Resposta fisiológica da cana-de-açúcar ao manejo de fertilizantes organominerais

Abstract

Sugarcane is a crop of relevant importance for Brazilian agribusiness. For a good productive performance of this crop, some measures are necessary, such as mineral fertilization. However, it is important to know the physiological responses of this culture to this type of management. In this sense, this study aimed to evaluate the physiological responses of the sugarcane crop to the use and management of different mixed mineral fertilizers in the edaphoclimatic conditions of BrejoParaibano. The experiment was carried out at the Experimental Farm of Chã de Jardim, in the municipality of Areia, Paraíba. A randomized block design was used. The variety RB 867515was evaluated submitted to different treatments with the mixture in different proportions of 3 different formulations of mixed mineral fertilizers. At 360 days after planting, the gas exchange variables were measured: internal carbon concentration (Ci), transpiration (E), stomatal conductance (gs), photosynthesis rate (A), instantaneous water use efficiency (USA), intrinsic water use efficiency (EiUA), and instantaneous carboxylation efficiency (EiC); as well as chlorophyll fluorescence variables: Initial Fluorescence (F0), Maximum Fluorescence (Fm), Photochemical Efficiency (Fv/Fm) and Terminal Fluorescence (Ft), as well as the contents of chlorophyll a and chlorophyll b. There was a significant effect of the different treatments on the gas exchange of RB 867515, but these did not influence the chlorophyll fluorescence variables, nor the chlorophyll a and chlorophyll b contents of this variety. T6 provided the best photosynthesis rate (A), instantaneous water use efficiency (USA), intrinsic water use efficiency (EiUA), and instantaneous carboxylation efficiency (EiC) values. Thus, based on the importance of these variables for obtaining a better physiological performance of sugarcane, the use of the T6 treatment is recommended for a better performance of this crop.