EPIDEMIOLOGICAL STUDIES OF STRIPE RUST OF WHEAT CAUSED BY Puccinia striiformis
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Date
2015
Authors
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Publisher
Division of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu Main Campus, Chatha, Jammu 180009
Abstract
The effect of epidemiological factors such as minimum temperature, maximum temperature, maximum
relative humidity, minimum relative humidity, rainfall, soil temperature, canopy temperature, cloud cover (morning and evening), wind speed, sunshine hours, vapour pressure (morning and evening) and crop age on the severity of stripe rust in four wheat varieties (RSP 561, HD 2967, Agra Local and PBW 343), under three sowing conditions
(early, normal and late), were studied during two rabi seasons of 2013-14 and 2014-15 under random block design (RBD) with four replications. The experiment regarding effect of three leaf wetness durations (12, 24 and 36 hours) on four wheat varieties on disease severity was conducted under laboratory conditions.
The disease appeared in 1st standard meteorological week (SMW) in both the rabi seasons of 2013-14 and
2014-15 in all the tested wheat varieties, under different sowing conditions (early, normal and late), when the crop was at 73, 53 and 29 days after sowing, respectively. Sharp increase in disease severity was observed during 6th to 8th SMW due to the conducive weather conditions which prevailed during the previous fortnight. Epidemiological factors like maximum temperature, minimum temperature, morning vapour pressure, evening vapour pressure, evaporation, canopy temperature, soil temperature and age of the crop had significantly positive correlation with the
disease severity in the tested wheat varieties, whereas, maximum relative humidity had significantly negative
correlation, followed by rainfall which had moderately positive correlation with the disease severity. The predictive models generated through stepwise multiple regressions analysis revealed that thermic, hydric and light variables contributed significantly for variance in disease severity of selected wheat varieties. Gompertz model was observed
to be the best fitted in predicting the severity of stripe rust in comparison to the Logistic model, when compared with observed disease severity.
Among the three principal components, Pc1 accounted for maximum variance in disease severity that was
contributed by various epidemiological factors (thermic and biological), followed by Pc2 (light variables) and Pc3
(hydric variables). Under laboratory conditions, 24 hours of leaf wetness duration was found to be adequate for the
appearance of stripe rust in all the four selected wheat varieties, whereas, minimum latent period of 7.25, 9.50, 7.5
and 7.25 days, maximum pustules size of 10.03, 9.38, 11.05 and 10.98 mm and maximum disease severity of 57.50,
30.00, 60.00 and 54.34 per cent was recorded during 36 hours of leaf wetness duration.
Description
M.Sc. Dissertation
Keywords
STRIPE RUST, EPIDEMIOLOGY, CORRELATION, STEPWISE MULTIPLE REGRESSIONS, PREDICTION EQUATIONS