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[目的]了解苜蓿种子形成过程中根瘤菌在植株各部位的动态分布,探明苜蓿种子内生根瘤菌的携带机理。[方法]取不同生育时期两个品种苜蓿植株的根、茎、叶、花、荚果、种子等部位,表面消毒后以稀释平板法对根瘤菌在苜蓿植株内的存在部位与数量变化进行研究。[结果]植株地下部分同时期根瘤菌数量比较:主根<侧根<毛根;不同时期主根和毛根根瘤菌数量:结荚期>分枝期>花期,侧根根瘤菌数量:分枝期>花期>结荚期;植株地上部分内生根瘤菌分布:茎部仅在分枝期和结荚期携带有少量根瘤菌(分别为155cfu/g,125cfu/g);分枝期内主要存在于花芽(9400cfu/g);现蕾期仅存在于子房壁组织(18cfu/5朵花蕾);花期少量存在于花粉(26cfu/5朵花)、受精胚珠(26cfu/50粒种子)、花托(15cfu/5朵花)和子房壁内(95cfu/5朵花);结荚期存在于荚果皮(3550cfu/5荚果)及幼嫩种子中(1135cfu/50粒);成熟种子的种皮内有大量分布(1435cfu/50粒),种胚及子叶内仅有少量分布(32cfu/50粒,22cfu/50粒)。[结论]内生根瘤菌在苜蓿植株地上部分各部位的分布有较大差异,且仅存在于与种子形成直接相关的部位。
[Objective] The research aimed to understand the dynamic distribution of Rhizobia in all parts of alfalfa seeds and to find out the mechanism of endogenous rhizobia in alfalfa seeds. [Method] The roots, stems, leaves, flowers, pods, seeds and other parts of alfalfa plants at different growth stages were inoculated. After disinfection on the surface, the changes of the existing parts and numbers of rhizobia in alfalfa plants were studied by dilution plate method. [Result] The numbers of rhizobia in the underground part of the plant were compared at the same time: main root branching stage> flowering stage, rhizobia number of lateral root: branching stage> Pod stage. The distribution of endogenous rhizobia on shoots of the plants: the stems carried only a small amount of rhizobia at the branching and podding stages (155cfu / g, 125cfu / g, respectively); mainly during flower buds (9400cfu / / g); budding stage only existed in the ovary wall tissue (18cfu / 5 flower buds); small amount of flowering occurred in pollen (26cfu / 5 flower), fertilized ovule (26cfu / 50 seeds) (35cfu / 5 pods) and young seed (1135 cfu / 50) at seed podding stage. There was a large distribution of seed coat in mature seeds 1435 cfu / 50 seeds), with only a small distribution (32 cfu / 50 seeds, 22 cfu / 50 seeds) in seed embryo and cotyledons. [Conclusion] The distribution of endophytic rhizobia in the aerial parts of alfalfa plants was quite different, and only existed in the parts directly related to seed formation.