Cultivo do girassol sob diferentes lâminas de irrigação com água salobra

Abstract

Among the agronomic production techniques, irrigation is an important ally in agronomic performance, however, one of the great problems of our time is the shortage of water. The global availability of fresh water for irrigation is decreasing due to increasing competition from urban and industrial development, so that the quality of water use less irrigation becomes a challenge and a necessity. In this context, the objective of this research is to evaluate the effect set of four brackish water in the replacement of evapotranspiration in sunflower cultivation, aimed at understanding the best irrigation strategy to minimize the negative impacts of the use of brackish water culture. The experiment will have an experimental randomized block design in split plot, with four replications. The treatments consist in applying four brackish waters in the portion (1.0; 2,5; 4,0 and 5.5 dS m-1), five levels of irrigation ( L1, L2, L3, L4 and L5 equivalent to 50, 75, 100, 125 and 150% of crop evapotranspiration) as subplots. Sunflower seeds were sown in pots 20 liters. The following variables for this research were analyzed: plant height; number of sheets; stem diameter; leaf area; biomass; phytomass partition; outer diameter of the chapter; water consumption, electrical conductivity of water drainage, and gas exchange. The collected data were analyzed by classical descriptive statistics. Were also applied tests to verify the normality of the data and later by analysis of variance, will assess the significance of the F test treatments when denoted significant effect, the qualitative treatments were evaluated as means comparison tests and quantitative data were subjected to regression studies. The growth (plant height, diameter of the outer chapter and leaf area) of sunflower plants suffered no restriction to be exposed to salt and water stress, since the production of biomass (dry weight biomass as a partition) were reduced stress suffered by salinity, as the water factor provided an improvement in the yield of biomass total. A mutual influence of factors salinity and water deficit sharpens the susceptibility of sunflower to high salinity, with increasing blade reduced the effect of the EC lift . Ca nutrient content, Na, Cl, grow positively with the increase of salinity and increased blade irrigation. Since the nutrient K drastically reduces with increasing salinity. The application of saline water during the final phase of the Sunflower cycle inhibits leaf gas exchange, however, the drought exercised a low influence, showing that sunflower and more tolerant irrigation lamina of variation in the different stage of development without causing a lot of damage in the photosynthetic process. The application of different strategies for irrigation management with brackish water in the most severe form could have led to more significant differences in the results obtained. Thus, it is suggested that further studies are conducted under different intensities of water stress throughout the different development stages of the crop. The use of irrigation with brackish water slides, provides an increase in the volume of water for the irrigation in semiarid regions.