Emergence and early growth physic nut (Jatropha curcas L.) grown under different levels of salinity in irrigation water.

Into account the potential of physic nut (Jatropha curcas L.) oil production for biodiesel and this being a suitable oilseed cultivation in semiarid region due to its hardiness and resistance to adverse conditions of climate and soil, primarily to water stress opens up new perspectives for studies focused on the relationship of the species with salinity. With emphasis on this aspect, this study aimed to evaluate the parameters of emergence and early growth of physic nut under different salinity levels of irrigation water. The experiment was conducted in a greenhouse at the Center for Science and Technology Agrifood UFCG in the period May-June 2012. The seedlings were grown in a mixture of soil and cattle manure (2:1), with treatments arranged in a randomized block design with three replications, five salinity levels of irrigation water regarding electrical conductivity (EC w) 0 , 2, 1.2, 2.2, 3.2 and 4.2 dS m-1. Each plot consisted of four plants. We evaluated the percentage of emergence, speed of emergence and at 46 days after sowing, plant height, stem diameter, leaf area, fresh and dry weight of shoot and root dry mass. The salinity of irrigation water affected only the stem diameter and fresh weight of shoots with decreases of 6.39 and 13.81%, respectively, per unit increase of ECw.