Long-term cropping systems shape rhizosphere microbiota of Kimchi cabbage and their influences on agriculture

Long-term monocropping is known to cause soil nutrient imbalances and promote soil-borne diseases resulting in substantial yield losses. Kimchi cabbage ( Brassica rapa subsp. pekinensis (Lour.) Hanelt) production has recently faced serious challenges, long-term monoculture is considered one of the major contributing factor. Although soil physiochemical comparisons under different cropping systems have been analysed, the response of the rhizosphere microbial communities in Kimchi cabbage remains poorly understood. In this study, we investigated the effects of three cropping systems -monoculture, rotation with soybean, and rotation with potato- on rhizosphere microbial structure in both field and pot conditions over nine or ten successive cropping cycles. High-throughput sequencing of bacterial 16S rRNA and fungal ITS regions revealed significant impacts of both the cropping systems and sequences on rhizosphere communities. Cropping sequence had the greatest influences on microbial communities, explaining 14% of the observed variance. Long-term cultivation reduced microbial diversity, with community dissimilarity more rapidly under monoculture compared than rotation alongside other crops. Continuous Kimchi cabbage cultivation increased the abundances of Rhodanobacter , Ktenobacteraceae, and Althernaria compared to the rotation treatments. Sphingomonas , Terrabacter , Pseudarthrobacter , Trichocladium , and Botryotrichum declined progressively in accordance with the cropping sequence in the rhizosphere soil of monoculture. Funtional prediction indicated reduced pathway potential under monoculture. Although cropping system had a modest effect, specific microbial groups were associated with monoculture. Cropping sequence had a pronounced cumulative impact on kimchi cabbage rhizosphere microbial diversity across all treatments. These findings provide a microbiota-based rationale for sustainable management strategy in kimchi cabbage production system.