BIBLIOGRAPHY

CADAP, EMILIO JR., M. APRIL. 2013. Agronomic and Postharvest Characters
of Pink and Violet-skinned Potato Entries for Organic Production in La Trinidad, Benguet.
Benguet State University, La Trinidad, Benguet.

Adviser: Belinda A. Tad-awan, PhD.


ABSTRACT

The study was conducted at the experimental area of Benguet State University,
Balili, La Trinidad, Benguet from January to May 2011 to: evaluate the potato entries for
organic production; determine the best performing potato entries in terms of yield,
resistance to pest and diseases; and determine the profitability of growing the organic
potato entries for organic production.

Among the potato entries under organic production, Gukungu, 676008 and Tubira
had the highest percentage of survival. All entries were observed to be highly vigorous at
30 to 60 DAP. Gukungu had the tallest plants. Canopy cover was comparable among the
potato entries at 45 and 75 DAP. At 30 to 75 DAP Gukungu had the widest canopy. In
terms of leaf miner incidence, all entries were highly resistant at 30 to 45 DAP. There was
no late blight occurrence observed.

Gukungu produced the highest number and heaviest weight of marketable tubers.
Gukungu, 676008 and Tubira were noted to have pink skin while Santa Ana had violet
tubers. Entry 676008 and Montañosa had smooth skin type while the other entries were
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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rough. In terms of flesh color, Gukungu and 676008 had yellow-cream while the other
entries had white. In terms on return cash expense, all entries obtained positive ROCE.





















Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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INTRODUCTION



The potato (Solanum tuberusum L.) plays an important role in our economy since
it is one of the profitable crops grown in Benguet and Mountain Province. It remains to be
a high value crop because of its local and export potential and growing market demand
(Aguirre, 2005). Potato as good contains high nutrition value, good source of
carbohydrates, proteins, minerals, vitamins and calcium (Smith, 1997). At present, the
demand of potato continues to increase. Rapid urbanization and the emerging importance
of potato processing will generate additional demand. This is to maintain and increase
number of fast food chain and the snack industry that requires high supply of potato. The
increase demand for potatoes has also included the clamor for pesticide-free produce. It is
a common observation that in Benguet and Mountain Province, potato production is done
through the conventional way.
At present organic production is recommended as an alternative to chemical-based potato
production. Organic production is the traditional practice utilizing diverse farming system
which avoided the use of synthetic chemical inputs such as fertilizers, pesticides, herbicides
growth stimulant and others. Organic farming depends on crop rotation, green manuring
and others. Pest control is done by applying non-chemical method such as biological
controls, mechanical cultivation, mulches, and other forms of natural control (Kuepper,
2002).
Potato is one of the banner crops of Benguet, thus, practices that can boost production
should be encouraged. Organic potato production is now being promoted to farmers in the
locality in order to have a sustained production. One of the practices to have sustainable
production is the use of varieties that can adapt to organic farming. Varieties for organic
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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production should be resistant to pest and diseases and acceptable to consumers. One of
the inherent characteristics of potato varieties that may contribute to the acceptability to
consumers is the color of the skin. Organic practitioners claim that pink, red and violet-
colored potatoes are promising under organic production and demand higher price than
yellow or white-skinned potato varieties.
The study was conducted to:
1. evaluate the growth, yield and postharvest characters of pink and violet skin potato
entries for organic production;
2. identify the best performing potato entries based on yield and resistance to pest and
diseases; and
3. determine the profitability of growing the potato entries under organic production.

The study was conducted at the Balili experimental area of the Benguet State
University, Balili, La Trinidad, Benguet from February 2011 to June 2011.











Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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REVIEW OF LITERATURE


Organic Farming Defined

Organic farming is a form of agriculture inputs, especially not using of synthetic fertilizer
and pesticides. It emphasizes the use of management practices in preference to the use of
off-farm inputs. This is accomplished by using, where possible agronomic, biological and
chemical methods. As opposed to using synthetics materials, to fulfill any specific function
within the system (PCARRD, 2006). Organic farming is related to the principle beyond
cultural practices such as fair trade and environmental stewardship (IFOAM, 2005).

Benefits of Organic Farming

The benefits of organic farming are mostly health related since produce has little or no
pesticide residue. Some practitioners of organic farming believe that organic food is more
nutrients that food produces by conventional farming (Hynes, 2006).

Organic farming maintains, improves soil organic matter and reduces the
occurrence of pest and diseases. It can also control of weeds combined with soil cultivation.
Organic agriculture also contributes to food security by increasing yields in low input areas,
concerning biodiversity and nature resources on the farm in the surrounding (IFOAM,
2005). Organic farming promotes crop diversity through crop rotation, mixed cropping,
multiple cropping, and relay inter cropping. The benefits of diversity include, reduce pest
incidence, improves weed control, reduce soil erosion and the recycling of nutrient reserves
from depth of the soil, and transfer of nitrogen fixing species and increase yield (Lem-ew,
2007).
Varietal Evaluation under Organic Production
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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The best variety to plant suited in organic production is a major decision to make. For
maximum production, the best variety that is adapted to the locality should be planted
(Singh, 1999). Organic farmer’s needs varieties that are adopted selection of variety;
farmer must also consider the maturity, market demand and consumer requirement to attain
the best production needed. Choosing the right varieties it is very important for marketing,
storage and pest management reason. Variety should produce good yield with moderate
resistant to common scab.
In a potato trial conducted under organic production in La Trinidad, CIP 96-06, PHIL.
5.19.2.2 and CIP 676089 produced the highest total yield. CIP 13.1.1, CIP 67608, PHIL.
5.19.1.1 and CIP 96-06 had moderate resistance to leaf miner at 60 DAP and highly
resistant to late blight. CIP 676089 obtained the highest return on cash expense (Ambales,
2009).
Montes (2006) in his study at Puguis, La Trinidad, Benguet found out that potato genotype
CIP 676080 was the best entry under organic production system as evidenced by its highly
vigorous and tall plants, high yield, high dry matter content of tubers and resistance to late
blight.
Imarga (2009) found that CIP 380241.17, MLUSA 5, MLUSA 8 and Igorota were adapted
under organic production at Beckel, La Trinidad, Benguet. Igorota and MLUSA 3 were
highly resistant to late blight. MLUSA 5 produced the heaviest weight of marketable
tubers.
Laweng (2006) in her study in La Trinidad found that potato entry CIP 13.1.1 had the
highest canopy cover and the most resistant to late blight. Catani produced the highest
marketable yield but was the susceptible to late blight.
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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MATERIALS AND METHODS


Land Preparation and Application of Organic Fertilizer

An area of 120 m2 was thoroughly prepared before planting and divided into four blocks,
which corresponds to four replications. Each block was further subdivided into five plots
measuring 1 m x 5 m. Compost was equally applied at 5kg per 5 m2 one week before
planting. The experiment was laid-out following the randomized complete block design
(RCBD) with four replications.

Planting and Cultural Management Practices
Sprouted potato tubers were planted in a double-row plot at a distance of 30 cm x 30 cm
between hills and between rows. Cultural management practices such as irrigation,
weeding, pest control and hilling-up were uniformly employed in all the treatments
through-out the growing duration. All management practices were done the organic way,
that is, non-application of synthetic fertilizers and pesticides, 10% diversity and application
of compost.

The treatments were the following:
Treatment
Name/ Skin Color
E1
Gukungu (Pink)
E2
Santa Ana ( Violet)
E3
676008 (Pink)
E4
Tubira (Pink)
E5
Montañosa (Yellow)


Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Data Analysis
All quantitative data was analyzed using analysis of variance (ANOVA) for RCBD. The
significance of difference among treatment means was tested using the Duncan’s Multiple
Range Test (DMRT) at 5% level of significance.
Data Gathered

A. Agro-climatic data. The temperature, relative humidity, rainfall were recorded
during the conduct of the study.

B. Soil chemical properties. Soil samples were taken from the experimental area
before and after harvest. The organic matter, nitrogen, phosphorous, and potassium content
of the soil and pH were analyzed at the Department of Agriculture, Soils Laboratory,
Pacdal, Baguio City.

C. Growth Parameters

1. Plant survival (%). The number of plants that survived were counted at 30, 45,
60 and 75 days after planting (DAP) and calculated using the formula:
No. of Plants that Survived

% Plant Survival =
x 100
Total Number of Plants Planted


2. Plant height. Height was taken at 30, 45, 60 and 75 DAP using a meter stick.
3. Canopy cover. Canopy cover was gathered at 30, 45, 60 and 75 DAP using a wooden
frame measuring 120 cm x 60 cm having grids of equal size of 12 cm x 6 cm.

4. Plant vigor. Plant vigor was rated at 30, 45, 60 and 75 days DAP based on a
rating by CIP (Gonzales et al., 2004).


Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Scale Description
Reaction
5
Plants are strong with robust stem and High vigorous
leaves, light color to dark green color.
4
Plants are moderately strong with robust Moderately vigorous
stem and leaves were light green in color.
3
Better than less vigorous
Vigorous
2
Plants are weak with few thin stems and Less vigorous
leaves, pale.
D. Reaction to Pest and Diseases
1. Reaction to late blight. Ratings were done at 30,45, 60 and 75 DAP using the CIP
rating scale as follows (Henfling, 1987).

Blight
Scale Description
0
1
No blight
0.1-1
2
Very few plants in larger treatment with lesions not more than 2
lesion 10m or row (+/-30 plants)
3.1-10
3
Up to 30 small lesions per plant or up to 1 inch leaflets attacked.
10.1-24
4
Most plants are visibly attacked and 1 m 3 leaflets infected.
Multiple infections per leaflets.
5-49
5
Nearly every leaflet with lesion. Multiple infections per leaflets
are common. Field of plot look green, but all plants are pots are
blighted.


Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Blight
Scale Description
50-74
6
Every plant blighted and half the leaf is destroyed by blight fields
look green, flecked, and brown, blight is very obvious.
75-90
7
As previous but ¾ of each plant blighted. Lower branches may be
overwhelming killed off, and the only green leaves, if any, are
spindly due to extensive
91-97
8
Some leaves and most steam are green, filed looks brown with
some leaves patches.
97.1-99.9 9
Few green leaves almost all with blight lesion remain. Many
stems lesions field look brown.
100
10
All leaves and stem dead.
Description: 1 – highly resistant, 2-3 – resistant, 4-5 – moderately susceptible,

8-9 susceptible.

2. Reaction to leaf miner. The reaction to leaf miner was recorded at 30, 45,
60 and 75 DAP using the following rating scale (CIP, 2001).
Scale
Description
Reaction
1
Leaf infected (1-20%)
Highly Resistant
2
Infected (20-40%)
Moderately Resistant
3
Moderately infected (41-60%)
Susceptible
4
Severely infected (61-80%)
Moderately Susceptible
5
Most serious (81-100%)
Very Susceptible

E. Yield and Yield Components

1. Number and weight of marketable tubers per plot (kg). All tubers that were of
marketable size, not malformed, free form cuts, cuts and without more than 10% greening
of the total surface were counted and weighed at harvest.
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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2. Number and weight of non-marketable tubers per plot (kg). These were obtained by
counting and weighing all tubers that were malformed, damaged by pests and diseases and
those pests and diseases and those with more than 10% greening.
3. Total yield per plot (kg). This was the sum of the weight of marketable and non-
marketable tubers per plot.

4. Computed yield (t/ha). This was computed on a hectare basis using the following
formula:
Computed Yield (t/ha) = Total Yield per Plot (kg/5m2) x 2
*Where: 2 is the factor used to convert yield in kg/5m2 to tons per hectare
assuming one hectare effective area.


F. Return on Cash Expense (ROCE). This was computed using the formula:
Net Income
ROCE =
x 100
Total Cost Production
G. Tuber Characters
1. Tuber skin color. This was described by visual observation as:
1 = White-cream
2 = Yellow
3 = Orange
4 = Brownish
5 = Pink
6 = Red
7 = Purplish-red
8 = Purple
9 = Dark purple-black


Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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2. Tuber skin type. This was recorded using the CIP descriptors list.
1 = Smooth
2 = Rough (flaky)
3 = Partially netted
4 = Totally netted
5 = Very heavily netted
6 = Other
3. Predominant tuber flesh color. Code indicating the flesh color present in most of the
tuber, expressed as:
1 = White
2 = Cream
3 = Yellow – cream
4 = Yellow
5 = Red
6 = Violet
7 = Purple
8 = Other
4. Secondary tuber flesh color. Code representing a secondary flesh color in the tuber,
expressed as:
1 = Absent
2 = White
3 = Cream
4 = Yellow – cream
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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5 = Yellow
6 = Red
7 = Violet
8 = Purple
9 = Other
5. General tube shape. Code describing the tuber outline, expressed as:
1 = Compressed (oblate) – major axis is the shortest axis.
2 = Round – an almost circular outline

3 = Ovate – an outline resembling an egg,The broadest part is within

1/3 of the distance from the stolen end.

4 = Obovate – an outline which is inversely ovate and broadest part is

within 1/3 of the distance from the apical end (rose or eye end).

5 = Elliptic – an outline showing the same breadth when measured at

equal distance from both the stolon and apical ends.

6 = Oblong – an almost rectangular outline with the sides nearly

parallel but the corners rounded. The length/breadth ration should

not be more than 3/2.

7 = Long-Oblong – an oblong outline with a length/breath ratio closer to

2/1.

8 = Elongate – a long rectangular outline with a length/breadth ratio
equal to or more than 3/1.
6. Unusual tuber shape. Code representing those variants of tuber shapes which cannot be
described under general tuber shape. It is expressed as follows:
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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1 = Absent
2 = Flattened – when the length of a transverse section, at any point of
the tuber, it’s more than three times longer than its breadth.
3 = Clavate – resembling an elongated club, thickened at one end.
4 = Reniform – shaped like a kidney
5 = Fusiform – spindle – shaped, tapering gradually at both ends
6 = Falcate – curved or shaped like a sickle or horseshoe
7 = Spiral – long and colored
8 = Digitate – resembling a hand or a fist
9 = Concertina – shaped – resembling a concertina
10 = Tuberoses – covered with few or many small lumps and tubers. It
includes those shaped like a pineapple, a cluster of grapes, and
raised internodes.
7. Depth of tuber eyes. Code indicating the depth of the eyes in the tuber, expressed as:
1 = Protruding
2 = Shallow
3 = Medium
4 = Deep
5 = Very deep




Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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G. Postharvest Characteristics
1. Dry mater content (%). One hundred gram tubers were weighed and sliced
into cubes and oven dried at 100oC for 24 hours. This was recorded and computed
using the following formula:
% Dry Matter = 100% - % Moisture Content
Fresh Weight – Oven Dry Weight
Where: % Moisture Content =






Fresh Weight
x 100

2. Sugar content. This was taken before and after storage using a digital refractro meter.
3. Percentage weight loss. Tubers were weighted every 3 days for one month and computed
using the formula;
Initial Weight – Final
Percentage Weight Loss =
x 100
Initial Weight

4. Number of sprouts. Sprouts per tuber were counted weekly for the month.
5. Visual quality rating. This was obtained weekly for one month using the
rating scale (Salda, 2003).

Scale Grade
Remarks
1 Firm (no defect)

Fresh
2 Minimal (moderate defect)
Good
3 Limit of stability (severe defect)
Poor





Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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6. Degree of decay. This was taken weekly for one month using the scale of
Bayogan (1986).
Scale
Description
1
No Decay
2
1-19 % decay/rotting of tuber surface area
Scale
Description
3
20-49% decay/rotting of tuber surface area.
4
50 – 79% decay/rotting of tuber surface area.
5
80% and above decay/rotting of tuber surface area.






Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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RESULTS AND DISCUSSION

Meteorological Data
Table 1 shows the temperature, relative humidity, sunshine duration and rainfall during the
conduct of the study. There was an extreme range of temperature during the conduct of the
study from 8.9 0C to 29.3 0C. The lowest temperature was recorded in February while the
highest was recorded in April. This temperature extreme was not favorable for potato
production since the optimum temperature is from 17 0C to 22 0C (HARRDEC 1996).
NPRCRTC (1996) also reported that the maximum yield of potato was produced when the
average temperature during the growing season which ranged from 15 oC to 18 oC. Rainfall
was low from January to April. Thus, irrigation was done. Relative humidity ranged from
80-94%.

Table 1. Meteorological data gathered during the conduct of the study (January-May
2011)


TEMPERATURE
RELATIVE RAINFALL
DAILY
MONTH
Max.
Min.
HUMIDITY
(mm)
SUNSHINE
(0C)
(0C)
(%)
DURATION
(min)
January





25.7
15.5
80
1.0
368.3
February
17.7
8.9
85
1.0
214.3
March
23.0
13.3
82
1.0
250.3
April
29.3
16.7
86
2.9
345.0
May
28.6
11.0
94
13.7
150.1



Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Chemical Properties of the Soil
Soil pH. The pH of the soil before and after harvest was 6.0 which favored the growth of
potato entries since the optimum pH for potato production ranged from 5.6 - 6.5.
Soil organic matter. The organic matter present in the soil increased from 2.5 to 3.0 % after
planting. This might be due to the compost application. According to Lambert (1996) the
normal organic content for potato production ranged from 1 to 4 %.
Phosphorus (ppm). There was a decrease in the phosphorus content of the soil from 139 to
125 at harvest. HARRDEC (1996) reported that during the early development of the crop
and early tuberization phosphorus is needed to increase the number of tubers produced by
the plant. For this reason, the decrease in phosphorus content may be caused by the high
phosphorus requirement of the potato plant.
Potassium (ppm). There was an increase in potassium content of the soil after harvest from
208 to 229 ppm. The increase could be attributed to the application of compost and vermi
compost.
Nitrogen (%). No change had been observed on the amount of nitrogen before and after
planting. This may imply that the nutrient content of the compost was sufficient for the
growth and development of the plants.

Table 2. Chemical properties of the soil before planting and after harvest

SAMPLING TIME
pH
OM (%)
N (%)
P (ppm)
K (ppm)
Before planting
6.0
2.5
0.33
139
208
After harvest
6.0
3.0
0.33
125
229





Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Percent Survival

The percent survival of the potato entries at 75 days after planting (DAP) is shown in Table
3. Significant differences among the entries were noted. Gukungu, 676008 and Tubira had
a 100% survival while Santa Ana had the lowest percent survival of 84.17%.
The decreased in survival of Montañosa and Santa Ana could be attributed to unfavorable
weather conditions such as the high temperature. Some of the tubers were also observed to
have been affected by bacterial wilt.

Plant Height
Table 4 shows the height of the plants at 30 DAP, 45 DAP, 60 DAP and 75 DAP. Highly
significant differences among the potato entries were noted. Gukungu produced the tallest
plants in all dates while Tubira produced the shortest plants.

Table 3. Plant survival of potato entries at 75 days after planting

ENTRY
PLANT SURVIVAL (%)

Gukungu
100.00a
Santa Ana
84.17b
676008
100.00a
Tubira
100.00a
Montañosa
92.50ab
CV (%)
6.74
Means with the same letters are not significantly different at 5% level by DMRT.



Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 4. Plant height of potato entries at 30, 45, 60 and 75 DAP


PLANT HEIGHT (cm)
ENTRY
(DAYS AFTER PLANTING)
30
45
60
75
Gukungu
20.55a
49.16a
70.68a
77.48a
Santa Ana
15.13c
28.72d
41.73d
54.70d
676008
17.83b
41.02b
65.02b
71.82b
Tubira
12.31d
24.55e
35.45e
51.88e
Montañosa
13.23cd
31.51c
60.71c
69.28c
CV (%)
10.41
4.92
2.56
2.51
Means with the same letters are not significantly different at 5% level by DMRT.

Canopy Cover
Table 5 shows the canopy cover of the potato entries. Canopy covers of the potato entries
at 30 DAP, 45 DAP, 60 DAP and 75 DAP significantly differed. Highest canopy cover was
obtained by Gukungu in all dates while the lowest canopy cover was obtained by Tubira.
There was an increase in canopy cover for all entries. This could be attributed to late blight
resistance. On other hand, Tubira having obtained 100% survival had low canopy cover.
This could be due to high temperature and susceptibility to leaf miner at 75 DAP.

Plant Vigor
Table 6 shows the plant vigor of the potato entries at 30, 45, 60 and 75 DAP. Most of the
potato entries were highly to moderately vigorous. However, Santa Ana was rated vigorous
at 75 DAP. The extreme temperatures might have contributed to the


Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 5. Canopy cover of potato entries at 30, 45, 60 and 75 DAP


CANOPY COVER
ENTRY
(DAYS AFTER PLANTING)
30
45
60
75
Gukungu
40.50a
54.00a
62.00a
67.50a
Santa Ana
25.25b
37.62bc
42.25bc
51.25b
676008
36.00a
47.50ab
55.00ab
62.50a
Tubira
22.25b
30.25c
37.00c
46.25b
Montañosa
20.50b
34.00c
39.00c
48.75b
CV (%)
13.86
18.44
18.14
12.11
Means with the same letters are not significantly different at 5% level by DMRT.


Table 6. Plant vigor of potato entries at 30, 45, 60 and 75 DAP

PLANT VIGOR
ENTRY
(DAYS AFTER PLANTING)
30
45
60
75
Gukungu
5.00a
5.00
5.00a
5.00a

Santa Ana
4.50ab
4.75
4.25b
3.25b
676008
5.00a
5.00
4.25b
4.00b
Tubira
4.25b
4.50
4.00b
3.50b
Montañosa
4.00b
4.50
4.25b
3.50b
CV (%)
8.03
9.80
9.62
14.62
Means with the same letters are not significantly different at 5% level by DMRT.


Legend:
5 - Highly vigorous

4 - Moderately vigorous

3 - Vigorous

2 - Less vigorous

1 - Poorly vigorous
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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decrease in plant vigor during the conduct of the study. A number of studies show that high
temperatures affect the growth of the plants.

Leaf Miner Incidence
Table 7 shows the leaf miner incidence of the potato entries at 30, 45, 60 and 75 DAP. It
was observed that all the entries were highly resistant at 30 and 45 DAP. At 60 DAP, there
was no leaf miner occurrence observed. However, at 75 DAP, Santa Ana and Tubira were
found to be susceptible while the other entries were found to be moderately resistant. The
occurrence of leaf miner of Santa Ana and Tubira at 75 DAP could have been caused by
the aging of the plants.

Late Blight Incidence
Late blight incidence of the potato entries at 30, 45, 60 and 75 DAP is presented in Table
8. Low late blight occurrence was observed.
Table 7. Leaf miner incidence of potato entries at 30, 45, 60 and 75 days after planting


LEAF MINER INCIDENCE
ENTRY
(DAYS AFTER PLANTING)
30
45
60
75
Gukungu
Highly resistant
Highly resistant
Highly resistant
Moderately resistant

Santa Ana
Highly resistant
Highly resistant
Moderately resistant Susceptible

676008
Highly resistant
Highly resistant
Moderately resistant Moderately resistant

Tubira
Highly resistant
Highly resistant
Moderately resistant Susceptible
Montañosa
Highly resistant
Highly resistant
Highly resistant
Moderately resistant



Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 8. Late blight incidence of potato entries at 30, 45, 60 and 75 DAP


LATE BLIGHT RATING

(DAYS AFTER PLANTING)
ENTRY
30
45
60
75
Gukungu
Highly resistant
Highly resistant
Resistant
Resistant
Santa Ana Highly resistant
Highly resistant
Resistant
Moderately resistant

676008
Highly resistant
Highly resistant
Resistant
Moderately resistant

Tubira
Highly resistant
Highly resistant
Resistant
Moderately resistant

Montañosa Highly resistant
Highly resistant
Resistant
Resistant

Number and Weight of Marketable Tubers per Plot
Table 9 shows the number and total weight of marketable tubers per plot of the potato
entries. Significant differences among the entries were observed. Gukungu produced the
highest number and the heaviest weight of marketable tubers. Entry 676008 also produced
high number and heavy weight of tubers. Santa ana and Tubira produced the lowest number
of tubers. It was observed that entries with the widest canopy also produced the highest
number and heaviest weight of marketable tubers (Figure 1-5).
The potato entries generally produced low yield which might be due to the extreme
temperature during the conduct of the study.

Number and Weight of Non-marketable Tubers per Plot
Table 10 shows the number and weight of non-marketable tubers of potato entries per plot.
There were no significant differences among the entries on the number and weight of non-
marketable tubers. Entry 676008 produced the lowest number and weight of non-
marketable tubers.
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 9. Number and weight of marketable tubers of potato entries


MARKETABLE TUBERS
ENTRY
Number
Weight (kg)
Gukungu
86
2.49
Santa Ana
65
1.63
676008
85
2.31
Tubira
69
1.63
Montañosa
70
1.93
CV (%)
11.52
8.91
Means with the same letters are not significantly different at 5% level by DMRT.

Table 10. Number and weight of non-marketable tubers of potato entries per plot


NON-MARKETABLE TUBERS
ENTRY
Number
Weight (kg)
Gukungu
11
0.73
Santa Ana
11
0.70
676008
10
0.63
Tubira
11
0.70
Montañosa
12
0.75
CV (%)
9.59
14.11
Means with the same letters are not significantly different at 5% level by DMRT.




Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Yield per 5 m2 and Computed Yield
Table 11 show the total yield of potato entries were Gukungu produced the highest yield
while Santa Ana and Tubira produced the lowest. Low yield could be attributed to the
unfavorable environmental condition specifically erratic temperature.
Gukungo also registered the highest yield per hectare. The high yield might be attributed
to its resistance to late blight and leaf miner and wide canopy.

Return on Cash Expense (ROCE)

The return on cash expense of organic potato production is presented in Table 12.
Entry 676008 had a return on cash expense of 59.40% which is the highest among the
entries. Gukungu follows with 47.80%, then by Montañosa with 24.20%. Santa Ana and
Tubira recorded the lowest return on cash expense with both 4.40%. All the entries
obtained a positive ROCE.

Table 11. Yield per plot and computed yield of the potato entries


YIELD
ENTRY
PER PLOT (kg/5m2) COMPUTED (t/ha)



Gukungu
3.11a
6.23a

Santa Ana
2.33c
4.65c
676008
3.04a
6.08a
Tubira
2.33c

4.65c

Montañosa
2.69b
5.38b
CV (%)
7.02
7.02
Means with the same letters are not significantly different at 5% level by DMRT.

Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 12. Return on cash expense of potato entries under organic production


COST OF
GROSS
NET
ROCE
TREATMENT
YIELD
PRODUCTION INCOME
INCOME
(%)






Gukungu
2.31
125
184.75
59.75
47.80
Santa Ana
1.63
125
130.50
5.50
4.40
676008
2.49
125
199.25
74.25
59.40
Tubira
1.63
125
130.50
5.50
4.40
Montañosa
1.94
125
155.25
30.25
24.20
*Total cost of production includes organic fertilizers and labor.
*Selling price of potato tuber was Php80.00 per kg

Primary Characters of Tubers
Table 13 summarizes the predominant tuber skin color, tuber skin type and predominant
tuber flesh color of potato entries. Gukungu and Tubira were noted to have pink skin while
Santa Ana had violet, 676008 had purplish-red and Montanosa had yellow. Among the five
entries, 676008 and Montanosa had a smooth tuber skin type compared with the other three
entries which was rough. In terms of the predominant tuber flesh color, Gukungu and
676008 were yellow-cream and other entries were white. The tuber with colored skinned
may be used as selection index for gourmet potato. Both yellow and cream white are
presently accepted for table processing purposes. For more beta-carotene, yellow colored
ones are preferred (Rastovski, 2003).

Secondary Characters of Tubers
All the entries were noted to have no secondary tuber flesh color. For the depth of tuber
eyes, all entries have shallow eyes. Shallow eyes are preferred since tubers gave
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 13. Predominant skin color, tuber skin type and predominant tuber flesh color of
the five potato entries


PREDOMINANT TUBER SKIN PREDOMINANT
ENTRY


SKIN COLOR TYPE TUBER FLESH
COLOR




Gukungu
Pink
Rough
Yellow-cream

Santa Ana
Violet
Rough
White
676008
Purplish-red
Smooth
Yellow-cream
Tubira
Pink
Rough
White
Montañosa
Yellow
Smooth
White
less trimming loss, shorter time in trimming, and higher volume of materials for chips
(Sabiano, 2006).

Tuber Shape
Generally, the following potato entries: 676008, Tubira and Montañosa have an oblong
shape while Gukungu has elliptic and Santa Ana has compressed tubers (Table 14). The
entries have unusual tuber shape, too. Gukungu, 676008 and Tubira were observed to have
clavate shape while Santa Ana and Montañosa have flattered shapes.

Dry Matter and Sugar Content
Table 15 shows the tuber dry matter and sugar content of the potato entries. There were no
significant differences on the dry matter content of the entries. However, 676008 obtained
the highest dry matter content with 23.50%. Numerically, the dry matter content of all the
potato entries were observed to be good for processing of chips since it ranges from 18 to

Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Table 14. Tuber shapes of the potato entries



ENTRY
GENERAL TUBER SHAPE UNUSUAL TUBER
SHAPE



Gukungu
Elliptic
Clavate

Santa Ana
Compressed
Flattered
676008
Oblong
Clavate
Tubira
Oblong
Clavate
Montañosa
Oblong
Flattered

Table 15. Dry matter and sugar content of the potato entries


DRY MATTER CONTENT SUGAR CONTENT
ENTRY
(%) (oBrix)



Gukungu
20.50
4.88

Santa Ana
22.25
4.48
676008
23.50
4.78
Tubira
21.25
4.48
Montanosa
23.25
4.78
CV (%)
2.93
1.70
Means with the same letters are not significantly different at 5% level by DMRT.

The potato entries did not also differ on their sugar content as shown in Table 15. Gukungu
had the highest sugar content with 4.88 oBrix. Santa Ana and Tubira had the lowest sugar
content of 4.48 oBrix.

Percent Weight Loss
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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The percent weight loss of the potato entries is presented in Table 16. Accordingly, the
potato entries significantly differed at 7, 14 and 21 days. At 28 days, however no significant
differences on percent weight loss among the five entries were observed.
Generally, Santa Ana had obtained the highest percentage of weight loss followed by
Tubira while entry 676008 had the least weight loss. Furthermore, the difference of weight
loss among these entries might be due to the well suberized peel which could be more
resistant to respiration of some entries as compared to the thinner skin of other entries and
genetic characteristics where some entries possess thick skin and cuticles (Rastovski et al.,
1979 ).
Table 16. Percent weight loss of the potato entries


DAYS AFTER STORAGE

ENTRY
7
14
21
28
TOTAL






Gukungu
2.25abc
4.68cd
5.94abc
6.43
19.27

Santa Ana
2.80a
6.82a
7.30a
7.82
24.74
676008
1.90c
3.90d
4.43c
5.86
16.09
Tubira
2.72ab
6.32ab
6.72ab
7.43
23.19
Montañosa
2.19bc
5.42bc
4.82bc
6.91
19.34
CV (%)
15.01
13.69
21.64
15.64

Means with the same letters are not significantly different at 5% level by DMRT.





Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Visual Quality Rating
After one month of storage, the tubers of the potato entries were still firm. No defects were
observed. Tubers with none or less defects even if stored for a longer period of time is
favorable for storage since potato can be preserved for future use without affecting its
quality and marketable. Hence, tuber could be sold at a better price (Myers, 1996).

Degree of Decay

No incidence of decay during one month of storage was observed.




Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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SUMMARY, CONCLUSION AND RECOMMENDATIONS
Summary

The study was conducted at the experimental area of Benguet State University,
Balili, La Trinidad, Benguet to: evaluate the potato entries for organic production;
determine the best performing potato entries in terms of yield and resistance to pest and
diseases; and determine the profitability of growing organic potato entries for organic
production.

Among the five potato entries under organic production, Gukungu, 676008 and
Tubira had the highest percentage of survival. All entries were observed to be highly
vigorous at 30 to 60 DAP. Gukungu had the tallest plants while Tubira registered the
shortest plants. Canopy cover was comparable among the five entries at 45 and 75 DAP.
At 30 to 75 DAP, Gukungu had the widest canopy while Tubira was noted to have the
narrowest canopy cover. In terms of leaf miner incidence, all entries were highly resistant
at 30 and 45 DAP. At 75 DAP, Santa Ana and Tubira were observed to be susceptible.
There was no late blight occurrence observed.

Gukungu produced the highest number and heaviest weight of marketable tubers.
Primary characters of tubers, Gukungu, 676008 and Tubira noted to have pink skin color
while Santa ana was violet. Entry 676008 and Montañosa had smooth skin type while the
other entries were rough. As to flesh color, Gukungu and 676008 had yellow-cream while
the rest of the entries had white. All entries were noted to have no secondary flesh color.
All entries were observed to have shallow eyes. Entry 676008, Tubira and Montañosa had
oblong tubers while Gukungu had elliptic while Santa Ana had compressed tubers.
Gukungu, 676008 and Tubira had clavate shaped tubers, while Santa Ana and Montañosa
Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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had flattered tubers. For return of cash expense, all entries had positive ROCE. Gukungu
obtained the highest ROCE.


Conclusion

Entries Gukungu and 676008 were the best performers based on marketable yield
and return on cash of expense under organic production at La Trinidad Benguet.

Recommendations

Based on the conditions and results of the study, Gukungu and 676008 can be
recommended for organic production under La Trinidad condition. However, further
evaluation of these entries should be conducted to determine their stability in terms of
growth, yield, resistant to pest and diseases and acceptability to famers.








Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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Agronomic and Postharvest Characters of Pink and Violet-skinned Potato Entries for
Organic Production in La Trinidad, Benguet. | CADAP, EMILIO JR., M. APRIL. 2013

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