Zou Yi, Xiao Haijun, Bianchi Felix J J A, Jauker Frank, Luo Shudong, van der Werf Wopke
Centre for Crop Systems Analysis, Wageningen University, P.O. Box 430, 6700 AK, Wageningen, The Netherlands.
Department of Environmental Science, Xi'an Jiaotong-Liverpool University, Suzhou, 215123, China.
BMC Ecol. 2017 Feb 21;17(1):6. doi: 10.1186/s12898-017-0116-1.
Insect pollinators play an important role in crop pollination, but the relative contribution of wild pollinators and honey bees to pollination is currently under debate. There is virtually no information available on the strength of pollination services and the identity of pollination service providers from Asian smallholder farming systems, where fields are small, and variation among fields is high. We established 18 winter oilseed rape (Brassica napus L.) fields along a large geographical gradient in Jiangxi province in China. In each field, oilseed rape plants were grown in closed cages that excluded pollinators and open cages that allowed pollinator access. The pollinator community was sampled by pan traps for the entire oilseed rape blooming period.
Oilseed rape plants from which insect pollinators were excluded had on average 38% lower seed set, 17% lower fruit set and 12% lower yield per plant, but the seeds were 17% heavier, and the caged plants had 28% more flowers and 18% higher aboveground vegetative biomass than plants with pollinator access. Oilseed rape plants thus compensate for pollination deficit by producing heavier seeds and more flowers. Regression analysis indicated that local abundance and diversity of wild pollinators were positively associated with seed set and yield/straw ratio, while honey bee abundance was not related to yield parameters.
Wild pollinator abundance and diversity contribute to oilseed rape yield by enhancing plant resource allocation to seeds rather than to above-ground biomass. This study highlights the importance of the conservation of wild pollinators to support oilseed rape production in small-holder farming systems in China.
昆虫传粉者在作物授粉中发挥着重要作用，但野生传粉者和蜜蜂对授粉的相对贡献目前仍存在争议。对于亚洲小农户种植系统中授粉服务的强度以及授粉服务提供者的身份，几乎没有相关信息，在这些系统中，田地面积小，田间差异大。我们在中国江西省沿着一个较大的地理梯度建立了18块冬油菜（甘蓝型油菜）田。在每块田中，油菜植株分别种植在排除传粉者的封闭笼子和允许传粉者进入的开放笼子里。在整个油菜花期，通过水盘诱捕法对传粉者群落进行采样。
排除昆虫传粉者的油菜植株平均结实率降低38%，坐果率降低17%，单株产量降低12%，但种子重量增加17%，与有传粉者进入的植株相比，笼中植株的花朵多28%，地上营养生物量高18%。因此，油菜植株通过产生更重的种子和更多的花朵来弥补授粉不足。回归分析表明，野生传粉者的局部丰度和多样性与结实率以及产量/秸秆比呈正相关，而蜜蜂的丰度与产量参数无关。
野生传粉者的丰度和多样性通过增强植物对种子而非地上生物量的资源分配来提高油菜产量。本研究强调了保护野生传粉者对支持中国小农户种植系统中油菜生产的重要性。
