Temporal Dynamics of Azadirachtin Accumulation and Identification of Optimal Harvest Stage in Azadirachta indica A. Juss

Abstract

Azadirachtin, a major tetranortriterpenoid from Azadirachta indica A. Juss., is widely utilized in eco-friendly pest management owing to its potent insecticidal and growth regulating properties. However, azadirachtin accumulation varies with fruit developmental stage, thereby influencing extraction efficiency and commercial value. The present study evaluated temporal variation in azadirachtin content across four fruit developmental stages (9th, 13th,17th, and 19th weeks after anthesis) in selected high and low azadirachtin neem genotypes. Azadirachtin accumulation increased progressively from early developmental stages and reached a maximum at the 17th week after anthesis (0.87 ± 0.026% in high genotypes and 0.39 ± 0.014% in low genotypes), followed by a decline at the 19th week. Two-way ANOVA revealed highly significant effects of developmental stage (F = 147.93, p < 0.001) and genotype category (F = 1616.02, p < 0.001) on azadirachtin content, whereas their interaction was not significant (p = 0.103). LSD analysis (CD = 0.031) confirmed significant differences among all developmental stages, with the 17th week recording the highest azadirachtin accumulation. The observed trend indicates maximum triterpenoid accumulation during physiological maturity, followed by a decline during fruit ripening. The study establishes the 17th week after anthesis (hard green stage) as the optimal harvest stage for maximizing azadirachtin yield and provides a scientific basis for standardizing harvest timing for improved neem-based biopesticide production. This study could serve as a basic information for the farmers to collect the fruits at their harvestable maturity for better returns.