内生根瘤菌在苜蓿芽苗与种子内的数量及优势度

Quantity and Ecological Dominance of Endogenesis Rhizobia in Bud Seedling and Seeds of Alfalfa

比较了内生根瘤菌在11个苜蓿品种种子和芽苗中的存在部位与数量,并对游客苜蓿胚珠、幼嫩种子及芽苗内的根瘤菌含量和在可检出菌中所占的比例进行研究。结果表明:不同品种种子间根瘤菌含量有显著差异(P<0.05),但其分布部位和比例基本一致,即主要存在于种皮内,而在子叶及胚中分布极少;游客苜蓿胚珠受精后开始有根瘤菌存在,含量随种子的发育而增大。种子储存1年后较刚收获时根瘤菌含量增加6.85倍,杂菌数量仅增大1.57倍;苜蓿芽苗中根瘤菌主要存在于子叶,仅37.24%的根瘤菌存在于茎,分别占其部位总可检出菌(同培养条件下)数的93.18%和76.78%,幼根内无可检出菌。说明在种子发育、储藏和发芽的过程中,根瘤菌在种子/芽苗中同一生态位下的内生菌菌落中占据优势。

Position and quantities of endogenous rhizobia in seeds of 11 alfalfa varieties were compared. Rhizobia quantity change in ovule-seed and bud seedlings, and the rate of rhizobia in all testable microbes under same culture condition in seeds and bud seedling of Eureka were studied. The results showed that the quantity of rhizobia varied with different alfalfa variety significantly （P〈0. 05）, while the distribution positions and ratios were basically unanimous, rhizhobia existed mainly in seed coat and little in cotyledon and embryo; Rhizobia appeared right after the fertilization of ovule, and the quantity increased with the seeds＇ development. Compared with the right harvested alfalfa seeds, rhizobia quantity increased by 6.85 times and undesired microbes were only by 1.57 times after 1 year＇s storage; rhizobia in bud seedling existed mainly in cotyledon and only 37.24% were in stem,which accounted for 93.18% and 76.78% of the total testable microbes under the same culture condition of the existed parts, respectively. No testable microbes in young roots of bud seedlings. This indicated that during the process of development, storage and germination of seeds, rhizobia were predominating in microbes under same niche in seeds and bud seedling.