Crop evapotranspiration in Argentinean maize hybrids released in different decades

Crop evapotranspiration (ET) is a major process influencing crop yield in water limited environments; and there is a lack of information on the influence of the breeding progress on crop ET. The objectives of this work were (i) to determine the seasonal crop ET and (ii) to characterize the soil water profile and pattern of soil water depletion along the season, in three Argentinean maize hybrids released in different decades. One old (DK2F10) and two modern (DK682RR and DK690MG) maize hybrids were sown during two seasons at Balcarce, Argentina under different water regimens (irrigated, rain-fed from silking and rain-fed). Soil water content was measurement weekly with a neutron probe and crop ET was estimated. Seasonal ET ranged from 646 mm to 284 mm depending on the water regime; and it was similar among hybrids at each water regime. Mean daily ET during the critical period for kernel set, however, was higher in the two modern hybrids than in the older hybrid. Differences in daily ET during this period were evident, in particular when AW was low (<57%). During the grain filling period, mean daily ET was similar among hybrids but soil available water was lower in the modern hybrids than in the old hybrid. A greater water extraction capacity, associated with greater soil water depletion at deeper soil layers (i.e. below 80 cm) in the modern hybrids than in the older maize hybrid, might have influenced daily ET differences among hybrids.