Relative Sensitivity of Grain Yield and Biomass Accumulation to Drought in Field‐Grown Maize

Abstract

Grain yields in maize (Zea mays L.) are decreased substantially by water deficits. Since the impact of drought stress on grain yield varies among growth stages, such responses are sometimes interpreted as indicators of varying drought sensitivities with crop growth stage. However, varying leaf area and biomass accumulation rate confound this interpretation because the use of water changes during the season. This research examined whether a proportional decrease in accumulated crop biomass of field‐grown maize was sufficient to account for the decrease in grain yield resulting from drought. A total of 11 field experiments were conducted at Gainesville, FL on an Arredondo fine sand (loamy, siliceous hyperthermic Grossarenic Paleudult) or a Kendrick fine sand (loamy, siliceous, hyperthermic Arenic Paleudult and Katherine, Australia on a Fenton clay loam (Oxic or Rhodic Paleustalf) in which irrigation was withheld for various periods to result in a range of severities in crop water deficits. At crop maturity, both grain yield and total accumulated biomass were measured and the relationship between these two parameters was examined. In all cases, high, linear correlations between grain yield and accumulated biomass were obtained. At moderate stresses, harvest index of the crop was stable. Under severe stress, where accumulated biomass was less than about 1100 g m‐2, grain yield was decreased to a greater extent than was accumulated biomass. Nevertheless, under a wide range of conditions, grain yield of field‐grown maize crops was closely linked to the accumulation of biomass.