Study of phenolics and related enzymes in the leaves of Brassica juncea (var. RLM 619) sprayed with salicylic acid under field conditions

Salicylic acid (SA) treatments of Brassica foliage of field grown plants were studied for the control of disease, Alternaria blight (Alternaria brassicae). The effect of these treatments on leaves collected randomly was evaluated. SA (10 ppm and 50 ppm) reduced the severity of leaf spotting disease in field by 32.5% as compared to the control. The activities of peroxidase, superoxide dismutase, phenylalanine ammonia lyase were found to be more than the control after 6th spray. Similar trend was observed regarding total phenols and o-dihydroxyphenols in leaves. Increased activities of enzymes were recorded up to 6th spray, where leaf samples were collected two days after each spray for six consecutive weeks.