SELECTION FOR RESISTANT VARIETIES OF OKRA TO YELLOW VEIN CLEARING MOSAIC VIRUS AND ITS MANAGEMENT THROUGH PEAK PERFORMANCE NUTRIENTS, IMIDACLOPRID AND SOBICRON

Abstract

A two factorial field experiment on okra was conducted at the Horticulture Farm of Sher-e- Bangla Agricultural University, Dhaka during April to August, 2015. The aim of the study was to find out the resistance of okra varieties against Yellow vein clearing mosaic virus (YVCMV) and it’s management. Four varieties viz. BARI dherosh-1, Green finger, Orca onamika and Nufield were selected as first factor and two insecticides (Imidacloprid and Sobicron) and one botanical nutrient namely Peak performance nutrients (PPN) was used as second factor. The plants were grown and natural inoculum was relied upon for the infection of YVCMV. Growth parameters, yield attributes and physiological features were significantly affected by okra varieties and two selected insecticides and PPN combinations. YVCMV incidence was significantly varied with these combinations. Among the varieties, the lowest disease incidence was found in BARI dherosh-1 (8.44, 9.78 and 7.22% per plot and 43.39, 67.51 and 54.27% per plant at 40, 60 and 80 days after sowing, respectively) followed by Green finger (10.16, 10.02 and 10.53% per plot and 44.66, 69.40 and 67.46% per plant at 40, 60 and 80 days after sowing respectively) and the highest in Orca onamika (18.03, 42.10 and 45.92% per plot and 55.87, 75.34 and 88.79% per plant at 40, 60 and 80 days after sowing, respectively). The highest plant height, root length, dry weight of the root, number of fruit per plant, length of single fruit, single fruit weight, fruit yield, net chlorophyll content, net assimilation rate, intercellular carbon-di-oxide concentration, stomatal conductivity and respiration rate was recorded in Green finger followed by BARI dherosh-1 and the lowest in Orca onamika. Application of Sobicron with PPN gave the lowest disease incidence (9.63, 14.12 and 10.78% per plot and 40.74, 59.26 and 67.52% per plant at 40, 60 and 80 days after sowing, respectively) and the highest disease incidence (17.92, 27.73 and 32.32% per plot and 58.30, 84.58 and 85.07% per plant at 40, 60 and 80 days after sowing, respectively) was observed in control where no insecticides and PPN was applied. Sobicron with PPN also gave the highest plant height, root length, dry weight of the root, number of fruit per plant, length of single fruit, single fruit weight and fruit yield, net chlorophyll content, net assimilation rate, intercellular carbon-di-oxide concentration, stomatal conductivity and respiration rate and that of the lowest where no insecticides and PPN were used. Green finger applied with Sobicron and PPN showed moderate resistance and gave the highest plant height, root length, dry weight of the root, number of fruit per plant, length of single fruit, single fruit weight, fruit yield, net chlorophyll content, net assimilation rate, intercellular carbon-di-oxide concentration, stomatal conductivity and respiration rate as compared to other combinations. II