TOLERÂNCIA DE HÍBRIDOS DE GIRASSOL TRATADOS COM MICRORGANISMOS E REGULADOR DE CRESCIMENTO SOB RESTRIÇÃO HÍDRICA

Abstract

Sunflower (Helianthus annuus L.) is an oilseed of significant economic importance which, in Brazil, is widely cultivated in the second crop season (safrinha), exposing the crop to periods of severe water restriction. To mitigate the abiotic damages caused by water deficit, the adoption of bioinputs, such as growth-promoting microorganisms and hormonal regulators, has been established as a promising strategy. Therefore, the present study aimed to evaluate the response of five sunflower hybrids under water restriction, subjected to seed treatment (ST) with a growth regulator and microorganisms. The experiment was conducted in a greenhouse at the Instituto Federal Goiano, Campus Urutaí, under a randomized block design in a 5x4 factorial scheme. The treatments evaluated the interaction of five hybrids (H250, H251, H260, T204CL, and T203CL) with four STs: control; hormonal treatment (cytokinin + gibberellin + indolealkanoic acid); biological treatment (Bacillus amyloliquefaciens + Trichoderma harzianum); and the combination of the products. The water deficit was imposed at 21 days after sowing by suspending irrigation for 7 days. Emergence percentage, plant height, number of leaves, stem diameter, and root length were evaluated. The results demonstrated that seed treatment positively influenced crop establishment, specifically the treatments containing biological agents (isolated or combined). There was a significant interaction between genotypes and treatments for the variables of height, stem diameter, and root length. It is concluded that the use of biostimulants and biological agents in seed treatment is efficient in mitigating water restriction, outperforming the untreated control. However, the choice of bioinput must be personalized, considering the specificity of each hybrid.