The effect of early season soil temperatures on corn canopy development: A quantitative approach
Corn leaf area and the geometry of the canopy determine the percentage of solar radiation intercepted. Early season soil temperatures have been reported to affect corn ontogeny. A two year field experiment was conducted to evaluate the growth and developmental characteristics of corn under different early soil temperatures during the period from planting to the V5 stage. Soil temperatures were controlled using warm and cool water circulating through copper pipes buried next to the corn rows. The treatments consisted in maintaining the temperature of the soil surrounding the corn growing point 5$\sp\circ$C above and below ambient temperature. Plant stage, individual leaf area, and leaf senescence were taken throughout the growing season. From planting to the 5-leaf stage, GDD were computed using the soil daily temperatures. After the soil temperature treatments were shut off the GDD calculation were based on daily air temperatures. Two Richards' functions were used in a piecewise manner to fit the observed data. Richards' function parameters were statistically analyzed to evaluate modifications in corn development. The data showed that cooler temperatures delayed corn development and modified the shape of the canopy. Plants under cooler conditions grew faster per unit of GDD accumulated. Warmer temperatures increased corn yield. Increase in the size of the leaves in the upper canopy of the plants under warmer temperatures are suspected to be responsible for yield differences. Although maximum LAI and leaf area duration were not significantly different among the treatments, it is believed they have a major effect on yields. The significant interactions of those two variables and years suggested that more years in the experiment are needed to effectively evaluate their effects.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign