GROWTH AND SEEDLING QUALITY OF JACARAND\uc1-DA-BAHIA IN RESPONSE TO POTASSIUM AND SULFUR FERTILIZATION

Estudos recentes d\ue3o \ueanfase \ue0s florestas nativas pela sua import\ue2ncia no contexto de produ\ue7\ue3o de madeira, frutos e na conserva\ue7\ue3o ambiental. Um dos pontos importantes, ainda a ser estudado, \ue9 a nutri\ue7\ue3o das esp\ue9cies utilizadas nestes reflorestamentos. O objetivo deste trabalho foi estudar as exig\ueancias nutricionais de jacarand \ue1-da-bahia ( Dalbergia nigra (Vell.) Allem\ue3o ex Benth.) em rela\ue7\ue3o \ue0 aduba\ue7\ue3o com pot \ue1ssio e enxofre, na fase de produ\ue7\ue3o de mudas. Para isso, foi conduzido um experimento no viveiro de pesquisas do Departamento de Engenharia Florestal, da Universidade Federal de Vi\ue7osa, utilizando vasos de polietileno r\uedgido com 2,0 dm3 de capacidade e como substrato um Latossolo Vermelho-Amarelo \ue1lico. Foi adotado um esquema fatorial, disposto em delineamento experimental inteiramente casualizado, utilizando-se como tratamentos cinco doses de pot \ue1ssio (0; 50; 100; 150 e 200 mg dm-3 de K) combinadas com seis doses de enxofre (0, 20, 40, 60, 80 e 100 mg dm-3 de S), as quais foram parceladas em quatro aplica\ue7\uf5es: 0, 30, 60 e 90 dias ap\uf3s o raleio. Ap\uf3s 157 dias de semeadura, foram colhidos dados da altura, do di\ue2metro do coleto, da mat\ue9ria seca da parte a\ue9rea e da raiz, al\ue9m das rela\ue7\uf5es altura/di\ue2metro do coleto, altura/massa seca parte a\ue9rea, massa seca parte a\ue9rea/massa seca de raiz e o \uedndice de qualidade de Dickson. As mudas de jacarand \ue1-da-bahia responderam negativamente \ue0 aduba\ue7\ue3o pot \ue1ssica para a maioria das caracter\uedsticas avaliadas. Considerando a produ\ue7\ue3o de mat\ue9ria seca total, recomenda-se a aplica\ue7\ue3o de 30 mg dm -3 de S e 30 mg dm -3 de K para a produ\ue7\ue3o de mudas de jacarand \ue1-da-bahia.Recent studies are focusing on native forests because of their importance on the production of timber, fruits and on the environmental conservation. One of the main aspects yet to be studied is the nutrition of the species used in these reforestations. The objective of this work was to study the demands of K and S jacarand \ue1-da-bahia ( Dalbergia nigra ) seedlings. An experiment was conducted in the nurseries of Forestry Department in the Federal University of Vi\ue7osa, Minas Gerais, Brazil, using a Complete Randomized Designed, with five doses of potassium (0, 50, 100, 150 and 200 mg dm-3 of K) and six doses of sulfur (0, 20, 40, 60, 80 and 100 mg dm-3 of S) . The nutrients were applied in four split doses, 0, 30, 60 and 90 days after sowing. The height data, the stem diameter and the root dry matter were recorded after 157 days of sowing. The relationships between shoot/root ratio, plant height stem diameter ratio and the Dickson quality index (DQI) were taken. The seedling showed a negative response to potassium fertilization for most of the characteristics evaluated. The application of 30 mg dm -3 of S and 30 mg dm -3 of K is recommended for jacarand \ue1-da-bahia seedling production for maximum dry mass production