Adubação potássica via solo e foliar na produção e qualidade da fibra do algodoeiro

• Autor(a) principal: FREITAS, Roberto José de
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tde/2641
• topic: Gossypium hirsutum; algodão-nutrição; adubação foliar; Gossypium hirsutum; cotton-fertilization; leaf-fertilization; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

Cotton as a crop in Brazil has undergone significant changes in production technology and geographical location in recent years. Cultivation has shifted from traditional producing zones in the southeast of Brazil and the south region of the State of Goiás to the cerrados of the country's central-western region and the western part of Bahia. These technological changes were triggered by the adoption of exotic cultivars (American and Australian), with higher yield potential, better fiber quality, but also greater nutritional requirements. During this process, more demanding cultivars were consequently adopted, concurrently with the occupation of soils of lower natural fertility. During this period, a productivity increase in excess of 100% was verified. The conjunction of these factors has disorganized the fertilization recommendation practices adopted for this crop, since they were no longer adequately supported by the existing calibrations, generated under different soil conditions and at a different technological level. The use of fertilizers was then greatly intensified, in a most disorderly manner. Within this context, potassium was the nutrient whose use increased the most, due to the specific characteristics of this nutrient on the plant's metabolism and to its high degree of absorption by cotton plants. The potassium fertilization of cotton in the cerrados has therefore been performed in the various producing areas with great variation in rates and application modes, from total applications in the soil at pre-planting, to split applications in the soil, to supplementary foliar applications, still without the proper support from current experimental results. In this work, we evaluated the effect of combined soil and foliar applications of potassium on the productivity and quality of ginned cotton, under the cerrado conditions of the State of Goiás, by the installation of two experiments, combining different potassium rates in both application modes, organized in random blocks with split-plots. One assay was installed in Ipameri, with the application of five treatments to the soil (0, 60, 120, 180, and 240 kg ha-1 K2O ha-1) combined with four foliar treatments ( 0; 7.2; 14.4; and 21.6 kg K2O ha-1). Another assay was installed in Santa Helena de Goiás, in which four potassium levels were evaluated in the soil (0, 80, 160, and 240 kg K2O ha-1), combined with foliar rates similar to those used in the Ipameri assay. Significant productivity gains were observed for the soil applications in both assays, and for the foliar applications in the Ipameri assay. No interactions were observed between application modes. Also, no significant potassium fertilization effects were observed on the technological quality of the fiber.