Effect of Light Duration and Calcium on Growth, Yield and Quality of Lettuce (Lactuca sativa cv. New Red Fire)

In order to study the effects of calcium and light duration on growth and quality of lettuce, this experiment was conducted as split plot based on the randomized complete design with three replications, in research greenhouse of University of Zanjan during 2020. The main plot consisted of light treatments at two levels included natural light duration (an average 7000-8000 lux) and natural light in addition four hourse complementary light (600 lux) and the subplot was consisted of three levels of calcium lactate (0.5, 1 and 1.5 g L-1(, calcium chlorid (3, 6 and 9 g L-1) and distilled water as a control. The results showed that increasing light duration significantly increased leaves number, plant fresh weight, total chlorophyll, phenols and flavonoids, vitamin C and anthocyanin contents. Application of calcium chlorid (6 and 9 g L-1) and calcium lactate (1.5 g L-1 ( increased plant fresh weight (10.3, 10.5 and 11.6 g) and Ca concentration of internal leaves (12.8, 12.9 and 12.2%) lettuce, and inhibiet tip burn disorder in lettuce lives. The highest tip burn leaf number (3.5) was observed in plants whitout Ca teated under complementary ligh treatment. Also the highest amount of plant fresh weight, anthocyanin, total phenol and flavonoids and antioxidant capacity was obtained by using calcium lactate 1.5 and calcium chloride 3 and 6 g L-1 with increasing light duration. According to the results, application of calcium lactate 1.5 g L-1 and calcium chlorid 6 and 9 g L-1 with increasing light duration can be preposed to improve growth and quality of lettuce.