The Regulatory Effects of Different Girdling Treatments on Leaf Senescence Characteristics and Fruit Quality in Kiwifruit

This study elucidates the regulatory mechanisms of girdling on leaf senescence and fruit quality in ‘Jinyan’ kiwifruit, providing a theoretical basis for high-yield and high-quality cultivation. Ten-year-old vines were subjected to single (5 mm, 9 mm) and double (5 mm, 9 mm) girdling treatments at two distinct stages: peak flowering stage (Group A) and 10 days post-anthesis (Group B). Physiological markers, including reactive oxygen species (ROS) and antioxidant enzyme activities, were monitored at 10, 35, and 70 days post-treatment and integrated with fruit quality metrics using Principal Component Analysis (PCA). Physiologically, girdling induced a transient oxidative burst, characterized by increased ROS accumulation proportional to girdling intensity. This triggered a robust antioxidant defense response, where superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities peaked at 35 days, effectively mitigating oxidative damage (MDA) during the healing phase. Concurrently, metabolic substrates (soluble protein, starch, and sugar) were significantly enriched in leaves. Agronomically, all treatments enhanced fruit yield, single-fruit weight, and soluble solids content (SSC). Notably, double girdling treatments specifically promoted fruit elongation and dry matter accumulation. Comprehensive evaluation identified distinct optimal strategies: while moderate single girdling (A2) was superior during flowering, double girdling (B3, B4) proved most effective post-anthesis. Ultimately, double girdling performed 10 days post-anthesis emerged as the optimal regimen, effectively balancing source-sink relationships to maximize both physiological function and fruit quality.