Effects of Bioorganic Fertilizers on the Leaf Antioxidant Enzyme Activity and the Photosynthetic Characteristics of Replanted Szechuan Pepper, Zanthoxylum simulans

Continuous cropping obstacles hamper the efficient growth and yield of Szechuan pepper, Zanthoxylum simulans. The current study investigated the impact of different levels of bioorganic fertilizer on the leaf physiological and photosynthetic characteristics of Z. simulans to provide a theoretical reference for continuous Z. simulans crop cultivation. A bioorganic fertilizer was used to treat seedlings growing in 25-year-old continuous cropping soil. Five fertilizer treatments were applied. The impacts of the treatments on the activity of defense enzyme and photosynthetic parameters of Z. simulans leaves were determined. The different concentrations of bioorganic fertilizer reduced to varying degrees the malondialdehyde (MDA) content and intercellular CO₂ concentration (Ci), and increased the activity of peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), as well as the chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of Z. simulans leaves. The results showed that most significant increases or decreases were achieved with 100 g/L bioorganic fertilizer (Y2). Thus, the application of bioorganic fertilizer at a rate of 100 g/L can significantly improve the activity of relevant defense enzymes and photosynthetic parameters of Z. simulans, and reduce the MDA content, enhancing the stress resistance of the plants, promoting their growth and addressing, to some extent, obstacles associated with continuous cultivation.