Vergara - 1976 - Physiological and morphological adaptability of ri

EPDDEMIOLOGY or SOLITHERN CORN LEAF BLIGHT 399
Table 1. The influence of dew period, dew temperature, and incubation temperature on size o1‘ lesions
incited by an Isolate of race T ul’ Hebnintkospanhm mqvdis on P-A-G hybrid 150291
Incubation Dew Lesion site {mm-‘J at indicated dew temp. WC)‘
temp.
period
(C) (hours) 2 l4 l6 I 8 20 22 2-1 26 28
'
LSD
4 U8 08 08 O8 l0 O8 08 08 l0 051i
6 0.5 05 25 15 0.8 0.8 1.8 23 l8
20 8 l.U l 3 2.7 10 1.5 13 2 2.2 24 01 21
l0 13 2G 21’) 13 20 2S 39 5.0 52
l2 1U 1O l0 15 2O 24 ~12 73 67
4 0.5 2.4 2.8 42 35 4.6 25 2.2 15 D5 23
6 0.8 2O 2.0 3.9 4-5 4.5 2.5 2.4 35 n1 32
25 B 2-1 19 24 56 4-9 59 42 45 52
IU 42 32 42 55 5.2 3B 55 11.9 109
l2 13 3.2 32 52 5.3 59 5 10.6 111
4 42 28 35 35 42 45 28 5.6 45 O5 34
6 49 .35 18 56 ~12 45 45 73 88 D146
28 8 4.2 35 3.5 56 56 61 7'7 10.7 11 '1'
It] 3.5 T’! 83 121 129 12.9 138 14.0 91
12 53 T? 9.4 109 119 145 1S4 10o 109
4 3.5 6.3 6.6 29 59 $2 S8 5.5 7?- (li 5i
6 5.2 4s 6.3 5s as 94 107 9.6 112 01-13
31 8 3.8 71' 91 11*) I32 13.11 112 133 111
1U 5.2 1U‘) I21 132 201 197 2U] 14.2 161
12 59 111 148 I89 21.6 197 182 1S5 18S
LSD
05 '39
01 52
001 66
‘Measurement of lesion size represents the average of two replications Measurements were taken
1'2 hours alter inoculation
lesion length and width. Thus, lesion sizes presented here were obtained by
measuring length and width and extrapolating total area from the chart.
Lesion measurements were taken 72 hours after inoculation. Each of two
replications consisted of 25-30 lesions per pot chosen at random on the second.
third, and fourth leaves. The relative differences in lesion size among treatments
remained essentially the same with increasing size afler longer incubation
periods. permitting us to use the shorter period. A factorial experiment
conducted as a randomized complete desigi with sub-sample consisted of 2
pots per experimental unit. Data were analyzed by the factorial analysis of
variance. The experimental errors were first- or second~order interactions.
Differences among treatments used L.S.D. as a reference. The data ivere
analyzed also by the multiple linear regression method.
Higher incubation and dew temperatures and increasing dew periods resulted
in significant increases in lesion size (Table l). There were significant differences
of interactions among treatments (incubation temp x dew period. dew temp x
dew period. incubation temp
variance or multiple linear regression analysis. Therefore. the results did not
show linear relationships. The interactions between and among these three
climatic parameters were striking. Higher incubation temperatures compensated
for shorter dew periods and for lower dew temperatures.