[Cover Crop-mediated Regulation of Rhizosphere Microecology and Mechanism of Alleviating Continuous Cropping Obstacles in Lycium barbarum L.]

Abstract

To address soil degradation caused by long-term continuous cropping in major Lycium barbarum L. （wolfberry） producing regions of Ningxia， this study established an intercropping system of L. barbarum and Raphanus sativus L. var. longipinnatus （oilseed radish）. A 4-year field experiment combined with high-throughput sequencing technology was used to systematically analyze the regulatory effects of cover cropping on soil microbial diversity， symbiotic network stability， and wolfberry fruit quality. The results showed that： ① Cover cropping significantly increased the bacterial Shannon index and the fungal Ace， Sobs， and Chao1 indices （P<0.05） and induced significant differentiation in the microbial community structure （P<0.05）. ② Under cover cropping， the relative abundances of bacterial phyla （Proteobacteria， Actinobacteriota， Chloroflexi， and Acidobacteriota） and the fungal phylum Basidiomycota significantly increased. ③ Cover cropping significantly increased soil available phosphorus （AP）， available nitrogen （AN）， and microbial biomass carbon （MBC） by 29.89%， 74.33%， and 23.60%， respectively， while significantly decreasing soil pH by 4.31% （P<0.05）； pH and available potassium （AK） were identified as key driving factors for the bacterial community. ④ FAPROTAX functional prediction revealed that bacterial functions such as chemoheterotrophy and urea hydrolysis were significantly enhanced under cover cropping； in contrast， FUNGuild analysis indicated a significant reduction in the functional abundance of plant-pathogenic fungi in the cover cropping group. ⑤ Symbiotic network analysis demonstrated that cover cropping promoted cooperative interactions among bacterial species and enhanced the interaction complexity and network stability of the fungal community. ⑥ This intercropping system significantly improved the single-fruit weight and yield of wolfberry by 5.66% and 3.35%， respectively （P<0.05）. Collectively， the findings of this study provide critical theoretical support for the ecological mitigation of continuous cropping obstacles and the sustainable， high-yield cultivation of L. barbarum.