Soybean Agronomics

Soybean maturities will vary from one year to the next depending on growing conditions. Some soybeans are more heat sensitive than others, therefore, during an extremely hot year these soybeans mature earlier than normal. All soybeans are photo-period sensitive and will mature according to night length. This is why a one week delay in planting results in only a 1 to 2 day delay in maturity. The Relative Maturity assigned each soybean product reflects its maturity in relationship to other soybeans, i.e., a soybean with a Relative Maturity of 29 is 2 days later than a soybean with a Relative Maturity of 27 and 2 days earlier than one with a Relative Maturity of 31. The Relative Maturity also indicates the position of the soybean in its maturity zone, i.e., a soybean with a Relative Maturity of 29 is a Group II maturity and is 90% of the way through the Group II maturity zone.

The height a soybean plant achieves is dependent on several factors including planting date, row width, maturity of the soybean for the area, growing conditions and genetic ability. The Relative Height given for each soybean is expressed in five categories: S = Short, MS = Moderately Short, M = Medium/Average, MT = Moderately Tall, T = Tall. This score indicates the height each soybean achieves in a given area relative to other soybeans of the same maturity.

All soybean plants have "hair" growing on the stem and leaves. This "hair" is referred to as pubescence, which expresses a definite color. Most soybean plants have either gray, tawny or light tawny colored pubescence. A soybean plant's pubescence color has no influence on yield or other agronomic characteristics.

The soybean seed hilum or eye is the point of attachment of the seed to the pod. Soybeans can be identified by the various hilum colors they express. Hilum color has no agronomic importance, but may be of importance to exporters. Hilum colors include Black (Bl), Brown (Br), Yellow (Y), Imperfect Black (Ib), Slate (Sl), Tan (Tn), Buff (Bf) and Gray (G).

Oil content (at 13 percent moisture) as determined by evaluation in Stine’s Elite Yield Trials

Protein content (at 13 percent moisture) as determined by evaluation in Stine’s Elite Yield Trials

The following items are rated on a scale from Excellent to Not Recommended based on the following scale: E - Excellent VG - Very Good G - Good AV - Average NR - Not Recommended

Emergence scores are often obtained through a laboratory procedure that primarily reflects hypocotyl length. This procedure can be misleading since some soybeans have short hypocotyls, therefore, score poorly in this test, but do emerge quite well when planted shallow. The emergence scores presented here are designed to reflect the ability of a soybean to emerge under field conditions.

The standability score assigned to each Stine soybean at harvest time is based on the following system: E = All Plants Erect, G = All Plants Leaning Slightly, NR = 20% Or More Plants Lodged

Soybeans with shatter ratings of G (Good) or better should not present shatter problems. Soybeans rated as NR (Not Recommended) can be planted and can produce exceptional yields if harvest occurs promptly and at moisture levels of 13% and above.

Iron Deficiency Chlorosis occurs on soils high in pH. Early in the season, new leaves turn yellow between the veins and, in severe cases, the leaf tissue turns brown and drops out. Soybeans are assigned scores based upon their tolerance to Iron Deficiency Chlorosis in field conditions. Soybeans rated E (Excellent) exhibit the highest degree of tolerance to chlorosis; varieties rated NR (Not Recommended) are the most susceptible to chlorosis and are not recommended for high pH soils.

Phytophthora tolerance scores indicate the ability of the soybean to withstand Phytophthora pressure under field conditions.

Brown Stem Rot is a soil-borne fungus. It survives in soybean residues for many years and infection occurs through the roots of the lower stem earlier in the growing season. Stine soybeans are rated relative to their abilities to withstand BSR in field situations.

Scores in these categories are based on field observations and may or may not predict or indicate actual field performance. Actual results may vary depending on conditions.

Scores in this category are based on laboratory test results. Actual results may vary.

Scoring of SCN-resistant soybeans consists of an alpha code showing the level of resistance or susceptibility as tested, where S = susceptible, MR = moderate resistance, R = resistance.