Abstract
The wide-scale adoption of transgenic crops has aroused public concern towards potential impacts to the ecological services of soil fauna, such as soil nematodes. However, few studies has examined whether the cultivation of transgenic rice would pose greater threats to soil nematode community and associated ecological functions than insecticides application. Moreover, what are determinants of soil nematode community in paddy fields remains unclear. During a 3-year field study, rhizosphere soil samples of transgenic-Bt rice, its counterpart non-Bt parental rice and not-Bt rice with insecticides application were taken at four times in the rice developmental cycle using a random block design with three replications for each treatment. We hypothesized that the effects of pest management practice on soil nematode abundance and metabolic footprint change with trophic group and sampling time. We also predicted there were significant differences in structure and composition of soil nematode community across the three treatments examined and sampling times. In agreement with our expectation, the effects of pest management practice on nematode abundance and metabolic footprints depend on trophic group and sampling time. However, pest management practice exerted no apparent effect on nematode diversity and community composition. Soil nutrient availability and C:N molar ratio are the primary regulating factor of soil nematode community in rice paddy fields. In conclusion, our findings implied that changes in abundance, diversity, metabolic footprints associated with the crop growth stage overweighed the application of Bt rice and insecticides. The cultivation of Bt rice Huahui-1 exerted no measurable adverse effect on soil nematode community in rhizosphere soil over 3 years of rice cropping.
Highlights
As an important cereal crop worldwide, rice (Oryza sativa L.) provides staple food and nutrition for about 50% of the global population (Lu and Snow, 2005)
In contrast to most of available studies addressing potential environment risks of Bt corn or cotton on soil nematode community in terrestrial ecosystems (Manachini and Lozzia, 2002; Griffiths et al, 2005; Höss et al, 2011; Karuri et al, 2013; Li and Liu, 2013; Neher et al, 2014; Yang et al, 2014; Höss et al, 2015; Liu et al, 2015; Čerevková et al, 2017; Liu et al, 2018b), we evaluated those of Bt rice in aquatic ecosystem
Our study revealed no significant adverse effect of Bt rice cultivation on soil nematode communities under paddy field
Summary
As an important cereal crop worldwide, rice (Oryza sativa L.) provides staple food and nutrition for about 50% of the global population (Lu and Snow, 2005). To reduce the yield loss resulting from pest damage, China devoted great effort in developing insect-resistant rice using transgenic technology and has developed multiple Bt rice lines (Chen et al, 2011). The Cry1Ab/Ac protein, which was continuously produced within plant tissue of Bt-rice, could be released through root exudates during growth and persistent in the rhizosphere in paddy soils (Wang et al, 2018). It might affect the activity, structure, diversity of soil fauna, and interactions among components of soil food webs, which in turn would influence soil fertility and plant productivity. There is a pressing need to understand the impacts of Bt rice on the sustainability of agricultural ecosystem
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