Crescimento radicular e sua relação com as trocas gasosas, produtividade e qualidade da fibra do algodoeiro cultivado em rotação de culturas

Abstract

Crop rotation and the use of cover crops can improve soil physical conditions, favoring root growth of cotton, reducing the impact of water deficiency on productivity, common in sandy soils. The present project aims to evaluate the root growth, water status, yield and quality of cotton grown in crop rotation systems. The study was conducted for two crops (2019-2021). The design was in randomized block design with five repetitions. The treatments were: forage; MIX; consortium 1 and consortium 2 and control. The use of cover crops (intercropped or single) maximized yield, but did not result in a difference in the quality of cotton fiber. The association of grasses with leguminous plants provided greater clumping. In the absence of cover crops, the leaf area index (LAI) was higher, but did not result in greater weight of aboveground dry matter. The use of grasses with aggressive root system provided greater length, dry matter and percentage of thicker cotton roots. The aerial dry matter of the cover crops was greater when the MIX of cover crops was used. However, the use of Urochloa ruziziensis alone resulted in greater length, dry matter and percentage of thicker roots. Regarding the water status of the cotton plant, in year of higher precipitation there was variation regarding net photosynthesis (A), stomatal conductance (gs), intercellular CO2 concentration (Ci) and transpiration (E) where the mix and forage plant obtained lower values. In both years, the use of single grass showed lower leaf proline content. The use of cover crops reduced soil density, especially when using aggressive root species. The use of Urochloa ruziziensis alone resulted in lower proline concentration in both years. The intercropping of Urochloa ruziziensis with a grass or legume provides greater root growth of cotton and less yield loss.