Atenuaçãodo estresse por calor em cultivares de algodoeiro pela aplicação de bioestimulante

Abstract

Cotton (Gossypium hirsutum L.) is essential for the textile industry, as well as for producing vegetable oil and animal feed. Brazil stands out as one of the leading producers, especially in tropical and subtropical regions, facing challenges due to adverse climatic variations. This study evaluated the productivity and fiber quality of different cotton cultivars treated with a biostimulant, aiming to mitigate thermal stress under high-temperature conditions in Mato Grosso. The experiment was conducted in a completely randomized design, with a subdivided scheme, comprising 12 treatments (combinations of cultivars and application of the biostimulant Megafol®) and four replicates, in the municipalities of Sorriso, Tabaporã, and Porto dos Gaúchos. The bio-stimulant was applied starting at the B1 stage (first floral bud appearance) at a dose of 250 mL/ha, with reapplications every 15 days, totaling six applications and an accumulated volume of 1.5 L/ha. Harvest evaluations included productive parameters and fiber quality attributes. The results indicated that genetic (cultivars) and environmental (cultivation sites) factors significantly influenced fiber productivity and quality. The cultivars DP 1949B3RF and FM 974GLT stood out in yield and fiber strength. Climatic conditions, especially temperature, directly affected cotton quality and performance, highlighting the need for adaptive strategies to mitigate thermal stress effects. It was concluded that there is a difference among cultivars regarding the yield and quality of cotton fiber in regions with high temperatures. The biostimulant showed a punctual and variable effect, with more consistent gains in Porto dos Gaúchos, especially in boll retention and seed formation, but it was not determinant for yield or fiber quality.