INITIAL GROWTH OF 14 NATIVE TREE SPECIES IN RESPONSE TO POTASSIUM FERTILIZATION

An experiment was carried out under greenhouse conditions, in order to evaluate the potassium response of fourteen native tree species. The studied species, according to its ecological group were: Pioneer speci es: Peltophorum aubium (Spreng) Taub., Senna spectabilis (DC) I.&B. (S preng), Senna multijuga (L.C. Rich) I.&B., Stenolobium stans (Jun.) Se em, Jacaranda mimosaefolia D. Don., Guazuma ulmifolia Lam. and Trema m icrantha Bloom; Secondary species: Anadenanthera peregrina (L.) Speg., Machaerium nictitans Veil. Benth., Cedrella fissilis Veil. and Senna macranthera (Collad.) I.&B.; Climax species: Copaifera langsdorffii De sf., Hymenaea courbaril L. (Hayne) Lee et Lang, and Platycianus regnel li Benth. L.; Annual: Zea maiz L. A soil with 0.72 mmol K+.dm(-3) soil by Mehlich-1 was used, establishing the following treatments: without potassium (-K), and with application of 84 mg K+/kg soil. In both tre atments, soil was previously limed and conveniently supplied with othe r nutrients. Differential response was observed among species and ecol ogical groups to the potassium fertilization. With exception of cassia -carnaval (Senna spectabilis), in all other pioneer species the total dry matter production was significantly increased with potassium ferti lization. In the group of secondary species, only cedro (Cedrella fiss ilis Vell.) and fedegoso (Senna macranthera (Collad.) I.&B.) were resp onsive to potassium application, while climax species did not. The hig hest responses were found for pioneer and secondary species with fast growth rate.