Evaluation of Soybean [Glycine max (L.) Merr.] F₁ Hybrids

Abstract

Heterosis is an important factor in development of hybrid cultivars. Few heterosis studies have been done in soybean [Glycine max (L.) Merr.]. This is because manual cross-pollination is difficult and time-consuming, and not economical to produce large quantities of hybrid seed. Male-sterility systems identified in soybean, combined with insect-mediated cross-pollination, have been shown to produce large quantities of hybrid seed. This procedure was used in this study to produce hybrid seed for replicated yield trials with the objectives to: 1) evaluate the agronomic performance of soybean F₁ hybrids; and 2) estimate heterosis for yield and other agronomic traits of the F₁ hybrids. Parental genotypes were two male-sterile, female-fertile lines with the ms3 and ms9 mutations, and a group of six high-yielding male-parent lines. The experiment was conducted in two years at several locations. In 2005, twelve F₁ hybrids were evaluated along with parent lines. Mid-parent heterosis (MPH) ranged from −29% to +32%, and high-parent heterosis (HPH) from −23% to +1%. In 2006, eleven hybrids were evaluated. MPH values ranged from −53% to −21%, and HPH from −66% to −35%. Seed size and seed protein content showed HPH for some combinations. For traits related to vegetative growth, such as height and lodging, positive MPH and HPH were observed. In general, depending on the year and parent combinations, there were hybrids that performed better than the mid-parent values, suggesting that heterosis was identified in soybean. Significant differences for yield between hybrids of the ms3 and ms9 groups also were observed.

KEYWORDS:

• Soybean
• Glycine max
• hybrids
• heterosis
• male-sterility
• insect-mediated cross-pollination
• agronomic performance
• yield

We are grateful to Gregory Gebhart and Innan Cervantes-Martinez for helping with planting and harvesting. Thanks also to Hunt Wiley from Dairyland Seed Co. Inc. for providing the Gilbert, Iowa, test location.

This is a joint contribution from the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project 4403, and from the USDA, Agricultural Research Service, Corn Insects and Crop Genetics Research Unit, and supported by the Hatch Act and the State of Iowa. The mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by Iowa State University or the USDA, and the use of the name by Iowa State University or the USDA imply no approval of the product to the exclusion of others that may also be suitable.