Crop water stress index of three maize hybrids grown in soils with different quality

Maize production in Argentina is obtained mostly under dryland conditions and grain yield is highly related to water availability around silking. Drought, and differences in soil quality caused by intensive land use, sometimes limit water availability for the crop. Field experiments were performed on silty clay loam soils in the temperate humid region of Argentina (32 degrees to 35 degrees S, 58 degrees to 62 degrees W), to (i) validate a methodology to determine maize water stress (Crop water stress index, CWSI), (ii) describe the behavior of CWSI along the crop cycle of three maize hybrids growing in environments with different soil quality, and () establish the effect of Soil quality and hybrids on the relationship between CWSI and available soil water. The CWSI methodology was satisfactorily validated. Crop water stress increased along the growing season in all environments and hybrids. No interactions between soil quality and hybrid on CWSI were found. The effect of soil quality on CWSI did not present a single and clear trend. Differences between hybrids in CWSI were detected. A relationship between CWSI and available soil water was fitted for all hybrids and environments (r(2) = 0.52, n = 51, P < 0.001). The threshold below which crops presented symptoms of water stress was 60% of available soil water. (C) 1998 Elsevier Science B.V.