College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu Province 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu Province 225009, China.
College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu Province 225009, China.
Sci Total Environ. 2024 Jan 1;906:167748. doi: 10.1016/j.scitotenv.2023.167748. Epub 2023 Oct 12.
The potential for commercial cultivation of genetically engineered (GE) alfalfa has raised ecological concerns due to the possibility of introgression of GE alleles into conventional populations. The main objectives of this study were to determine the key affecting factors (i.e. size of pollen source, number of pollinating bees) on forming alfalfa pollen cloud density and test the mitigating effect using maize barrier rows on alfalfa pollen dispersal. The results showed that the mean pollen densities of alfalfa pollen source (Ø = 10 or 20 m) were statistically similar when treated with the same number of worker bumblebees and increased accordingly with increasing the worker bees (887 and 853 pollens m h for Ø = 10 and 20 m with 100-150 worker bees, respectively; 1040 and 1070 pollens m h for the two plots with 200-300 worker bees, respectively), demonstrating that the number of worker bees but not the size of the pollen source was the key determinant for forming alfalfa pollen density. A maize barrier row established at 0.5 m from the alfalfa edge consistently decreased downwind pollen densities (percent pollen density of pollen source) to 0.2-4.4 % at 1-9 m compared to 3.4-25.4 % and 7.5-37.8 % at the same distance range for the upwind and downwind sites without maize barrier rows, respectively. Based on the pods formed on the emasculated alfalfa flowers (due to pollen dispersal) located at various distances from the pollen source and subsequent prediction model, the pollen density threshold value for fertilizing alfalfa recipient under the wind-blown condition was determined of 65.8 pollens m h at 14.7 m from the pollen source edge. The results would help in understanding the pollination biology (minimum pollen density for fertilizing alfalfa recipient ovule) and the process of pollen-mediated gene flow and helpful in developing management strategies to reduce the pollen density and thus mitigate the gene flow in alfalfa.
基因工程（GE）苜蓿的商业种植潜力引起了生态关注，因为 GE 等位基因有可能渗入常规种群。本研究的主要目的是确定影响形成苜蓿花粉云密度的关键因素（即花粉源大小、传粉蜜蜂数量），并测试利用玉米隔离带减少苜蓿花粉传播的效果。结果表明，当用相同数量的工蜂处理时，苜蓿花粉源（Ø=10 或 20m）的平均花粉密度在统计学上相似，并随着工蜂数量的增加而相应增加（Ø=10 时分别为 100-150 只和 887 和 853 个花粉 m h，Ø=20 时分别为 200-300 只和 1040 和 1070 个花粉 m h），表明工蜂数量而不是花粉源大小是形成花粉密度的关键决定因素。在距苜蓿边缘 0.5m 处建立的玉米隔离带可使下风处的花粉密度（花粉源的花粉密度百分比）持续降低至 0.2-4.4%，而在上风处和下风处无玉米隔离带时，同一距离范围内的花粉密度分别为 3.4-25.4%和 7.5-37.8%。根据位于花粉源不同距离处的去雄苜蓿花（由于花粉传播）形成的荚果和随后的预测模型，确定了在风吹条件下受粉苜蓿受体的花粉密度阈值为 65.8 个花粉 m h，距花粉源边缘 14.7m。研究结果有助于了解授粉生物学（受粉苜蓿受体胚珠的最小花粉密度）和花粉介导的基因流过程，并有助于制定管理策略来降低花粉密度，从而减少苜蓿中的基因流。
