THE EFFECT OF FLOODING PRETREATMENT ON COLD HARDINESS AND SURVIVAL OF WINTER CEREALS IN ICE ENCASEMENT

Cold-hardened plants of Dover winter barley and Fredrick and Norstar winter wheats show a decreased cold hardiness when exposed to low temperature flooding of increased severity and increased duration. In both cases, this is accompanied by increased moisture content, and there are strong correlations between cold hardiness and crown water content. Fredrick and Norstar wheat plants show enhanced survival when ice-encased after flooding, as compared to nonflooded plants, but this promotive effect is not observed in Dover barley. Eight winter wheats and one winter rye cultivar show the response, but only one of three barley cultivars tested. The promotive effect on survival in ice encasement is produced by 2 and 4 wk prior flooding, but after 6 wk the flooding effect is lost in most cultivars. It is assumed that anaerobic processes initiated during flooding have an indirect survival-positive effect during subsequent ice encasement.