转双价基因棉SGK321不同秸秆还田量对土壤线虫群落的影响

为了更好地监测转基因作物秸秆还田对土壤生态系统的影响,通过盆栽试验研究了转双价(Bt+CpTI)基因棉秸秆不同还田量对土壤线虫密度、多样性以及群落结构的影响。以转双价(Bt+CpTI)基因棉SGK321和常规棉石远321为材料进行盆栽试验,设置5个还田量:不还田(对照)、半量还田1.0 g·kg~(-1)(2250 kg·hm~(-2))、全量还田2.0 g·kg~(-1)(4500 kg·hm~(-2))、1.5倍还田量3.0 g·kg~(-1)(6750 kg·hm~(-2))、2倍还田量4.0 g·kg~(-1)(9000 kg·hm~(-2)),取棉花蕾期和花铃期土壤进行线虫分离鉴定,并进行数据分析。结果表明:秸秆不还田时,两个棉花品种土壤线虫密度无显著差异;秸秆还田后,SGK321土壤线虫密度仅在蕾期3.0 g·kg~(-1)还田处理时高于石远321,存在显著差异,其他处理无显著差异;转双价(Bt+CpTI)基因棉SGK321土壤中鉴定出线虫19科34属,其中食细菌性线虫(Bacterivores)13属,食真菌性线虫(Fungivores)3属,植食性线虫(Plant-parasites)11属,杂食/捕食性线虫(Omnivores-predators)7属。常规棉石远321土壤中鉴定出线虫19科37属,其中食细菌性线虫13属,食真菌性线虫3属,植食性线虫12属,杂食/捕食性线虫9属。秸秆还田增加了食细菌性线虫的丰度,秸秆还田量超过3.0 g·kg~(-1)就会抑制植食性线虫的生长,使其丰度减小;从生态指标来看,两种棉花不同还田处理下的多样性指数(H′)、线虫通路指数(NCR)均无显著差异。研究表明,转双价(Bt+CpTI)基因棉SGK321的种植没有改变土壤线虫的营养类群,并且土壤线虫密度也无显著差异,两种棉花不同还田处理下的多样性指数(H′)、线虫通路指数(NCR)也均无显著差异。秸秆还田量在一定范围内会使土壤线虫增多,增加丰富度。多因素方差分析表明,相对于品种的影响,棉花生育期和秸秆还田量对线虫群落的影响更显著。

Effect of transgenic cotton SGK321 with different amounts of straw on soil nematode communities

In order to better monitor the impact of transgenic crop straw returning on soil ecosystems, we carried on the plot experiment to study the effects of different transgenic (Bt+CpTI) cotton straws on soil nematode density, diversity and community stucture. We used the transgenic (Bt+CpTI) cotton SGK321 and non-transgenic parental cotton Shiyuan 321,with five straw-returning amount, which was set as control (0), half-returning (1.0 g·kg^-1), total returning (2.0 g·kg^-1), 1.5 times returning (3.0 g·kg^-1) and 2 times returning (4.0 g·kg^-1). Soil samples were collected at budding stage and flowering and boll-forming stages for identification of nematodes. The results showed that there was no significant difference in soil nematode density between these two cotton varieties without straw return. After the returning of straw, the density of soil nematode in SGK321 was significantly higher than that in non-transgenic cotton under the treatment of 1.5 times returning at bud stage, but no significant difference was observed in other treatments at both stages. A total of 34 nematode genera were identified in the soil of transgenic (Bt+CpTI) cotton SGK321, including 13 genera of Bacterivores, 3 genera of Fungivores, 11 genera of Plant-parasitic nematodes and 7 genera of Omnivores-predators. Also 37 genera were present in the soil of non-transgenic cotton, including 13 genera of Bacterivores, 3 genera of Fungivores, 12 genera of Plant-parasitic nematodes and 9 genera of Omnivores-predators. Straw returning increased the abundance of Bacterivores, yet the amount of straw returning with more than 3.0 g·kg^-1 would inhibit the growth and abundance of herbivorous nematodes. This study showed that the planting of transgenic (Bt+CpTI) cotton did not change the nutritional group, and the ecological index analysis indicated that there was no significant difference in soil nematodes in terms of Shannon-Wiener Index (H'') and Nematode Channel Ratio (NCR) between these two cotton varieties under different treatments. Overall, the amount of straw returning to the field, can increase the abundance of soil nematodes. Multivariate analysis showed that the cotton growth period and the amount of straw returning to field had much more significant effect on the nematode community than the cotton variety.