Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2008
Publication Date: 4/10/2009
Citation: Perez, P.T., Cianzio, S.R., Palmer, R.G. 2009. Evaluation of Soybean [Glycine max (L.) Merr.] F1 Hybrids. Journal of Crop Improvement. 23:1-18. Interpretive Summary: Plant breeders continually try to improve plant cultivars, e.g., for yield potential, pest tolerance or resistance, seed and/or forage quality, etc. The use of hybrid plants, i.e., that are the result of crosses between two parents, generally exhibit superior agronomic performance. Hybrids that have been successful in cross-pollinated plants have suitable sterility systems, e.g., maize. In most highly self-pollinated crops, commercial hybrids are not economical or agronomically superior to conventionally bred cultivars. However, the self-pollinated crop, rice, has been a commercial success worldwide. Soybean is a highly self-pollinated crop with the male and female reproductive organs within the same flower. Male-sterile, female-fertile genetic types are available in soybean. Our objective was to use insect-mediated cross-pollination to produce large quantities of hybrid seed to test agronomic performance, i.e., heterosis. Parents were two male-sterile, fertile-fertile lines (female) with the ms3 and ms9 mutations. The male parents were six high yielding agronomic lines. The experiment was conducted at several locations for two years. In the first year positive heterosis was observed for several parent combinations. In year two, no positive heterosis was expressed. In general depending upon the year and the parental combination, there were hybrids that gave positive heterosis. These results give support towards the commercialization of soybean. Increased seed yields from hybrid soybean should benefit the farmer (profit) and the seedsmen (profit), and ultimately the consumer through stable food costs with possible enhanced quality.
Technical 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 conducive as an economical way 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 the conduct of 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. In future research, it will be important to introgress the ms3 and ms9 mutations and other male-sterile genes into high-yielding backgrounds, to maximize hybrid performance.