Produção de mudas de catingueira-verdadeira (Caesalpinia pyramidalis Tul.) em função de substratos e luminosidades Production of Caesalpinia pyramidalis Tul. seedlings in substrates and light intensities

Resumo: A catingueira-verdadeira (Caesalpinia pyramidalis Tul.) e uma especie nativa da caatinga dotada de resistencia a seca e de potencial economico. Objetivou-se avaliar o efeito de substratos e de niveis de luminosidade na emergencia, e crescimento inicial de plântulas de catingueira-verdadeira. As sementes foram semeadas em recipientes preenchidos com solo, areia e esterco, em diferentes combinacoes, e substrato comercial. Os recipientes foram mantidos sob quatro condicoes de luminosidade: 100; 70; 50 e 25%. Foram avaliados porcentagem de emergencia de plântulas; indice de velocidade de emergencia, tempo medio de emergencia, coeficiente de velocidade de emergencia, massas fresca e seca totais, comprimento total, area foliar, numero de folhas e indice relativo de clorofila (IRC). As plântulas apresentaram maior porcentagem e velocidade de emergencia e maior IRC quando semeadas em solo+areia+esterco e mantidas a ceu aberto. Os substratos com apenas solo e com solo e areia, em alternativa ao substrato comercial, induziram maior crescimento inicial das plântulas. Conclui-se que a utilizacao de telados de baixo sombreamento e substratos com apenas solo e com solo e areia favorece a obtencao de mudas de catingueira-verdadeira. Palavras-chave adicionais: arvore, propagacao, forrageira, sombreamento, caatinga. Abstract: Caesalpinia pyramidalis is a native silvicultural drought resistant species of the caatinga (type of veg- etation of an ecoregion in the northeastern part of Brazil) showing good economical potential. The objective of this study was to find the best substrata and levels of luminosity for the production of seedlings of this species. The vases in which the seeds were sown were filled with mixtures in differ- ent proportions of soil, sand, and manure. In addition to that, a commercial substratum was also used. Seed germination took place under luminosity degrees of 100, 70, 50, and 25%. Seedling emergence in percentage, speed of emergence index, mean time for seedling emergence, speed of emergence coefficient, total fresh weight, total length, leaf area, number of leaves, and relative chlorophyll index (IRC) were observed. The highest percentage of seedling emergence, speed of emergence and IRC were observed when the seeds were sown in a mixture of soil, sand, and manure with germination taking place under open sun light. The substrata in which only soil or soil and sand were used re- sulted in seedlings with a higher initial growth. The results showed that well illuminated green houses and soil or soil and sand as substrata are conditions favoring the development of C. pyramidalis seed- lings.