THE RELATIONSHIP BETWEEN THE ROOTING OF CUTTINGS, PHOTOPERIODISM AND PLANT GROWTH HORMONES IN CHRYSANTHEMUM

Abstract

The behaviour of endogenous growth substances in the vegetative organs of two species of Chrysanthemum (C. frutescens, L as a iong-day plant and C. morifolium, Ramat. as a short day plant) in relation to root initiation under photoperiodic treatments showed that gibberellin- like substances decreased gradually under short-day conditions while increased under Iong-day conditions until it reached highly significant level when roots were formed. A similar result was obtained for auxin levels, whereas inhibitors were somewhat increased especially at rooting time under short-day conditions. The cuttings of the two species of _Chrysanthemum plants formed more roots under long-day than under short-day conditions. Treatments of defoliation, disbudding, decapitation or using hard wood cutings decreased the number of roots either short- or long-day conditions. The inhibition of rooting ability caused by short-day under treatment was dlue to the decreasing of auxin contents and increasing ot inhibitors, whereas long-day treatment resulted in increasing auxin content and decreasing of inhibitors in the cuttings and thus promoted root production. Treatments of defoliation, disbudding, decapitation or using hard wood cuttings resulted in reducing auxin content at rooting time, whereas inhibitor content increased due to these treatments. It wae that gibberellic acid (GA) treatment found increased the number of roots while abscisic acid treatment decreased it on the basal parts of cuttings in the twc species of Chrysantemum plants. This was concomitant to a significani increase of growth promoters in the basal parts of cuttings with gibberellic acid treatment and similar increase ot inhibitors with abscisic acid treatment.