Thus,
the study evaluated the chip quality of Igorota applied with different volumes of water.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
The objectives of the study were to:
1. determine the growth and yield of potato applied with different volumes of water;
2. determine the chip quality of potato applied with different volumes of water; and
3. identify the best water volume for maximum yield and chip quality of potato var Igorota.
The study was conducted from October 2012 to February 2013 at the Benguet State
University Experimental Farm Station under a nethouse in Balili, La Trinidad, Benguet.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
REVIEW OF LITERATURE
Demand of Processed Potato Product
In the Philippines, the demands for potatoes continue to increase because of the growing
population, rise in the number of fast food chains and restaurants (Yano, 2009). Palangchao
(2009) reported that McDonalds and Jollibee, serving French fries in Baguio and La
Trinidad alone need at least 2,000 to 6,000 kilos a week of potato suitable for French fries.
The demand of convenient foods such as chips and fries, to be particular, has led to the
expansion of the potato industry (Garcia, 2006).
Distribution and Area of Production
Benguet and Mountain Province have a total of 10, 960 hectares planted with potato
annually ( DA-CAR, 2005), and Benguet alone is planting 10,240 hectares planted yearly
which often suffer from lack of irrigation during dry season (Jose, 2008).
Potato Processing Quality
Chipping quality is genetically transmissible character. Potatoes that produced light-
colored chips after cold storage and reconditioning were shown to transmit the ability to
produce light- colored chips to their products (Oltmans and Novy, 2002).
For more processed products, a starch content of 13% or higher, a solid or dry
matter content of 20% or higher, and specific gravity of 1.080 or higher is preferred (Stark
et al., 2003).
Color is the most important factor in the evaluation of tubers for chipping. Hence,
the yellow ones are the most preferred, whereas any other skin color may follow as long as
it will pass the certain requirements of the processors (Sabiano, 2006). Similarly, Rastovski
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
(2003) added that yellow fresh color tubers are accepted not only for processing but also
for table purposes. According to him, for more beta-carotene colored ones are preferred.
In addition to this, potatoes with low reducing sugar content give an acceptable golden
yellow chips which are acceptable for chipping industry.
Tuber size, shape, appearance, absence of disease or defects, flavor and texture all
contribute to potato quality. Quality may be related to visual appeal, culinary preference of
the consumer, or ability to match market specifications. Two of the most important quality
characteristics of potatoes on the other hand, are starch content, which impacts cooked
product texture, and sugar content, which has a direct bearing on fried product color (Stark
et al., 2003).
Potato tuber characteristics such as shallow eyes, round or elongated tuber shape,
smooth skin and freedom from defects are important characteristics because it requires
lesser trimmings, provide preferred sizes, high chip yield, absence of discoloration or
browning during frying and good quality. A study conducted, found out that shallow eye
is one of the characters preferred by processors because there is less trimmings. Potatoes
free from defects and disease are also considered whereas the round tubers are preferred
for chips and the oval to elongated shape is otherwise preferred for French fries production
(HARRDEC, 1996).
Specific Gravity and Dry Matter Content
Tuber specific gravity is the measure for estimating starch content and
characterizing the processing potential of tubers. Low specific gravity potatoes, typically
of red varieties for example, tend to be best for boiling and canning. Because specific
gravity is related to maturity, tubers that have a longer time to accumulate car4bohydrates
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
will generally have higher specific gravity than those with shorter growing periods.
Therefore, early planting can increase the number of days that can potentially contribute to
tuber starch deposition (Stark et al, 2003).
Numerous workers have shown that potato quality is directly associated with dry matter
content. Specific gravity has been used as criterion of potato quality because of its close
relationship to dry matter content and the rapidity with which it may be determined. High
specific gravity potatoes are better suited for baking, frying, mashing, and chipping while,
low specific gravity for boiling and canning. The potato chip manufacturers prefer potatoes
of high specific gravity because they yield more chips per pound of potatoes. This outlet
of potatoes is important in the potato industry at Hastings because over two million bushels
of the annual crop are sold for chips (Mhyre, 1959).
High specific gravity is particularly important in the production of potato varieties for chips
because of greater surface area to volume ratio and potatoes with high specific gravity are
also preferred because they have been shown to absorb less oil during chipping process
(Scanlon, 2006).
Water loss through transpiration is an inevitable cost of dry matter production, and
there is about 200 to 800 g of water needed to produce a gram of dry matter for a range of
climates. On the average, crop plants use 500 to 700 pounds of water to produce a single
pound of dry matter. Thus, the required dry matter for the production of French fries should
be containing 20 to 24 %. Higher or lower content of dry matter may give a negative result
on the quality. A more mature potato usually has higher specific gravity or higher solid
content and can be harvested with less skinning and bruising injuries (Smith, 1977).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Sugar and Starch Content
In the Processing Industry, accepted values for the reducing sugars are 0.2 % for
chips and 0.5 % for French fries (Alingbas, 2007).
High starch content is favored by processors to ensure products have acceptable texture
and to keep processing costs down by limiting the amount of raw product needed, the
cooking time required and the amount of oil absorbed. Tuber sugar content on the other
hand, has an important effect on the quality of processed products because of its large
influence on fried potato color. When exposed to high levels of heat, which is typical of
frying process, sugars combine with amino acids and other compounds to form dark color
and flavor we associate with ‘burned’ food. This process is known as “Maillard Reaction”.
The reducing sugars glucose and fructose create the most serious problems during frying
because they are chemically reactive. Sucrose however, contributes too little dark color
development but is the substrate for creating more reducing sugars under the right
environmental and physiological conditions. Potatoes intended for chip production should
have a reducing sugar level below 0.35 mg/g or 0.035% of fresh tuber weight. Potatoes for
processing as French fries therefore, should have less than 1.2 mg/g or 0.12% of tuber fresh
weight. Potatoes with higher values will usually show color problems after cooking (Stark
et al., 2003).
Sugar content of potatoes is affected by climatic factors in a location, such as
temperature during growth, minimal nutrition, and irrigation. It is determined by genotype
and several pre and postharvest factors and as tubers begin to grow, they are low in starch
and high in sugars. Near the end of vine growth, the tubers reach the point known as
physiological maturity- when they achieve maximum dry matter content and minimum
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
sugar content. Moreover, potatoes destined for making chips, French fries and other fried
products, need to have low sugar content to avoid browning of the finished product (Kumar
et al., 2004).
It is found that very low sugar content is apparently important to prevent darkening
of chips. Sugar content should be below 2%. Potatoes of low sugar content result in a lighter
color chips desired by consumers (Smith, 1977).
Tuber Shape
Tuber shape is more uniform between 60o and 70o F than at temperatures above or
below this. Tubers grown at 50o to 55o F are more spherical compared with the oblong
shape of the Russett Burbank and White Rose varieties. Russett Burbank tubers are
extremely knobby and the White Rose is spindle –shaped when grown at 80 to 85o F. There
are also multiple developments on a single stolon. This is often observed in the field with
low moisture and high soil temperatures prevailing (Smith, 1977).
Cultivar/Variety
A three-year variety trial of more than 20 varieties conducted, showed that Donald,
Remarka and Signal are the only varieties which produced high yields with a dry matter
content of 21 to 23% when grown in Buguias under deficient irrigation (Jose, 2008).
Using the right variety ensures high yield and better quality of produce. In planting, the
first decision is to know the best variety that is adapted to the locality to have a profitable
production (HARRDEC, 1996).A processing variety must have high dry matter and low
sugar content. Such varieties often have higher chip yield, crispy and slightly oily crops
(Alingbas, 2007).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Irrigation
Potato needs frequent irrigation for its good growth and yield. The yield is greatly
influenced by timing, amount and frequency of irrigation applied. Soil moisture is probably
the most important factor determining potato yield and quality. Irrigation increases potato
tuber quantity. It is very sensitive against water stress in all growing seasons, in particular
at the duration of tuber formation. There is a decrease in tuber yield, tuber quality, income,
and marketing degree in the conditions of deficit irrigation. Even the decrease for the level
of 10% in the optimum water treatment in the growing period could have caused a decrease
in yield. It was reported that potato was more sensitive to water stress at the stolonization
and tuberization stages than the bulking and tuber enlargement stages. In the tuber
enlargement stage, water deficit could be applied with a slight decrease in yield (Kiziloghu
et al., 2006).
Early studies have shown that water is the most important limiting factor for potato
production and it is possible to increase production levels by well- scheduled irrigation
programs throughout the growing season (Bojujelben et al., 2001).
Excessive and deficit soil water availability during the growing season normally
has a substantial adverse effect on crop yield and quality. In irrigated agriculture, proper
water application depth and timing relative to crop growth is paramount for optimum
economic return and maximum water use efficiency (Erdem et al., 2006).
Since no irrigation system is perfectly uniform, application uniformity should be
quantified in order to measure irrigation system efficiency, because an irrigation must
continue long enough to adequately water plants receiving the least water. The scale of the
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
uniformity measurement should be related to the soil volume water occupied by potato
roots (Pereira and Shock, 2006).
It was reported that irrigation of potatoes reduced specific gravity of potatoes. In contrast
to this, another study found out that it was increased with soil moisture where the specific
gravity of irrigated tubers were from 0.0002 to 0.004 lower than those not irrigated. It is
due because maturity is promoted and specific gravity is higher when potatoes have been
grown in low to medium soil moisture than at high soil moisture (Smith, 1977).
Tuber market grade and stem-end fry color is improved by moderate stress before tuber
initiation (Pereira and Shock, 2006).
Potatoes have a shallow root system that requires more frequent irrigation when compared
to other crops. Extreme variations in irrigation management and nitrogen availability
influence tuber yield, size, grade, external quality, and internal quality (Pereira and Shock,
2006).
Irrigation should be continued to as close to harvest as possible to obtain maximum yields.
When the last irrigation was 7, 14, and 21 days before harvest, yields where progressively
reduced, as much as 205 reductions followed when irrigation was stopped 21 days before
harvest. Moreover, by irrigation twice a week with the water level maintained at land 5
inches in the furrow, infiltration rate for the 5-inch depth was 40% more than the 1-nch
depth, but yield was decrease 17% by irrigating only once a week, the infiltration rate was
doubled with no effect on yields. Moreover, timing of irrigation may be altered at various
stages of growth. Excessively frequent irrigations are more harmful from time of first
bloom than later in the season. Plants are better able to withstand high moisture tension
levels when evaporative conditions are less severe (Smith, 1977).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Potato is one of the most important crops in the world. Due to its sparse and shallow
root system, potato is very sensitive to water stress and tuber yield maybe considerably
reduced by soil water deficits Therefore, irrigation is always needed for production of high
yielding crops. But with the increasing shortage of water resources, optimization of
irrigation management therefore is required in order to improve water use efficiency (Liu
et al., 2005).
Because of the sensitivity of potato to water stress, most researched has been
focused on avoiding deficiencies in soil water. Tuber yield responses to irrigation decrease
with over-irrigation (Pereira and Shock, 2006).
Deficit irrigation is a strategy which allows a crop to sustain some degree of water
deficit in order to reduce irrigation costs and potentially increase revenues (Shock and
Feibert, 2003).
During drought stress cycles, water savings under carbon dioxide allowed
photosynthesis to continue for one to two days compared to ambient carbon dioxide
treatment (Baker and Aller, 2005).
Water stress during early tuber bulking reduces specific gravity and increases
reducing sugars associated with dark stem-end fry color (Shock and Feibert, 2003).
Water stress imposed from tuber initiation until the end of tuber bulking was the
most detrimental to biomass and tuber production. Water stress imposed from tuber
initiation until the end of tuber bulking storage and between emergence and tuber initiation
stage produces the lowest yield (Steyn et al., 2003).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Water stress which occurs before tuber bulking, followed by resumption of
irrigation may favor to occurrence of second growth since top growth is stimulated
vigorously after a period of drought and high temperature (Van Loon, 1981).
Potato should be irrigated as even as possible, particularly at four to nine weeks after
emergence when the tubers are forming to avoid tuber skin cracking and malformation
(Ferreria and Carr, 2002).
Water Use Efficiency in Potato
Potato is one of the most important crops in the world. The increasing worldwide
shortage of water resources then, requires optimization of irrigation management in order
to improve water use efficiency (WUE).The term water use- efficiency describes a plant’s
photosynthetic production rate relative to the rate at which it transpires water to the
atmosphere. It is a measure of plant performance that has long been of interest to
agronomists, foresters, and ecologists. Among the irrigation regimens, the highest water
use efficiency was generally obtained from application of irrigation when 30% of the
available water was consumed. In addition to this, a study conducted to assess water use
efficiency rate from different irrigation methods found out that drip irrigation method
yielded higher values of WUE than furrow irrigation, since drip irrigation consumed less
water (Erdem et al., 2006).
Water Resources
Seemingly abundant, water in the country is now becoming a scarce resource. A
study on water resource accounting done in 1988 to 1994 by the environmental and Natural
Resource Accounting-Integration Environment Management for Sustainable Development
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Program (ENRA-IESMDP) showed that the stock of surface water has been decreasing t
an average rate of 37%, while stock of groundwater has been decreasing at an average of
1.4 %. The diminishing stock can be attributed to the lower recharge rates compared to the
rates of abstraction for both types of water resources. In 2001, NIA’s irrigation systems
(national and communal irrigation systems) as well as private irrigation systems, served
only 44% of the potential, irrigable area, signaling an apparent water shortage especially
during the dry season (PCARRD-DOST, 2003).
Political constraints, rising costs, and groundwater scarcities are resulting in less
water available for agriculture. In some areas, groundwater supplies are being exhausted.
Competition for world supplies is a worldwide phenomenon (Shock and Feibert, 2003).
Importance of Elevation to Potato Production
Potatoes are grown in higher elevations than other crops. In the tropics, the typical
mountainous areas that produce potatoes is cold, best temperature fluctuated sharply from
day to night and the average relative humidity is high. Soils are well-drained that there is
great variation in altitude, slopes, soil fertility and other environmental variables that
influence yields. Production hazards like frost cause low yields in highland areas, where
the chances of crop failures are great, farmers often economize to purchase inputs in order
to minimize their financial risks (Alingbas, 2007).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
MATERIALS AND METHODS
Potato tubers of the Igorota variety from the Northern Philippines Rootcrop Research and
Training Center, Benguet State University (NPRCRTC-BSU) were used as planting
materials. One tuber was planted in a pot measuring 12 inches diameter. This was
replicated three times and laid out using Completely Randomized Design (CRD). All
cultural management practices were strictly employed like weeding to avoid competition
of both water and nutrients. The different volumes of water which served as treatment, was
strictly implemented three days after planting and applied based on the treatment as
follows:
Code
Treatment
W1 (control) 600 ml of water applied twice a week (Farmer’s Practice)
W2
1000 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W3
800 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W4
400 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W5
200 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
Chipping quality was evaluated by treatment after harvesting.
Chipping of potato. The tubers were washed, peeled, and sliced into 1-1.5 mm. The sliced
tubers were again washed with tap water to remove the starch adhering to the slices. The
slices were then wiped with clean cloth to remove excess moisture and fried in hot oil until
bubbles are few (NPRCRTC, 1998).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
a.) Washing
b.) Peeling
d.) Washing of chipped potato
c.) Chipping/ slicing
e.) Pat drying
F.) Frying
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Figure 1. Chipping of potato tubers applied with different volumes of water
Data Gathered
1. Meteorological data. Temperature and relative humidity were taken using a digital
hygrometer. Light intensity was recorded using a digital light meter.
2. Percent survival. Percent survival was taken at 30 DAP by counting the number of plants
that survived and computed using the formula:
Percent Survival= No. of plants planted/ No. of plants that survived x 100
3. Plant vigor. This was taken at 30, 45, and 60 DAP using the following rating scale
(Palomar and Sanico, 1994):
Scale Description
Remarks
5
Plants are strong with robust stems Highly vigorous
and leaves; light to dark green in color
4
Plants are moderately strong with Moderately vigorous
robust stem and leaves; light green in
color
3
Plants are better than less vigorous
Vigorous
2
Plants are weak with few thin stem Less vigorous
and leaves; pale
1
Plants are weak with few thin and Poor vigor
leaves; pale
4. Pest and disease incidence. The crop was rated during the different growth stages using
the following rating scales:
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
a. Late blight incidence. Late blight was rated using the following CIP rating scales
(Henfling, 1981):
CIP
Blight %
Symptoms
Scale
Mean Limit
value
1
0
No late blight observable.
2
2.5
Traces-5 Late blight present. Maximum of 19 lesions per
plant.
3
10
5-15
Plants look healthy, but lesions are easily seen at
closer distance. Maximum foliage are affected by
lesions or destroyed corresponds to no more than
20 leaflets.
4
25
15-35
Late blight easily seen on most plants about 25%
foliage is covered with lesions or destroyed.
5
50
35-65
Plot looks green; however, all plants are affected.
Lower leaves are dead. About half the foliage area
is destroyed.
6
75
65-85
Plot looks green with brown flecks. About 75% of
each plant is affected. Leaves of the lower half of
plants are destroyed.
7
90
85-95
Plot neither predominantly green nor brown. Only
top leaves are green. Many stems have large
lesions.
8
97.5
95-100
Plot is brown- colored. A few top leaves still have
some green areas. Most stems have or are dead.
9
100
All leaves and stems dead.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
b. Leaf miner incidence. The appearance of insect pest was observed during the growth
stages at 30, 45, and 60 days after planting using the following scales (CIP, 2001):
Scale Description
Reaction
1
Less than 20% of plants per plot Highly resistant
infested
2
21-41% of plants per plot infested
Moderately resistant
3
41-60% of plants per plot infested
Susceptible
4
61-80% of plants per plot infested
Moderately susceptible
5
80-100% of plants per plot infested
Very susceptible
5. Yield Parameters.
a. Marketable Yield (g/pot). During harvest, quality tubers were weighed.
b. Non-marketable Yield (g/pot). Tubers that were cracked, greened, and marble
sizes were separated and weighed at harvest.
c. Total Yield (g/pot). The summation of marketable and non-marketable yield after
harvest was taken.
6.Percentage Dry Matter and Moisture Content (%).This was taken by slicing thinly tubers
into very small cubes taken from different treatments and oven dried 90g of sliced potato
tubers for 48 hours at 100°C. It was taken using the following formula.
Moisture Content= Fresh weight –Oven dry weight/ Fresh Weight x 100
Dry Matter Content (%)= 100%− % Moisture Content
7. Sugar Content (oBrix). This was taken by extracting the juice of 20g of potato tubers and
measured by the use of a refractometer.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
8. Sensory Acceptability of Chips. Sensory test was done by 10 untrained panelists
composed of agronomy major students and faculty members and evaluated the chips using
the following parameters (McDonald’s, 1986).
a. Crispness
Scale
Description
Remarks
1
Very crispy
Very easy to crumble
2
Crispy
Easy to crumble
3
Moderately crispy
Crumbled without difficulty
b. Flavor Acceptability
Scale
Description
Remarks
1
Very perceptible
Very strong flavor
2
Perceptible
Strong flavor
3
Moderately perceptible
Little flavor
4
Slightly perceptible
Very little flavor
5
Not perceptible
No flavor
c. Oiliness
Scale
Remarks
1
Not oily
2
Slightly oily
3
Moderately oily
4
Oily
5
Very oily
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
d. General Acceptability
Scale
Remarks
1
Like very much
2
Like much
3
Like moderately
4
Like slightly
5
Not like/dislike
Data Analysis
All quantitative data were analyzed using Analysis of Variance (ANOVA) for
Completely Randomized Design (CRD). Differences among treatment means were
analyzed using Duncan’s Multiple Range Test (DMRT) at 5% level of significance.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
RESULTS AND DISCUSSIONS
Agro-meteorological Data
The temperature during the growing period range from 14°C to 29°C, relative
humidity of 75% to 82% and light intensity of 1314fc to 1805 fc. The observed temperature
range was above the requirement for potato production which greatly affected the yield.
Mussell and Staples (1979) said that high temperatures are often associated with water
stress. Also, Ferreria (2002) said that in hot dry climates or high temperatures, high
evaporative demand increase crop water requirements which may compound the sensitivity
of the crop to water stress resulting in greater yield reductions.
Driver and Hankes (1943) said that one of the physical component of the environment,
temperature and its two extremes (heat and frost), has the capacity to reduce yields. They
also suggested that excessive respiration due to high temperatures reduce the growth of
tubers because of the decrease in the amount of available carbohydrates to be translocated
to the underground parts. In addition, Borah and Milthorpe (1953) reported that a greater
proportion of assimilates was used in stem, root, and stolon growth at 25°C than at lower
temperature. This signifies that at lower temperature, the concentration of translocated
carbohydrates at the stolon tip level was higher than at high temperature. Further, Mussel
and Staples (1979) stated the interaction between physical (high temperature, excess and
scarce moisture) and chemical (soil pH and nutrient supply) aggravates the biological
factors such as diseases.
The relative humidity provides favorable condition for the growth of blight which
contributed to the low yield. High relative humidity increases late blight incidence because
of the presence of moisture that favors the occurrence of the disease (Tosay,
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Table 1. Monthly temperature, relative humidity, and light intensity from October 2012
to January 2013
TEMPERATURE
RELATIVE
LIGHT
MONTH
(°C)
HUMIDITY
INTENSITY
MIN MAX
(%)
(fc)
October
17
29
80
1314
November
15
27
82
1758
December
14
29
75
1559
January
14
26
82
1805
MEAN
15
28
80
1609
2008). With regards to the high light intensity, Zaag (1992) reported that high light
intensity is favorable for potato production for more efficient production of assimilates.
Percent Survival
There were significant differences among the different water volumes applied on
the percent survival of potato plants (Table 2). The application of 200, 400 and 800ml water
produced the highest percent plant survival but not significantly different with the
application of 600ml. In contrast, plants applied with 1000ml water recorded the lowest
with 71% survival. The low survival observed with the application of 1000 ml was because
of the early infestation of bacterial wilt.
Plant Vigor at 30, 45, and 60 Days after Planting
Results showed that at 30 DAP, all treatments had highly vigorous plants (Table 2).
This is maybe attributed to the genetic characteristics of the variety used because it was in
consonance with what Daagdag and Tandang (2005) said that Igorota was preferred by
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
farmers in Abra because of its uniform robust stems with good vigor. Generally, there was
a noted decline in vigor at 45 to 60 DAP. Also, greater decline was observed in plants
applied with the highest (1000ml) and lowest (200ml) volume of water. This means that
high and low water application affects the yield because excess and little amount of water
are not good in the growth of the plants. Vigor is affected primarily by the inherent
characteristics, secondly is the environment including irrigation or moisture where the crop
is grown (OSU, 1997).
Reaction to Late Blight
At 30 DAP, the data showed no infection in all the treatments, but a considerable
change was noted at 45 to 60 DAP as shown in Table 3. During the later period of the
study, greater variations were observed because the plants applied with 200, 400, and 1000
ml water were already severely infected implying susceptibility to the disease. This
Table 2. Percent survival and plant vigor at 45, and 60 DAP of potato plants applied with
different volumes of water
WATER
PERCENT
PLANT VIGOR
VOLUME
SURVIVAL
%
45 DAP
60 DAP
600ml (control)
86ab
4
3
1000ml
71b
3
4
800ml
95a
3
5
400ml
91a
5
3
200ml
100a
4
5
CV (%)
2.43
Means with the same letters are not significantly different at 5 % level of DMRT
Legend: 1-poor; 2-less vigor; 3-vigorou; 4- moderately vigorous; 5-highly vigorous
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
means that extremes, both high and low volumes favor the severity of the disease.
According to Mussel and Staples (1979), it is due to the interaction between physical (high
temperature, excess and scarce moisture) and chemical (soil pH and nutrient supply)
aggravates the biological factors such as diseases considering that the variety used was
moderately resistant to the disease (Shrestha, 1997). However, the prevailing condition
during the study enhanced the occurrence of the disease that made the plants susceptible.
According to Munns and Pearson (1995), high humidity and cool temperature are the major
favorable conditions for the development of the disease. The agro-meteorological data
showed that the prevailing weather during the conduct of the study favored the occurrence
of the disease.
Table 3. Reaction to late blight at 45, and 60 days after planting of potato plants applied
with different volumes of water
WATER VOLUME
REACTION TO LATE BLIGHT
45 DAP
60 DAP
600ml (control)
2
3
1000ml
3
5
800ml
2
3
400ml
2
3
200ml
3
5
Legend: 1-highly resistant; 2-resistant; 3-4 moderately resistant; 5- susceptible;
6-7 moderately susceptible; 8-9 highly susceptible
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Leafminer Incidence
Leaf miner incidence was taken at 30, 45, and 60 days after planting. During the
entire study, all plants applied with different volumes of water are found to be highly
resistant with less than 20% of the plants per pot infected.
Weight of Marketable, Non-marketable and
Total Yield of Tuber
There were no significant differences on the weight of marketable tubers as shown
in Table 4. Numerically, the data revealed that 600ml (control) of water produced the
heaviest weight of marketable tubers and yielded the lowest weight of non-marketable
tubers. The application of 1000ml of water in potato plants produced the lowest weight of
marketable tubers while the plants applied with 800ml water had the heaviest weight of
non-marketable tubers. Plants applied with 800ml water recorded the heaviest weight of
total yield but also had the heaviest weight of non-marketable tubers. The plants subjected
to1000ml irrigation had the lowest yield which is attributed to the low percent survival rate
taken during the first month. The plants applied with water volumes above 400 ml
excluding 1000ml had a better yield. According to Bawang (1981), limited soil moisture
decreases number of tubers by 18-22%.
Percentage Dry Matter and Moisture Content
There were significant differences among the treatments as shown in Table 5 tubers
irrigated with 1000ml water produced the lowest dry matter content of 18.28% whereas,
600 ml application gave the highest value of 23.07% comparable with plants applied with
200ml (22.86). Thus, 1000ml application is not advisable for processing variety like
Igorota since high dry matter content is required while the control of 600ml water was the
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
best volume to be applied because it was noted to have the highest dry matter content that
suit the potato processing requirement. Stark et al (2003) stated that a value of 20% or
higher is preferred for processing. Thus, the application of 400 and 800ml of water is also
enough. Accordingly, Kellock (1995) said that a genetic characteristic of a crop however,
excess of water during the growth of the plants will result to low dry matter content and
Rastovski (2003) added that dry matter content is affected by genetic characteristics but
maybe influenced by water uptake, photoperiod, and other factors. Further, Feltran (2004)
found the same result that dry matter content is influenced by the conditions in the site.
Sugar Content
The sugar content of the tubers was not significantly different with each
other (Table 5). Mean sugar content ranges from 3.3 to 3.5° Brix. The lowest was obtained
from the potato plants applied with a volume of 1000ml water with a value of 3.3°Brix.
Table 4. Weight of marketable, non-marketable and total yield of potato tubers applied
with different volumes of water
WATER VOLUME
YIELD (g)
MARKETABLE NON-MARKETABLE
TOTAL
600 ml (control)
453
52
505
1000ml
256
67
312
800ml
425
111
536
400ml
368
70
438
200ml
354
50
404
CV (%)
5.67
19.64
27.45
Means with the same letters are not significantly different at 5% level using DMRT
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Table 5. Dry matter and sugar content of potato plants applied with different volumes of
water
WATER VOLUME
DRY MATTER CONTENT
SUGAR CONTENT
(%)
(°Brix)
600 ml (control)
23.07a
3.50
1000ml
18.68c
3.33
800ml
20.86b
3.53
400ml
21.35b
3.40
200ml
22.86a
3.53
CV (%)
9.33
3.42
Means with the same letters are not significantly different at 5% level using DMRT.
Moreover, all the treatments yielded good chips. The application of 1000ml
volume registered the lowest sugar content. Findings of Stark et al (2003) showed that
potatoes with higher values usually show color problems after cooking. Also, Feltran
(2004) said that accessions with low sugar contents higher than 2% are unacceptable for
frying however, there were cases when accessions with as high as 6.690 Brix were used for
frying with no problems on chip quality. In 2007, Peet said that sugar content is a varietal
characteristic that maybe influenced by environmental factors and this statement was
corroborated with the results found by Kumar et al (2004) that sugar content of potatoes is
affected by climatic factors in a location such as temperature during growth, minimal
nutrition, and irrigation. Likewise, Nader and Heuer (1995) said that dry soil conditions in
the later growth stages increases reducing sugar contents of the tubers.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Sensory Acceptability of Chips
Table 6 showed the results of the sensory acceptability of the chips. The potato
chips from the application of 200, 400, and 600 ml had a crispy, slightly oily to not oily,
perceptible, and liked much by the panelists. In contrast, 800 ml and 1000ml water volume
applied to potato produced a moderately crispy, slightly oily to oily, perceptible, and liked
much tubers by the evaluators. However, even 800ml water volume possessed moderately
crispy and slightly oily chips, it could also be regarded as a potential volume for potato
processing because it recorded an acceptable dry matter and low sugar content suitable for
processing yielding. Further, 1000ml or excess irrigation is not advisable for potato
processing production because it yielded chips that are not suitable for potato processing
primarily because of its low dry matter content producing undesirable chip
Table 6. Sensory evaluation of the potato tubers applied with different volumes of water
for chipping quality
WATER
SENSORY CHARACTERISTICS
VOLUME
FLAVOR
GENERAL
CRISPNESS OILINESS ACCEPTABILITY ACCEPTABILITY
600ml
Crispy
Not oily
Perceptible
Liked much
(control)
1000ml
Moderately
Oily
Moderately
Liked slightly
Crispy
Perceptible
800ml
Moderately
Slightly
Perceptible
Liked much
Crispy
oily
400ml
Crispy
Slightly
Perceptible
Liked much
oily
200ml
Crispy
Not oily
Perceptible
Liked much
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
characteristics. Feltran in 2004, said that crispness, oiliness, and texture are influenced by
dry matter content. In addition, NIVAP (2007) found that varieties with high dry matter
absorb less oil during chipping process.
600ml
1000ml
800ml
400ml
200ml
Figure 2. Chips of potato tubers applied with different volumes of water
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
600ml (control)
1000ml
800ml
400ml
200ml
Figure 3. Overview of the chopped potato tubers before oven drying for dry matter
determination
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
SUMMARY, CONCLUSION, AND RECOMMENDATION
Summary
Yield and chip quality of potato var Igorota applied with different volumes of water
was conducted at Balili, La Trinidad, Benguet under a nethouse condition from October
2012 to January 2013. The objectives of the study were to determine the growth and yield
of potato applied with different volumes of water, determine the chip quality of potato
applied with different volume of water, and to identify the best water volume for maximum
yield and chip quality of potato var Igorota.
Generally, no significant differences were observed in all the data gathered except
for percent survival and dry matter content. The application of 200, 400 and 800ml
significantly produced high percent survival comparable to the control of 600ml. In the
contrary, lowest was obtained from tubers applied with 1000ml water. The heaviest
marketable yield was obtained from the application of 600ml (control) while the heaviest
total yield was obtained from the application of 800ml water.
The lowest value of sugar and dry matter content was obtained from the potato
plants applied with a volume of 1000ml water. Whereas, 600 ml application gave the
highest dry matter content.
The application of 200, 400, and 600 ml had a crispy, slightly oily to not oily,
perceptible, and liked much by the panelists.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Conclusion
Based on the findings, irrigation of 600 (farmer’s practice) and 800 ml water
are the best to potato plants in terms of yield and chip qualities based on survival, dry
matter content, crispy, slightly to moderately oily, perceptible and liked much chips.
Recommendation
Based on the results of the study, it is recommended that the application of farmer’s
practice of 600 ml and 800 ml volumes of water for irrigation are the best volumes.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
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Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
MAPANAO, JULIET D. APRIL 2013. Yield and Chip Quality of potato var
Igorota Applied with different Volumes of Water under La Trinidad, Benguet Condition.
Benguet State University, La Trinidad, Benguet.
Adviser: Janet P. Pablo, MSc.
ABSTRACT
The study aimed to determine the growth and yield of potato applied with different
volumes of water, to determine the chip quality of potato applied with different volumes
of water, and to determine the best water volume for maximum yield and chip quality of
potato var Igorota.
Generally, no significant differences were observed in all the data gathered except
for percent survival and dry matter content. The application of 200, 400 and 800ml
significantly produced high percent survival comparable to the control of 600ml. The
heaviest marketable yield was obtained from the application of 600ml (control) while the
heaviest total yield was obtained from the application of 800ml water.
The lowest sugar and dry matter contents were obtained from the potato plants
applied with 1000ml water. Whereas, 600 ml application gave the highest dry matter
content.
The application of 200, 400, and 600 ml resulted in a crispy, slightly oily to not
oily, perceptible, and liked much potato chips by the panelists.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
INTRODUCTION
Potato (Solanum tuberosum L.) is one of mankind’s valuable foods and is produced
in 130 countries where three-fourths of the world’s populations live. In addition, the best
quality and largest yields are produced under cool climate and high altitude with elevations
higher than 2000 meters such as Benguet and Mountain Province (HARRDEC,
1996).Thus, Benguet and Mountain Province are producing 74% of the Philippine potato
production while the remaining percentage is produced from Mindanao.
Consumption of potato and potato by-products is growing rapidly in the
Philippines. This scenario alone projects the increase in the demand of processing varieties
considering the rising number of fast food chains and snack house like Jollibee and
McDonalds coupled with the increasing population.
However, most of the potatoes grown like granola variety are not suitable for
processing due to their inherent excessive moisture and sugar content. To address this
problem, the Philippine government imported 61,699 metric tons of a wide range of
processed potato products (PCARRD, 2008). The importation cannot compensate all the
demands and needs of the country and it is just a short-term solution to the problem leading
to the evaluations of different potato cultivars by researchers of the different agencies and
institutions. These evaluations led to selection of several processing varieties and Igorota
variety is one. The Igorota variety is one of the varieties developed at Benguet State
University possessing a high dry matter content of 18-21% suitable for processing.
On the other hand, with the arising problem in climate change, FAO (2002) reported
that agriculture is one of the most vulnerable sectors. Thus, food production and security
will be most affected. It is stated that most agricultural regions experience periods of
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
deficient moisture. It is reported that the prolonged drought of five to six months is common
in the northern highlands of the Philippines like Benguet and Mountain Province. In these
areas, potato as one of the major crops planted with a total 10, 960 hectares cultivated with
potato annually (DA-CAR, 2005). Further, Jose (2008) stated that Benguet alone is
planting 10,240 hectares planted yearly with crop often suffers from lack of irrigation
during dry season.
To alleviate this problem, researchers have been working on the development of
high yielding varieties with resistance to abiotic stresses such as drought or the
development of drought tolerant genotypes.
Increased production of processing varieties is greatly needed due to the rising demand of
the processing companies and the ever-increasing population. In fact, fast food chains
particularly McDonalds and Jollibee, serving French fries in Baguio and La Trinidad alone
need at least 2,000 to 6,000 kilos a week of potato suitable for French fries (Palangchao,
2009).
This demand however, cannot be attained because of some abiotic factors particularly
drought or scarce water supply during summer in the rain-fed areas that contribute to low
production. In addition to this, the poor and scarce water is a problem of vegetable farmers
in the region, particularly Benguet. The scarcity of water in Benguet during the dry season
results to less extensive production of food crops. On the other hand, with climate change,
continuous rainfall is also being experienced in the growing area that causes flooding or
above the saturation of the soil affects the growth and development of the potato. It is
therefore necessary to determine the water use efficiency of potato for processing. Thus,
the study evaluated the chip quality of Igorota applied with different volumes of water.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
The objectives of the study were to:
1. determine the growth and yield of potato applied with different volumes of water;
2. determine the chip quality of potato applied with different volumes of water; and
3. identify the best water volume for maximum yield and chip quality of potato var Igorota.
The study was conducted from October 2012 to February 2013 at the Benguet State
University Experimental Farm Station under a nethouse in Balili, La Trinidad, Benguet.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
REVIEW OF LITERATURE
Demand of Processed Potato Product
In the Philippines, the demands for potatoes continue to increase because of the growing
population, rise in the number of fast food chains and restaurants (Yano, 2009). Palangchao
(2009) reported that McDonalds and Jollibee, serving French fries in Baguio and La
Trinidad alone need at least 2,000 to 6,000 kilos a week of potato suitable for French fries.
The demand of convenient foods such as chips and fries, to be particular, has led to the
expansion of the potato industry (Garcia, 2006).
Distribution and Area of Production
Benguet and Mountain Province have a total of 10, 960 hectares planted with potato
annually ( DA-CAR, 2005), and Benguet alone is planting 10,240 hectares planted yearly
which often suffer from lack of irrigation during dry season (Jose, 2008).
Potato Processing Quality
Chipping quality is genetically transmissible character. Potatoes that produced light-
colored chips after cold storage and reconditioning were shown to transmit the ability to
produce light- colored chips to their products (Oltmans and Novy, 2002).
For more processed products, a starch content of 13% or higher, a solid or dry
matter content of 20% or higher, and specific gravity of 1.080 or higher is preferred (Stark
et al., 2003).
Color is the most important factor in the evaluation of tubers for chipping. Hence,
the yellow ones are the most preferred, whereas any other skin color may follow as long as
it will pass the certain requirements of the processors (Sabiano, 2006). Similarly, Rastovski
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
(2003) added that yellow fresh color tubers are accepted not only for processing but also
for table purposes. According to him, for more beta-carotene colored ones are preferred.
In addition to this, potatoes with low reducing sugar content give an acceptable golden
yellow chips which are acceptable for chipping industry.
Tuber size, shape, appearance, absence of disease or defects, flavor and texture all
contribute to potato quality. Quality may be related to visual appeal, culinary preference of
the consumer, or ability to match market specifications. Two of the most important quality
characteristics of potatoes on the other hand, are starch content, which impacts cooked
product texture, and sugar content, which has a direct bearing on fried product color (Stark
et al., 2003).
Potato tuber characteristics such as shallow eyes, round or elongated tuber shape,
smooth skin and freedom from defects are important characteristics because it requires
lesser trimmings, provide preferred sizes, high chip yield, absence of discoloration or
browning during frying and good quality. A study conducted, found out that shallow eye
is one of the characters preferred by processors because there is less trimmings. Potatoes
free from defects and disease are also considered whereas the round tubers are preferred
for chips and the oval to elongated shape is otherwise preferred for French fries production
(HARRDEC, 1996).
Specific Gravity and Dry Matter Content
Tuber specific gravity is the measure for estimating starch content and
characterizing the processing potential of tubers. Low specific gravity potatoes, typically
of red varieties for example, tend to be best for boiling and canning. Because specific
gravity is related to maturity, tubers that have a longer time to accumulate car4bohydrates
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
will generally have higher specific gravity than those with shorter growing periods.
Therefore, early planting can increase the number of days that can potentially contribute to
tuber starch deposition (Stark et al, 2003).
Numerous workers have shown that potato quality is directly associated with dry matter
content. Specific gravity has been used as criterion of potato quality because of its close
relationship to dry matter content and the rapidity with which it may be determined. High
specific gravity potatoes are better suited for baking, frying, mashing, and chipping while,
low specific gravity for boiling and canning. The potato chip manufacturers prefer potatoes
of high specific gravity because they yield more chips per pound of potatoes. This outlet
of potatoes is important in the potato industry at Hastings because over two million bushels
of the annual crop are sold for chips (Mhyre, 1959).
High specific gravity is particularly important in the production of potato varieties for chips
because of greater surface area to volume ratio and potatoes with high specific gravity are
also preferred because they have been shown to absorb less oil during chipping process
(Scanlon, 2006).
Water loss through transpiration is an inevitable cost of dry matter production, and
there is about 200 to 800 g of water needed to produce a gram of dry matter for a range of
climates. On the average, crop plants use 500 to 700 pounds of water to produce a single
pound of dry matter. Thus, the required dry matter for the production of French fries should
be containing 20 to 24 %. Higher or lower content of dry matter may give a negative result
on the quality. A more mature potato usually has higher specific gravity or higher solid
content and can be harvested with less skinning and bruising injuries (Smith, 1977).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Sugar and Starch Content
In the Processing Industry, accepted values for the reducing sugars are 0.2 % for
chips and 0.5 % for French fries (Alingbas, 2007).
High starch content is favored by processors to ensure products have acceptable texture
and to keep processing costs down by limiting the amount of raw product needed, the
cooking time required and the amount of oil absorbed. Tuber sugar content on the other
hand, has an important effect on the quality of processed products because of its large
influence on fried potato color. When exposed to high levels of heat, which is typical of
frying process, sugars combine with amino acids and other compounds to form dark color
and flavor we associate with ‘burned’ food. This process is known as “Maillard Reaction”.
The reducing sugars glucose and fructose create the most serious problems during frying
because they are chemically reactive. Sucrose however, contributes too little dark color
development but is the substrate for creating more reducing sugars under the right
environmental and physiological conditions. Potatoes intended for chip production should
have a reducing sugar level below 0.35 mg/g or 0.035% of fresh tuber weight. Potatoes for
processing as French fries therefore, should have less than 1.2 mg/g or 0.12% of tuber fresh
weight. Potatoes with higher values will usually show color problems after cooking (Stark
et al., 2003).
Sugar content of potatoes is affected by climatic factors in a location, such as
temperature during growth, minimal nutrition, and irrigation. It is determined by genotype
and several pre and postharvest factors and as tubers begin to grow, they are low in starch
and high in sugars. Near the end of vine growth, the tubers reach the point known as
physiological maturity- when they achieve maximum dry matter content and minimum
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
sugar content. Moreover, potatoes destined for making chips, French fries and other fried
products, need to have low sugar content to avoid browning of the finished product (Kumar
et al., 2004).
It is found that very low sugar content is apparently important to prevent darkening
of chips. Sugar content should be below 2%. Potatoes of low sugar content result in a lighter
color chips desired by consumers (Smith, 1977).
Tuber Shape
Tuber shape is more uniform between 60o and 70o F than at temperatures above or
below this. Tubers grown at 50o to 55o F are more spherical compared with the oblong
shape of the Russett Burbank and White Rose varieties. Russett Burbank tubers are
extremely knobby and the White Rose is spindle –shaped when grown at 80 to 85o F. There
are also multiple developments on a single stolon. This is often observed in the field with
low moisture and high soil temperatures prevailing (Smith, 1977).
Cultivar/Variety
A three-year variety trial of more than 20 varieties conducted, showed that Donald,
Remarka and Signal are the only varieties which produced high yields with a dry matter
content of 21 to 23% when grown in Buguias under deficient irrigation (Jose, 2008).
Using the right variety ensures high yield and better quality of produce. In planting, the
first decision is to know the best variety that is adapted to the locality to have a profitable
production (HARRDEC, 1996).A processing variety must have high dry matter and low
sugar content. Such varieties often have higher chip yield, crispy and slightly oily crops
(Alingbas, 2007).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Irrigation
Potato needs frequent irrigation for its good growth and yield. The yield is greatly
influenced by timing, amount and frequency of irrigation applied. Soil moisture is probably
the most important factor determining potato yield and quality. Irrigation increases potato
tuber quantity. It is very sensitive against water stress in all growing seasons, in particular
at the duration of tuber formation. There is a decrease in tuber yield, tuber quality, income,
and marketing degree in the conditions of deficit irrigation. Even the decrease for the level
of 10% in the optimum water treatment in the growing period could have caused a decrease
in yield. It was reported that potato was more sensitive to water stress at the stolonization
and tuberization stages than the bulking and tuber enlargement stages. In the tuber
enlargement stage, water deficit could be applied with a slight decrease in yield (Kiziloghu
et al., 2006).
Early studies have shown that water is the most important limiting factor for potato
production and it is possible to increase production levels by well- scheduled irrigation
programs throughout the growing season (Bojujelben et al., 2001).
Excessive and deficit soil water availability during the growing season normally
has a substantial adverse effect on crop yield and quality. In irrigated agriculture, proper
water application depth and timing relative to crop growth is paramount for optimum
economic return and maximum water use efficiency (Erdem et al., 2006).
Since no irrigation system is perfectly uniform, application uniformity should be
quantified in order to measure irrigation system efficiency, because an irrigation must
continue long enough to adequately water plants receiving the least water. The scale of the
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
uniformity measurement should be related to the soil volume water occupied by potato
roots (Pereira and Shock, 2006).
It was reported that irrigation of potatoes reduced specific gravity of potatoes. In contrast
to this, another study found out that it was increased with soil moisture where the specific
gravity of irrigated tubers were from 0.0002 to 0.004 lower than those not irrigated. It is
due because maturity is promoted and specific gravity is higher when potatoes have been
grown in low to medium soil moisture than at high soil moisture (Smith, 1977).
Tuber market grade and stem-end fry color is improved by moderate stress before tuber
initiation (Pereira and Shock, 2006).
Potatoes have a shallow root system that requires more frequent irrigation when compared
to other crops. Extreme variations in irrigation management and nitrogen availability
influence tuber yield, size, grade, external quality, and internal quality (Pereira and Shock,
2006).
Irrigation should be continued to as close to harvest as possible to obtain maximum yields.
When the last irrigation was 7, 14, and 21 days before harvest, yields where progressively
reduced, as much as 205 reductions followed when irrigation was stopped 21 days before
harvest. Moreover, by irrigation twice a week with the water level maintained at land 5
inches in the furrow, infiltration rate for the 5-inch depth was 40% more than the 1-nch
depth, but yield was decrease 17% by irrigating only once a week, the infiltration rate was
doubled with no effect on yields. Moreover, timing of irrigation may be altered at various
stages of growth. Excessively frequent irrigations are more harmful from time of first
bloom than later in the season. Plants are better able to withstand high moisture tension
levels when evaporative conditions are less severe (Smith, 1977).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Potato is one of the most important crops in the world. Due to its sparse and shallow
root system, potato is very sensitive to water stress and tuber yield maybe considerably
reduced by soil water deficits Therefore, irrigation is always needed for production of high
yielding crops. But with the increasing shortage of water resources, optimization of
irrigation management therefore is required in order to improve water use efficiency (Liu
et al., 2005).
Because of the sensitivity of potato to water stress, most researched has been
focused on avoiding deficiencies in soil water. Tuber yield responses to irrigation decrease
with over-irrigation (Pereira and Shock, 2006).
Deficit irrigation is a strategy which allows a crop to sustain some degree of water
deficit in order to reduce irrigation costs and potentially increase revenues (Shock and
Feibert, 2003).
During drought stress cycles, water savings under carbon dioxide allowed
photosynthesis to continue for one to two days compared to ambient carbon dioxide
treatment (Baker and Aller, 2005).
Water stress during early tuber bulking reduces specific gravity and increases
reducing sugars associated with dark stem-end fry color (Shock and Feibert, 2003).
Water stress imposed from tuber initiation until the end of tuber bulking was the
most detrimental to biomass and tuber production. Water stress imposed from tuber
initiation until the end of tuber bulking storage and between emergence and tuber initiation
stage produces the lowest yield (Steyn et al., 2003).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Water stress which occurs before tuber bulking, followed by resumption of
irrigation may favor to occurrence of second growth since top growth is stimulated
vigorously after a period of drought and high temperature (Van Loon, 1981).
Potato should be irrigated as even as possible, particularly at four to nine weeks after
emergence when the tubers are forming to avoid tuber skin cracking and malformation
(Ferreria and Carr, 2002).
Water Use Efficiency in Potato
Potato is one of the most important crops in the world. The increasing worldwide
shortage of water resources then, requires optimization of irrigation management in order
to improve water use efficiency (WUE).The term water use- efficiency describes a plant’s
photosynthetic production rate relative to the rate at which it transpires water to the
atmosphere. It is a measure of plant performance that has long been of interest to
agronomists, foresters, and ecologists. Among the irrigation regimens, the highest water
use efficiency was generally obtained from application of irrigation when 30% of the
available water was consumed. In addition to this, a study conducted to assess water use
efficiency rate from different irrigation methods found out that drip irrigation method
yielded higher values of WUE than furrow irrigation, since drip irrigation consumed less
water (Erdem et al., 2006).
Water Resources
Seemingly abundant, water in the country is now becoming a scarce resource. A
study on water resource accounting done in 1988 to 1994 by the environmental and Natural
Resource Accounting-Integration Environment Management for Sustainable Development
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Program (ENRA-IESMDP) showed that the stock of surface water has been decreasing t
an average rate of 37%, while stock of groundwater has been decreasing at an average of
1.4 %. The diminishing stock can be attributed to the lower recharge rates compared to the
rates of abstraction for both types of water resources. In 2001, NIA’s irrigation systems
(national and communal irrigation systems) as well as private irrigation systems, served
only 44% of the potential, irrigable area, signaling an apparent water shortage especially
during the dry season (PCARRD-DOST, 2003).
Political constraints, rising costs, and groundwater scarcities are resulting in less
water available for agriculture. In some areas, groundwater supplies are being exhausted.
Competition for world supplies is a worldwide phenomenon (Shock and Feibert, 2003).
Importance of Elevation to Potato Production
Potatoes are grown in higher elevations than other crops. In the tropics, the typical
mountainous areas that produce potatoes is cold, best temperature fluctuated sharply from
day to night and the average relative humidity is high. Soils are well-drained that there is
great variation in altitude, slopes, soil fertility and other environmental variables that
influence yields. Production hazards like frost cause low yields in highland areas, where
the chances of crop failures are great, farmers often economize to purchase inputs in order
to minimize their financial risks (Alingbas, 2007).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
MATERIALS AND METHODS
Potato tubers of the Igorota variety from the Northern Philippines Rootcrop Research and
Training Center, Benguet State University (NPRCRTC-BSU) were used as planting
materials. One tuber was planted in a pot measuring 12 inches diameter. This was
replicated three times and laid out using Completely Randomized Design (CRD). All
cultural management practices were strictly employed like weeding to avoid competition
of both water and nutrients. The different volumes of water which served as treatment, was
strictly implemented three days after planting and applied based on the treatment as
follows:
Code
Treatment
W1 (control) 600 ml of water applied twice a week (Farmer’s Practice)
W2
1000 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W3
800 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W4
400 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
W5
200 ml of water applied twice a week starting from 3 days after planting until 2
weeks before harvest
Chipping quality was evaluated by treatment after harvesting.
Chipping of potato. The tubers were washed, peeled, and sliced into 1-1.5 mm. The sliced
tubers were again washed with tap water to remove the starch adhering to the slices. The
slices were then wiped with clean cloth to remove excess moisture and fried in hot oil until
bubbles are few (NPRCRTC, 1998).
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
a.) Washing
b.) Peeling
d.) Washing of chipped potato
c.) Chipping/ slicing
e.) Pat drying
F.) Frying
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Figure 1. Chipping of potato tubers applied with different volumes of water
Data Gathered
1. Meteorological data. Temperature and relative humidity were taken using a digital
hygrometer. Light intensity was recorded using a digital light meter.
2. Percent survival. Percent survival was taken at 30 DAP by counting the number of plants
that survived and computed using the formula:
Percent Survival= No. of plants planted/ No. of plants that survived x 100
3. Plant vigor. This was taken at 30, 45, and 60 DAP using the following rating scale
(Palomar and Sanico, 1994):
Scale Description
Remarks
5
Plants are strong with robust stems Highly vigorous
and leaves; light to dark green in color
4
Plants are moderately strong with Moderately vigorous
robust stem and leaves; light green in
color
3
Plants are better than less vigorous
Vigorous
2
Plants are weak with few thin stem Less vigorous
and leaves; pale
1
Plants are weak with few thin and Poor vigor
leaves; pale
4. Pest and disease incidence. The crop was rated during the different growth stages using
the following rating scales:
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
a. Late blight incidence. Late blight was rated using the following CIP rating scales
(Henfling, 1981):
CIP
Blight %
Symptoms
Scale
Mean Limit
value
1
0
No late blight observable.
2
2.5
Traces-5 Late blight present. Maximum of 19 lesions per
plant.
3
10
5-15
Plants look healthy, but lesions are easily seen at
closer distance. Maximum foliage are affected by
lesions or destroyed corresponds to no more than
20 leaflets.
4
25
15-35
Late blight easily seen on most plants about 25%
foliage is covered with lesions or destroyed.
5
50
35-65
Plot looks green; however, all plants are affected.
Lower leaves are dead. About half the foliage area
is destroyed.
6
75
65-85
Plot looks green with brown flecks. About 75% of
each plant is affected. Leaves of the lower half of
plants are destroyed.
7
90
85-95
Plot neither predominantly green nor brown. Only
top leaves are green. Many stems have large
lesions.
8
97.5
95-100
Plot is brown- colored. A few top leaves still have
some green areas. Most stems have or are dead.
9
100
All leaves and stems dead.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
b. Leaf miner incidence. The appearance of insect pest was observed during the growth
stages at 30, 45, and 60 days after planting using the following scales (CIP, 2001):
Scale Description
Reaction
1
Less than 20% of plants per plot Highly resistant
infested
2
21-41% of plants per plot infested
Moderately resistant
3
41-60% of plants per plot infested
Susceptible
4
61-80% of plants per plot infested
Moderately susceptible
5
80-100% of plants per plot infested
Very susceptible
5. Yield Parameters.
a. Marketable Yield (g/pot). During harvest, quality tubers were weighed.
b. Non-marketable Yield (g/pot). Tubers that were cracked, greened, and marble
sizes were separated and weighed at harvest.
c. Total Yield (g/pot). The summation of marketable and non-marketable yield after
harvest was taken.
6.Percentage Dry Matter and Moisture Content (%).This was taken by slicing thinly tubers
into very small cubes taken from different treatments and oven dried 90g of sliced potato
tubers for 48 hours at 100°C. It was taken using the following formula.
Moisture Content= Fresh weight –Oven dry weight/ Fresh Weight x 100
Dry Matter Content (%)= 100%− % Moisture Content
7. Sugar Content (oBrix). This was taken by extracting the juice of 20g of potato tubers and
measured by the use of a refractometer.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
8. Sensory Acceptability of Chips. Sensory test was done by 10 untrained panelists
composed of agronomy major students and faculty members and evaluated the chips using
the following parameters (McDonald’s, 1986).
a. Crispness
Scale
Description
Remarks
1
Very crispy
Very easy to crumble
2
Crispy
Easy to crumble
3
Moderately crispy
Crumbled without difficulty
b. Flavor Acceptability
Scale
Description
Remarks
1
Very perceptible
Very strong flavor
2
Perceptible
Strong flavor
3
Moderately perceptible
Little flavor
4
Slightly perceptible
Very little flavor
5
Not perceptible
No flavor
c. Oiliness
Scale
Remarks
1
Not oily
2
Slightly oily
3
Moderately oily
4
Oily
5
Very oily
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
d. General Acceptability
Scale
Remarks
1
Like very much
2
Like much
3
Like moderately
4
Like slightly
5
Not like/dislike
Data Analysis
All quantitative data were analyzed using Analysis of Variance (ANOVA) for
Completely Randomized Design (CRD). Differences among treatment means were
analyzed using Duncan’s Multiple Range Test (DMRT) at 5% level of significance.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
RESULTS AND DISCUSSIONS
Agro-meteorological Data
The temperature during the growing period range from 14°C to 29°C, relative
humidity of 75% to 82% and light intensity of 1314fc to 1805 fc. The observed temperature
range was above the requirement for potato production which greatly affected the yield.
Mussell and Staples (1979) said that high temperatures are often associated with water
stress. Also, Ferreria (2002) said that in hot dry climates or high temperatures, high
evaporative demand increase crop water requirements which may compound the sensitivity
of the crop to water stress resulting in greater yield reductions.
Driver and Hankes (1943) said that one of the physical component of the environment,
temperature and its two extremes (heat and frost), has the capacity to reduce yields. They
also suggested that excessive respiration due to high temperatures reduce the growth of
tubers because of the decrease in the amount of available carbohydrates to be translocated
to the underground parts. In addition, Borah and Milthorpe (1953) reported that a greater
proportion of assimilates was used in stem, root, and stolon growth at 25°C than at lower
temperature. This signifies that at lower temperature, the concentration of translocated
carbohydrates at the stolon tip level was higher than at high temperature. Further, Mussel
and Staples (1979) stated the interaction between physical (high temperature, excess and
scarce moisture) and chemical (soil pH and nutrient supply) aggravates the biological
factors such as diseases.
The relative humidity provides favorable condition for the growth of blight which
contributed to the low yield. High relative humidity increases late blight incidence because
of the presence of moisture that favors the occurrence of the disease (Tosay,
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Table 1. Monthly temperature, relative humidity, and light intensity from October 2012
to January 2013
TEMPERATURE
RELATIVE
LIGHT
MONTH
(°C)
HUMIDITY
INTENSITY
MIN MAX
(%)
(fc)
October
17
29
80
1314
November
15
27
82
1758
December
14
29
75
1559
January
14
26
82
1805
MEAN
15
28
80
1609
2008). With regards to the high light intensity, Zaag (1992) reported that high light
intensity is favorable for potato production for more efficient production of assimilates.
Percent Survival
There were significant differences among the different water volumes applied on
the percent survival of potato plants (Table 2). The application of 200, 400 and 800ml water
produced the highest percent plant survival but not significantly different with the
application of 600ml. In contrast, plants applied with 1000ml water recorded the lowest
with 71% survival. The low survival observed with the application of 1000 ml was because
of the early infestation of bacterial wilt.
Plant Vigor at 30, 45, and 60 Days after Planting
Results showed that at 30 DAP, all treatments had highly vigorous plants (Table 2).
This is maybe attributed to the genetic characteristics of the variety used because it was in
consonance with what Daagdag and Tandang (2005) said that Igorota was preferred by
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
farmers in Abra because of its uniform robust stems with good vigor. Generally, there was
a noted decline in vigor at 45 to 60 DAP. Also, greater decline was observed in plants
applied with the highest (1000ml) and lowest (200ml) volume of water. This means that
high and low water application affects the yield because excess and little amount of water
are not good in the growth of the plants. Vigor is affected primarily by the inherent
characteristics, secondly is the environment including irrigation or moisture where the crop
is grown (OSU, 1997).
Reaction to Late Blight
At 30 DAP, the data showed no infection in all the treatments, but a considerable
change was noted at 45 to 60 DAP as shown in Table 3. During the later period of the
study, greater variations were observed because the plants applied with 200, 400, and 1000
ml water were already severely infected implying susceptibility to the disease. This
Table 2. Percent survival and plant vigor at 45, and 60 DAP of potato plants applied with
different volumes of water
WATER
PERCENT
PLANT VIGOR
VOLUME
SURVIVAL
%
45 DAP
60 DAP
600ml (control)
86ab
4
3
1000ml
71b
3
4
800ml
95a
3
5
400ml
91a
5
3
200ml
100a
4
5
CV (%)
2.43
Means with the same letters are not significantly different at 5 % level of DMRT
Legend: 1-poor; 2-less vigor; 3-vigorou; 4- moderately vigorous; 5-highly vigorous
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
means that extremes, both high and low volumes favor the severity of the disease.
According to Mussel and Staples (1979), it is due to the interaction between physical (high
temperature, excess and scarce moisture) and chemical (soil pH and nutrient supply)
aggravates the biological factors such as diseases considering that the variety used was
moderately resistant to the disease (Shrestha, 1997). However, the prevailing condition
during the study enhanced the occurrence of the disease that made the plants susceptible.
According to Munns and Pearson (1995), high humidity and cool temperature are the major
favorable conditions for the development of the disease. The agro-meteorological data
showed that the prevailing weather during the conduct of the study favored the occurrence
of the disease.
Table 3. Reaction to late blight at 45, and 60 days after planting of potato plants applied
with different volumes of water
WATER VOLUME
REACTION TO LATE BLIGHT
45 DAP
60 DAP
600ml (control)
2
3
1000ml
3
5
800ml
2
3
400ml
2
3
200ml
3
5
Legend: 1-highly resistant; 2-resistant; 3-4 moderately resistant; 5- susceptible;
6-7 moderately susceptible; 8-9 highly susceptible
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Leafminer Incidence
Leaf miner incidence was taken at 30, 45, and 60 days after planting. During the
entire study, all plants applied with different volumes of water are found to be highly
resistant with less than 20% of the plants per pot infected.
Weight of Marketable, Non-marketable and
Total Yield of Tuber
There were no significant differences on the weight of marketable tubers as shown
in Table 4. Numerically, the data revealed that 600ml (control) of water produced the
heaviest weight of marketable tubers and yielded the lowest weight of non-marketable
tubers. The application of 1000ml of water in potato plants produced the lowest weight of
marketable tubers while the plants applied with 800ml water had the heaviest weight of
non-marketable tubers. Plants applied with 800ml water recorded the heaviest weight of
total yield but also had the heaviest weight of non-marketable tubers. The plants subjected
to1000ml irrigation had the lowest yield which is attributed to the low percent survival rate
taken during the first month. The plants applied with water volumes above 400 ml
excluding 1000ml had a better yield. According to Bawang (1981), limited soil moisture
decreases number of tubers by 18-22%.
Percentage Dry Matter and Moisture Content
There were significant differences among the treatments as shown in Table 5 tubers
irrigated with 1000ml water produced the lowest dry matter content of 18.28% whereas,
600 ml application gave the highest value of 23.07% comparable with plants applied with
200ml (22.86). Thus, 1000ml application is not advisable for processing variety like
Igorota since high dry matter content is required while the control of 600ml water was the
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
best volume to be applied because it was noted to have the highest dry matter content that
suit the potato processing requirement. Stark et al (2003) stated that a value of 20% or
higher is preferred for processing. Thus, the application of 400 and 800ml of water is also
enough. Accordingly, Kellock (1995) said that a genetic characteristic of a crop however,
excess of water during the growth of the plants will result to low dry matter content and
Rastovski (2003) added that dry matter content is affected by genetic characteristics but
maybe influenced by water uptake, photoperiod, and other factors. Further, Feltran (2004)
found the same result that dry matter content is influenced by the conditions in the site.
Sugar Content
The sugar content of the tubers was not significantly different with each
other (Table 5). Mean sugar content ranges from 3.3 to 3.5° Brix. The lowest was obtained
from the potato plants applied with a volume of 1000ml water with a value of 3.3°Brix.
Table 4. Weight of marketable, non-marketable and total yield of potato tubers applied
with different volumes of water
WATER VOLUME
YIELD (g)
MARKETABLE NON-MARKETABLE
TOTAL
600 ml (control)
453
52
505
1000ml
256
67
312
800ml
425
111
536
400ml
368
70
438
200ml
354
50
404
CV (%)
5.67
19.64
27.45
Means with the same letters are not significantly different at 5% level using DMRT
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Table 5. Dry matter and sugar content of potato plants applied with different volumes of
water
WATER VOLUME
DRY MATTER CONTENT
SUGAR CONTENT
(%)
(°Brix)
600 ml (control)
23.07a
3.50
1000ml
18.68c
3.33
800ml
20.86b
3.53
400ml
21.35b
3.40
200ml
22.86a
3.53
CV (%)
9.33
3.42
Means with the same letters are not significantly different at 5% level using DMRT.
Moreover, all the treatments yielded good chips. The application of 1000ml
volume registered the lowest sugar content. Findings of Stark et al (2003) showed that
potatoes with higher values usually show color problems after cooking. Also, Feltran
(2004) said that accessions with low sugar contents higher than 2% are unacceptable for
frying however, there were cases when accessions with as high as 6.690 Brix were used for
frying with no problems on chip quality. In 2007, Peet said that sugar content is a varietal
characteristic that maybe influenced by environmental factors and this statement was
corroborated with the results found by Kumar et al (2004) that sugar content of potatoes is
affected by climatic factors in a location such as temperature during growth, minimal
nutrition, and irrigation. Likewise, Nader and Heuer (1995) said that dry soil conditions in
the later growth stages increases reducing sugar contents of the tubers.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Sensory Acceptability of Chips
Table 6 showed the results of the sensory acceptability of the chips. The potato
chips from the application of 200, 400, and 600 ml had a crispy, slightly oily to not oily,
perceptible, and liked much by the panelists. In contrast, 800 ml and 1000ml water volume
applied to potato produced a moderately crispy, slightly oily to oily, perceptible, and liked
much tubers by the evaluators. However, even 800ml water volume possessed moderately
crispy and slightly oily chips, it could also be regarded as a potential volume for potato
processing because it recorded an acceptable dry matter and low sugar content suitable for
processing yielding. Further, 1000ml or excess irrigation is not advisable for potato
processing production because it yielded chips that are not suitable for potato processing
primarily because of its low dry matter content producing undesirable chip
Table 6. Sensory evaluation of the potato tubers applied with different volumes of water
for chipping quality
WATER
SENSORY CHARACTERISTICS
VOLUME
FLAVOR
GENERAL
CRISPNESS OILINESS ACCEPTABILITY ACCEPTABILITY
600ml
Crispy
Not oily
Perceptible
Liked much
(control)
1000ml
Moderately
Oily
Moderately
Liked slightly
Crispy
Perceptible
800ml
Moderately
Slightly
Perceptible
Liked much
Crispy
oily
400ml
Crispy
Slightly
Perceptible
Liked much
oily
200ml
Crispy
Not oily
Perceptible
Liked much
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
characteristics. Feltran in 2004, said that crispness, oiliness, and texture are influenced by
dry matter content. In addition, NIVAP (2007) found that varieties with high dry matter
absorb less oil during chipping process.
600ml
1000ml
800ml
400ml
200ml
Figure 2. Chips of potato tubers applied with different volumes of water
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
600ml (control)
1000ml
800ml
400ml
200ml
Figure 3. Overview of the chopped potato tubers before oven drying for dry matter
determination
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
SUMMARY, CONCLUSION, AND RECOMMENDATION
Summary
Yield and chip quality of potato var Igorota applied with different volumes of water
was conducted at Balili, La Trinidad, Benguet under a nethouse condition from October
2012 to January 2013. The objectives of the study were to determine the growth and yield
of potato applied with different volumes of water, determine the chip quality of potato
applied with different volume of water, and to identify the best water volume for maximum
yield and chip quality of potato var Igorota.
Generally, no significant differences were observed in all the data gathered except
for percent survival and dry matter content. The application of 200, 400 and 800ml
significantly produced high percent survival comparable to the control of 600ml. In the
contrary, lowest was obtained from tubers applied with 1000ml water. The heaviest
marketable yield was obtained from the application of 600ml (control) while the heaviest
total yield was obtained from the application of 800ml water.
The lowest value of sugar and dry matter content was obtained from the potato
plants applied with a volume of 1000ml water. Whereas, 600 ml application gave the
highest dry matter content.
The application of 200, 400, and 600 ml had a crispy, slightly oily to not oily,
perceptible, and liked much by the panelists.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
Conclusion
Based on the findings, irrigation of 600 (farmer’s practice) and 800 ml water
are the best to potato plants in terms of yield and chip qualities based on survival, dry
matter content, crispy, slightly to moderately oily, perceptible and liked much chips.
Recommendation
Based on the results of the study, it is recommended that the application of farmer’s
practice of 600 ml and 800 ml volumes of water for irrigation are the best volumes.
Yield and Chip Quality of potato var Igorota Applied with different Volumes of Water under
La Trinidad, Benguet Condition. | MAPANAO, JULIET D. APRIL 2013
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