Effect of NAA, PGPR, and micronutrients on flowering phenology and fruit set behavior of mango (Mangifera indica L.) cv. Amrapali

Abstract

The present investigation was conducted was conducted at at Horticulture complex, Department of Horticulture, JNKVV, Jabalpur (M.P.)to investigate the combined effect of Naphthalene Acetic Acid (NAA), Plant Growth-Promoting Rhizobacteria (PGPR - Pseudomonas sp.), and micronutrients (ZnSO4 + borax) on flowering phenology and fruiting behavior of mango cv. Amrapali. The study was laid out in a factorial randomized block design with three replications and 27 treatment combinations consisting of three factors: PGPR (Pseudomonas at 0%, 0.5%, and 1%), NAA (0, 20, and 40 ppm), and micronutrients (ZnSO4 + borax at 0%, 0.5%, and 1%). Results revealed that the combined application of 1% PGPR, 40 ppm NAA, and 1% micronutrients (P2N2M2) significantly accelerated 50% panicle emergence (8.50 days) and 50% flowering (41.83 days), while also producing the most robust panicles (32.67 cm length with 35.5 paniclelets). For fruiting behavior, the combination of 1% PGPR, 20 ppm NAA, and 1% micronutrients (P2N1M2) was superior, achieving the highest initial fruit set (3.96% at pea stage) and final fruit retention (0.56%). These findings demonstrate that the integrated foliar application of PGPR, NAA, and micronutrients creates a synergistic effect, significantly improving flowering phenology and fruit retention, thereby offering a sustainable and effective strategy to enhance the yield potential of mango cv. Amrapali.