Plant Growth Regulators Alleviate Effects Of Drought Stress On Germination Indices In Tomato (Lycopersicon Esculentum Mill.)

The aim of present study was to determine the role of salicylic acid and ascorbic acid in osmotic stress tolerance of two tomato cultivars. Two water potentials of -0.6 &-0.12 MPa levels were created by externally adding artificial osmotia (PEG8000) in growth medium. Effects of drought stress and interaction of both plant growth regulators were investigated on seed percent germination, germination time, germination rate, radical length, plumule length and fresh weight of seedling under normal and osmotic stress conditions. Results revealed that imposition of both the levels of drought stress caused a significant reduction in the values of germination percentage, plumule length, germination rate and seedling fresh biomass, except radical length, while in contrast caused non-significant increase in mean germination time. Rate of reduction due to water potential -0.6MP level was less compared to -0.12 MPa. Both cultivars differed significantly from each other but cultivar Feston showed less decrease than Walter. However, pre-soaking seed treatment of both cultivars with both growth regulators applied at different (0, 100mg L-1 and 200mg L-1) concentrations proved significantly effective in alleviating the adverse effects of drought stress and increased the values of all the attributes, whereas, non significant decrease was noted for germination time. Moreover, drought stress alleviative effects of salicylic acid were higher than ascorbic acid. Among all the concentration 200mg L-1 proved extra effective. Cultivar Feston was more responsive to both the growth regulators than Walter