Foliar fertilization, an efficient agricultural production strategy, is relatively rare in bamboo cultivation and management. Phosphorus assumes an indispensable role in controlling plant sugar metabolism and antioxidant defense. Whether foliar application of triple superphosphate (TSP) can enhance carbohydrate metabolism in new bamboo leaves, improve the antioxidant defense system, and thereby promote the growth and development of new leaves remains to be investigated. In this study, we conducted foliar application of TSP on the new leaves of 1-year-old Neosinocalamus affinis culms to analyze the effects of exogenous phosphorus on leaf morphological, anatomical, and physiological characteristics. The results showed that 0.3% TSP was the optimal concentration. This treatment significantly increased leaf length (maximum growth rate of 24.3% on day 21) and mesophyll cell thickness. It also significantly increased total chlorophyll content (maximum increase rate of 71.10% on day 14). The 0.3% TSP treatment significantly enhanced the activities of critical enzymes involved in sucrose biosynthetic and catabolic processes and starch synthesis, inhibited starch degrading enzyme activity, and promoted the accumulation of soluble sugars, starch, and total non-structural carbohydrates. Furthermore, TSP treatment significantly increased the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and significantly reduced the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) (45.11% and 54.64% reduction on day 7, respectively), indicating effective alleviation of oxidative stress and enhanced leaf stress resistance. Generally, foliar application of 0.3% TSP synergistically optimized leaf structure, photosynthetic capacity, sugar metabolism, and antioxidant defense system, comprehensively promoting the development of new N. affinis leaves and enhancing their stress resistance.
Wang et al. (Tue,) studied this question.