Crescimento inicial do pinhão manso (Jatropha curcas L.) em função de níveis de água e adubação nitrogenada.

Abstract

This work has as objective evaluating the physic nut initial growth in function of the water levels and nitrogenated fertilization. The experiment was conducted in a greenhouse of EMBRAPA ALGODÃO, Campina Grande in the period from March 25th to September 5th, 2007. The experimental design adapted was a randomizes complete blocks, in which the treatments were distributed in factorial scheme (4x4) with four replicates and a plant per portion (vase), being these factors: four doses of nitrogen (N1=0 (witness), N2=60, N3=120, and N4=180kg ha-1), applied in an ammonium sulfate form (NH 4) SO4, and four levels of water in the soil (L1=100, L2=80, L3=60, and L4=40% of the available water), resulting in 64 portions. The water levels available in the soil during the treatments were derminated using the tensiometry. The plants growth was followed monthly by the measurement of: height, stem diameter and leaf area, beginning from the plants emergence, and at the end of the experiment were determined the development variables: dry mass of the leaves, dry mass of the stems and dry mass of the roots. There was a positive result for all the growth variables to the increasing applications of nitrogen doses and the water levels available in the soil. We can also highlight that, in all the cases there was a significant interaction between these two factors, indicating that there was a conjugated effect over the growth variables of physic nut plant, that is, one’s effect depends on the other’s effect. Most of the estimates to the growth variables (plant height and leaf area) and to the phytomass variables, were obtained in the highest dose of nitrogen and in the highest level of water studied, corresponding to 180kg ha-1 of N and to the level of 100% of water available in the soil. There was an exception to the growth variable in the stem’s diameter in the physic nut plant, whose biggest result was to the dose of 154kg ha-1 of N and the level of 100% of water available in the soil.