The results of the Iowa Agriculture Experiment Station Corn Yields are presented annually as a service to Iowa agriculture. The single-cross data presented herein are intended to provide preliminary information on the performance of inbred lines in hybrids in comparison with lines included in previously tested hybrids. We also include lines released from other public breeding programs when they become available. The information could be of value to the breeders and seed producers who consider use of experiment-station-developed lines as sources of germplasm in breeding programs. Additional information on the performance of specific hybrids remains the responsibility of the producers of these hybrids.

Trials were planted at 21 locations and data were obtained at 18 locations in 2001. Planting dates ranged from late April to mid May with seedbed conditions variable among locations because of wet conditions. Harvesting was completed later than in recent years because weather conditions delayed grain dry down. The dates of planting and harvesting for each trial are shown in the title of each table. Conditions for planting, emergence, growth, and development in 2001 were generally favorable at most locations, but dry conditions in the southern half of the state occurred during July and August. Warm, dry conditions during July and August affected yields at some of the southern locations. Yield data were not obtained at Pocahontas and Waverly because severe windstorms caused excessive plant damage and root lodging. The Fairfield location was not harvested because of standing water in the field after planting. Conditions during September and October were not as conducive as 1998, 1999, and 2000 for grain dry down after physiological maturity. Compared with 1994 (154 bushels per acre), 1995 (121 bushels per acre), 1996 (140 bushels per acre), 1997 (142 bushels per acre), 1998 (145 bushels per acre), 1999 (152 bushels per acre), and 2000 (145 bushels per acre), the estimated yield for 2001 for Iowa is 141 bushels per acre and is the 8th consecutive year for good to excellent corn yields within the state. The warm, dry conditions during July and August affected yields in some areas, but other areas had excellent yields if timely, local rains occurred during and after pollination in latter part of July and early part of August. Disease pressures were not as evident in 2001 as in previous years, but 2nd-generation European corn borer infestations tended to be higher.

Plots generally were 18 feet long and included two rows spaced 30 inches (90 sq. ft.) at most locations. There were minor variations in plot length among locations, and the differences in plot size were considered in yield conversions. Actual plant stands for each hybrid are shown in the 1000’s (M/ha) of plants/hectare. The plant stands can be converted to plants/acre by multiplying with a factor of 0.4 (e.g, 67,000 plants/ha x 0.4 = 27,080 plants/acre). Seedbed preparation, fertilizer application, and cultivation practices were those normally recommended for optimum corn production at the locations where the trials were grown.

All trials were planted and harvested with equipment adapted for planting and harvesting small experimental corn plots. There was no gleaning of either dropped ears or ears on broken stalks at harvest. Consequently, some harvest losses because of root and stalk lodging and dropped ears are reflected for hybrids at the sites where lodging and dropped ears occurred. Root and stalk lodging occurred at most sites in 2001, but root lodging was severe at some locations and for some specific hybrids. Rainstorms accompanied by strong winds occurred at some locations during July and August and local hailstorms affected some locations. Root lodging was more severe at Pocahontas, Waverly, Kanawha, Crawfordsville, and Ankeny. Gray leaf spot and anthracnose infection were minimal at most of the harvest locations.

Planting of ISU trials started April 25, 2001 at Ames, and all locations were planted by May 16, 2001. Planting dates for the cooperators were similar to those for the ISU trials. Harvest of the ISU trials started later in 2001 than in previous three years. Because of cooler, wetter conditions in September and October, corn matured slower and grain moistures at harvest were generally higher than for most previous years. For locations with dry conditions (e.g., Lewis), moisture levels at harvest were similar to 2000. Harvest of ISU trials started October 3 at Ames, and harvest was completed October 26 at Nashua, which was two weeks later to complete harvest of ISU yield trials than in 2000. The cooperators had similar dates of harvest. Conditions were good during harvest throughout the state, but harvest interruptions did occur because of local rains. The quality of data varied among locations because of the extent of root and stalk lodging and dry conditions. A few entries had lower, more erratic yields because of the occurrence of root lodging in some plots at some locations.

Weather and pests usually have important effects on corn evaluation trials. These effects are not predictable and the ranges of conditions experienced were evident in 2001. The major weather factor at some locations was limited rainfall and warm conditions during July and August after a wet May and June. Other locations were affected by hail, windstorms, and the frequent rains that either destroyed the plots (e.g., Pocahontas and Fairfield) or impacted yield levels (e.g., Slater and Lewis). Weather conditions during anthesis were generally warm and dry. But below average rainfall and above average temperatures in July and August affected final yields throughout the state.

Single crosses tested were produced between lines released by ISU and other states. Because fewer lines are being released by other public breeding programs, fewer single crosses that included lines released from other states were available for testing. Data are presented for the lines that have experiment station designations and for a few experimental lines from the ISU breeding program that have survived testcross and initial single-cross evaluations. We have included data for each of the 2001 locations, data averaged over locations for the three sets of trials, and 3-year averages for each location. Three-year averages are more reliable for comparing hybrid performance. Yields are given in quintals/hectare (q/ha). Yields in bushels/acre are obtained by multiplying the values in the tables by a factor of 1.6 (e.g., 90 q/ha x 1.6 = 144 bu/acre). We have included a column in the tables designated as adjusted value. Adjusted value is the value in dollars per acre assuming $2.00 per bushel for corn, 1.35% shrinkage, and $0.035 per bushel per point drying cost.

Single-cross trials were conducted at 21 locations with nine locations handled by ISU and 12 handled by commercial plant breeders. Data from additional locations provide a better basis for discriminating among hybrids for consistency of performance. Least Significant Differences (LSD values) are shown at the bottom of each table. LSD values for means across locations were calculated using the location by hybrid interaction mean square. Differences among hybrids are due to genetic differences, variations in soil type, soil fertility, moisture availability, temperature stress, insect and disease pressures, and planting and harvesting techniques. Differences among hybrids greater than the LSD value can be attributed to genetic differences; differences less than the LSD value are not statistically different and could be due to other factors.

Each year we conduct an experiment for the inbred lines that are evaluated in the single-cross trials. Inbred lines were evaluated at the Agronomy Research Center near Ames in 2001 and means for the various traits are included in Table 44.

ACKNOWLEDGMENTS

We wish to acknowledge the following individuals and their respective organizations for assisting us in conducting the 2001 single-cross trials.

Individual Organization Location of test

Kermit Bohning Cargill Conrad

Dwight Bostwick Novartis Seeds Harlan

Philippe Chartier Pau Seeds, Inc. Waverly

Arlen Eggerling Hawkeye Hybrids, Inc. Pella

Jon Geadelmann Holdens Foundation Seeds Kenyon, MN

Bob Getschman Monsanto Global Seeds Pocahontas

Duane Grensteiner Golden Harvest Estherville

Kory Maughan Golden Harvest Stanhope

Robert Miller Novartis Seeds Washington

David Peters Monsanto Global Seeds Atlantic

Jim Stewart Mycogen Seeds Slater

Lance Veldboom Holdens Foundation Seeds Williamsburg