Delayed planting effects on flowering and grain maturation of dent corn
2002
Nielsen, R.L. | Thomison, P.R. | Brown, G.A. | Halter, A.L. | Wells, J. | Wuethrich, K.L.
Delayed planting shortens the effective growing season for corn (Zea mays L.), increasing the risk of exposure to lethal cold temperatures late in the season before grain maturation. Consequently, growers often must decide whether to switch to early maturity hybrids to minimize this risk. The objective of this study was to determine whether delayed planting influenced the growing degree day (GDD) ratings of silking and kernel black-layer (BL) development of corn. The effects of delayed planting on the phenological responses of three corn hybrid maturities common to the eastern U.S. Corn Belt were investigated at four locations in Indiana and Ohio over 4 yr. Thermal time from planting to silk emergence decreased an average of 34 GDDs for June vs. early May plantings while the grain-fill period decreased an additional 110 GDDs with late plantings. The total decrease in GDDs from planting to BL was 144 GDDs for corn planted in early June compared with early May, equal to a linear response to delayed planting of 3.8 fewer GDDs per day of delayed planting. The three hybrids responded differently to delayed planting, with greater GDD decreases occurring with late-maturity hybrid. Linear rates of GDD decrease with delayed planting ranged from 4.5 to 3.2 GDDs per day of delayed planting for late- and early maturity hybrids, respectively. Delayed planting decreases the GDD requirements of corn hybrids, resulting in less risk to grain maturation for adapted hybrid maturities from late-season killing freezes than previously thought.
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