Influência da torta de mamona na morfofisiologia, nutrição e produtividade de manjericão sob estresse salino

Abstract

In the Brazilian semiarid region, the occurrence of water sources with high levels of salts stands out as a limiting factor for the production of most crops. In this scenario, studies report that the use of organic fertilizers can mitigate saline stress in plants. Thus, the objective was to evaluate the physiological, biochemical, nutritional and productive aspects of basil under saline stress and doses of castor cake. The experiment was carried out in randomized blocks with five electrical conductivities of water (0.5, 1.2, 3.0, 4.7 and 5.5 dS m-1) and five doses of castor oil (0.0, 1 .4, 5.0, 8.5 and 10 t ha-1), with four replications. The variables analyzed were growth, gas exchange, chlorophyll fluorescence, photosynthetic pigments, osmoregulators, antioxidant enzymes, oxidative damage, foliar and soil nutritional contents, oil production and soil salinity. Data were submitted to analysis of variance and regression analysis. The use of castor bean cake up to 5 t ha-1 attenuated the deleterious effect of light salinity (3 dS m-1) on the accumulation of biomass and oil content of basil plants by increasing antioxidant defense, accumulation of osmoregulators, photochemical efficiency and gas exchange, increasing ionic homeostasis in basil, retaining sodium in the soil under saline water application. However, castor bean cake was not able to mitigate the deleterious effects of severe salt stress, and high doses of the cake further intensified the effects of high salinity in basil plants. Thus, the use of castor bean cake up to 5 t ha-1 was effective in mitigating moderate saline stress in basil plants.