EFFECT OF BLACK POINTED SEEDS OF DIFFERENT SEVERITY GRADES (0-5) ON LEAF BLIGHT (Bipolar;s sorokin;ana) DEVELOPMENT AND YIELD OF WHEAT

Abstract

Effect of black pointed seeds of different severity grades (0-5) on germination, seedling vigour, leaf blight development and yield contributing characters of wheat" were studied in the laboratory and field condition during the period of 2007-2008. The experiment was conducted in the M.S. laboratory, Department of Plant Pathology and in the farm of Sher-e-Bangia Agricultural University, Dhaka. Seed germination and seedling emergence were significantly decreased with the increase of different severity grades of black pointed seed. The sample having grade-S seeds (T 6) resulted maximum reduction in germination by 31.67% and 47.50% in the blotter and rolled paper towel method, respectively. Significantly highest (2219.00) and lowest (700.10) seedling Vigour Index (VI) was found in best seed (grade-D) and (grade-S), respectively. Significant variation in leaf blight severity under different severity grades of black pointed seed at all growth stages. The highest and lowest leaf blight severity was recorded in T6 (Grains are shriveled, almost completely discolored or more than Y2of grains were discolored) and TI (Free from infection) at flag leaf, panicle initiation, flowering, milking and hard dough stages. It has been found that plant growth characters (Plant height, ear length), spikelet formation and grain formation was decreased with the increase of severity grades of black pointed seed. The highest 1000 seed weight, straw yield and grain yield was recorded under Tl (Free from infection). The Tl treatment was increased 29.69 % grain yield over control. Considering the findings of the present studies, it has been found that seed sample having grade-D seeds (Free from infection) showed good result of germination, seedling vigour, leaf blight severity, grain formation and yield and yield contributing characters .