Magnetização de água para atenuação de estresse salino em feijão-caupi.

Abstract

Saline water can be an alternative source of fresh water for agricultural irrigation in water scarce areas, as long as alternatives are used to reduce the presence of salts in the irrigation water. The magnetization of saline water enables the precipitation of carbonates. The aim of this study was to evaluate the magnetization of irrigation water using the AMAI magnetizer to mitigate saline stress in irrigated species. The following variables were evaluated: electrical conductivity, pH, infrared light absorption and the calcium, magnesium, potassium, chloride, bicarbonate and carbonate content after the magnetization of supply water, supply water with added salts (3.3 dSm-1) and deionized water which were magnetized with intensities of 200, 300 and 400 mT. These analyses were carried out in the laboratory and it was found that the electrical conductivity of the water magnetized with the AMAI magnetizer increased, with the exception of the deionized water and supply water added with salts, which was magnetized with 300 mT and reduced the EC. The pH of the water decreased when the deionized water was magnetized with 400 mT. The concentration of calcium, magnesium, sodium, chlorides, bicarbonates and carbonates decreased as the water was magnetized. The absorption of infrared light decreased with the magnetization of the water. In addition, the effects of saline water magnetized with AMAI on gas exchange, enzyme and proline production in cowpea were also analyzed. This study used a factorial design (3 x 2 x 2), with 3 levels of salinity applied by irrigation (0.38; 2.0 and 4.0 dSm-1), two forms of water treatment (non-magnetized water and water magnetized with 200 mT) and analyses carried out before and after irrigation, with seven replications, totaling 84 experimental units. For the proline and enzyme contents, the factorial scheme (3 x 2 x 3) with 3 levels of salinity applied by irrigation (0.38; 2.0 and 4.0 dSm-1) and two forms of water treatment (non-magnetized water and magnetically treated water), and three irrigation intervals, with seven repetitions, totaling 42 units. Leaf gas exchange levels were analyzed (CO2 assimilation rate, transpiration, stomatal conductance, internal CO2 concentration, instantaneous water use efficiency and instantaneous carboxylation efficiency). Proline content and enzyme activity (catalase, superoxide dismutase and ascorbate peroxidase) were also assessed. Seed weight per plant, number of grains per plant and pod length were also ix quantified. The production of superoxide dismutase was stimulated by the magnetized water in the AMAI, the plants that were irrigated with saline water of 0.38, 2 and 4 dSm-1 and magnetized increased by 20.64, 9.16 and 11.23%, respectively when compared to the plants that were irrigated with water of the same salinity but without magnetization. Proline production also increased with the process of magnetizing water with AMAI, with an increase of 34.94 % when compared to plants irrigated with saline water without magnetization.