Using Corn Maturity to Maintain Grain Yield in the Presence of Late-Season Drought

Corn (Zea mays L.) grain yield is sensitive to water availability from emergence to maturity. Using early-maturing corn hybrids might avoid the late-season stress that frequently occurs with dryland culture. This research was conducted to determine whether early-maturing corn hybrids could yield similarly to late-maturing hybrids under dryland conditions. Field studies were conducted at Mead, NE, on a Sharpsburg silt clay loam (fine, montmorillonitic, mesic Typic Argiudolls) in 1991 and 1992. In Lincoln, NE, the soils were a Kennebec silt loam (fine-silty, mixed, mesic Cumulic Hapludolls) in 1991 and a Crete silt loam (fine, montmorillonitic, mesic Pachic Argiustolls) 1992. Three early-maturing (95 to 99 d) hybrids and three late-maturing (114 to 118 d) hybrids were grown at 10 000, 18 000, 26 000, and 34 000 plants /acre. Little late-season water stress occurred in 1992, thus, hybrids produced high yields that increased with increasing population up to 26 000 plants/acre and even 34 000 plants/acre. However, substantial late-season water stress occurred in 1991. Environments dominated by late-season water stress caused yield reduction at high plant populations for all three late-maturing hybrids and one early-maturing hybrid. Two of the three early-maturing hybrids produced similar yield responses to increased plant population, independent of degree of late-season water stress. This indicates use of well adapted early-maturing hybrids might improve yield stability, since their response was not dependent upon yearly weather conditions, in contrast to the late-maturing hybrids. Two early-maturing corn hybrids did not consistently yield comparably to late-maturing hybrids. These two early maturing hybrids appeared to lack the water stress tolerance and yield potential required to consistently yield comparably with late-maturing hybrids. However, the early-maturing hybrid, Pioneer 3737, produced grain yields comparable to late-maturing hybrids in nearly every instance. These results indicate a well adapted early-maturing hybrid can produce yields comparable to or better than late-maturing hybrids, particularly where late-season water stress is prevalent. However, the optimum plant population may be higher for early-maturing compared to late-maturing hybrids. Research QuestionCorn grain yield is sensitive to water availability from plant emergence to maturity. The water stress that often occurs late in the growing season with dryland corn culture might be avoided by using early-maturing corn hybrids. Producers often are reluctant to accept this strategy, because late-maturing hybrids generally have greater yield potential than early-maturing hybrids. This study was conducted to determine the yield of early-maturing and late-maturing hybrids in a dryland environment. Literature SummaryConventional corn production practices assume light is the limiting production factor and uses the entire growing season. This practice of maximizing light interception often increases late season plant water stress and causes unstable productivity. Since corn grain development and yield are extremely susceptible to water stress during early reproductive growth stages, adverse effects of late season water stress might be avoided or alleviated by using earlier maturing corn hybrids. However, photosynthate supply usually limits yield of early-maturing corn hybrids because of decreased leaf area production compared with late-maturing hybrids. Light interception could be increased by increasing plant population and thus improve photosynthate supply and grain yields. Study DescriptionDryland field studies were conducted at Mead, NE (Sharpsburg silt clay loam), and Lincoln, NE (Kennebec silt loam and Crete silt loam), for 2 yr, 1991 and 1992. Three early-maturing (95–99 d) hybrids DEKALB DK 501, NC+ 2165, and Pioneer 3737, and three late-maturing (114–118 d) hybrids DEKALB DK 646, NC+ 6414, and Pioneer 3162 were used. The hybrids were grown at 10 000, 18 000, 26 000, and 34 000 plants/acre. Minimal or conventional tillage practices were used to prepare the land. Corn was planted as early as possible according to guidelines recommended by the University of Nebraska Cooperative Extension. Grain yield, canopy leaf area, and light interception were measured. Applied QuestionsCan the grain yields of any early-maturing corn hybrids be as good as those of late-maturing corn hybrids under dryland conditions? The early-maturing hybrid, Pioneer 3737, yielded comparably to the late-maturing hybrids (Table 1). Although one late-maturing hybrid yielded more than 3737 in a favorable year, 3737 produced higher yields than two of the three late-maturing hybrids in a year with high late-season stress. The other two early-maturing hybrids failed to demonstrate enough yield potential or late-season water stress tolerance to consistently compete with late-maturing hybrids. This indicates early-maturing hybrids may substantially differ in their ability to produce grain yields comparable to the late-maturing hybrids. Canopy light interception of the two highest yielding early-maturing hybrids were generally similar to the late-maturing hybrids at the highest plant population used in this study. This indicates that grain yield differences were related to factors other than light interception capability. How did plant population affect corn production? Increasing plant population increased the leaf area index of the hybrids. Generally, the early-maturing hybrids required a higher plant population to intercept as much light and produce similar yields as the late-maturing hybrids (Table 1). Grain yields increased with increasing plant population in a favorable growing season. However, hybrid yield response to plant population varied when high early season temperatures or late season water stress occurred. Early-maturing hybrids' leaf area development was variable and more sensitive to high temperatures during vegetative development than the late-maturing hybrids. However, the lack of sensitivity to stress during vegetative development did not necessarily predict sensitivity during reproductive development. This is reflected by yield reduction at high plant populations of all three late-maturing hybrids when substantial late season water stress occurred. Two of the three early-maturing hybrids produced greatest yields at the highest plant population, despite the presence of high water stress, which indicates these early-maturing hybrids may have avoided the late-season water stress better than the late-maturing hybrids. One of the early-maturing hybrids had severe yield reduction and poor leaf area development at high plant populations, demonstrating poor water and heat stress tolerance. What field situations warrant consideration of early-maturing corn hybrids? The early maturing hybrid, Pioneer 3737, successfully produced grain yields similar to or better than late-maturing hybrids, particularly when late season water stress was high, if the plant population was increased accordingly. However, selection of early-maturing hybrids with good drought tolerance and yield potential is critical to high yield production. Two of the three early-maturing hybrids produced greatest grain yields at the high population, independent of degree of late-season water stress. This indicates use of well adapted early-maturing hybrids might improve yield stabiity, since their response was not dependent upon yearly weather conditions, in contrast to the late-maturing hybrids. Early to normal planting dates and favorable early-season growing conditions should improve productivity of early-maturing hybrids grown dryland in the western Great Plains. Table 1Comparison of corn grain yield and light interception of each hybrid's most desirable plant population, defined as the highest yielding treatment in an average environment. 19911992Hybrid†Plant population‡Grain yieldLight interceptionGrain yieldLight interceptionbu/acre%bu/aere%Early maturity DK 50126 00080 c*90 c179 b89 b NC+ 216534 000119 ab93 bc151 c93 a Pioneer 373734 000127 a94 ab170 b94 aLate maturity DK 64626 000113 b95 ab166 bc94 a NC+ 641426 000125 ab94 ab169 b92 ab Pioneer 316234 000112 b96 a200 ab94 a*Values within a column followed by the same letter are not significantly different at t 0.05. †DEKALB Genetics Corp., NC+ Hybrids, Pioneer Hi-Bred International, Inc. ‡Mead, 1992 approximated the 15-yr average (PWD = 0.093).