Nitrogênio e espaçamento de plantio do crambe na região semiárida paraibana.

Abstract

Among the various species being studied for biodiesel production, crambe (Crambe abyssinica) proves to be a promising plant. It has low planting cost, high oil content, as well as an easy extraction process; in addition, it is an alternative to the crop rotation system and exhibits considerable adaptability in semi-arid climatic conditions. However, as it is a little known species in the semi-arid Northeast, several studies on its management need to be carried out. Due to the need for knowledge to expand the cultivation of this species, this study aimed to evaluate the development and production of crambe (Crambe abssynica Hoechst.) under different nitrogen fertilization rates and spacing, in semi-arid conditions. The study was conducted through experiments on a property in the research field of the Instituto Nacional do Semiárido-INSA, located in the city of Campina Grande-PB. The experimental design used was randomized blocks, in a 4 x 2 factorial scheme, consisting of four nitrogen rates (30; 60; 90; 120 kg ha-1), with three replications and two distinct spacings (0.20 and 0.40 meters); totaling eight installments for each block. The dosages were divided and applied in three dosages, at 15, 30 and 45 DAS. The parameters evaluated were: plant height, number of branches per plant, number of siliques per plant, yield, 1000 grain mass, plant dry mass. The data obtained were submitted to analysis of variance (F test) using the Statistical Analysis Program – SISVAR. In which, results were obtained that show, under the conditions in which this experiment was conducted, nitrogen fertilization of 120 kg ha-1 , with a spacing of 0.40 m between planting lines, provided the best results for plant height, although, the absolute growth rate from 60 to 75 DAE, in the 0.20 m spacing, stood out from that of 0.40 m, from the dose of 90 kg ha-1. The best biometric results regarding the stem diameter occurred under the dose of 30 kg ha-1, with no interference of the spacing studied in these variables. Nitrogen fertilization with a spacing of 0.40 m between the planting lines provided the best results in relation to the production components, however, when measuring the yield per area, the spacing of 0.20 m with the fertilization of 120 kg ha- 1 exceeds the values found in spacing of 0.40m in the same dosage. Because, despite the lower production per plant, in this condition, there is a greater number of plants per planted area and, therefore, a higher incidence of siliques per area.