Emergência, crescimento e produção da mamoneira sob estresse salino e doses de nitrogênio.

Abstract

Castos is an oilseed crop belonging to the family Euphorbiaceae, with significant socioeconomic vague, with products and coproducts ricinoquimica used in industry and agriculture, which has great economia potencial 6or the semi-arid northeastern Brazil. The objective of this research was to evaluate the et6ect of diflêrent salinity leveis of irrigation water associated with nitrogen fertílization on the castos bean cv. BRS Energy, grown in lysimeters under field conditions. We adopted the experimental design of randomized blocks, arranged in a 5 x 5 factorial design with three replications and the treatments consísted offive leveis ofelectrical conductivity of irrigation water - ECw (0.4, 1.4, 2.4; 3.4 and 4.4 dS m ') and teve doses of nitrogen (50, 75, 100, 125 and ]50 % ofthe indication ofnitrogen 100 mg kg ' ' for testing in pot) . From the salinity ofthe irrigation water of 0.4 dS m ' ' were linear decreases in the percentage of emergency, the index of germination speed, number of leaves, plant height and stem diameter of castor bean. Increasing leveis of nitrogen attenuated the effect of salinity of irrigation water to the levei of 2.4 dS m ' ' promoting higher specifíc leaf área of the castor. The number of seeds of the pastor bean primary raceme was the variable most sensitive to salt stress, resulting in reduction respectively of 1 8.3 % per unit increase in the electrícal conductivity of irrigation water. The interactíon between salinity and N leveis was significant for number of leaves and stem diameter, with increasing doses of nitrogen mitigated the negative ef6ect of water salinity to the levei of 2.4 dS m ' '. The electrical conductivity of írrigatíon water up to 1.9 dS m - l and nitrogen from 134 % of the recommended favor greater number of racemes per plant.