土壤强还原处理对连作芥蓝产量、微生物数量及活性的影响

芥蓝是一种重要的十字花科蔬菜,但高强度单一的种植模式以及不合理的养分管理使得土壤连作障碍现象日益突出,严重制约着芥蓝的可持续生产。土壤强还原处理(reductive soil disinfestation,RSD)是一种作物种植前的土壤处理方法,不仅可以有效杀灭土传病原菌,还具有改善土壤结构、增加土壤有机质含量、重建土壤微生物区系、恢复微生物活性等作用。我们以云南省昆明市安宁县的芥蓝生产基地中连作障碍严重的地块作为研究对象,设置3个处理:不做任何处理的对照(CK),固体有机物料(C/N:122,12 t/hm~2)RSD处理(RSD_BA);液体有机物料(C/N:30,6t/hm~2)RSD处理(RSD_MO),测定RSD处理后土壤理化和生物学性质的变化,并统计芥蓝产量和根肿病的发病率。结果表明,与CK处理相比,RSD处理能够显著提升土壤pH,降低土壤NO_3~–-N和有效态重金属的含量;并且能够显著增加芥蓝产量,降低根肿病的发病率,其中RSD_MO和RSD_BA处理后产量分别提高268%和397%,发病率分别降低37.3%和56.7%。RSD处理还能明显提高细菌与真菌的比值(B/F),降低芸薹根肿菌的数量,增加土壤微生物活性,其中RSD_BA处理的杀菌率达到90.6%,微生物活性提高2倍。因此,固体有机物料的土壤强还原处理能够显著改善芥蓝连作生产系统的土壤质量,降低发病率,提高产量,是一种具有快速缓解十字花科蔬菜地连作障碍,实现可持续种植的有效措施。

Effects of Reductive Soil Disinfestation on Yield, Population and Activity of Microorganisms in Continuously Cropped Soils of Chinese Kale

Chinese kale is an important cruciferous vegetable, but the intensive monoculture cropping system and the inappropriate nutrient management cause serious continuous cropping obstacles which severely limits its sustainable production of Chinese kale. Reductive soil disinfestation (RSD), a soil treatment before crop cultivation, can not only effectively suppress soil-borne pathogens, but also improve soil structure, increase soil organic matter, restructure soil microbial community and restore soil microbial activity. An experiment was conducted in the fields with severe clubroot disease incidence in Chinese kale production base in Anning County, Kunming City, Yunnan Province, and three treatments were designed: no treatment control (CK), RSD treatment incorporated with 12 t/hm² sugar bagasse (RSD_BA), RSD treatment incorporated with 6 t/hm² molasses (RSD_MO). Soil chemical and biological properties were measured, and the yield and clubroot incidence of Chinese kale were recorded. Results indicated that RSD treatments (RSD_MO and RSD_BA) significantly improved soil pH and decreased the contents of soil NO₃^--N and available heavy metals as compared to CK. Moreover, RSD treatments significantly enhanced the yields of Chinese kale coinciding with a considerable reduction of clubroot disease incidence, with a yield increase of 268% and 397% and incidence decrease of 37.3% and 56.7% in RSD_MO and RSD_BA treatments, respectively. RSD treatments also increased the ratio of bacteria/fungi (B/F), reduced the population of Plasmodiophora brassicas, and improved soil microbial activity. Particularly, the disinfestation efficiency was up to 90.6% and microbial activity was increased by 2-fold in RSD_BA treatment. Therefore, RSD treatment incorporated with sugar bagasse is effective to improve soil quality, decline disease incidence, enhance crop yields, mitigate the extent of continuous cropping obstacles, and further achieve sustainable cultivation of cruciferous vegetables in a mono-cropping system.