Prohexadione calcium and KH2PO4 synergy optimizes pod pepper plant architecture for mechanized harvesting and boosts yield and fruit quality.

Labor shortages and rising high labor costs are primary drivers of increased production costs in pod pepper cultivation. While mechanization represents a viable solution, current incompatibility between agronomic practices and agricultural machinery constrains its efficiency. This underscores the critical need for plant architecture regulation technologies to enable effective mechanized production. This study evaluated the effects of foliar spraying of plant growth regulator prohexadione calcium (ProCa) combined with different substances on the plant architecture, yield and quality of pod peppers. Five treatments were set up in the experiment: (1) ProCa, (2) ProCa + KH₂PO₄ (ProCa + KDP), (3) ProCa + boron (ProCa + B), (4) ProCa + mepiquat chloride (ProCa + MC), (5) water (CK). The results demonstrated that all treatments significantly altered pod pepper plant architecture indices relative to CK. Specifically, treatments reduced plant height and width, while increasing branch number and decreasing branch angles, with ProCa + KDP treatment exhibiting the most pronounced effects. These effects led to a compact and multiple-branched architecture conductive to mechanical harvesting. Meanwhile, ProCa + KDP treatment enhanced root activity and leaf pigment content of pod pepper during initial and full fruit stages. All treatments except ProCa + B increased fruit dry matter accumulation. ProCa and ProCa + KDP evaluated fruit yield primarily through increased fruit number per plant and individual fruit dry weight. Furthermore, ProCa + KDP treatment significantly improved fruit quality parameters versus control, elevating soluble protein, vitamin C and capsaicin contents. These findings demonstrate that foliar application of ProCa + KDP represents a promising strategy for optimizing plant architecture to enhance mechanized production suitability while simultaneously boosting pod pepper yield and quality.