Emergence and initial growth of albizia seedlings under irrigation with saline water/ Emergencia e crescimento inicial de plantulas de albizia submetidas a irrigacao com agua salina

In order to evaluate the effect of different concentrations of salts in irrigation water on emergence and growth of albizia seedling (Albizia lebbeck (L.) Benth.) an experiment was conducted in the greenhouse of the Department of Plant Sciences, Federal Rural University of Semi-arid, Mossoro, RN, in a completely randomized design with six treatments and four replications with 24 seeds in each plot. The treatments consisted of saline concentrations (EC) of 0.68 (supply water), 1.5, 3.0, 4.5, 6.0 and 7.5 dS [m.sup.-1], which were obtained by the addition of NaCl in water. The evaluated variables were: percentage of emergence of seedling, speed of emergence index, shoot length, root length, number of leaves, accumulated electrical conductivity of the substrate index, chlorophyll content, dry mass of root, stem, leaves and total. The salinity negatively interferes in all parameters assessed in proportion to its increase in irrigation water. With major damage at concentrations above 1.5 dS [m.sup.-1], characterizing this species considered as a glycophyte little tolerant to salinity. Key words: Albizia lebbeck saline stress tolerance development Objetivou-se, com este trabalho, avaliar o efeito de diferentes concentracoes de sais na agua de irrigacao sob a emergencia e o crescimento inicial de plantulas de albizia (Albizia lebbeck (L.) Benth.). O experimento foi desenvolvido em casa de vegetacao do departamento de Ciencias Vegetais da Universidade Federal Rural do Semiarido, Mossoro, RN, usando-se o delineamento inteiramente casualizado, com seis tratamentos e quatro repeticoes, com 24 sementes em cada parcela. Os tratamentos foram constituidos das concentracoes salinas 0,68 (agua de abastecimento); 1,5; 3,0; 4,5; 6,0 e 7,5 dS [m.sup.-1], obtidas atraves da adicao de NaCl em agua. As variaveis avaliadas foram: porcentagem de emergencia de plantulas, indice de velocidade de emergencia, comprimento da parte aerea, comprimento de raiz, numero de foliolos, condutividade eletrica acumulada do substrato, indice de conteudo de clorofila, massa seca da raiz, do caule, das folhas e total. O aumento da salinidade na agua de irrigacao interfere negativamente na emergencia e no crescimento inicial de plantulas de albizia, sendo recomendado agua com concentracao salina ate 1,5 dS [m.sup.-1], caracterizando esta especie como glicofita, sensivel a salinidade. Palavras-chave: Albizia lebbeck estresse salino tolerancia desenvolvimento