Treated domestic effluent and levels of boron on growth and flowering of sunflower

The expansion of oilseed cultivation under semiarid conditions is related to the use of alternative water and efficient fertilization management. Thus, the aim of this study was to evaluate the growth and flowering of sunflower (EMBRAPA 122-V2000) irrigated with treated domestic effluent under different doses of boron (B). Hence, this study tested the application of five B doses (0 - control, 1.0, 2.0, 3.0 and 4.0 mg kg-1 applied as basal dose in the form of boric acid) in plants irrigated with two types of water (treated domestic effluent and public-supply water). These treatments were arranged in a completely randomized design, analyzed in a 5 x 2 factorial scheme, with three replicates, totaling 30 experimental units. Statistical analysis included analysis of variance and regression analysis for the quantitative factor and test of Tukey for the qualitative factor at 0.05 probability level. It was found that the interaction between boron doses and type of water had an influence on stem diameter in all stages of the cycle until flowering; the beginning of flowering, number of petals and capitulum internal diameter were not influenced by boron doses or types of water used in irrigation; however, the plants showed a maximum external diameter of the capitulum under the dose of 1 mg kg-1 of boron, applied as basal fertilization, regardless of the type of water used in irrigation.