Stimulate® na germinação de sementeas, vigor de plântulas e crescimento inicial de Jatropha curcas L.

Abstract

Faced with a shortage of informations about the cultivation of Jatropha, it aimed to evaluate seed germination, seedling vigor and plant initial growth of Jatropha plants, when submitted to pre-soaking in distilled water and Stimulate® (90 mg L-1 kinetin, 50 mg L-1 gibberellin, 50 mg L-1 auxin and 99.981% inert ingredients). The experiments were conducted at the Laboratory of Plant Physiology and in the greenhouse at the Center for Agricultural Sciences, Environmental and Biological of Federal University of Recôncavo of Bahia. The seeds went through a disinfecting solution of sodium hypochlorite 2% for 2 minutes and washed in running water. The treatments were: control in distilled water (0.0) and concentrations Stimulate® (6.0, 12.0, 18.0, 24.0 and 30.0 mL. product. L-1 solution), for eight hours, in four replications of 50 seeds for germination test and 10 seeds for seedling energy of seedling test in Germitest paper. We used 25 seeds in four replications for Speed Emergency Index (IVE) installed in plastic trays on benches in a greenhouse, with washed sand as substrate. The initial growth was evaluated in five uniform plants, the following characteristics: plant height (cm), stem diameter (mm), leaf number, weight dry root (g), weight dry stem (g), weight dry leaves (g) and total dry mass (g). The plants were evaluated in 40 days after sowing (DAS). For growth analysis, samples were taken in decade of five random plants per plot from 21 days after sowing (DAS) until 71 DAS, for the determination of dry matter (g plant-¹) and leaf area of plant (dm2), as the basis for determining the physiological indices: absolute growth rate (AGR), relative growth rate (RGR), net assimilation rate (NAR) and leaf area ratio (LAR) and leaf area ratio (LAR). In relationship to germination test and vigor, the biostimulant has a depressing effect on the evaluated characteristics, except for root length, in which there is an increase of 12% to the estimated concentration of 9.3 mL L-1 Stimulate®. However, it influences, positively, the initial growth of Jatropha plants, with concentrations up to 18.0 mL L-1, the most efficient in the promotion of those haracteristics. Besides, there is no significant difference in the concentrations used, in physiological indices, varying only in time of sampling. For experiments in a greenhouse with jatropha, the optimum size plot should be ten plants.