Challenges of continuous cropping in Rehmannia glutinosa: Mechanisms and mitigation measures

Rehmannia glutinosa is a widely cultivated medicinal herb, which faces significant challenges due to continuous cropping obstacles (CCO). After one year of cultivating in the same field, replanting is unsuccessful for the next 8–10 years due to the accumulation of allelochemicals, deterioration of soil properties, and disruptions in soil microbial communities. These factors severely impact plant growth, quality, and overall soil health. This review examines the causes and adverse effects of CCO in R. glutinosa cultivation and evaluates various strategies to mitigate them. CCO arise from complex interactions between the plant root system, soil properties, and microbial communities. A key contributor is the accumulation of phenolic acids in the rhizosphere, which alters soil physicochemical properties and promotes the proliferation of root pathogens, including fungi and root-knot nematodes. This creates a self-reinforcing cycle of soil degradation and plant stress, exacerbating CCO. Approaches such as variety selection, optimized crop rotation patterns, and the application of plant growth-promoting rhizobacteria are discussed in the article. Additionally, soil disinfection techniques, including fumigation, organic amendments, flooding, and mulching, are reviewed for their potential to suppress pathogens and restore soil health. The role of biochar, compost, and beneficial microorganisms, applied individually or in combination, to alleviate CCO and improve soil conditions are also highlighted. This review aims to provide a theoretical framework and practical guidance for overcoming CCO in R. glutinosa cultivation, contributing to sustainable agricultural practices for this important medicinal crop. • The plant-soil-microbe interactions underlying CCO in R. glutinosa were analyzed. • The detrimental effects of CCO on the growth of R. glutinosa were summarized. • Various strategies for mitigating CCO in R. glutinosa were reviewed. • The potential use of biochar as innovative solutions was proposed.