Comparison of soil and hydroponic cultivation systems for spinach irrigated with brackish water

摘要

The sustainable use of brackish water in agriculture demands the use of compatible cultivation systems. The objective of this study was measure differences in the water status of spinach plants (Spinacia oleracea L.), cv. Viroflay, cultivated in covered and uncovered soil and in a hydroponic floating system, using brackish water (EC = 0.8, 1.5, 3.0, 4.5, 6.0 and 7.5 dS m(-1)) in the irrigation of plants in soil and replacement of nutrient solution in the floating system. At 38 days after transplanting, leaf water potential and osmotic potentials of the crop and of the systems were determined, as well as the osmotic adjustment, water consumption, leaf succulence, water use efficiency, leaf sodium content and yield. The hydroponic system showed a linear increase in the fresh weight of the leaves due to the salinity increase. The use of plastic cover attenuated the effects of salinity by 16 % in comparison to the uncovered soil, but the hydroponic system was the least affected by salinity, despite having the highest water consumption, which was 58 % higher than that of the uncovered soil. The main adaptive strategies observed in Spinacia oleracea L. cv. Viroflay in response to salinity were: increase in osmotic adjustment and leaf succulence and reduction in leaf water potential. The responses, positive in general, are corroborated by the values of sodium concentration in the leaves and fresh weight, which showed the highest results in the hydroponic cultivation for both variables. It is recommended to use the plastic cover or hydroponic methods during spinach cultivation, especially when using brackish water.