Doses de boro na qualidade de fibra do algodoeiro colorido

Abstract

The cultivation of herbaceous cotton (Gossypium hirsutum L) is the main source of natural fiber exploited by humans. It is produced in more than 60 countries and contributes to the generation of more than 350 million direct and indirect jobs, moving billions of dollars every year. This species can produce various fiber colors, ranging from white to different shades of green and brown. The main product is its fibers, which are destined for the textile industry for clothing manufacturing. Various other products and by-products are produced from cotton and are directly part of people's daily lives, such as cooking oil, biofuel, banknote paper, gunpowder, animal feed, among others. It requires fertile soils to express the maximum genetic potential in productivity and quality of its fibers. Among the essential micronutrients required by the plants, boron (B) is the most limiting for the development of the crop, as it participates in various fundamental biochemical reactions in the cotton plant's metabolism. Therefore, the objective of this study was to explore the effect of the application of different doses of boron on the fiber quality of commercial Brazilian colored cotton cultivars. The study was conducted in a greenhouse in the city of Uberlândia-MG during the 2022/23 growing season, using a randomized block design in a factorial scheme with 4 repetitions, 4 doses of B (0.0; 1.0; 1.5 and 2.0 kg.ha-1), and 4 commercial colored cotton cultivars (BRS Verde, BRS Rubi, BRS Safira, and BRS Jade). Seven technological fiber characteristics were evaluated, namely Micronaire (MIC), Fiber Maturity (MAT), Fiber Length (UHML), Length Uniformity (UI), Short Fiber Index (SFI), Fiber Strength (STR), and Fiber Elongation (ELG). Among the evaluated genotypes, BRS Jade stood out in fiber technological quality for all the analyzed variables, with great potential for large-scale production as well as for use as a parent in colored cotton breeding programs. The colored cotton genotypes express different fiber quality responses when subjected to different boron dosages, indicating the need for dosage adjustment for each cultivar. More studies with higher doses compared to the present study are also necessary.