Exogenous application of glycinebetaine and potassium for improving water relations and grain yield of wheat under drought

Abstract

Compatible solutes rescue plants in the hour of intense water deficit conditions. Glycinebetaine (GB) and potassium (K) are main solutes, playing role in improving plant water potential and ultimately the crop yield. However, only a few attempts have been made so far to study their optimum dozes and interactions to ameliorate the drought stress in wheat. To explore this, GB solutions of 0, 50,100 and 150 mM concentration and K solutions of 0, 0.5, 1.0, and 1.5% concentration were sprayed at milking stage of two wheat varieties under stress (Auqab-2000; drought sensitive and Lasani-2008; drought resistant). The stress was created by withholding water up till appearance of wilting symptoms and then the solutes (alone and/or in combination) were sprayed with carboxymethyl cellulose as a sticking agent, whereas Tween-20 was used as a surfactant for foliar spray. At maturity, ten random plants from field-experiments and three in case of pot experiment were selected to estimate plant height, spike length, number of spikelets spike-1, number of grains spike-1, and grain yields. Besides, water potential, osmotic potential and turgor potential of crop were also estimated. The results indicated that the drought stress adversely affected all the above parameters. The exogenous application of GB and K to wheat significantly improved spike length, number of grain per spike and grain yields. Moreover, a significant interaction between these solutes was observed since at a given level of GB all these yield parameters were increased (p < 0.05) with K concentration. The highest values were obtained when GB and K were applied in combination at 100 mM and 1.5%, respectively. The same treatment also improved the leaf water potential, osmotic potential and turgor potential to maintain plant water potential gradient under stress. These findings lead us to conclude that application of GB and K (100 mM and 1.5%, respectively) is the best strategy to ameliorate the drought impact on wheat at milking stage with improved production.