The effect of calcium lactate foliar spray on growth, yield and quality of lettuce cv. New Red Fire under water deficit stress

In order to investigate the effect of calcium lactate (CL) on growth, yield, water use efficiency (WUE) and quality of lettuce cv. New Red Fire under water deficit stress, a split plot experiment based on randomized complete block design with three replications was conducted at Research Farm of University of Zanjan, during 2017. Treatments consisted arrangement of three levels of CL (0, 0.75 and 1.5 g.l-1) and three levels of irrigation (starting irrigation at 100, 85 and 70% ETc (crop evapotranspiration)). The results showed that water deficit stress significantly reduced plant growth and yield. The lowest value of yield (9644.2 Kg.ha-1), total chlorophyll (0.51 mg gFW-1), vitamin C (44.48 mg.100gFW-1) and titratable acidity (19.55 %), and the highest carotenoids (0.251 mg.gFW-1), anthocyanin contents (26.56 μmol.g-1) and WUE (15.37 kg.m-3) were obtained at deficit irrigation 70% ETc. Irrigation treatment had no significant effects on total soluble solid content. Application of CL significantly increased total chlorophyll, carotenoid, vitamin C, titratable acidity, anthocyanin contents, plant yield and WUE. The highest plant yield (13710.77 Kg.ha-1), vitamin C (48.05 mg.100gFW-1) and total chlorophyll contents (0.64 mg.gFW-1) were obtained with application of CL 1.5 g.l-1 under irrigation 100% ETc. Also, the interaction effects of treatments had no significant effect on titratable acidity and TSS. According to the results, application of CL 1.5 g.l-1 is recommended to improve yield, WUE and quality of lettuce under normal irrigation and water deficit stress.