PJB-2017-296
Mathematical models based on different thermal and moisture regimes for development of Ascochyta blight of chickpeas
Abid Riaz, Chaudhary Abdush Shakoor and Gulshun Irshad
Abstract
Two separate models have been developed to describe the mathematical relationship of temperature and leaf wetness durations with Ascochyta blight development on two chickpea cultivars under controlled conditions. Plants of Balkasar-2000 (moderately resistant cultivar) and AUG-424 (highly susceptible cultivar) of our field trials were artificially inoculated with Ascochyta rabiei isolate ID-1 prepared @5x105 conidia ml-1 and subjected to various controlled environments to determine the impact of temperature and leaf wetness durations on disease establishment. Disease severity (%) was significantly affected by temperature, wetness durations and their interactions and depended on the level of resistance of the cultivar. It increased with increasing wetness duration (6-96h) at all the temperatures tested (10-25°C). At least 18h of leaf wetness were required for significant disease establishment (50%) at the optimum temperature of 20°C in AUG-424 and for Balkasar-2000, this value was 96 h. Quadratic trend in disease severity was found in relation to temperature and linear trend was recorded with regard to leaf wetness periods in both the cultivars. This study gives a systematic evaluation of host-pathogen interactions in controlled conditions. This approach of finding out quantitative relationship of disease with these most important variables may serve as a criterion for selection of cultivar for a specific area
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