Evaluation of different levels of calcium lactate on morpho-physiological characteristics of lettuce cv. New Red Fire under water deficit stress

Lettuce (Lactuca sativa L.) is an annual plant and the most important vegetable salad in the world. Water stress is one of the most important environmental stresses that limitsthe growth and production of plants around the world. Calcium plays a role in the regulation of various mechanisms of plants under environmental conditions such as water stress, heat, cold and salinity. In addition, calcium is needed to reduce the adverse effects of water stress on plants and increase the tolerance to dehydration. Therefore, this experiment was conducted to evaluate the effect of calcium lactate (CL) on some of the morphophysiological characteristics of lettuce cv. New Red Fire under water deficit stress conditions, a split-plot experiment based on randomized complete block design with three replications was conducted in Zanjan climatic conditions during 2017. Experiment treatments consisted of three different irrigation regimes (70, 85 and 100 %ETc) as the main factor and calcium lactate at three levels (0, 0.75 and 1.5 g.l-1) as a sub-factor. The water requirement of the plant for control treatment was estimated using the long-term average of daily data and current year data of meteorological indicators recorded at Zanjan Meteorological Station and the FAO-Penman-Mantis standard. Water requirement of other treatments was estimated and distributed based on the water requirement of control treatment and water stress. Based on the results of this study, water deficit stress significantly increased the peroxidase and catalase enzymes activity and decreased the chlorophyll a, b and total contents, leaf number, leaf fresh and dry weight and yield. The foliar application of 1.5 g l-1 CL under water deficit stress significantly increased leaf number chlorophyll content and plant yield. According to the results, application of 1.5 g l-1 CL treatment under water deficit condition with increasing growth and enzymes activity improved plant yield that this positive effect of calcium in improving stress tolerance can be attributed to regulate of water status, antioxidant activity systems, osmolithics accumulation, improving photosynthetic pigment content, and nutritional balances.

Keywords:

Water deficit stress , Catalase , Peroxidase , Calcium lactate , Yield