甲基溴土壤消毒替代技术条件下的线虫生态学研究

Ecological researches on nematodes in alternative technologies to the use of methyl bromide in soil fumigation

为评价和筛选几种甲基溴替代技术及其对土壤线虫群落的影响 ,2 0 0 1年 6月～ 2 0 0 2年 3月对 5种土壤消毒处理的线虫数量和群落结构及微生物量动态作了测定和分析。试验共分离到土壤线虫 4个目 14个科属 ,包括小杆目 (Rhabditida)、垫刃目(Tylenchida)、矛线目 (Dorylaimida)、单宫目 (Monhysterida)。小杆目线虫占总数的 88.7% ,表明食细菌的小杆目线虫是该温室土壤线虫群落的优势类群。分析表明甲基溴 +VIF、威百亩、威百亩 +VIF三种措施的消毒效果达到了甲基溴处理的水平 ,可作为甲基溴土壤消毒替代技术 ,而太阳能 +BCA处理未达到甲基溴消毒的效果。研究显示同一处理的线虫数量在两个番茄品种(AF179和毛粉 80 2 )间不存在显著差异 ,即表明这两种番茄品种不是影响土壤线虫数量动态的主要因素。对消毒处理后土壤线虫各营养类群在群落中的比例进行分析 ,发现与对照相比 ,化学消毒提高了线虫群落中优势类群 (即食细菌线虫 )的比例 ,而使弱势类群的比例下降 ,这表明土壤线虫的弱势类群对化学熏蒸剂更加敏感。两番茄品种小区中土壤食细菌、食真菌线虫数量与微生物量碳之间呈显著正相关关系 ,表明微生物生物量的消长受土壤消毒措施的影响 ,同时也证实了上述两营养类群线虫与土壤微生物间的食物依赖关系。

The application of methyl bromide in soil fumigation can control the soil borne diseases much effectively. However methyl bromide has been proved as one of ozone depletion substances (ODS). Based on the Copenhagen Amendment of Montreal Protocol, the consumption of methyl bromide will reduce 20% and until 2015 it will be banned completely in China. In order to take necessary and adequate technical preparation before the reduction and phase out of methyl bromide in Chinese agriculture, China and Italy started to launch a cooperation project in 2001. The study was a part of the cooperation project, and it was conducted in four greenhouses in Qingzhou of Shandong province, aimed to identify feasible alternative technologies under the current conditions in agricultural production, economical and social sector of China. Two tomato cultivars (Maofen-802 from the Xian Institute of Vegetables and AF179 Brillante from Israeli Hazera Quality Seeds) were selected as crops. Four alternative technologies were chosen in the experiment. They were MB (methyl bromide) +VIF (virtually impermeable film), MS (metham sodium), MS+VIF, SS (soil solarization)+BCAs (biological control agents). Population dynamics and community structure of soil nematodes were measured from June, 2001 to March, 2002. Four orders with fourteen families or genera were detected, mainly in Rhabditida, Tylenchida, Dorylaimida, Monhysterida. Rhabditida was the dominant group, with 88.7% of the soil nematode community. And the proportion of Tylenchida, Dorylaimida, Monhysterida were 7.2%, 4.0% and 0.1%, respectively. In terms of the functional groups, bacterivous nematode was the most abundant in the experimental plots, with 88.8% of the total number of nematodes sorted out, and the herbivores, fungivores and omnivores/predator were 5.0%, 2.2% and 4.0% respectively. For the nematodes abundance, there was significant difference between treatments. For example, in Maofen plot the nematode number/100g soil in CK (control plot) was 71 and 45 in SS+BCA treatment, there was a significant difference between these two plots. In the four chemical fumigation treatments, the nematodes in MB, MB+VIF, MS, MS+VIF were 15, 12, 16 and 11 per 100g soil. This result implied that the impact of three chemical alternatives (MB+VIF, MS and MS+VIF) on nematodes abundance and functional groups abundance were very similar to the impact associated with the use of methyl bromide. At this point, it could be concluded that the three alternatives to MB were equal in impact on suppression of soil nematodes. The impact of soil solarization on nematodes and functional groups abundance was noticeable between CK and the four chemical treatments. In the study, no significant difference was found between the two cultivars(AF179 and Maofen)in nematodes abundance. After soil fumigation, an increasing tendency of bacterivores nematodes proportion was observed as compared with CK plot, and the percent of minority nematodes declined obviously. It indicated the minority nematodes in the soil were more sensitive to the chemical fumigants. Analysis of soil nematodes dynamics during the sampling period was conducted in CK plot and found that the abundance of all soil nematodes reached the peak in July and began to decline in September, and kept a low level until next January, then the abundance started to increase again. Furthermore, it was found that bacteriviore and fungivore nematodes were positively correlated with microbial biomass whether in AF179 or Maofen cultivar. The proper explanation might be that soil microbial biomass responded much rapidly as a whole to the changes in management and the soil microorganisms were the main food resources of these two functional groups.