Comparative analysis of exogenously applied synthetic auxin for fruit drop management and quality enhancement in date palm.

BACKGROUND: Fruit drop and quality deterioration are major constraints limiting date palm (Phoenix dactylifera L.) productivity, particularly under environmental constraints. While plant growth regulators (PGRs), particularly synthetic auxins like 2,4-Dichlorophenoxyacetic acid (2,4-D), have demonstrated potential in managing these physiological limitations, cultivar-specific responses and optimal application protocols remain insufficiently characterized. RESULTS: This study evaluated the impact of foliar-applied 2,4-D at three concentrations (25, 50, and 75 mg/L) on fruit retention and quality traits in two date palm cultivars under field conditions. Application of 2,4-D, particularly at 50 mg/L during the kimri stage, significantly improved key agronomic parameters, including bunch weight, fruit and pulp weight, fruit length and width, and moisture content. Fruit quality parameters such as total soluble solids (TSS), total sugars, reducing and non-reducing sugars, ascorbic acid, and tannins were also enhanced. Furthermore, antioxidative enzymes peroxidase and catalase, flavonoids, and phenolic content were significantly higher compared to the untreated control. Among the tested cultivars, differential responses were observed, with one cultivar consistently showing superior outcomes in terms of fruit quality. CONCLUSION: The exogenous application of 2,4-D demonstrated a positive effect on reducing fruit drop and enhancing both physical and quality traits in date palm cultivars. These findings suggest that 2,4-D can serve as an effective tool in sustainable date palm production by improving yield and fruit quality under stress conditions.