SOIL WATER-SOIL TEMPERATURE INTERACTIONS IN THE GERMINATION AND EMERGENCE OF CORN (Zea mays L.)

Germination and emergence of corn as affected by soil water and soil temperature were measured on the hybrids Pioneer 3995, Northrup King 403 and Pride 1108 on an Almasippi loamy sand and a Carroll clay loam. It was found that both germination and emergence rates could be adequately described by a relationship to the proportion of potentially available water, i.e. that between field capacity and permanent wilting percentage, present in the soil. In the case of germination, a separate relationship was required for each hybrid. On the other hand, emergence rate of all three hybrids was adequately estimated by a single relationship. The response to temperature was measured in terms of maximum rate, i.e. at optimum water, of both germination and emergence. Maximum germination rate decreased rapidly with temperature and was found to be hybrid dependent. In the case of emergence, the relationship to temperature was the same for all three hybrids. The results of this study were used to develop a model with which...