Rogério Dantas de Lacerda

Consumo de água e eficiência do uso para duas cultivares de mamona submetidas a estresse hídrico

Although the productivity of castor bean reduces under water deficit it is considered resistant to low precipitation conditions, thus constituting an alternative form of income for the semi-arid. Among its production derivates the ricinoleic acid stands out as a substitute for petroleum derivates. The scarce information on the effects of water deficit on castor seed production in areas where the low precipitation does not satisfy the evapotranspiration needs motivated this study, which deals with the water consumption and use efficiency of two castor cultivars (BRs-149 and BRs-188) submitted to different soil water contents. The study was conducted in a greenhouse located at the Federal University of Campina Grande - Campus I, during the period of February 7 to August 5, 2004, following a 2 x 4 factorial design with two cultivars, four soil water levels (40, 60, 80 and 100% of the available soil water) and three replicates. Analyzing the phytomass, the water consumption and water use efficiency it was observed that both cultivars show a similar behavior. The plants without water stress, presented a high phytomass production, thus indicating an elevated efficiency on the conversion of water used into dry matter.

Uso de propriedades físico-hídricas do solo na identificação de camadas adensadas nos Tabuleiros Costeiros, Sergipe

The presence of subsurface high density soil layers has an important effect upon the infiltration and water movement into the soil, difficulting the water management during the irrigation. Aiming to identify and characterize this high density soil layers at the Neopolis Plato, Sergipe State, Brazil, the physico-hydrical properties density, porosity, water retention and capillary conductivity were determined and utilized. The capillary conductivity was determined throughout the instantaneous soil profile using the Libardi Model. The studied characteristics (density, porosity, water retention and capillary conductivity) were very effective at identifying and characterizing the hardsetting layers.

Efeito da água disponível do solo no desenvolvimento de dois cultivares de mamona, nos primeiro e segundo ciclos

Castor bean is an oleaginous of relevant economic and social importance. It is a very important culture for the economy of the Northeast of Brazil due to its social inclusion, employment and devises guaranty. In the present research was studied different castor bean management aspects, aiming the optimization of water use and crop yields in the first and second cycles, being this last one obtained after a drastic pruning of the plant at the end of the first cycle. The experiment was conducted at the field in Lagoa Seca, PB. The experimental design was a randomized block in a factorial 2 x 4 scheme, consisting of two castor bean cultivars (BRS 188 - Paraguacu and BRS 149 Nordestina) and 4 levels of available soil water (40, 60, 80, and 100%) with three replicates. The data was analyzed statistically through analysis of F variance. Plant height, stem diameter, leaf area and phytomass of shoots were evaluated. Available soil water increased all growth and development indices of the plants. The second cycle of the culture (regrowth), presented behavior similar to that observed in the first cycle, demonstrating the technical feasibility of conducting a second cycle of Castor bean.

PRODUTIVIDADE E TEOR DE ÓLEO DO GIRASSOL SUBMETIDO A DIFERENTES NÍVEIS DE AGUA E NITROGÊNIO NO SOLO

Aiming to study the effects of the available soil water for plants and nitrogen fertilization on sunflower water consumption and efficiency, an experiment was carried out on an area of the Federal University of Paraiba – UFPB, at Lagoa Seca – PB. The study was conducted in a 5x4 factorial with randomized blocks and four replications using the hybrid sunflower Helio 360 submitted to five irrigation depths (40, 55, 70, 85 e 100 % of the Reference Evapotranspiration)and four nitrogen doses (25; 50; 75 e 100 kg ha-1). The data was analyzed through analyses of variance using the F test and regression analyses. The increased available soil water for plants, associated with increasing doses of nitrogen increased significantly the sunflower productivity and oil content of the seeds.