EFFECT OF DIFFERENT LEVELS OF SEED INFECTION (Bipolaris Sorokiniana) AND POPULATION DENSITY ON LEAF BLIGHT DEVELOPMENT AND HEALTHY SEED PRODUCTION OF WHEAT

Abstract

An experiment was conducted during the period from March 2010 - April 2011 to find out the influence· of seed infection level' by Bipo/aris sorokiniana .and population .. density on Jeaf blight development, healthy seed production and yield of wheat, cv. ·shatabdi .~he seed inf!3ction level and ·the population. density 'influenced ·the 'pathogenic actiVities through creating microclimate variability thal modify the leaf blight/spot development by Bipo/aris sorokiniana of wheat, six different seed infection levels viz. T1'= 0%, T2 :: 5.1-15%, T3 ~ 15.'1-25%, T4!!: 25:1-35%, T5:: 35.1- 45%, T8 = 45.1-60% were tested. Using three different method· namely blotter method, water agar method and rolled paper towel method the germin'ation percentage, normal seedling percentage and vigor- index was maximum at 0% seed infection and minimum at 45.1-60% seed infection. '% Number of infected 'seedlings and % dead seed was higher at max~mum ~eed infection .level and tower .at OOA,.seed infection level. In green house tray method % seed germination and vigor. index decreased with the increase of seed infection .level by Bipo/aris sorokinian~ . Field -experiment was carried out 'in -split-plot design where ·the population -densities '(200 seeds! m2, 300 seeds! m2 and 400 seeds! m2) were allotted in main plot and seed infection level (described above) in the sub>-plot . Different seed infection increased the seventy of Bipo/ar1s sorokiniana up to 45.1-600/0 seed infection .Population density and seed infection levels had Significant -influence on plant growth parameters and yietd and yield contributing character. Population density 300 seeds! m2 showed best performance in case of grain and straw yield. The highest grain yield (2.64 tlha) and straw yiefd (6.87 tIha) was obtained from 300 seeds/ m2 population density. The Highest grain yield (3.14 tlha) was also produced from ·0% seed infection treatment, whereas, 45.1-60% seed infection treatment produced the lowest grain yield (1.04 t/ha) . The. highest straw yield was observed with 300 seedsl m2 and. the lowest from 200 seeds! m2. The influence of the development of leaf blight disease of whE!at by Bipo/aris sorokiniana ·with increased plant density attributed ·to favorable microctlmate produced in the field condition.