Relações hídricas do amendoim irrigado com águas salobras sob gotejo pulsado e contínuo

Abstract

Peanut, the 5th most produced oilseed in the world, has been grown in Brazil mainly in the Southern Region with two growing seasons per year. In the Northeastern region, due to rainfall ununiformity, it has been grown in the rainy season. Therefore, irrigation comes as an alternative to promote agricultural operations in those áreas, early considered inappropriate. Thus, pulsed dripping irrigation stands out for its lower amount of water used, high water efficiency, and for maintaining soil moisture. Moreover, an efficient water management in irrigation is vital to optimize water efficiency, especially when using brackish water. Thus, this work was carried out aiming to evaluate grain and pod production based on the water relations of peanut plants, cultivar BR-1, irrigated with brackish waters (EC = 0.12; 1.6; 2.8; 4.0 and 5.2 dS m-1) via pulsed and continuous dripping. It was used an experimental randomized block desing in a 5x2 factorial scheme with four replications, adding up to forty experimental units. The experiment was carried out at the Fertigation and Salinity Laboratory - DEAGRI/UFRPE. The plants were grown in drainage lysimeters in an open field from September to November 2019. The data for grain and pod production (g plant-1); water use efficiency (g mm-1); instant water use efficiency - A/E (μmol CO2/mmol H2O); intrinsic water use efficiency - A/gs (μmol CO2/mmol H2O); stomatal conductance - gs (mmol H2O m-2 s-1); transpiration - E (mmol H2O m-2 s-1); leaf water potential (MPa); osmotic potential (MPa); osmotic adjustment (MPa); leaf succulence (g of H2O dm-2) and relative water content (%) were subjected to the analysis of variance at the level of 0.05 probability. It was found that the use of pulsed dripping did not mitigate the deleterious effects of salinity, but it provided greater grain and pod production compared to continuous dripping. It was also found that the use of brackish water by pulsed dripping provides greater water use efficiency compared to continuous dripping. Moreover, the increase in the electrical conductivity of the water affected the water, pressure and osmotic potentials, along with the osmotic adjustment.