CHANGE IN TISSUE MINERAL ELEMENTAL CONCENTRATION DURING ROOT INITIATION AND DEVELOPMENT OF POINSETTIA CUTTINGS

Variation in tissue elemental concentration in apical stem cuttings of 'Lilo' and 'V-10 Amy' poinsettia (Euphorbia pulcherrima Willd. ex. Kl otzch) were studied during the initiation and development of adventiti ous roots. Changes in selected macro- and microelement concentrations coincided with root initiation (i.e., Pe, Cu, and Mo accumulated in th e basal portions of stem cuttings during early root initiation before root primordia elongation); P, K, Ca, and Mg concentrations declined. During root primordia elongation and root emergence, Fe, Cu, and Mo an d Mg, Mn, B, and Zn concentrations continued to increase at the cuttin g bases, but P and K concentrations remained low compared to when cutt ings were initially inserted in the propagation medium. When all cutti ng of both cultivars had rooted, foliar N, Fe, and Mo concentrations d eclined, but Cu increased compared to when cuttings were initially pro pagated.