半夏连作障碍成因及防治研究进展

Research advances on causes and prevention for the continuous cropping obstacle of Pinellia ternata

半夏是一味传统常用中药材,但连作障碍导致其产量和品质下降,从而严重制约产业可持续发展.究其成因,半夏连作导致土壤酸化、酶活下降和营养失衡,特别是酚酸类、醌类、醛类和酮类化合物等化感物质积累,抑制半夏种子萌发和幼苗生长,并造成根际镰孢霉(Fusarium)、产酸克雷伯氏杆菌(Klebsiella oxytoca)和胡萝卜软腐果胶杆菌(Pectobacterium carotovorum)等致病菌增加,而土壤微生物多样性降低.目前半夏连作障碍的防治措施主要包括轮作与间作、土壤和块茎灭菌以及施用微生物制剂和有机物料等,但这些措施存在运转周期长、成本高、操作困难等缺点或机制不清、效果不稳定等问题.因此建议将半夏植株-根系分泌物(如化感物质等)-根际土壤-根际微生物群落视为一个整体,系统研究其互作关系,并拓展半夏连作障碍防治技术及原理研究,为保障和促进半夏种植产业的可持续发展提供理论与技术参考.(图1参96)

Pinellia ternata(Thunb.) Breit. is a common traditional Chinese medicine. The continuous cropping obstacle(CCO) lowers both the quality and yield of P. ternata, thereby hindering the sustainable development of the planting industry. The underlying mechanism involves soil acidification, a decline in soil enzyme activity, and nutrient imbalance induced by the CCO of P. ternata. Particularly, phenolic acids are the main allelochemicals, while some quinones, aldehydes, and ketones are special allelochemicals present in P.ternata. These allelochemicals inhibit seed germination, seedling growth, and lead to an increase in pathogens in the rhizospheres of P. ternata. In addition, the continuous cropping of P. ternata results in a decrease in microbial diversity. Pathogens such as Fusarium, Klebsiella oxytoca, and Pectobacterium carotovorum were found to increase after continuous cropping of P. ternata. At present, reported measures to alleviate the CCO of P. ternata include rotation and intercropping, soil and tuber sterilization, microbial agents, and application of organic materials. However, these measures have some shortcomings, such as a long operation cycle, high cost, difficulty in operation, unclear mechanism, and instability of effectiveness. Therefore, to better alleviate the CCO of P. ternata, the plant rhizosphere secretions(such as allelochemicals), rhizosphere soil and microbial community should be considered as a whole system, and the interactions among them should be studied in depth to better explain the causes of CCO. Moreover, research on the mitigation techniques and mechanisms of the CCO of P. ternata should be further expanded to provide theoretical and technical guidance for promoting and guaranteeing the sustainable development of P. ternata planting industry.