Morphological and biochemical variations induced by synergy of salicylic acid and zinc in cockscomb

Abstract Celosia argentea var. cristata is an edible plant mainly cultivated as an ornament for its spectacular flowering and is highly appreciated by horticulturists for its originality, unique appearance of flower and better vase life. Utilisation of plant growth regulator [salicylic acid (SA)] and mineral nutrition [zinc (Zn)] is a sustainable approach to ameliorate crop health and yield. A field experiment was performed on a randomised complete block design with 12 treatments in 36 blocks to investigate the effectiveness of the combined application of SA (50 ppm and 100 ppm) and Zn (ZnSO4: 0.5 ppm, 1.5 ppm and 2.5 ppm) as well as when each one is applied separately on vegetative, reproductive, physiochemical attributes in C. argentea var. cristata. Results analysed through Tukey's honestly significant difference (HSD) test, biplot and heat map indicated a significantly greater improvement up to 2.5 folds in the growth attributes when plants received foliar application of 100 ppm of SA combined with 2.5 ppm of Zn as compared to control group. All treatments modified the physiobiochemical responses of plants by lowering catalase (CAT) activity significantly, and enhancing photosynthetic pigments, total protein content and peroxidase (POX) and polyphenol oxidase (PPO) activities as compared to the control group. It was concluded that foliar application of SA (100 ppm) + Zn (2.5 ppm) at pre-flowering stage could be applied to obtain better growth and flower quality in cockscomb.