CROP WATER-STRESS INDEX OF 3 MAIZE HYBRIDS GROWN IN SOILS WITH DIFFERENT QUALITY

Maize production in Argentina is obtained mostly under dryland conditi ons and grain yield is highly related to water availability around sil king. Drought, and differences in soil quality caused by intensive lan d use, sometimes limit water availability for the crop. Field experime nts were performed on silty clay loam soils in the temperate humid reg ion of Argentina (32 degrees to 35 degrees S, 58 degrees to 62 degrees W), to (i) validate a methodology to determine maize water stress (Cr op water stress index, CWSI), (ii) describe the behavior of CWSI along the crop cycle of three maize hybrids growing in environments with di fferent 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 incr eased along the growing season in all environments and hybrids. No int eractions between soil quality and hybrid on CWSI were found. The effe ct of soil quality on CWSI did not present a single and clear trend. D ifferences between hybrids in CWSI were detected. A relationship betwe en CWSI and available soil water was fitted for all hybrids and enviro nments (r(2) = 0.52, n = 51, P < 0.001). The threshold below which cro ps presented symptoms of water stress was 60% of available soil water. (C) 1998 Elsevier Science B.V.