Cultivo do milho irrigado no semiárido alagoano e modelagem com o AquaCrop/FAO®.

Abstract

Corn is used for various purposes, with emphasis on human food, animal feed and bioethanol feedstock. However, the ecosystems of cultivation are variable as far as the edaphoclimatic conditions are concerned, making necessary the use of technologies that allow their cultivation in different places. The use of hybrids, associated with adequate soil water management and prediction techniques for biomass production and yield, are essential for the successful harvesting of the cereal. The objective of this study was to analyze the components of production and water use efficiency, to verify the suitability of multivariate analysis to evidence relevant information for this study, to calibrate the AquaCrop/FAO® model for the agroclimatic conditions of Pão de Açúcar, AL, and to relate gaseous exchange to grain yield as a strategy to aid decision making on maize cultivation under irrigation depths. Two experiments were carried out in two different experimental periods between April and December 2015, in a randomized block design with six irrigation depths and four replications. The production components and efficiency of maize water use were not statistically influenced by the variation of irrigation depths in the first experimental period. In the second season, the increase of the depths promoted gains in the mass of a thousand grains, yield of dry grains, number of grains per row, number of grains per spike, mass of cob and debris spike mass, reducing the efficiency of water use. The use of multivariate analysis was efficient to show differences between irrigation depths and experimental times. The AquaCrop/FAO® model was calibrated for AG 7088 hybrids cultivated under irrigation depths in the Pão de Açúcar agro-climatic conditions in the semi-arid region, showing good performance, accuracy and fit quality of the model between observed and simulated values. The hybrid AG 7088 had a good physiological performance under full irrigation (100% of ETo), with a yield of 5.75 t ha-1, being the gas exchange measurement important for predicting crop yield, in order to subsidize crop strategies in future crops.