山药根腐线虫病发生动态及连作土壤线虫群落结构特征

Occurrence of Root-lesion Disease on Yams and Characteristics of Nematode Community in Continuous Cropping Soil

【目的】探索早熟和晚熟品种、浅生槽定向栽培和传统栽培连作山药田根腐线虫的发生动态及山药连作土壤线虫群落结构的变化,以期为山药根腐线虫病的科学防治提供参考。【方法】以早熟品种永丰淮山传统栽培田、晚熟品种泰和竹篙薯浅生槽定向栽培田和传统栽培田连作土壤为研究对象,依据不同品种山药生长特点定期采集土样,采用贝尔曼漏斗法对土壤线虫进行分离,利用线虫形态学特征将线虫鉴定到属,并进行计数,分析线虫群落随着山药生长在土壤中的变化特征。【结果】永丰淮山和竹篙薯田土壤短体线虫属Pratylenchus种群数量分别从6月和8月之后开始急剧增加,10月达到高峰。不同品种和不同栽培方式山药田土壤分别共分离到9属、13属和12属线虫,且线虫群落均主要由食细菌类线虫和植物寄生类线虫组成。10月土壤中短体线虫属相对丰度急剧增加的同时,永丰淮山土壤中食细菌类线虫拟丽突线虫属Acrobeloides的相对丰度显著降低93.55%,而泰和竹篙薯浅生槽定向栽培和传统栽培土壤中食细菌类线虫小杆线虫属Rhabditis相对丰度分别显著降低52.80%和75.99%。此外,泰和传统栽培田土壤中拟丽突线虫属的相对丰度也大幅降低96.01%。对线虫生态指数分析表明,不同品种和不同栽培方式山药田的不同时期土壤线虫生态指数表现不同,但10月时连作土壤线虫多样性指数H’、均匀度指数J’和瓦斯乐思卡指数WI均显著降低。【结论】10月是根腐线虫发生的关键期,其相对丰度的急剧增加会打破土壤生态原有的平衡状态,导致土壤食细菌类线虫相对丰度、线虫群落多样性和均匀度以及土壤健康程度均大幅下降,对土壤环境产生不利影响。

【Objective】Occurrence of the root-lesion disease on yams caused by nematodes on continuously cropped fields and the parasite community in soil were investigated for the disease control.【Method】Soil specimens at the continuous cropping fields cultivating early-maturing Yongfeng yam using the traditional method,late-maturing Zhugaoshu yam using the directional shallow trough method and the traditional farming in Taihe county were collected for analysis.Nematodes in the soils were isolated by Baermann funnel method,identified to genus,and counted separately based on their morphology.Variations on the nematode community during the growth of yams were observed.【Result】The population of the nematodes that caused the root-lesions on the fields grown Yongfeng yams increased significantly beginning from June,and that grown Zhugaoshu,from August.Both peaked in October.The 9,13,and 12 genera of largely bacterivorous and herbivorous nematodes were isolated from the fields of different varieties of yams grown by using different cultivation methods.In October,when the parasite abundance peaked,the population of Acrobeloides decreased significantly by 93.55%in the soil at the Yongfeng yam field,those of Rhabditis by 52.80%at the Zhugaoshu field cultivated by directional shallow trough method and by 75.99%at the field farmed by the traditional method,while that of Acrobeloides at the Zhugaoshu traditionally cultivated field by 96.01%.The ecological indexes on the nematodes varied depending upon the associated yam varieties,cultivation methods,as well as sampling time.For instance,the indexes of H',J',and WI were significantly lower in October than other times in a year.【Conclusion】October appeared to be the critical month in a year for controlling the nematodes in yam fields.A significant rise in the parasite population would disrupt the ecological balance resulting in a considerable reduction on bacterivores that ill-effects health of the farm soil.