Relationship between physiology and production of maize under different water replacements in the Brazilian semi-arid¹

Relação entre fisiologia e produção de milho sob diferentes reposições hídricas no semiárido brasileiro

HIGHLIGHTS:

Water deficit in the soil reduces leaf gas exchange and maize grain yield.

Replacements of 100% and 175% of ETo increase the leaf gas exchange and maize grain yield.

Grain yield can be estimated from physiological variables obtained during flowering.

ABSTRACT

Water restriction causes physiological disorders and reduces maize yield in semi-arid regions. The objective of this study was to correlate instantaneous physiological variables with the grain yield of maize using different replacement percentages of water lost through evapotranspiration and to fit a multiple regression model to estimate grain yield in the dry season in the Brazilian semi-arid region. The experiment was installed in a randomized block design, with six percentages of reference evapotranspiration (ETo) repositioning (50, 75, 100, 125, 150, and 175%). The AG 7088 hybrid had a higher CO₂ assimilation rate, stomatal conductance, transpiration, and instantaneous water use efficiency, and reduced leaf temperature and vapor pressure deficit under full irrigation (100% of ETo, 458 mm), with yields of 5.75 t ha^-1, reaching 6.8 t ha^-1 (572 mm) and 7.65 t ha^-1 (801 mm) with replacements of 125 and 175% of ETo, respectively. Measurements of leaf gas exchange, vapor pressure deficit, and leaf temperature can be performed at phenological stage R1 to estimate grain yield with greater robustness when combined with water rates applied during the crop cycle.

Key words:
Zea mays L.; irrigation depths; gas exchange; grain yield estimation