| Abstract (English): |
To clarify the effects of biochar on the regulation of photosynthetic physiology, yield of continuous cropping soybean and its relationships under long-term conditions and to explore the feasibility of biochar application, four treatments were set up：CK（fertilizer application, no biochar application）, B1（biochar 12 t·hm-2 ）, B2（biochar 24 t·hm-2 ）, and B3（biochar 48 t·hm-2 ）in a long-term field trial. The effects of biochar application（9 years）on the material basis of photosynthesis, physiological functions, product accumulation, and yield of continuous cropping soybean were investigated. The results showed that the application of biochar enhanced the chlorophyll content （Chla, Chlb）, leaf area, and leaf area index of continuous cropping soybean significantly. At the same time, biochar enhanced the photosynthetic capacity of continuous cropping soybean, with a net photosynthetic rate（Pn）, transpiration rate（Tr）, stomatal conductance （Gs）, and water-use efficiency significantly increased, and the intercellular CO2 concentration（Ci）decreased. Additionally, the Pn, Tr, and Gs of the B3 treatment increased by 15.44%, 14.98%, and 117.73%, respectively, compared to the CK. Meanwhile, the biocharmediated endowment light energy conversion efficiency（Fv/Fm）, potential photochemical efficiency（Fv/Fo）, and heat dissipation quantum ratio（Fo/Fm）in the PSⅡ reaction center of continuous cropping soybean increased, and the plant efficiency of soybean photosynthesis was enhanced. Further, the soluble protein, soluble sugar, sucrose content, and leaf dry matter weight of the biochar-treated continuous cropping soybeans increased to varying degrees, and the accumulation of photosynthetic products increased. The final yields showed that the biochar treatments were higher than the CK, with the soybean yields of the B2 and B3 treatments being 7.69% and 15.38% higher than the CK, respectively. Further correlation analysis showed that the long-term biochar-mediated yield response of continuous soybean cropping was closely related to Chla, Pn, Tr, and Gs, as well as leaf soluble sugar content, important factors contributing to the yield enhancement of continuous soybean. Biochar application enhanced photosynthetic physiological functions of the soybean, promoted the accumulation of photosynthetic products, and increased the yield of the continuous cropping soybean. [ABSTRACT FROM AUTHOR] |
