Calcium supplementation in nutrient solutions to mitigate salt stress in fertigated okra

ABSTRACT The objective of this study was to evaluate the effect of calcium supplementation on saline water as a minimizing agent of saline stress in okra cultivars. The experiment was carried out in a greenhouse in Mossoró-RN using a completely randomized experimental design in a 2x5 factorial scheme with four replications. Two okra cultivars (Santa Cruz 47 and Valença) were tested fertigated with five fertigation managements [F1= irrigation with non-saline water (0.5 dS m-1) and fertigation with a standard dose of calcium (4,733.8 mg plant-1); F2, F3, F4 and F5= irrigation with saline water (3.5 dS m-1) and fertigation with increasing doses of calcium (4,733.8; 7,100.7; 9,467.7 and 11,834.5 mg plant-1, respectively)]. Plants were collected at 120 days after emergence and evaluated for growth variables (plant height, leaf number, stem diameter, leaf dry mass, stem, fruit and total) and yield (fruit number, average length of fruits, average diameter and yield). Cultivar Santa Cruz 47 presented the highest vegetative development but cultivar Valença was earlier and presented the largest number of harvests (19), allowing more harvested fruits (27 fruits per plant) and the highest yield (659 g plant-1). The cultivars were not affected by the saline level and showed little response to extra calcium fertilization.