苜蓿生育过程中植株体内内生根瘤菌的运移动态

[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。

Dynamic Transportation of Endophytic Rhizobia in Plants during Growth Development of Alfalfa

[ Objective] The aim of this study was to investigate the dynamic distribution of endophytic rhizobia in different plant parts during seed development of alfalfa and the carrying mechanism of endophytic rhizobia from alfalfa seeds. [ Method] Root, stem, leaf, flower, pod and seed from two varieties of alfalfa in different development stages were used for surface disinfection, and then the present site and quantity change of rhizobia in alfalfa were studied by the dilution - plate method. [ Result] The number of rhizobia from underground plants in the same stage was as follows： main root 〈 lateral root 〈 hair root. The number of rhizobia from main root and hair root in different stages was as follows： bearing pod stage 〉 branching stage 〉 florescence, while that from lateral root was as follows： branching stage 〉 florescence 〉 bearing pod stage. The distribution of endophytic rhizobia from aerial plants was as follows： few rhizobia was found in stem during branching stage and bearing pod stage, which accounted for 155 cfu/g and 125 cfu/g respectively. Rhizobia mainly distributed in flower bud during branching stage accounting for 9 400 cfu/g, while only in ovary wall during squaring stage accounting for 18 cfu/5 flowers, and few in pollen （26 cfu/5 flowers）, fertilized ovules （26 cfu/50 grains）, receptacle （15 cfu/5 flowers） and ovary wall （95 cfu/5 flowers） during florescence. Rhizobia existed in pod peel （3 550 cfu/5 pods） and immature seed （1 135 cfu/50 grains） during bearing pod stage, and greatly distributed in seed coat of mature seeds （1 435 cfu/50 grains）, but only few in embryo （32 cfu/50 grains） and cotyledon （22 cfu/50 grains）. [ Cenclusion] There is a significant difference in the distribution of endophytic rhizobia from different parts of aerial alfalfa, which only exists in the parts directly related to seed development.