Assessing the role of biochemical constituents in resistance to Alternaria blight in rapeseed-mustard.

摘要

The present study was conducted to assess the role of different biochemical constituents in imparting resistance to rapeseed-mustard against Alternaria blight caused by Alternaria brassicae. Higher amount of total sugars were present in healthy leaves and pods of moderately resistant genotypes at pre-inoculation stage and the lowest in the diseased samples of highly susceptible genotypes at pre-harvest stage. Total soluble proteins were highest in the healthy samples of susceptible plants at pre-harvest stage while it was lowest in diseased samples of moderately resistant genotypes at pre-inoculation stage. It was observed that with increase in infection of A. brassicae the protein content increased. Higher amount of total phenols was observed in diseased samples as compared to healthy leaves and pods and it was higher in moderately resistant varieties at pre-harvest stage. Present investigations on total chlorophyll content revealed that higher content was observed in healthy leaves and pods of moderately resistant varieties as compared to diseased leaves and pods. The highest total carotenoid content was found in the diseased samples of highly susceptible genotypes at pre-harvest stage and the lowest was recorded at pre-inoculation stage in the healthy samples of moderately resistant genotypes. Positive correlations were found between disease intensity and total soluble proteins, total phenols and total carotenoids, while correlations were negative between disease intensity and total sugars, total chlorophyll content in both moderately resistant as well as highly susceptible varieties.