Genival Barros Júnior

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.

Produção e qualidade do fruto da mamona em semeio e rebrote sob estresse hídrico fenológico

The castor bean crop has a social and economical importance for the Northeast region due to the social inclusion and employment. The experiment aimed to study the sensitivity of the castor bean to soil water levels applied at different phenological stages, evaluating the production and fruit quality in the seeding and regrowth cycles. The experimental design was a randomized block in a 2 x 4 factorial scheme, consisting of two castor bean cultivars (BRS Paraguacu and BRS Nordestina) and 4 levels of available soil water (40, 60, 80, e 100%) applied during growth and frutification with three replications. The data were analysed statistically through analysis of variance (F teste) and Tukey test was used for the comparison of the cultivars and regression analysis for the quantitative factor. The increase of soil water availability for the plant at the different phenological stages studied increased production significantly and promoted positive alterations in the fruit quality of both cultivars. Both cycles presented similar performance with an elevated quality of the final product. The best performance of the castor bean was obtained when the available soil water content during the whole phenological period was kept at 100%.