EFFECT OF 28-HOMOBRASSINOLIDE ON THE DROUGHT INDUCED CHANGES IN THE SEEDS OF VIGNA RADIATA

A study was undertaken to examine the different levels of drought stress during early seed germination and to explore the response of 28-homobrassinolide (HBL) as potent stress alleviator. Sterilized seeds of Vigna radiata (T-44 and PDM-139) were soaked in distilled water for 24 h then placed in 12 sets of 3 petri dishes representing various treatments. 7 days old seedlings were exposed to drought stress equivalent to -6 bar (DS I) and - 12 bar using PEG-6000 and at 14 days stage seedlings exposed to 10(-6), 10(-8), 10(-10) M of HBL. At 15 days stage, seedlings were harvested to evaluate the percent germination, proline, carbohydrate, nitrogen, phosphorus and potassium content. The results clearly indicated that seed germination, carbohydrate, nitrogen, phosphorus and potassium decreased in response to drought stress whereas, accumulation of proline increased. HBL increased proline accumulation significantly in the presence and absence of drought stress. It is concluded that drought stress (DSI) deteriorates the metabolism of Vigna radiata by decreasing mineral-nutrient status and per cent germination more effectively in PDM-139 over T-44. However, HBL played pivotal role in maintaining the homeostasis of mineral-nutrient status of Vigna radiata and overcome drought stress through higher accumulation of proline.