USE OF HIGH SALT CONCENTRATION WATER IN SORGHUM PRODUCTION IN THE BRAZILIAN SEMI-ARID REGION

Abstract

In arid and semi-arid regions, due to the low rainfall and high evapotranspiration rate, salts are concentrated in the soil and in the water, causing the salinization of the medium. Irrigation is necessary in these regions, but the volume required by the crops is high. Deficit irrigation is an alternative since it alleviates plant stress, but without affecting the crop yield. Sorghum is a plant that tolerates soil moisture deficit and surplus. The objective of this work was to verify the influence of irrigation water salinity and depth in the sorghum (Sorghum bicolor (L.) Moench) crop in terms of yield. The experiment was conducted from February to May 2016, in the municipality of Mossoró / state of Rio Grande do Norte. The treatments studied consisted of three factors as follows: irrigation water salt concentration (ECw) of 0.8, 2.4, 3.43 and 4.81 dS m-1; irrigation depths of 80, 98 and 127% of ETc applied via drip irrigation; and BRS 506, IPA 2502 and Ponta Negra sorghum cultivars, arranged in a (4x3)x3 factorial scheme with split plots, cultivars in sub-plots, with four blocks. Supplemental irrigations were implemented, being around 9% of the crop demand supplied by rainfall that occurred in the period. Soil electrical conductivity presented a reduction tendency when larger water volumes were applied. Irrigation depth and salinity did not influence yield aspects, even with a 20% reduction in the ideal irrigation depth and water salt concentration of at least 4.81 dS m-1 of electrical conductivity.