STIMULATION OF GROWTH AND NITRATE ASSIMILATION IN LEUCAENA-LEUCOCEPHALA SEEDLINGS IN RESPONSE TO SPERMIDINE SUPPLY

Supply of 100 muM spermidine (Spd) in the nutrient solution containing 10 mM nitrate as the sole nitrogen source, increased growth of roots and shoots, total nitrogen content and in vivo or in vitro nitrate red uctase (NR) activity of leaves of 10-d old Leucaena leucocephala seedl ings. Spd and the cytokinins benzyladenine or kinetin also increased g rowth, total nitrogen and in vivo NR activity of isolated cotyledons. The synergistic effects of nitrate, kinetin and Spd in increasing NR a ctivity, indicate that the Spd acted at different level than the nitra te or cytokinin.