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 additional sources of germplasm in breeding programs.  Further information on the performance of specific hybrids remains the responsibility of the producers of these hybrids.

            Trials were planted at 22 locations and data were obtained at 20 locations in 2003.  Planting dates ranged from late April to mid May.  Wet conditions in during the first two weeks of May delayed planting until May 14 or later in many locations.  Most locations were harvested in October, which is normal for Iowa.  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 2003 were generally favorable after planting at most locations.  Dry, warm conditions occurred in the southern and western edges of the state during July and August and affected yields at the southern and western locations.  Yield data were not obtained at Eagle Grove because poor emergence of the trial. The trial also had to be discarded at Cannon Falls, MN. In contrast, growing conditions were favorable for excellent yields in central and north-central areas.    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), 2000 (145 bushels per acre), 2001 (141 bushels per acre), and 2002 (165 bushels per acre) the estimated average yield for 2003 for Iowa is 157 bushels per acre, which surpasses the record yields of 1992 and 1994, but is not as great as 2002.  Except for 1993, we have experienced good to excellent corn yields during the past 10 years within the state.  Although warm, dry conditions during July and August affected yields in some areas, other areas had excellent yields because of timely rains during and after pollination in latter part of July and early part of August to compensate for the lower yields in the droughty areas.  Disease pressures were not as evident in 2003 as in previous years and 2nd-generation European corn borer infestations did not seem to be important.

            Plots generally were 18 feet long and included two rows spaced 30 inches (90 sq. ft. per plot) 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/acre) of 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, but data for stand and root and stalk lodging were recorded before harvest.  Harvest losses because of root and stalk lodging and dropped ears are reflected for hybrids at the sites where lodging and dropped ears occurred. 

            Planting of ISU trials started April 26, 2003 at Nashua, but planting did not get completed until May 21 because of wet conditions.  Planting dates for the cooperators were similar to those for the ISU trials.  Harvest of ISU trials started October 5 at Ankeny, and harvest was completed October 24 at Ames.  The cooperators had similar dates of harvest.  Conditions were generally good during harvest throughout the state, but harvest interruptions did occur because of either local rains or snow showers.  The quality of data varied among locations because of the incidence of extensive root lodging 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 2003. 

            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 2003 locations, data averaged over locations for the three sets (4 locations for earlier maturity, 4 locations for mid-maturity, and 12 trials for later maturity) of trials, and 3-year averages for each location.  Three-year averages are more reliable for comparing hybrid performance.  Yields are given in bushels per acre (bu/ac).  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 conducted at 22 locations included 10 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.

ACKNOWLEDGMENTS

            We wish to acknowledge the following individuals and their respective organizations for assisting us in conducting the 2003 single-cross trials.

            Individual                               Organization                                       Location of test

            Kermit Bohning                      Mycogen                                             Conrad

            Tom Prest                                Syngenta                                             Harlan

            Philippe Chartier                     Pau Seeds, Inc.                                   Janesville, WI

            Dan Currier                             Illinois Foundation Seeds                   Alexander

            Arlen Eggerling                       Hawkeye Hybrids, Inc.                       Pella

            Jon Geadelmann                     Holdens Foundation Seeds                 Cannon Falls, MN

            Bob Getschman                      Monsanto Global Seeds                      Pocahontas

            Duane Grensteiner                  Golden Harvest                                   Estherville

            Jason Cromley                         Golden Harvest                                   Eagle Grove

            Robert Miller                           Novartis Seeds                                    Hampton

            Bob Getschman                      Monsanto Global Seeds                      Prescott

            Lance Veldboom                    Holdens Foundation Seeds                 Williamsburg

ISU Inbred Line Pedigrees

 

Inbred

Peidgree

B97

BSCB1(R)C9-2

B98

BS11(FR)C5-2803

B99

BSCB1(R)C10-7233

B100

(B85 x H99)-361-1-1-1-1-1-1

B102

(B85 x H992) - 336-1-2-1-1-1-1-1-1

B103

Mex. 41-C15-9-1-1-1-1-1-1-1-1

B104

BS13(S)C5-13-1-1-2-1-1-1

B105

BSSS(R)C9-88-5-1-1-1-1-1-2-1-1-1

B106

BS26-2-552-1-1-1-1-1-1-1-1-1-1

B107

MEX. 41-C15-19-1-1-1-1-1

B108

IA41-C15-55-1-1-1-1-1-1

B109

(B73 X BS20 sel.)-144-1-1-1-1-1-1

B110

BS13(S)C5-12-2-1-1-1-1

B111

BSSS(R)C9-107

B112

BSCB1(R)C11-9081

B113

BS11(FR)C9-3237-12-1

B114

MEX.41-C15-19-2

B115

BS11(FR)C9-3227-9

B116

B97/B99)-047-1-1-1-1-1-1-1-B-B (02SARH:BREED:0197)

B117

B97/B99)-024-1-1-2-1-1-1-1-B-B (02SARH:BREED:0185)

B118

B97/B99)-024-1-1-2-1-2-1-1-B-B (02SARH:BREED:0191)

B119

BS13(S)C7)-0008-1-1-1-1-1-B-B (02SARH:BREED:0157)

B120

BSCB1(R)C12)-6826-1-1-1-1-1-1-B-B (02SARH:BREED:0167)

B121

BS13(S)C6)-7884-1-1-1-1-1-1-1-1-2-1

B122

BSKRL2(HI)C0-7203-3-2-01-01-03-B-B (02SKRL:B4:8620)

B123

BSKRL2(HI)C0-7314-2-1-01-01-01-B-B (02SKRL:B4:8635)

B124

BSKRL2(HI)C0-7370-2-2-02-01-02-B-B (02SKRL:B4:8650)

B125

BSKRL2(HI)C0-7383-3-2-01-01-03-B-B (02SKRL:B4:8665)

 

Information on licensing ISU inbreds can be found at:  http://www.ag.iastate.edu/centers/cad/index.html.