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To determine the distribution characteristics of rhizobium in alfalfa plants and seeds, the distribution and abundance of endogenous rhizobium in different parts and seed of alfalfa at different growth stages were analyzed.

为探明根瘤菌在苜蓿植株及其种子内的分布规律，对苜蓿植株及种子各部位在不同生育期内生根瘤菌的分布和数量变化进行了研究。

Similar to global cratons, numerous Paleo-proterozoic mafic dyke swarms occur in the North China Craton.

华北克拉通同世界上其它克拉通一样，广泛发育前寒武纪基性岩墙群。