James E. Beuerlein, Professor, Dept. of Horticulture & Crop Science
A. F. Schmitthenner, Professor, Dept. of Plant Pathology
Steve St. Martin, Associate Professor, Dept. of Horticulture & Crop Science
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. The choice of a soybean variety, brand or blend for planting should be based on performance data, i.e., Yield, Disease Reaction, Relative Maturity, Plant Height, Lodging, Seed Size, etc.
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 1997 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 non-RR entries. RR entries were tested at the C2 and S1 test sites in a separate study using no-till culture. The performance of RR entries and non-RR 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 five maturity groupings. The maturity groups are: R.M. 1.9-2.4, R.M. 2.5-2.9, R.M. 3.0-3.4, R.M. 3.5-3.9, R.M. 4.0-4.5. 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. Plots were end trimmed to a length of 41 ft. and combine harvested.
The production practices used at each location are shown in Table 1. Soil moisture available for plant growth and development is extremely important in soybean production, particularly during the flowering and pod-fill period in July, August and early September. 1997 rainfall is shown in Table 2.
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 = 2.4, 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 varieties evaluated were susceptible. This rating provides an estimate of the relative susceptibility of soybean varieties to white mold. All of the varieties were evaluated 3 times in the growth chamber by the cotyledon inoculation technique. The mean disease ratings from the 3 growth chamber studies were ranked based on the percent seedlings killed. The rating consists of 1=cultivars ranked 1-10; 2-cultivars ranked 10.1 to 20; 3=20.1 to 30; and 4=30.1 to 40. Ratings for varieties ranking higher than 40 are not presented with the exception of public lines which were used as standard varieties in these evaluations. Varieties rated 1 to 4 should have less disease incidence than more susceptible varieties under similar inoculum pressure and environmental conditions as confirmed by field evaluations of public and selected private varieties in 1996 and 1997. The standard least susceptible check, NK1990, had a rating of 2 (ranked 10.4) and the most susceptible check, Williams82, had a rating of 9 ranked 88.6.
Phytophthora Resistance. All lines for which seeds were available were tested with race 4, race 1, race 3, and race 18, or race 4, race 25, race 17 and race 7 to detect Rps 7, 1a, 1c, 1b, 1k, 3a or 1k+6. A resistance no. of 1 = no resistance, 2 = Rps7, 3 = Rps1-a, 5 = Rps3-a, 6 = Rps1-c, 7 = unspecified gene controlling a few races, 9 = Rps1-b, 10 = Rps1-k, 20 = unspecified genes controlling all races. Most Phytophthora races are controlled by numbers of 9 or higher. Numbers of 5 and 6 control only some of the races and do not provide complete control. Numbers of 1, 2 and 3 provide no effective control.
Phytophthora tolerance: The tolerance number is the mean of three replications from a greenhouse inoculum layer test. Varieties with resistance numbers of 1, 2, 3, and 6 were evaluated with race 4, varieties with resistance numbers of 9 and 10 were evaluated with race 25 and varieties with a resistance number of 5 were evaluated with race 7. Ratings of 1-3.9 can be considered highly tolerant, and will provide good control without resistance or if resistance fails. Ratings of 4.0 to 4.9, can be considered moderately tolerant, and will provide partial control. Ratings over 5 can be considered as having little or no tolerance and will provide no effective Phytophthora control.
Yield. Each soybean variety was harvested at a moisture content between 13 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, Phytophthora tolerance and resistance, grain oil and protein content. These characteristics are important in selecting a variety for a particular set of cultural practices, soil and weather conditions.
While variety selection is very important, other production practices are also important in that they determine the degree to which a variety can realize its yield potential. For example, if soil and weather conditions are satisfactory for planting, each day of delay reduces the yield potential by up to one-third bushel per acre.
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/soyvs98a.exe
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