Influence of Exogenous Glycinebetaine on Hot Pepper under Water Stress

A study was conducted to evaluate the effect of exogenous application of glycinebetaine (GB) on physiological response in hot-pepper (Capsicum annuum L. vs. Arka Lohit and Pusa Jwala) under water stress. Glycinebetaine was applied to seeds as well as plants through foliar applications. Water stress affected considerably the morphophysiological parameters in both the cultivars. However, in glycinebetaine (GB) treated plants, plant height, leaf area (LA), flower and fruit number and total dry matter (TDM) were greater compared to the untreated stress plants (T4) under water stress. Glycinebetaine application enhanced the photosynthesis (P_N) in water deficit experiencing plants, mostly due to a greater stomatal conductance (g_s) and carboxylation efficiency of CO₂ assimilation. In both the cultivars after 12 day of stress, the P_N decreased from 10.1 to 1.0-1.3 μ mol m^-2 s^-1 in untreated stressed plants (T4), while in the treated stressed plants P_N had reduced to 2.0 - 3.0 μ mol m^-2 s^-1 (T1 - T3). The application of GB increased the WUE in both the cultivars. The better WUE in treated plants of hot-pepper under stress was attributed to the improved P_N. The higher per plant yield in the GB applied plants under stress in both the cultivars associated with higher P_N rate, gs and WUE in treated plants. Though there was an increase in P_N rate, WUE and plant yield in the treated plants (T1 - T3), the better results were found in the plants (T2) where seeds were treated and foliar application was given at the time of imposing stress.