CULTIVARES DE CANA-DE-AÇÚCAR RESPONDEM IGUALMENTE À DISPONIBILIDADE DE FÓSFORO? UM PONTO DE PARTIDA PARA AUMENTO DA EFICIÊNCIA NO USO DESSE NUTRIENTE

Abstract

It is estimated that around 15 million tons of phosphate fertilizers are used annually, with a utilization rate of 15% by crops. Clearly, one of the main challenges faced by the Brazilian agricultural sector is related to phosphate fertilization, especially due to its dependency on imported fertilizers. This dependency, coupled with projections indicating the phosphate rock reserves depletion by the end of the century, raises concerns for agriculture. Considering the notable and undeniable importance of phosphorus in plants, where it plays a crucial role in regulating photosynthesis and plant development, there are several alternatives to enhance its efficiency of use by crops. However, there is a research gap aiming to understand how different genotypes of the same species respond to varying levels of phosphorus availability individually. It is essential that before seeking strategies to improve P usage efficiency, understanding the behavior and performance of the crop regarding its absorption at different availabilities is necessary. This approach can provide a foundation for future studies employing tools aimed at enhancing phosphorus absorption efficiency in sugarcane cultivation. The purpose of this study was to assess the performance of various sugarcane varieties concerning the P availability. For this purpose, an experiment was conducted using a randomized block factorial design, involving six sugarcane cultivars under five different levels of phosphorus availability, with four replications. The plants were evaluated for gas exchange parameters, chlorophyll a fluorescence, chloroplastic pigment content, plant height, and biomass accumulation. Phosphorus is crucial for the proper functioning of the photosynthetic machinery; however, despite the established relationship between photosynthesis and biomass accumulation, a direct correlation between these two processes is not always feasible. The results of this study indicate that, even without a specific focus on genetic improvement, there are no significant differences among different sugarcane cultivars in terms of phosphorus assimilation efficiency at the early stages of their development.