REGENERATION FROM RHIZOME FRAGMENTS OF AGROPYRON-REPENS (L) BEAUV .4. EFFECTS OF LIGHT ON BUD DORMANCY AND DEVELOPMENT OF DOMINANCE AMONGST SHOOTS ON MULTI-NODE FRAGMENTS

Irradiating 7-node rhizome fragments of Agropyron repens (L.) Beauv. incubated at 23 °C , with light of increasing far-red to red ratio, increased the incidence of a light-imposed inhibition, which subsequently could be broken by transfer to darkness. Inhibition did not occur when fragments were sprouted in the dark for three days before being exposed to light. Removal of wavelengths below 600, 690 and 720 nm from tungsten light by filters, successively lessened the incidence of inhibition compared with the unfiltered controlsThe reassertion of dominance amongst shoots and buds on multi-node rhizome fragments was lessened by light of increasing far-red to red ratios, and dominance was not reasserted under 'tungsten lights. Wavelengths between 690 and 720 nm appeared to be responsible for this effect, but the magnitude of the effects varied seasonally. Dormant (correlatively inhibited) buds on rhizome fragments with developed dominant shoots were not reactivated when the fragments were transferred from dark to 'tungsten light. © 1978 Annals of Botany Company.