A Growth Analysis Comparison of Corn Grown in Conventional and Equidistant Plant Spacing
- D. G. Bullock,
- R. L. Nielsen * and
- W. E. Nyquist
Corn (Zea mays L.) grown in an equidistant plant-spacing pattern (EPS) often yields more grain per unit area of land than that grown in conventional plant-spacing patterns (CPS). The objective of this study was to determine the effect of equidistant plant spacing on aboveground dry matter production in corn. Two hybrids (‘Pioneer brand 3732’ and ‘B73 ✕ LH58’) were grown in two planting patterns (EPS and CPS) in field studies on a Chalmers silty clay loam soil (Typic Haplaquoll) near West Lafayette, IN, in 1983 and 1984. Measurements of plant dry matter accumulation and leaf area development began at growth stage V4 and continued weekly through R6. Growth analysis components were estimated from growth curves fitted to the relationships between the measured plant variables (dry weight per plant and dry weight per leaf) and a temperature index measured in growing degree days (GDD). Crop growth rate was greater for EPS than for CPS early in the growing season for both hybrids. An increase in plant biomass was primarily responsible. Although relative growth rate (RGR) tended to be smaller for EPS compared to CPS, the data suggested that the increase in plant biomass caused by EPS may be related to an increased RGR prior to 400 to 500 GDD after planting. Net assimilation rate was not significantly increased by EPS early in the season. Early and mid-season leaf area indexes, however, were greater for EPS for both hybrids.
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