Effects of compound fungi inoculant application on growth, root configuration, and photosynthetic characteristics of Chinese flowering cabbage cultivated in continuous cropping soil

Abstract [Objective] The study aims to explore the effects of compound fungi inoculant application on the growth, root morphology, and photosynthetic characteristics of Chinese flowering cabbage seedlings, and provide a theoretical basis for the application of compound fungi inoculant to alleviate the obstacle of continuous cropping of Chinese flowering cabbage. [Methods] The Chinese flowering cabbage variety ‘Jianye- 70’, with which microbial agents and soil had been continuously cropped for 9 years, were used in pot experiments. Four treatments were set up: No compound microbial agents (control), foliar spraying, soil spraying, and foliar spraying plus soil spraying. The plant growth indicators, root system configuration, and leaf photosynthetic characteristics were observed after sowing for 30 days. [Results] Every application method could increase growth indicators, root system conformation, leaf photosynthetic characteristics net photosynthetic rate (Pn), actual photochemical efficiency (ΦPSⅡ ), and photochemical quenching coefficient (qp) etc., as well as decrease transpiration rate (Tr), intercellular carbon dioxide concentration (Ci), and non photochemical quenching coefficient (NPQ) etc. Among the application methods, foliar spraying had the best effect. Its above-ground and underground dry weight and root length were significantly increased by 128.57%, 85.71%, and 91.81%. Pn, qp, and ΦPSⅡ were significantly increased by 24.55%, 22.68%, and 23.93%, while Tr, Ci, and NPQ were significantly decreased by 72.73%, 20.01%, and 39.78%, respectively. [Conclusion] Foliar spraying of compound fungi can effectively promote the growth of continuous cropping cabbage seedlings, improve root configuration, enhance plant photosynthetic efficiency, which is the best way of compound fungi application