© 1972 by Institute of Chartered Foresters
The Distribution of Latent Root Primordia in stems of Populusxrobusta, and factors affecting the Emergence of Preformed Roots from Cuttings
Department of Botany, University College of Wales Aberystwyth
Latent root primordia form in lignified parts of new stems of Populus x robusta trees from early in July, as revealed by examination of bark rings. Such primordia, in the summer and autumn of their inception, cannot emerge as roots from stem cuttings placed in darkness. Older preformed root primordia can emerge in the following spring from cuttings maintained above 12°C throughout the winter. Provided that latent roots were sufficiently mature in the cortex the presence of buds and a period of chilling were other factors which increased emergence of such roots.
By excising batches of cuttings from source plants at the middle and at the end of the bud dormancy period and subjecting the cuttings to natural winter chilling before providing rooting temperatures, the quantity of preformed roots which emerged was similar for both excision groups; but wound-root production was significantly greater from those cuttings excised towards the end of bud dormancy.