BIO STIMULANT ACTIVITY OF CHITOSAN DISSOLVED IN DIFFERENT ORGANIC ACIDS ON TOMATO PLANT

Abstract

This study aims to evaluate and compare the stimulant capabilities of the foliar application of chitosan, dissolved in aqueous solutions of four organic acids (acetic acid, ascorbic acid, citric acid, and malic acid), on tomato (Solanum lycopersicum L.). A pot experiment was carried out under greenhouse conditions during the summer season. Morphological traits, photosynthetic pigments, ascorbic acid, total phenol, osmolytes, antioxidant enzyme activities (peroxidases, polyphenol oxidases, Superoxide dismutase, and catalase), and yield parameters were evaluated. The results indicated that chitosan treatments showed improvements in almost all aforementioned parameters, these responses were different according to the associated organic acid. Moreover, chitosan treatments, compared to control, significantly increase all the studied yield parameters in tomato plants, especially chitosan dissolved in an aqueous solution of malic acid and ascorbic acid that gave the most potent effect regarding the number of flower/ plant, the number of fruits, as well as the weight of fruits/ plant in comparison with plants treated with chitosan dissolved in an aqueous solution of citric acid, or acetic acid, respectively. Since it is a non-toxic, biocompatible, biodegradable, and available material in the global market, the foliar application of chitosan, especially that dissolved in aqueous solutions of ascorbic or malic acids, are recommended to be used as commercial applications under normal conditions (not stressed) as pre and after flowering biostimulants to improve tomato plant health and thus increasing the yield. The results can be extended to all the plants of the family Solanaceae after further investigations.