Physiological and Biochemical Responses in Onion Crop to Drought Stress

Drought is one of the major abiotic constraints limiting onion world-wide. To address the issue, study was conducted to investigate the effect of drought on morpho-physiological and biochemical parameters in onion variety Bhima Kiran in Rabi 2016. Drought stress was imposed on well-established seedlings by with-holding irrigation for continuous 40 days. The soil moisture and plant water status decreased gradually as the drought stress progresses beyond 30 days. Result showed that drought stress significantly reduces the leaf length and leaf area without any significant variation for other morphological traits namely, leaves per plant, height, pseudo-stem length and diameter. The onion variety Bhima Kiran maintains chlorophyll content confirming its functional stay-green property and accumulate higher proline, total soluble solids and antioxidant enzyme activity in response to drought as one of the tolerance mechanism. Water deficit stress lead to 65% yield reduction with more C grade bulbs (< 30mm). Additionally, slightly decreases in quality parameters like protein, phenol, flavanoids and pyruvic acid in bulbs were observed subjected to drought. Hence, the popular Rabi onion variety Bhima Kiran respond to drought stress by altering it biochemical pathway and thereby maintain its survival under stress. This finding briefly highlights the drought tolerance mechanisms in Bhima Kiran but future research needs to be focused on improving its yield potential for drought prone areas.