Hormonal dynamics in contrasting bearing habits of mango grafted on different rootstocks

Mango productivity is heavily dependent on the physiological transition from vegetative to reproductive growth, yet the integrated role of rootstock-mediated hormonal crosstalk in regulating these reproductive traits remains poorly understood. This study evaluated hormonal profiles and reproductive traits in regular-bearing ‘Amrapali’ and alternate-bearing ‘Dashehari’ grafted onto four rootstocks. Eight scion–rootstock combinations were evaluated with three biological replicates each. Leaf and bud concentrations of indole-3-acetic acid (IAA), gibberellic acid (GA 3 ), zeatin and abscisic acid (ABA) were quantified using high-performance liquid chromatography, alongside assessments of flowering traits. Hormonal concentrations exhibited scion × rootstock × tissue interactions, with Kurukkan-associated bud IAA exceeding leaf concentrations in Amrapali (10.37 versus 4.92 ng g⁻ 1 ) and Dashehari (9.93 versus 1.40 ng g⁻ 1 ). Bud GA₃ also exceeded leaf concentrations under Kurukkan in both cultivars, whereas ABA showed contrasting tissue distributions. Amrapali/Olour produced the highest total flower number (1,077.33 per panicle), whereas Amrapali/PAM-2 exhibited the greatest hermaphrodite flower number (372.67 per panicle) and proportion (38.78%). Exploratory correlations associated bud zeatin with male flower number in Amrapali (r = 0.963, P = 0.037) and bud ABA with panicle length in Dashehari (r = 0.962, P = 0.038). These findings indicate rootstock-associated hormonal and reproductive variation without establishing causal relationships.