Abstract: The differentiation of primary vascular tissue and the development of quiescent centre in the primary root apex of Glycine max (L.) Merr. were observed. The quiescent centre in soybean primary root originated 24 hours after germination, in size to a maximum, and studied by means of [3H]thymidine autoradiography. The height of quiescent centre gradually decreased with an increase of days and was cor- related with the diameter of the root (r=0.94 p=0.01). By the mierodensitometer, most of the cells of quiescent centre are at the 2c level of DNA content and that are in G1. We find that no possible direct relationship between the quiescent centre and the differentiation of vascular tissue of soybean primary root was revealed. The former may not regulate the latter.

Key words: Vascular differentiation, Quiescent centre, Soybean, Root apex