BIBLIOGRAPHY CALVERO, AURORA F. APRIL,...
BIBLIOGRAPHY
CALVERO, AURORA F. APRIL, 2013. Evaluation of CornCultivars
Against Diseases Under La Trinidad Condition, Benguet Condition. Benguet State
University, La Trinidad, Benguet.
Adviser: Andres A. Basalong, MSc.
ABSTRACT
The study was conducted to determine the resistance of different corn
cultivars against major corn diseases; and to document the most prevalent and the
most severe corn diseases under La Trinidad, Benguet condition.
The most prevalent corn disease was leaf blight caused by
Helminthosporium maydis, followed by corn rust caused by Puccina sorghi, downy
mildew caused by Peronosclerospora maydis, and corn smut caused by (Ustilago
maydis).
Among the corn cultivars evaluated, TSG corn had the lowest leaf blight
infection rating while the highest infection was recorded in the Sweet corn cultivar.
Meanwhile, Bioseed corn cultivar had the highest infection and Popcorn had the
lowest infection rating on downy mildew. Rust infection was the highest in the
Sweet corn cultivar while Rr with bio-n, Dekalb, Bioseed and TSG corn were
susceptible to smut infection. High infection was due to favorable conditions for
disease development.TSG corn cultivar had the highest marketable yield than
Popcorn cultivar. Sweet corn cultivar was the most favored in the sensory
evaluation than Indigenous corn.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
RESULT AND DISCUSSION
Occurrences of Leaf Blight,
Downy Mildew and Rust
Based on the leaf blight infection from emergence, Indigenous corn was the
first cultivar to be infected at 18.5 days from emergence, while infection of diseases
were TSG corn and Rr with bio-n was at 23 days (Table 1).
Downy mildew infection was observed to occur later than leaf blight.
Infection was first observed in the cultivar Popcorn at 22.75 days and last to be
infected was Rr with bio-n at 26 days from emergence, while Indigenous corn was
infected at 23.00 days.
As to rust infection, TSG corn was the first cultivar to be infected at 65.75
days while the last cultivar to be infected was Dekalb at 73 days (Table 1).
The statistical analysis show no significantly difference among all the
cultivars in all the diseases observed.
Table 1. Mean number of days from emergence to the initial disease infection
CULTIVARS
LEAF BLIGHT
DOWNY MILDEW RUST
Indigenous corn
18.50
23.00
72.50
(control)
22.75
22.75
70.25
Popcorn
Dekald
21.75
23.75
73.00
Bioseed
21.75
24.25
69.75
Sweet corn
21.00
25.25
69.00
TSG corn
23.00
24.00
65.75
Rr with bio-n
23.00
26.00
66.75
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Leaf Blight Infection
Observation of leaf blight infection started 7 days after emergence. Initial
infection recorded after 14 days showed that four cultivars had infection of 6.25%
and three with 5%, (Table 2). Statistical analysis, however, did not show significant
differences among the cultivars.
Weekly leaf blight infection ratings taken from 21 to 91 days from
emergence, showed that TSG corn consistently had the least infection rating except
on the 49th day where leaf blight infection was slightly higher than the control
Indigenous corn. Likewise, Bioseed as the 2nd with low leaf blight final infection
rating, showed gradual increase of infection from earlier period of growth, but
showed minimal progress of leaf blight infection towards maturity as compared to
other cultivars.
Sweet corn had a consistently low leaf blight infection from 21st up to 70th
day from emergence, but which increased from 77th day to the last rating period. A
trend which implies that sweet corn cultivar become susceptible as it matures,
(Figure 2). However, Rr with bio-n had the third least percentage of leaf blight
infection rating which was followed by cultivar.
Moreover, Popcorn had the least infection of leaf blight at 21th days of
infection, at 42th had the highest infection of leaf blight until reaches its maturity.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Table 2. Weekly mean percentage infection (%)
CULTIVAR
DAYS AFTER PLANTING
14
21
28
35
4 2
49
56
63
70
77
84
91
Indigenous 0 8.75
11.25
16.25
20.75
25.00
30.25
35.75
43.75
50.50
60.75
78.75ab
Popcorn
0 8.75
11.25
20.50
26.25
31.50
37.50
48.50
56.75
63.50
70.25
100a
Dekalb
0 8.75
11.25
16.25
22.50
28.75
38.50
45.50
51.50
56.75
58.75
65.25b
Bioseed
0 11.25
16.25
17.75
22.75
25.50
28.75
32.75
35.50
41.25
49.50
55.50bc
Sweet corn
0 8.75
11.25
16.25
18.75
24.50
27.75
31.75
39.50
50.50
78.75
100a
TSG corn
0 7.50
10.25
14.75
16.25
21.25
26.75
30.75
34.50
38.5
38.5
43.75c
Rr with bio
n
0 8.75
13.75
16.25
20.5
28.75
31.25
35.75
40.25
45.75
50.50
57.00bc
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet Condition | ALVERO, AURORA F. APRIL, 2013
Table 3. Mean length of lesion
Cultivars
LENGTH OF LESION (cm)
Indigenous corn
28.99c
Popcorn
23.78bc
Dekalb
13.54ab
Bioseed
13.10b
Sweet corn
21.52bc
TSG corn
9.30a
Rr with Bio-n
14.71ab
CV (%)
26.40
Means of the same letter have no significantly different at 5% level of DMRT
Length lesion was observed that TSG corn had significantly the shortest leaf blight
lesion at 9.30cm and the longest was Indigenous corn at 28.84mm (Table 2). Result further
revealed that cultivars that had lower percentage of leaf blight infection also had
significantly shorter length of lesions. Aside from cultivar TSG corn this was exhibit by
cultivars Bioseed, Deklalb, and Rr with bio-n.
The prevalence of leaf blight infection was due favored by the temperature during
the conduct of the study which ranged from 21.980C to 24.130C (Table 10). These coincide
to the report of Jugenheimer (1976) that leaf blight infection is favorable to temperature
range of 20℃ − 32℃ and 89% relative humidity. Actual relative humidity of 86.61%
(Table 10), however, does not conform to the 89% as cited.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
120
indigenous
100
corn
popcorn
80
tion
dekald
fec
In 60
t
bioseed
h
g
i
l 40
sweet corn
af B
Le
TSG corn
% 20
Rr with bio-n
0
14
21
28
35
42
49
56
63
70
77
84
91
Days
Figure 2. Weekly mean percentage of leaf blight infection
Downy Mildew Infection
The cultivars Sweet corn and Popcorn had the lowest downy mildew infection rating
of 8.75 which is significantly lower than infection in other cultivars (Table 4).
The favorable temperature for downy mildew infection is 240C at 89% relative
humidity as reported by Cardwell (2000).Such temperature falls within the range of actual
temperature during the conduct of the study. However, downy mildew infection was
generally low in most of the cultivars. Therefore, infection may have come from seed
infections but not from inocula in the field, as downy mildew could be a seed borne disease.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Table 4. Downy mildew infection rating (%)
CULTIVARS
MEAN
Indigenous corn
13.75b
Popcorn
8. 75a
Delakb
11.25b
Bioseed
45.00c
Sweet corn
8.75a
TSG corn
10.00bc
Rr with bio-n
10.00bc
CV (%)
172.23%
Means of the same letter are not significant to 5% level of DMRT
Leaf Rust Infection
The cultivar TSG corn had the lowest infection rating at 8.75%, while Sweet
corn had the highest infection rating at 100 %.Statistical analysis show significant
differences among the cultivars.
The 100% rust infection on sweet corn conforms with the observations in other
countries mostly Tropical America and United State of America that Sweet corn is very
susceptible to rust infection and damage cause heavy losses to yield (Niedehauser and
Barnes, 1955).
The temperature during the conduct of the study ranged from 21.980C to 24.130C
(Table 10) which is within the range reported by Martin et.al., (1992) that rust infection
is favorable at high humidity with cool evening temperature of 16-23.33℃, follow by
moderate daytime temperature. Hence, Bioseed cultivar was susceptible to rust infections.
Table 5. Rust infection rating (%)
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
CULTIVARS
MEAN
Indigenous corn
76.25bc
Popcorn
77.50bc
Dekalb
15.00b
Bioseed
16.25b
Sweet corn
100.00c
TSG corn
8.75a
Rr with Bio-n
11.25b
CV (%)
37.16
Means of the same letter are not significant to 5% level of DMRT
Smut Diseases
Two pathogens were observed as causal agents of smut diseases. The head smut is
caused by Sphacelotheca reliana, (Figure 5) and corn smut caused by Ustilago maydis,
(Figure 6).
The severity of smut diseases occurred in Dekalb, Bioseed, TSG corn and Rr with
bio-n. However, among all the cultivars Indigenous corn, Popcorn and Sweet corn were
resistant to smut diseases (Table 6).
The low incidence and infection of corn smut diseases could be attributed to the
low temperature (21.980C to 24.130C) during the conduct of the study. Koehning, (2005)
reported that the smut fungus grows best at a temperature range of 25−34℃ .
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Table 6. Percent incidence of smut infection rating
CULTIVARS
MEAN
ACTUAL
TRANSFORMED
Indigenous corn
0
0.71a
Popcorn
0
0.71a
Dekalb
0.93
0.93a
Bioseed
1.29
1.29a
Sweet corn
0
0.71a
TSG corn
1.83
1.83a
Rr with bio-n
2.73
2.73a
106.44
CV (%)
Means of the same letter are not significant to 5% level of DMRT
A
B
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Figure 3. Leaf blight: symptom (A), Conidia, 400X (B)
A
B
Q
Figure 4. Rust infection; symptom (A), uredospores 400X (B)
A
B
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Figure 5. Head smut; symptoms (A), teliospores (B) 400X
A
B
C
Figure 6. Corn smut ; symptoms (A and B), spores (C) 400X
Agronomic Characteristics
Ear length with and without husk (cm) The longest ear length with husk was
obtained on Rr with bio-n the shortest was from Popcorn. However, as to ear length without
husk, Dekalb had significantly longer ear length compared to the other cultivars except
TSG corn and Rr with bio-n.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Some cultivars have thick husk but do not have long ear. Cultivars with longer ear
would generally have a higher yield which would translate to higher income. Statistical
analysis show significant difference among all the cultivars.
Table 7. Ear length and diameter
EAR LENGTH
EAR DIAMETER
CULTIVARS
W/ HUSK
W/O HUSK
W/ HUSK W/O HUSK
(cm)
(cm)
(cm)
(cm)
Indigenous corn
22.38ab
14.68a
5.21c
4.35b
Popcorn
21.49a
15.87ab
3.17a
2.72a
Dekalb
23.24bc
20.36c
4.88bc
4.05b
Bioseed
22.64ab
17.33b
4.93bc
3.96ab
Sweet corn
22.98ab
18.15b
5.12b
4.44c
TSG corn
21.68b
19.21bc
5.40c
4.18bc
Rr w/ Bio-n
23.88c
19.22bc
5.04b
4.19bc
CV (%)
6.49%
6.03%
7.98%
6.32%
Means with the same letter are not significant to 5% level of DMRT
Ear Diameter with and without Husk (cm)
Aside from having longer ears, TSG corn also had significantly wider ear diameter
with husk intact while the cultivar Popcorn had the shortest cobs. Sweet corn had the widest
cobs without husk
Corn plants that produce the narrowest ear cobs but a wider diameter with a
maximum of 2cm of marketable young corn would mean a higher weight and higher
revenue.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Figure 7. Measuring ear length with and without husk
Figure 8. Measuring ear diameter with and without husk
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Total Marketable Yield per Plot (kg)
TSG corn had significantly the highest marketable yield with significantly
produced the lowest yield which mean of 13.19kg
per plot. The cultivars Sweet corn and Popcorn did not out yield the check variety
Indigenous corn. It was observed that all the cultivars had significant differences.
Table 8. Total marketable yield per plot (kg)
CULTIVARS
MEAN
Indigenous corn
6.69bc
Popcorn
1.99a
Dekalb
9.13ab
Bioseed
8.75ab
Sweet corn
2.94b
TSG corn
13.19c
Rr with Bio-n
8.94ab
Means of the same letter are not significantly different at 5% level of DMRT
Sensory Evaluation
Ten respondents selected randomly from BSU students were asked to evaluate the
boiled corn cultivars according to flavor, appearance, palatability, texture, aroma, and
general acceptance.
In terms of flavor, Sweet corn cultivar was liked better by the ten respondents.
However, Popcorn and Bioseed disliked moderately while other cultivars like moderately
according to appearance.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
In relation to palatability or taste, Indigenous corn was considered the most
delicious followed by Sweet corn. Young cobs of Popcorn were disliked moderately.
Considering the ratings in all the parameters Sweet corn was liked better than Indigenous
corn.
Table 9. Sensory evaluation of the different corn cultivars
PARAMETERS
CULTIV
ARS
FLAVOR APPEAR
PALATA
TEXTURE
AROMA GENERAL
ANCE
BILITY
ACCEPTANCE
Indigenou
4.4
4.3
4.4
4.3
4.4
4.36
s corn
Popcorn
2.1
2.6
2.3
2.6
2.3
2.38
Dekalb
2.9
3.6
2.9
3.0
3.0
3.08
Bioseed
2.8
2.9
3.5
3.5
3.1
3.0
Sweet
4.6
4.2
4.2
4.3
4.4
4.34
corn
TSG corn 3.3
4.1
3.4
3.5
3.6
3.58
Rr with
3.8
3.8
3.5
3.6
3.9
3.72
Bio-n
Scale: 1- Dislike very much
2- Dislike moderately
3- Neither like nor dislike
4- Like moderately
5- like very much
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Meteorological Data
Table 10. Average meteorological data from April to July, 2012
RELATIVE
Date
TEMPERATURE
HUMIDITY
RAINFALL
MIN
MAX
(%)
(mm)
April
19.70
25.23
81.25
1.83
May
24.40
87.75
17.80
June
22.75
23.98
88.50
10.95
July
22.88
23.88
89.00
13.05
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
Summary
The study was conducted at Benguet State University, La Trinidad, Benguet from
April to July, 2012. The study aimed to determine the resistance of different corn cultivars
against major corn diseases; and to document the most prevalent and the most severe corn
diseases under La Trinidad, Benguet condition.
The corn diseases that were observed to be prevalent were leaf blight, rust, downy
mildew and smut. It was observed that Sweet corn was the most susceptible to leaf blight
and rust infection. Bioseed was most susceptible to Downy mildew. Smut infection was
observed only in cultivars Rr with bio-n, Dekalb, Bioseed and TSG corn.
TSG corn was observed to be resistant to leaf blight and rust infection while Sweet
corn was resistant to downy mildew and Indigenous corn, Popcorn and Sweet corn were
resistant to corn smut.
The longest ear length with husk was obtained in Rr with bio-n and the shortest was
from Popcorn. The longest ear length without husk was noted from Dekalb and the shortest
was from Popcorn.
Meanwhile, TSG corn had larger ear diameter with husk intact and Popcorn had
the shortest cobs. Sweet corn had the largest cobs and Popcorn was the smallest.
Conclusions
The results revealed that TSG corn is resistant to leaf blight infection and rust while
Bioseed is most susceptible to downy mildew. On the other hand, Sweet corn is the most
susceptible to rust infection and Rr with bio-n, Dekalb, Bioseed and TSG corn are most
susceptible to smut.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
Recommendations
TSG corn cultivar is recommended for planting in La Trinidad, Benguet due to its
moderate resistance to leaf blight and rust diseases.
Further, it is recommended that cultivated corn plants should be evaluated and to
be done also during dry and rainy season.
Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013
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Evaluation of CornCultivars Against Diseases Under La Trinidad Condition, Benguet
Condition | ALVERO, AURORA F. APRIL, 2013