Effects of chemical fertilizer reduction and application of microbial fertilizers on the photosynthetic physiological characteristics of Lilium davidii var. willmottiae

Abstract [Objective] The study aims to explore the effects of chemical fertilizer reduction and application of microbial fertilizers on growth and photosynthetic physiological characteristics of Lanzhou lily (Lilium davidii var. willmottiae), and to provide scientific fertilization management for continuous cropping of Lanzhou lily. [Methods] From 2019 to 2021, fertilization was applied in the experimental field of Lanzhou lily located in alpine humid area in Gansu Province. The studies set up three different treatments: 100% chemical fertilizers (control), chemical fertilizer reduction by 30% with microbial fertilizers, and chemical fertilizer reduction by 50% with microbial fertilizers. After three years of continuous fertilization, the changes of physiological indexes such as growth, photosynthetic characteristics, and antioxidant enzyme activity of Lanzhou lily were investigated. [Results] Compared with control, chemical fertilizer reduction by 30% and 50% with microbial fertilizers improved seedling index, photosynthetic characteristics, and antioxidant enzyme activities of Lanzhou lily to different degrees, with the treatment of fertilizer reduction by 30% with microbial fertilizers had the best effect. Under the treatment of fertilizer reduction by 30% with microbial fertilizers, plant height, stem thickness, leaf area, underground biomass, and seedling index were increased. The photosynthetic pigment content was increased. Maximum photochemical efficiency of PSⅡ, actual photochemical quantum efficiency, electron transfer rate increased, none photochemical quenching coefficient were decreased. The enzyme activity of the antioxidant (SOD, POD, CAT, APX) was increased. The content of osmoregulatory substances (proline, soluble protein) was increased. The content of malondialdehyde was decreased, and the root vitality was enhanced. [Conclusion] The treatment of fertilizer reduction by 30% with microbial fertilizers promotes the growth of Lanzhou lily, enhances leaf photosynthesis, improves protection enzyme activities and osmoregulatory substances, alleviates the degree of membrane lipid peroxide, and improves root vitality.This treatment effectively improves the cultivation environment of continuous cropping Lanzhou lily.