Using evaporative cooling to fight heat stress in corn. The potential of sprinkler irrigation to reduce air and reproductive organ temperature.

During the flowering of corn, heat stress combined with a low water supply may be the cause of unsuccessful fertilization. In order to reduce the heat stress of reproductive organs, evaporative cooling using sprinkler irrigation is a method applicable in seed production. The objective was to characterize the canopy microclimate under irrigation (air temperature at three levels) and quantify the ear temperature reduction as a function of irrigation periodicity and intensity The experimental study was carried out in the Toulouse region of France on two plots. One plot was irrigated once a week, the other irrigated daily during the warm period of the day (12-17 h GMT). The results showed that ear and tassel temperature decreased immediately after irrigation started, whereas air temperature decreased 2 h later. Under higher irrigation frequencies, the mean temperature difference between the two plots was about 3 degrees C for ears and 2 degrees C for air at mid-height inside the canopy; for lower frequencies, the mean temperature difference was 2 degrees C for ears and 1 degrees C for air inside the canopy The potential of sprinkler irrigation to reduce heat stress duration on reproductive organs is discussed.