Pepino (Solanum muricatum Aiton) is highly susceptible to Alternaria solani-induced early blight, a well-studied pathogen in other Solanaceae but rarely investigated in pepino. Although branching critically shapes plant architecture and environmental adaptability, its relationship with disease resistance remains unclear. Field trials compared natural growth (W1) and manual bud removal (W2); W2 showed a disease incidence of 51.0% ± 4.8, significantly lower than that of W1 (64% ± 4.8), and a reduced disease index (DI) of 3.79 ± 1.46 at 30 days after treatment. Pot experiments evaluated three plant growth regulators (PGRs): flumetralin (TA), pendimethalin (TB), and butralin (TC). All suppressed lateral buds, with TA most effective—achieving a 75.25% ± 1.23 bud suppression rate (BSR) and 61.00% ± 1.46 bud suppression efficacy (BSE), along with shorter plant height (16.0 ± 1.4 cm), thicker stems (7.43 mm ± 0.29), and larger leaves (12.39 cm2 ± 0.73) compared to the control. Under A. solani stress, PGR-treated plants exhibited markedly enhanced resistance, as evidenced by smaller lesion areas, elevated superoxide dismutase (SOD) and peroxidase (POD) activity, reduced malondialdehyde (MDA), and increased defense hormones—especially salicylic acid (SA) and indole-3-acetic acid (IAA). TA boosted SA and IAA by 2.25× and 2.35× compared to the control. These findings demonstrate that PGRs mediated bud suppression not only optimizes plant architecture but also strengthens antioxidant and hormonal defenses, offering a sustainable strategy for pepino production.
Ma et al. (Tue,) studied this question.