Crescimento e componentes de produção da mamoneira sob estresse salino e doses de nitrogênio.

Abstract

The castor bean (R/c/nus commt/n/s L.) is a plant of the Euphorbiaceae family, which has great adaptation capacity to varied climatic conditions, beyond of resistance to water deficit and possibility of cultivation in severas sons. In this sense, aimed at with this research, to evaluate the effect of different salinity leveis of irrigation water associated to dose of manuring nitrogen, on growth and components of production of castor bean cv. BRS Energia, cultivated in lysimeters under field conditions. The treatments consisted of the combination of ave leveis of electric conductivity of the irrigation water (0.4; 1 .4; 2.41 3.4 and 4.4 dS m'l) and ave doses of nitrogen (501 75; 1001 125 and 150% of the dose recommended for pot experiment). A blocks randomized design was adopted in factorial 5 x 5, with three replications, totaling seventy ave experimental units. Salinity of irrigation water reduce growth of pastor bean cv. BRS Energia, observed by decrease of plant height, stem diameter, number of leaves and leaf área. Mass of one hundred seeds, oil content and number of fruits of the primary raceme are affected negatively by salinity of irrigation water larger than 0.4 dS m'l, being the number of fruits the most sensitive variable. Salinity of irrigation water up to 1 .37 dS m'l provides content of seeds oil of 47% for castor bean cv. BRS Energia. The increase of doses of manuring nitrogen reduced the effect of the salinity on leaf área of castor bean cv. BRS Energia. Castor bean answers significantly to interaction between the factors water salinity and doses of nitrogen to stem diameter and length of the primary raceme.