Performance of Selected Phytochemicals and Botanical Nutrient on Physiological Features of Okra Varieties against Yellow Vein Clearing Mosaic Virus

Abstract

A two-factorial field experiment on okra was conducted at the Horticulture Farm of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh from April to August, 2017. The study aimed to find out the physiological responses of okra varieties against Yellow vein clearing mosaic virus under a management progamme to control the disease. Four okra varieties viz. BARI dherosh-1, Green finger, Nuffield and Orca onamika were selected as first factor and two phytochemicals (Imidacloprid and Sobicron) and one botanical nutrient namely Peak performance nutrients (PPN) were used as the second factor. The plants were grown and natural inoculum has relied upon the infection of Yellow vein clearing mosaic virus. Physiological features of okra plants were significantly affected by Yellow vein clearing mosaic virus. So that, regular physiological activities of okra varieties were hampered due to the attack of the virus. The highest exclusive chlorophyll content, net assimilation rate, intercellular carbon-di-oxide concentration, stomatal conductivity and respiration rate were recorded in Green finger and the lowest in Orca onamika. Sobicron with PPN also gave the highest net chlorophyll content, net assimilation rate, intercellular carbon-di-oxide concentration, stomatal conductivity and respiration rate and the lowest were recorded when no phytochemicals and PPN combination was used. Green finger with the application of Sobicron with PPN showed the best performance of these physiological responses compared to other okra varieties and phytochemicals combinations. All of these physiological changes are closely related to reduced rates of photosynthesis as well as effects on chloroplast number, ultrastructure and chlorophyll metabolism, deterioration of chloroplast structure, pigment composition and electron transport. So that, less energy is produced thus resulting the suppress of proper physiological functions of okra plants.