Salinidade da água no solo e no comportamento vegetativo e produtivo da mamoneira BRS energia.

Abstract

This research aimed to evaluate the growth and production o f the castor oil plant, cultivar BRS Energia, in function of the irrigation water salinity in lisimetry system, with the purpose of generating technology for its cultivation in the Northeastern semiarid. The study was developed in the experimental area o f Irrigation and Drainage of the Bahia Federal Institute, Campus of Senhor do Bonfim. The used experimental design was entirely randomized with seven treatments and three repetitions, totaling 21 experimental plots. The treatments were constituted of levels of salinity of the irrigation water, being the lowest level (0.12 dS m"1) the one of the water of urban provisioning o f the municipal district, which was considered as the control; the other levels were: 0.8; 1.6; 2.4; 3.2; 4.0 and 4.8 dS m"1 (25 °C). The salinity of the soil, of the soil solution and of the drained suspension increased lineally with the increase of the salinity o f the irrigation waters; however, in spite of the increase of the salinity of the irrigation waters has elevated the saline character of the soil, it didn't interfere in its sodicity. The growth of the plants decreased in a linear way with the increase of the salinity of the irrigation waters in all analyzed variables. The absolute growth rate in height of plants and in leaf area decreased in function of the increase of the salinity of the irrigation waters and of the time of cultivation, while the relative growth rate of those variables decreased just with the time of cultivation. The absolute growth rate of the stem diameter increased in function of the salinity of the irrigation waters and of the time of cultivation; already its relative growth rate decreased as the increase of the time of cultivation independently of the increase of the salinity of the irrigation waters, for which, in a certain time o f cultivation, the relative growth rate of the stem diameter tended to be practically constant. The increase of the salinity o f the irrigation waters inhibited the productive capacity of the castor oil plant and promoted larger peel percentage in the fruits. Even for the largest level of salinity of the irrigation waters, the yield in oil (49.18%) was satisfactory in relation to other oleaginous ones.