Effect of Saline Stress and Calcium Nitrate on Lettuce Grown on Coconut Fiber

This study aimed to evaluate the use of saline solutions enriched with calcium nitrate in the production of lettuce grown in coconut fiber. The experiment was carried out from July to August 2017 in a greenhouse, at the Federal Rural University of the Semi-Arid Region (UFERSA), Mossoró-RN, Brazil. A randomized block design was used, in 2 × 5 factorial scheme, with three replicates. Treatments resulted from the combination of two lettuce cultivars [Elba (Curly) and Irene (Crisphead)] and five nutrient solutions (S1- standard nutrient solution; S2-S1 + NaCl (28.48 mmol L-1); S3-S2 + Ca(NO3)2 (6.89 mmol L-1); S4-S2 + Ca(NO3)2 (9.15 mmol L-1); S5-S2 + Ca(NO3)2 (11.43 mmol L-1)]. Plants were harvest 30 days after transplantation and the following variables were analyzed- head diameter, stem diameter, number of leaves, fresh weight, dry weight, leaf area, specific leaf area and leaf succulence. The cv. Irene (Crisphead) is more tolerant to nutrient solution salinity compared with the cv. Elba (Curly). Nutrient solutions enriched with 50 and 100% of Ca(NO3)2 promoted better performance of the cultivars Elba and Irene, respectively, fertigated with saline nutrient solution.