Interactive effects of gibberellic acid and NPK on morpho-physio-biochemical traits and organic acid exudation pattern in coriander (Coriandrum sativum L.) grown in soil artificially spiked with boron.

It was aimed to examine the role of gibberellic acid (GA) and NPK fertilizer in alleviating boron (B) toxicity in coriander (Coriandrum sativum L.) plants. Two weeks old C. sativum seedlings were subjected to different NPK fertilizers [low NPK (30 kg ha) and normal NPK (60 kg ha)], which were also supplied by GA (50 mg L), under varying levels of B i.e., 0, 200 and 400 mg kg in the soil. Results revealed that B toxicity led to a substantial decreased in the plant growth and biomass, photosynthetic pigments, gas exchange characteristics, sugars and essential nutrients in the roots and shoots of C. sativum seedlings. However, B toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of malondialdehyde (MDA), which is the indication of oxidative stress in C. sativum seedlings and was also manifested by hydrogen peroxide (HO) contents and electrolyte leakage (EL) to the membrane bounded organelles. Although, activities of various antioxidative enzymes like superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), non-enzymatic antioxidants like phenolic, flavonoid, ascorbic acid and anthocyanin contents and organic acids from the roots such as oxalic acid, malic acid, formic acid, citric acid, acetic acid and fumaric acid contents were increased with the increasing levels of B in the soil. The application if NPK and GA mitigated B toxicity by stimulated plant growth and biomass, photosynthetic efficiency, nutritional status and antioxidant machinery of the plant by decreasing MDA contents, HO initiation and EL (%) in the roots and leaves of C. sativum seedlings. In addition, the application of NPK and GA further decreased the organic acids exudation contents in the roots C. sativum seedlings. Research findings, therefore, suggested that NPK and GA application can ameliorate B toxicity in C. sativum seedlings and resulted in improved plant growth and composition under B stress as depicted by balanced contents of organic acids.