Resposta de genótipos de cana-de-açúcar à salinidade e bioestimulante no desenvolvimento inicial

Abstract

Brazil is the world's largest producer of sugarcane (Saccharum spp.), with an emphasis on sustainable energy production, such as ethanol and biomass, among other byproducts. However, one limiting factor for its cultivation is soil salinity, commonly found in semi-arid regions, which reduces soil fertility and hinders plant development. The use of varieties that show tolerance to salinity is a viable alternative for these regions, as well as the use of biological products that mitigate abiotic stresses. Therefore, this study aimed to evaluate salinity tolerance in 49 sugarcane genotypes and the effects of different doses of the products Roadster® (Ascophyllum nodosum) and Trichodermil® (Trichoderma harzianum) on the growth of seedlings cultivated in sodic soil. The experiment was conducted in a greenhouse at the field crops sector of the Department of Agriculture at the Federal University of Lavras. Two trials were carried out using a completely randomized design. The first trial followed a 2x49 factorial scheme, with the first factor being two NaCl concentrations: control [naturally occurring concentration in the soil, with electrical conductivity of 0.083 dS m⁻¹] and enriched soil [with the addition of 100 mM NaCl (EC = 7.2 dS m⁻¹)]; the second factor comprised 49 genotypes. After 33 days, shoot dry mass and sprouting speed index were measured, and sodicity tolerance indices were calculated based on this data. The results revealed significant variation among genotypes, with H. Kawandang and RB72454 standing out. The second part of the study followed a 2x6 factorial scheme, with the first factor being two levels of soil sodium concentration (naturally occurring and enriched with 100 mM NaCl), and the second factor being different doses of Roadster® [0; 1.25; 2.5; 5.0; 10.0 mL•L⁻¹], plus an additional treatment of 2.5 mL•L⁻¹ of Trichodermil®. After 60 days, stalk height, shoot dry mass, and shoot salinity tolerance index were evaluated. The 10 mL•L⁻¹ dose of Roadster® stood out with the best results in most of the variables analyzed, while intermediate doses of Roadster® showed possible negative effects—except in the genotypes H. Kawandang and SP80-1842—regarding tolerance to salt stress. Regarding Trichodermil®, only the variety CTC 9002 did not differ significantly from the highest Roadster® dose, showing the best results.