EFFECT OF DIFFERENT LEVELS OF SEED INFECTION (Bipolaris sorokiniana) AND PLANT POPULATION DENSITY ON LEAF BLIGHT SEVERITY AND YIELD OF WHEAT

Abstract

The experiment was conducted during the period from May 2011 to April 2012 to find out the effect of seed infection levels and plant population density on leaf blight severity and yield of wheat. Three population density viz. 200 seed/m/, 300 seed/m2 and 400 seed/nr' and six seed infection levels viz. 0%, 5.1 - 15%, 15.1 - 25%, 25.1 - 35%, 35.1 - 45% and 45.1-60% were used. Maximum leaf spot severity in flag leaf stage (0.36), panicle initiation stage (0.64), flowering stage (1.57), milk stage (1.84) and hard dough stage (2.30) was found in the interaction between sowing seeds @ 400 seeds/rrr' with 45.160% seed infection level. In every growth stage of the plant significantly lower leaf blight severity was recorded in the interaction between 200 seeds/nr' with sowing of 0.0% infected seeds. Similar trends in disease severity were recorded on penultimate leaf in above mentioned growth stage. Significantly higher number of grains/ear (58.00) and healthy grains/ear (55.67) was recorded under the treatment TI (0% seed infection) with a seed rate of 200 seeds/m/. Lower number of diseased grains/ear (2.33) were recorded under the treatments T6 with 400 seeds/m/ and Tl with 200 seeds/m'. Weight of diseased grains/ear ranged from 0.07 g to 0.75 g where the lowest value was recorded under Tt X 200 seeds/nr' treatment combination. Significantly higher (45.60) grain weight of 1000 seeds was recorded under the treatments TI (0% seed infection) with a seed rate of 200 seeds/mi. Straw yield under different treatment combinations ranged from 3.17-4.21 t/ha where the highest straw yield was obtained under the treatment combination of TI X 200 seeds/mi. Grain yield was significantly the highest (3.43 t/ha) when healthy seeds (0% infection) were sown @ 200 seeds/m'.