Response of jatropha to organic and phosphate fertilization under irrigated conditions

Abstract

Jatropha (Jatropha curcas L.) is a perennial species that requires expressive amounts of nutrients in order to produce satisfactorily. An experiment was conducted using pots, arranged in a randomized block design, with four replicates and one plant per plot, in order to evaluate different fertilization recommendations (phosphate fertilizer and cattle manure) based on soil analysis. The treatments consisted of a 4 x 4 factorial scheme, which represented 4 recommendations of organic fertilization [absence of organic fertilization (0 t ha -1 ), recommended dose (4 t ha -1 ), 1.5 times the recommended dose (6 t ha -1 ) and 2 times the recommended dose (8 t ha -1 )] and 4 recommendations of phosphate fertilization [absence of phosphate fertilization (0 kg ha -1 ), recommended dose (90 kg ha -1 ), 1.5 times the recommended dose (135 kg ha -1 ) and 2 times the recommended dose (180 kg ha -1 ). One hundred and eighty days after seedlings were transplanted to the pots, growth variables and production components were measured. Plant height, number of branches, stem diameter, leaf area, number of inflorescences, number of fruits, number of bunches, number of fruits per bunch, mass of fruits, number of seeds per fruit, number of seeds per plant and total mass of seeds per plant were influenced by the fertilization recommendations. The recommendation of organic and phosphate fertilization suggested by the laboratory of soil analysis (4 t ha -1 of organic matter and 90 kg ha -1 of phosphorus) was insufficient to obtain productive plants. The isolated use of organic matter in fertilization of jatropha promotes positive effects on growth variables and production components. The application of 1.5 the dose of organic matter recommended by the laboratory of soil analysis, corresponding to 6 t ha -1 of cattle manure, isolated, or associated with 135 kg ha -1 of P, is sufficient to supply the nutritional demand for N and P in the first cultivation cycle. Phosphate fertilization associated with organic fertilization significantly influenced plant height, number of branches, stem diameter, leaf area, number of seeds per plant and total mass of seeds of jatropha plants.