Effect of Drought Application on Flower, Yield and Leaf Mineral Content of Durian (cv. Monthong) in Cambodia

Abstract

While synthetic plant growth regulators (PGRs) like paclobutrazol and chlorate compounds are conventionally used to suppress gibberellic acid and induce flowering, their chronic application results in chemical residues, strict export phytosanitary violations, and tree dieback. Water deficit (water stress) presents a sustainable alternative by naturally mimicking chemical retardants to trigger reproductive shifts. However, the exact physiological mechanisms underlying this transition remain incomplete. This study addresses this gap by investigating the dynamic fluctuations of critical macronutrient (N, P, and K) alongside leaf-tissue carbon balances during water deficit to induced flowering. the duration of induced drought stress significantly regulates both the reproductive performance and internal foliar nutrient dynamics of the crop. Prolonged moisture deficit over 28 days markedly optimizes reproductive phenology, driving a significant increase in floral density (P = 0.012), which directly enhancements in fruit-set (P < 0.001) and harvested fruit count (P < 0.001). Consequently, total crop yield per tree significantly increased by roughly 30.7%, without altering individual fruit weight or fruit drop percentages. Physiologically, these reproductive advancements are accompanied by significant alterations in leave macronutrient status; as drought duration extends to 28 days, leaf nitrogen and phosphorus concentrations significantly decline to minimum thresholds of 1.69% (P = 0.006) and 0.146% (P = 0.009), respectively, whereas potassium and total carbon levels remain unaffected. This drives a significant upregulation of the leaf C/N ratio from 25.78 to 30.13 (P = 0.007), identifying this physiological carbon-nitrogen balance as a critical operational mechanism underlying drought (water deficit) mediated floral induction and enhanced yield productivity.