Understanding fruit drop: Causes, mechanisms, and management strategies: A review

Abstract

Fruit drop is a widespread physiological disorder that significantly reduces yield, fruit quality, and economic returns across tropical and subtropical fruit crops. It results from the formation and activation of an abscission zone at the fruit pedicel, driven by complex interactions among anatomical, physiological, genetic, and environmental factors. Hormonal imbalances particularly reduced auxin flow and elevated ethylene and abscisic acid levels play a central role in triggering abscission. Environmental stresses such as drought, high temperatures, frost events, nutrient deficiencies, and biotic pressures further intensify these hormonal signals, leading to excessive shedding at different developmental stages. Fruit crops like mango and citrus exhibit characteristic waves of fruit drop (e.g., post-set, June drop, pre-harvest), each influenced by specific physiological processes. Advances in molecular biology and transcriptomics have highlighted intricate hormonal crosstalk involving auxin, ethylene, ABA, and jasmonates, offering deeper insight into abscission regulation. Effective management strategies including optimized nutrition, irrigation scheduling, plant growth regulators (NAA, GA₃, 1-MCP, AVG), canopy management, and stress-mitigation practices can substantially reduce fruit drop. This review synthesizes current knowledge on the causes, mechanisms, and management approaches for fruit drop, providing a comprehensive framework for improving fruit retention and productivity in major fruit crops.