The Impact of Potassium Phosphite on Growth Parameters and Antioxidant Activities of Lime (Citrus aurantifolia (Christm.) Swingle) under Salinity Conditions

Salinity is among the abiotic stresses restricts citrus growth. In this regard, the selection of appropriate method to improve growth characteristics and antioxidant response under salt stress conditions can be useful. The present pot research was conducted as factorial reperiment in a completely randomized design with three replications in the greenhouse of University of Hormozgan during 2021. The used lime plants were six-month-old seedlings (height about 60 cm) healthy and disease-free. Experimental treatments were included salinity (1.5, 3, 4.5, and 6 dS/m) and potassium phosphite (0, 1.5, and 3 g L-1). The results revealed the 6 dS/m of salt led to a decrease in leaf number, stem length and root volume (25.27, 13.8 and 47.8% respectively) and increased ion leakage and malondialdehyde (50.47 and 34.5%, respectively). Application of potassium phosphite (1.5 g L-1) increased leaf number, stem length, root volume and root length (33.87%, 32.38%, 15.5% and 11.05%, respectively). In addition, the potassium phosphite treatment increased protein content and activity of catalase, superoxide dismutase, phenylalanine ammonialyase, guaiacol peroxidase and ascorbic peroxidase (36.9, 95.97, 69.1, 30.20, 65.7 and 78.5%, respectively) and decreased ion leakage and malondialdehyde (75.7% and 40.6%, respectively). Based on the results, it can be expected that potassium phosphite (1.5 g L-1) by stimulating the antioxidant system and neutralized oxygen free radicals, improves growth characteristics and moderates the harmful effects of salinity stress in lime.