Crescimento do pinhão manso (Jatropha cursas L.) sob estresse salino e adubação nitrogenada.

Abstract

Jatropha (Jatropha curcas L.) is an alternative for biodiesel production due to its hardiness and can be grown in various regions of the country, including the northeast Brazil. In order to study the growth of Jatropha irrigated with saline water and application of nitrogen and their interactive effects on the morphological variables. An experiment was conducted in a greenhouse located in the experimental area of the Academic Unit of Agricultural Engineering, Natural Resources and Technology Center of the Federal University of Campina Grande in the state of Paraíba. The crop was sown in plastic pots adapted as drainage lysimeters with a 240 kg of Typic Regolithic eutrophic sandy loam soil characterized as non-saline non-sodic as substrate. The salinity factor was based on electrical conductivity of irrigation water - ECw (0.6, 1.6, 2.6, 3.6 and 4.6 dS m-1) prepared by adding NaCl in the municipal supply water of Campina Grande -PB, and doses of nitrogen used were on the basis of recommendation of Novais (1991) for experiments in pots (50, 75, 100, 125 and 150%). The statistical experimental design was in randomized blocks in 5x5 factorial scheme with three replications. The growth variables analysed were the plants height, stem diameter, leaf number, leaf area, absolute growth rate of height, relative growth rate , absolute growth rate of the diameter and relative growth rate of the diameter at 50, 70, 85, 100, 115, 130, 145, 175.205 and 235 days after sowing. There was no significant effect of the nitrogen or its interaction with salinity in the variables studied. The salinity affected linearly plant height, stem diameter, leaf number, leaf area, the absolute growth rate of height, the relative growth rate, the absolute growth rate of the diameter and relative growth rate of the diameter and the leaf area being the most sensitive variable.