Effect of protected and unprotected conditions on epidemiological components of alternaria blight and yield of indian mustard

Studies with nine genotypes of Indian mustard revealed that plots protected with mancozeb showed average number of leaf spots/10 cm² (3.78), size of leaf spots (6.89 mm), number of conidia/leaf spot (1.46 x 10³), disease index on leaves (39.7%) and leaf defoliation (39.9%). While, unprotected plots exhibited number of spots (4.66), size of spots (7.90 mm), number of conidia (2.09 x 10³), disease index (56.1%) and leaf defoliation (50.9%). Similarly, protected plots showed number of spots/pod (19.60), size of pod spot (2.45 mm), number of conidia/pod spot (0.34 x 10³), disease index on pods (36.6%), and yield (12.14 q/ha) while, in unprotected plots, number of spots (23.60), size of spots (2.94 mm), number of conidia (0.44 x 10³), disease index (47.8%) and yield (10.53 q/ha) were recorded. Moreover, genotypes PR 8988, PR 9024 and Kranti exhibited less number of spots, reduced spot size, least number of conidia, low disease index and low defoliation in both protected and unprotected conditions than others.