James E. Beuerlein, Professor, Dept. of Horticulture & Crop Science
Steve St. Martin, Professor, Dept. of Horticulture & Crop Science
Anne Dorrence, Assistant Professor, Dept. of Plant Pathology
Chris D. Kroon Van Diest, Research Associate, Dept. of Horticulture & Crop Science
The purpose of the Ohio Soybean Performance Trials is to evaluate soybean varieties, brands and blends for yield, and other characteristics. This evaluation gives the soybean producer comparative information for selecting the best varieties for a unique production system.
Entries in Trials. Entries in the Ohio Soybean Performance Trials are accepted if the seed will be available to Ohio farmers for the planting season following the trials. All 1998 entries were submitted voluntarily by seed companies and the Ohio Seed Improvement Association. Entry fee charges were made per entry and location.
Roundup Ready (RR) Test. The same production, testing and evaluation techniques, except for weed control, were used for RR entries and Normal entries. The performance of RR entries and Normal entries is not comparable statistically because they were not tested together and because different weed control programs were used for the two tests. "Roundup Ultra" was applied immediately after planting and again 40 days after planting for weed control. There were no weeds present at harvest and no herbicide damage to the soybeans was observed.
At all locations, the tests were planted in a randomized complete-block design for each of three maturity groupings. The maturity groups are: R.M. 2.0 - 3.3, R.M. 3.4 - 3.8, R.M. 3.9 - 4.3. Each entry was replicated four times and planted in plots 45 ft. long and 5 ft. wide containing four rows seeded at 170,000 seeds per acre.
The production practices used at each location are shown in Table 1. 1998 rainfall is shown in Table 2. Excessive rainfall and flooding during the growing season severely reduced the yield of all entries at the N1 and S2 test sites.
Relative maturity. Relative maturity is a rating designed to account for all of the factors that affect maturity date and number of days from planting to maturity. These factors include variety, planting date, rainfall, latitude and disease. The method used to determine maturity was the 95% brown pods reading. The reference varieties and maturities used were: Vertex = 2.3, Resnik = 3.4, Flyer = 3.9. Thus, a variety with a maturity rating of 2.8 is about halfway between Vertex and Resnik in maturity.
Plant height was taken just prior to harvest. The average height (inches) of several plants was recorded.
Lodging score. 1 = nearly all plants erect; 2 = either all plants leaning slightly or a few plants down; 3 - either all plants leaning moderately (45) or 20-50 percent of plants down; 4 = either plants leaning considerably or 50-80 percent of plants down; 5 = 80 percent or more of plants down.
Seed size is reported as 1000s of seeds per pound.
Protein and oil % analysis was determined by near infrared transmittance technology. The test was performed by the OSU Grain Quality Lab using a Tekator Infratec whole grain analyzer calibrated with the Composition Systems Calibration developed at Iowa State University and is reported at 13% moisture.
Sclerotinia Rating. All of the varieties that were evaluated were susceptible in the growth chamber test. There are no known sources of immunity to this pathogen. All of the varieties were evaluated three times in the growth chamber assay and ranked based on the percent kill. Varieties that were not significantly different from Northrup King S 1990 (have moderate to good resistance) were given the designation 'M' to indicate moderate levels of resistance to Sclerotinia. Some varieties not identified by this test as having moderate levels of resistance may actually have reduced amounts of disease in the field due to canopy structure or other factors. If inoculum levels are high and the environment is very favorable, all varieties will develop Sclerotinia stem rot.
Phytophthora Resistance. All lines for which seeds were available were tested using a hypocotyl inoculation with race 1 (defeats Rps 7); race 4 (defeats Rps 1a, 1c, 7); race 17 (defeats Rps 1b, 1d, 3a, 6, 7); race 21 (1a, 3a, 7); and race 25 (defeats Rps 1a, 1b, 1c, 1k, 7). From the combination of these results the Rps gene in the varieties was determined. Some of the varieties gave a mixed response and those are indicated with an 'S'. A "nd' indicates those varieties killed by race 1 in the hypocotyl test, and therefore have no major gene resistance.
Phytophthora Partial Resistance (Tolerance). The partial resistance number is the mean disease score of three replications from a greenhouse inoculum layer test. Varieties were challenged with a race that killed seedlings in the hypocotyl inoculation test. Ratings of 1 to 3.9 are considered to have high levels of partial resistance and will provide good control. Ratings of 4.0 to 5.0 are considered to have moderate levels of partial resistance and will have some yield reductions when environmental conditions favor Phytophthora. Ratings over 5.0 have very little partial resistance.
Yield. Each soybean variety was harvested at a moisture content between 10 and 17 percent and yields computed to bushels per acre at 13 percent moisture.
LSD. A Least Significant Difference (LSD) for yield was computed for each maturity group. LSD's are reported in bushels per acre at 13 percent moisture. Yields of two varieties within a maturity group are significantly different 70% of the time if their yields differ by more than the LSD shown for that maturity group.
Tables 3 through 8 contain yield data as well as measurements for relative maturity, plant height, lodging, seed size, grain oil and protein content, Phytophthora tolerance and resistance, and Sclerotinia resistance. These characteristics are important in selecting a variety for a particular set of cultural practices, soil and weather conditions.
An additional aid in variety selection exists in the form of a computer program which uses producer supplied information to select outstanding varieties which are ideally suited to a set of conditions described by a grower. Precise seeding rates adjusted for row spacing, planting dates and variety characteristics are also generated. The program and database are available on a diskette from the county extension office or for download at http://ohioline.ag.ohio-state.edu/software/
DATA USE
Inclusion of entries in the Ohio Soybean Performance Trials does not constitute an endorsement of a particular entry by the Ohio State University, Ohio Agricultural Research and Development Center, or the Ohio State University Extension.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.
TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868