CARACTERÍSTICAS PRODUTIVAS E VALOR NUTRICIONAL DE VARIEDADES DE LEGUMINOSAS EM FUNÇÃO DA ADUBAÇÃO FOSFATADA.

Abstract

The objective of this study was to evaluate the effect of phosphate fertilization on root and shoot dry matter production, morphological composition, quantify number of nodules and evaluate the chemical composition of three crotalaria cultivars (Crotalária juncea, Crotalária spectabilis e Crotalária ochroleuca) e o feijão guandu (Cajanus cajan). The experiment was carried out at the Federal University of Maranhão in a greenhouse using pots with 6 dm³ of soil and with irrigation monitored. The experimental design was completely randomized in a 4 × 4 factorial scheme, with four doses of phosphate fertilization (0, 100, 200, 300 kg / ha P2O5) and four legume cultivars (Crotalaria juncea, spectabilis, ochroleuca and feijão guandu), with four replicates, totaling 64 vessels. There was positive linear effect for leaf dry matter production, stem dry matter yield and total dry matter production. The highest values of leaf dry matter production occurred for Crotalaria spectabilis, with an average yield of over 2000 kg when compared to the other species analyzed. Crotalaria spectabilis showed lower stem production (2071.61 kg/ha) and, consequently, a higher leaf: stem ratio (2.38). The highest dry matter yield of the stem (6878.45 kg / ha) was observed for Crotalaria juncea, compared to the other legumes, this species presented an average yield of more than 3000 kg/ha of stem when compared to the other legumes studied. There was a positive linear effect for root length where the highest level of phosphorus provided greater root length. The greater number of nodules occurred in Crotalaria spectabilis. The highest levels of neutral detergent fiber in the leaf were observed for Crotalaria spectabilis, Crotalaria ochroleuca and feijão guandu. The lowest levels of neutral detergent fiber of the stem, acid detergent fiber of the leaf and the acid detergent fiber of the stem, 74.43; 31.94 and 64.35%, were observed in Crotalaria spectabilis, respectively. There was an increasing linear effect for crude protein contents of the leaf, only for Crotalaria juncea and feijão guandu. Therefore, phosphate fertilization achieved higher fertilization efficiency at the dose of 100 kg/ha. The addition of phosphorus promoted better results as a function of the four legumes studied.