Ionic stress; antioxidant enzymes, CO2 efflux

Soil salinity is an abiotic stress that requires constant investigation because it directly affects plant production, especially in regions with arid and semi-arid climates. The interaction of ions with the surface of solids occurs dynamically and is dependent on the mineralogical assemblage of soils and the nature of electrical charges. Thus, researches that investigate the interaction of salinity in soils of different mineralogical nature, allied to commercially important crops for regions affected by salts are of great relevance. In this context, cowpea (Vigna unguiculata) has stood out for its tolerance to moderate levels of salinity, and has proved to be a promising crop for cultivation in these regions, especially because it is a source of nutrients, and for its forage potential. Thus, this research aimed to evaluate the tolerance of common bean to salinity based on the time of exposure to the ionic phase of saline stress, as well as to identify the effect of soil mineralogy and increasing levels of salinity on the ecophysiology of the common bean and its temporal evolution. of salinity in two orders of soils with different mineralogy. The experimental design adopted was randomized blocks (DBC), in a double factorial scheme (6x2), with six levels of electrical conductivity being tested: 0; 1.5; 3; 4;5; 6.5 and 9 dS m-1. To test the effect of mineralogy, samples of the Argisol (A) and Luvissol (L) orders with similar clay contents and contrasting mineralogy quality were collected, with the Ultisol having more weathered clay minerals 1:1 and the Luvissol with lesser minerals. weathered 2:1. The monitoring of the physiological and biochemical performance of the culture was carried out in the final phenological stage from the determination of the total water potential in the plant and its osmotic and pressure components, chlorophyll fluorescence, determination of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) ; analysis of nutrient content; biometric evaluation of the plant; biomass and productivity. Plants grown in soil with 1:1 mineralogy suffered earlier the effects of salts, in soil with 2:1 mineralogy at the highest saline concentration level the stress effect was more pronounced. Signaling of antioxidant defenses was expressive through enzymes, CAT, SOD and APX, demonstrating that they are more expressive when there is an increase in salt concentration. There was an increase in the temporal evolution of soil salinity in different mineralogies. The productivity and biomass of cowpea plants were directly affected in soils with distinct mineralogy and the physiological parameters of the bean plant were influenced by irrigation with saline water, in soils with mineralogy 1:1 and 2:1.