Abstract:
Alternaria blight caused by Alternaria brassicae (Berk.) Sacc. has been reported as one of
the most serious threat to the production of rapeseed and mustard which is reflected in
various yield attributing factors eventually affecting the yield. The matter is of grave
concern as both the crops have economic importance and fetch return to the growers
merely on the basis of oil content. The present study was conducted in order to assess yield
loss of rapeseed and mustard with respect to various yield attributing factors in various
varieties under natural conditions. Differential response to Alternaria blight was observed
which clearly instigated a scope of using resistant host varieties against Alternaria blight.
Variety Kalyan (393.83) showed maximum number of pods per plant whereas the
minimum number was shown by Agrani (232.87). Maximum number of seeds per pod
(14.43) was seen in variety Kalyan followed by Bhagirathi (13.56). Likewise the test
weight of 1000 seeds was found between 4.07g (Agrani) to Kalyan (8.70g). Variety
Kalyan gave maximum yield (1544.75 kg/ha) while, it was minimum in case of variety
Agrani (786.65 kg/ha). The observations also show that Alternaria has a direct effect on
yield of rapeseed and mustard which was revealed by the fact that moderately resistant
varieties had more yield (w.r.t. yield and other yield attributing factors) as compared to
highly susceptible varieties. The pattern of yield of various cultivars gave almost similar
results to prior studies based on different epidemiological parameters thus, showing the
potential of forming a baseline for determining the reaction group of the
varieties/genotypes against Alternaria blight under natural conditions.
