Leaf Carbon Assimilation Of Maize And Soil Microbial Biodiversity In Maize/Oyster Mushroom Intercropping

Maize?Zea mays L.?is not only one of the three major food crops in the world,but also a high-quality animal feed and important industrial raw material.Maize production in China accounts for 21.9%of total maize output.The northeast area is the largest maize production area in China,especially in Jilin province,which accounts for 1/8th of maize production.However,the maize planting patterns in the Northeast China based on conventional agricultural practices?e.g.,monoculture cropping,tillage and removal of crop residues?caused soil erosion and fertility decline.Therefore,conservation agricultural practices such as intercropping,no tillage and mulching,benefited the soil quality and maintained crop productivity.In terms of practice,the maize/oyster mushroom intercropping has achieved outputs yet,few experiment have been conducted to investigate the carbon assimilation of maize leaves and soil microbial community diversity during the intergrowth period of maize/oyster mushroom intercropping under the high-efficiency protective planting pattern of maize in central Jilin Province.There were setup monoculture maize?C?and maize/oyster mushroom intercropping?CM?treatments.This study evaluated the effects of maize/oyster mushroom intercropping on carbon assimilation in maize leaves and the structure,diversity of soil microbial community at 0²0 cm soil depth in the black soil zone of northeast China.The soil microbial community was characterized by Illumina MiSeq sequencing.The main results were following:Intercropping significantly increased the air humidity and CO₂ concentration during the intergrowth period of maize and mushroom?7/11⁸/23?,which improved the microclimate of the maize field.At the interval of first and second mushroom peak period,compared with the monoculture maize,the air humidity and CO₂concentration in the intercropping field showed a downward trend,and the difference was significant reduced.Intercropping has a significant effect on the soil physiochemical properties.At the interval of first and second mushroom peak period,intercropping increased soil pH,while decreased the contents of organic matter?SOM?,total nitrogen?TN?,nitrate nitrogen?NO₃^--N?and ammonium nitrogen?NH₄⁺-N?,compared with monoculture maize.At the end of mushroom harvest period,soil pH were higher than monoculture maize under intercropping conditions?P<0.05?.Intercropping changed soil microbial community structure,significantly improved bacterial and fungal diversity,and promoted bacterial carbon and nitrogen metabolism.At the interval of first and second mushroom peak period,intercropping reduced the relative abundance of Sphingomonas and Rhodobacter?P<0.05?.At the second peak mushroom,intercropping increased fungal operational classification unit?OTU?richness,and relative abundance of Proteobacteria and bacterial amino acid metabolism,and reduced the relative abundance of Phoma and Penicillium?P<0.05?.At the end of mushroom harvest period?8/22?,intercropping increased bacterial OTU richness,Shannon index,and relative abundance of Fusarium and carbohydrate metabolism?P<0.05?.Redundancy analysis showed that soil SOM and pH played a key role in bacterial community structure;soil pH and TN had a significant impact on fungal community distribution.Correlation analysis showed that the Shannon index of bacteria was positively correlated to TN,while the Shannon index of fungi was negatively correlated to TN,NO₃^--N and NH₄⁺-N?P<0.05?.Intercropping increased the carbon assimilation efficiency of maize leaves,which laid the foundation for the accumulation of photosynthetic products in the middle and late stages of maize growth.At the first mushroom peak period,intercropping significantly improved photosystem II maximum light energy conversion efficiency?Fv/Fm?and adenosine diphosphate glucose pyrophosphorylase?AGPase?activity in maize leaves;at the second mushroom peak period,the net photosynthetic rate and malate dehydrogenase?MDH?activity of intercropped maize significantly higher than monoculture maize,and the content of soluble protein,soluble sugar and starch increased.Correlation analysis showed that Fv/Fm and soluble protein content positively correlated to the micro environment parameters?air temperature,CO₂concentration?.In 2017 and 2018,the maize yield increased by 376 kg·hm^-2and 325kg·hm^-2compared with monoculture maize,the oyster mushroom yield increased by16560 kg·hm^-2and 14064 kg·hm^-2,the land equivalent ratio was 2.5 and 2.4,respectively.The results of this study revealed that maize/oyster mushroom intercropping effect on the micro-environment,soil microbial community and carbon assimilation in maize leaves under high-efficiency protective planting pattern in the black soil region of central Jilin Province.These findings demonstrated that intercropping could provide stronger carbon sources for maize photosynthesis and suitable growth environment for maize,lead to significant influence on soil physiochemical properties,alter the structure of soil microbial community and increase bacterial and fungal diversity,which could contributed to improving soil quality,and increase maize production.Hence,intercropping provide a theoretical and practical reference for sustainable land use and high yield of maize.