Influence of girdling on flower sex ratio, biochemical constituents, and fruit set intensity in mango (Mangifera indica L.)

The study was conducted in mango to understand the relationship of various metabolites with flower sex ratio (hermaphrodite/male) and fruit set using stem girdling technique. Girdling one year old branches was carried out in two cultivars, Mangifera indica 'Alphonso' and 'Totapuri' to retain 50, 100 and 150 leaves to vary the content of hormones, sugars, total carbohydrates, and amino acids. The increased leaf number was found to increase the total carbohydrates, glucose, fructose, and other sugars. Girdling also significantly increased the concentration of abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), indole acetic acid, indole butyric acid but decreased gibberellins and cytokinins. Amino acids also increased in the girdled branches. Girdling improved the flower sex ratio as well as fruit set more efficiently in 'Alphonso' than in 'Totapuri'. Results indicate that the increase in production of hermaphrodite flowers may be more related to the higher production of growth inhibitors, like ABA, SA, and JA along with increased concentration of sugars. Increased auxin concentration also might play an important role in increasing the fruit set.