Vulnerability studies of okra genotypes to bhendi yellow vein mosaic virus(BYVMV)

Abstract

India is the leading okra producer globally, but its production suffers due to losses causes by Bhendi yellow vein mosaic virus (BYVMV) disease which is transmitted by whitefly. Due to its unstable resistance nature and limited availability of sources of resistance in cultivated types, the crop improvement programme of okra has not taken a fast pace. In this study, sixty-four distinct genotypes of okra were screened for their resistance to BYVM under natural epiphytotic conditions in Delhi. It was found that the disease incidence (DI), coefficient of infection (CI), vulnerability index (VI), and adult whitefly count (AWC) varied significantly amongst the different okra genotypes. The highest mean DI was recorded in Pusa Sawani (86.5%) and DI was 0 % in the genotypes Pusa Bhindi-5 (DOV-66), DOV-89 and DOV-92. The coefficient of infection (CI) was highest in Pusa Sawani (70.39 %). Maximum VI was recorded in Pusa Sawani (83 %) and 0 % VI in the wild genotypes IC-141040, IC-90560 and cultivated Pusa Bhindi-5, DOV-81 and DOV-92. Similarly, AWC was maximum in Pusa Sawani (30.4) and the lowest number in DOV-26 (1.2). The number of whiteflies peaked at 80 days after sowing and subsequently decreased. Pusa Sawani was the most susceptible genotype and Pusa Bhindi-5 and DOV-92 were the most resistant genotypes based on this study. The resistant genotypes Pusa Bhindi-5 and DOV-92 can be used for the transfer of BYVMV resistance in other susceptible lines or varieties and also for hybrid development in future okra improvement programmes.