In Vitro and ex Vitro Adventitious Root Formation in Asian Jasmine (Trachelospermum asiaticum) I. Comparative Morphology.

by R. C. Apter, E. L. McWilliams, and Fred T. Davies, Jr.

One-node explants and one-node stem cuttings of Asian jasmine [Trachelospermum asiaticumm (Siebold and Zucc.) Nakai] were rooted, respectively, in vitro [tissue culture (TC)] or by conventional macropropagation (MACRO). The TC and MACRO stem bases were then analyzed for differences in the time-course sequence of 1) root primordia initiation and development and 2) adventitious root xylem development and root-to-shoot xylem connections. Early root primordia were observed at Day 3, and, by Day 7, root-to-shoot xylem connections were equally developed in TC and MACRO systems. Continued development and emergence of adventitious roots were observed at Days 8 to 10. At Days 13 and 18, when viewed using scanning electron microscopy, TC root hairs were morphologically thicker and one-third to one-half the length of MACRO root hairs. There was no apparent difference in root-hair density. Inferior TC root-hair length may be a factor in the acclimation of TC-generated plantlets.

J. Ameri. Soc. Hort. Sci. 118(6): 902-905, 1993.