Missouri 2007 Soybean Performance Tests

Comparing Hybrids

The performance of a variety cannot be measured with absolute precision. Uncontrollable variability is involved in the determination of each yield average. This variability sometimes occurs because the soil is not uniform, but many other conditions may also contribute. Because variability exists in all field experimentation, statistics are used as a tool to assist in making decisions. The statistical tool used in these tests is the test of least significant difference (LSD). The LSD is quite simple to apply. When two entries are compared and the difference between them is greater than the LSD, the entries are judged to be significantly different. Differences smaller than the LSD may have occurred by chance and are judged to be not significant.

Variety performance may seem inconsistent across locations and from year to year because of differences in rainfall, temperature, soil fertility, diseases, insects and other factors. To obtain an improved estimate of relative variety performance, readers should consider results from more than one location or year. In this publication, the authors have tried to facilitate comparisons across years and locations.

In each test, the "top yielding" varieties in each maturity group have been identified. These varieties did not yield significantly less than the highest yielding variety in the same maturity group. They are denoted in the tables by an asterisk (*) next to their yields. Thus, by going down a column, readers can readily identify the highest yielding varieties. By going across the page, readers can evaluate the relative performance of a variety during several years or at several locations. From the standpoint of yield, the most desirable varieties will be those that rank among the "top yielding" varieties (that is, have an asterisk) the greatest number of times.

Although yield usually receives first consideration, other agronomic characteristics may be equally important when selecting a soybean variety. Standability, maturity, herbicide tolerance and disease resistance are among the characteristics that deserve careful consideration. Several diseases prevalent in Missouri can be devastating to susceptible varieties. Lodging may reduce yields and slow harvest. Poor seed quality is often associated with varieties that mature while temperatures are still high. Late-maturing varieties are occasionally killed by frost. Selection of varieties from several maturity groups can be helpful in spreading out harvest dates. Therefore, information presented on disease reaction, lodging, herbicide tolerance and maturity should also be considered when selecting a variety.

The Missouri Variety Testing Program does not recommend specific varieties. Farmers growing a new variety for the first time should consider all available information and then grow a small acreage to determine adaptability. This should be the practice for all new varieties regardless of origin.