IMPACTS OF WATER STRESS AND HARVEST TIME ON PHYSIO-BIOCHEMICAL CHARACTERISTICS OF LETTUCE

Abstract

Water scarcity has emerged as a serious concern for the agricultural sector. There is an urgent need to conserve the existing water resources by using them economically. Moreover, we can prevent excessive use of water in agriculture by determining the water requirement of plants during different periods. In this study, we determined the changes in the growth and physiological and biochemical contents of lettuce grown under limited irrigation conditions during different developmental periods. The study was designed with three replications in a random trial pattern of 20 parcels. Five irrigation levels, namely I₁₀₀, I₈₀, I₆₀, I₄₀, and I₂₀, and four harvest times, were used according to the development period of lettuce. The principal component analysis revealed significant changes in physiological and biochemical parameters, such as leaf water content (LWC), membrane damage (MD), carotenoids (CT), protein (PT), proline (PL), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), under water stress conditions in lettuce. In addition, significant changes in growth parameters were observed during harvest periods. Water productivity (WP) values ranged from 6.81 to 22.83 g/L, and the highest WP value was obtained at I₁₀₀ irrigation level and harvest-IV. The I₁₀₀ irrigation level in the fourth harvest period yielded the best results. The results show that water could be saved with limited irrigation in arid and semi-arid regions, with water scarcity of 48 days, after planting the lettuce seedlings.