Organic matter-induced physiological responses and modulation of the enzymatic system in Sorghum bicolor (L) Moench genotypes cultivated in saline soil

Sorghum bicolor (L.) Moench is a crop with numerous applications that serves as a food source for humans and animals. However, soils with high salt concentrations compromise the initial development of the crop, and the addition of organic matter can mitigate the damage caused by salinity. The present study aimed to verify the effect of organic matter on salinity on the physiology and enzymatic profiles of two sorghum varieties, BRS Ponta Negra and BRS 373. The experiment was conducted in a completely randomized design (DIC) in a 4 x 4 x 2 arrangement, using different doses of organic matter as recommended (100%, 200%, 300%, and 400%) and the two sorghum varieties, with 4 replications. The variables analysed were: photosynthetic rate (A), transpiration (E), stomatal conductance (Gs), and enzymatic activity of ascorbate peroxidase (APX), polyphenoloxidase (POL), and catalase (CAT). The results showed that the A, E, and Gs responded differently to different doses of organic matter (OM); these responses were influenced by the isolated effects of the varieties or doses of organic matter, and their behaviour differed between the two analysed varieties. The A, E, and Gs showed contrasting response patterns between different doses of OM in variety 1 (BRS Ponta Negra) and variety 2 (BRS 373). These responses were influenced by the isolated effects of the varieties and/or doses of organic matter, showing different behaviours among the tested varieties.