Yellow Vein Mosaic Virus Resistant Okra Varieties Found Exceptionally Sensitive to Salinity Stress

Background: Okra is a nutritious vegetable crop which is highly susceptible to yellow vein mosaic virus (YVMV), a biotic stress factor. Chemical control of YVMV is very difficult; hence a number of tolerant varieties are developed for cultivation. The abiotic stress factors like salinity, which may reduce the yield of YVMV resistant okra, are not yet assessed. Results: Six okra genotypes (Arka Anamika, Anjitha, Manjima, Aruna, Kiran and Susthira) exhibiting resistance to Yellow YVMV were screened for their tolerance to an abiotic stress, salinity. Individual healthy seeds were monitored from 7 to 50 days under saline conditions for seed germination and emergence assays respectively. Parameters like number of geminated seeds and the radicle length were measured and documented at 3rd, 5th and 7th day for the germination assay. Number of seeds emerged from soil by the first 5, 10 and 15 days, the length of the emerged plantlet on the 15th and 30th day and morphological changes of emerged plantlets thereafter, up to 50 days were observed for the emergence assay. The rate of germination, radicle length, percentage of emergence and plantlet length were found to decrease with increasing salinity. Conclusions: All the six YVMV resistant varieties were found to be sensitive to salinity stress irrespective of whether it is germination, emergence or vegetative phase. The resistance to YVMV thus couldn’t contribute any preformed intracellular osmoticum to overcome salt induced cell damage in okra.