Efeito do conteúdo de água do solo em diferentes estádios fenológicos de duas cultivares de mamona em condições de semeio e rebrote.

Abstract

he study aimed to study the sensitivity of the castor bean cultivars BRS 188 - Paraguaçu and BRS - 149 Northeastern at various levels of water available in the soil, at different phenological stages, evaluating the effects on the growth, development and production, in the sowing and regrowth cycle cycles. The research was conducted at the Center for Agricultural and Environmental Sciences - CAAC, Campus II, State University of Paraíba - UEPB, located on the Site Imbaúba, s / n, Rural Zone, Lagoa Seca, PB, Microregion of Campina Grande, Paraíba Agreste, with an average altitude of 634 m in the period October 2009 to October 2009. It was used a sandy loam soil with low organic matter content. The experiment was a randomized block design in factorial scheme 2x4, consisting of 2 cultivars and 4 levels of available soil water (100, 80, 60 and 40%) applied on the growth and fructification stages, with three replicates. Each plot consisted of an area of 100.0 m2 in which were grown in 50 plants, spaced at 2 x lm. The soil was fertilized with triple superphosphate in foundation in the amount of 120 kg ha"1 P205 and included 100 kg.ha"1 K20 and 100 kg.ha"1 N in the forms of potassium chloride and urea, split in equal portions at intervals of 10 days via fertigation, with the first application occurring 20 days after sowing. The experiment was conducted for two consecutive cycles, the first 180 days and the second from the pruning of plants to a height of 30 cm from the ground level, starting the second cycle of cultivation, for another 180 days. The water content of the soil was monitored every two days using a segmented TDR probe. Irrigation was made at the same time intervals. The data were processed statistically using analysis of variance (ANOVA) and Tukey test for comparison of the qualitative treatments and regression analysis to the quantitative factors available water. The castor bean cultivars showed increased responses of growth, development and production depending on the application of sheets of rising waters. The efficiency of BRS 188 Paraguaçu and BRS 149 Northeastern to turn the water consumed in biomass, fruits and seeds, increased with the addition of available soil water. Water availability in the different levels and phenological stages produced significant alterations in physiological processes essential to the productivity of both cultivars. It was observed that all variables generally increased with increasing water content in the soil at different growth stages. So the best performance of castor in the periods, was obtained when the water content of the soil was kept at field capacity, with 100% of available soil water to plants.