Morfologia e produção do girassol irrigado com água de diferentes naturezas catiônicas e adubação nitrogenada.

Abstract

In the Brazilian semiarid is common to find water with high salt concentrations and variation in its cationic composition. In this sense, the aim with the present work was to evaluate the influence of irrigation water of different salinities and cationic nature associated to nitrogen rates on the growth, physiology and production of sunflower cv. BRS 324. The study was conducted vases adapted as lysimeters under field conditions at the Center for Technology and Natural Resources of the Federal University of Campina Grande, during the period from November 2014 to January 2015. The design utilized was a randomized blocks in a factorial 5 x 5 with three replications, five combinations of salinity and cationic nature of water - S (S1 - Witness; S2 - NaCl; S3 - CaCl2; S4 - KCl and S5 – NaCl+CaCl2+MgCl2) and five nitrogen rates (N1 - 50; N2 - 75; N3 - 100; N4 - 125 and N5 - 150 mg N kg-1soil). Used in water irrigation with electrical conductivity – CEw de 0,5 dS m-1 to the witness (S1), and 5,0 dS m-1 to other treatments (S2; S3; S4 and S5); 70 days after sowing (DAS) were evaluated: stem diameter (DC), plant height (PH), leaf area (LA), dry matter of the stem (FSC) and dry mass of leaves (FSF); Already at 56 DAS, it was obtained stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E), CO2 assimilation rate (A) and intrinsic efficiency of water use (USA); Also determined whether it diameter of the outer chapter (DCE), the internal diameter chapter (DCI), chapter of biomass with achenes (FCA), dry mass of the chapter (FSCa) and biomass of achenes (FA). The data obtained were subjected to analysis of variance by the test 'F'; when significant was held a mean comparison test (Tukey) for the factor "cationic nature of water" and regression analysis to the factor "nitrogen rates." The growth and production parameters. sunflower cv BRS 324 were more affected by salinity when compared to the cationic nature of the irrigation water; The gas exchanges were influenced negatively by cationic nature of irrigation water, principamente in stomatal conductance and CO2 assimilation rate, and among the evaluated cations, potassium afforded the highest values for these variables; with respect to nitrogen fertilizer, doses of 50 mg N kg-1 soil provided better results for plant height; as to leaf area and dry mass production leaves the best dose was 100 mg N kg-1 soil.