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ARS Home » Southeast Area » Raleigh, North Carolina » Soybean and Nitrogen Fixation Research » Research » Publications at this Location » Publication #194629
Title: HETEROSIS AND INBREEDING DEPRESSION IN TWO SOYBEAN SINGLE CROSSES

Author
item BURTON, JOSEPH
item BROWNIE, CAVELL - N.C. STATE UNIV.

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2006
Publication Date: 11/21/2006
Citation: Burton, J.W., Brownie, C. 2006. Heterosis and inbreeding depression in two soybean single crosses. Crop Sci. 46:2643-2648.

Interpretive Summary: Hybrid vigor is generally is considered to be of little importance in soybean and yield loss due to inbreeding is thought to be rare. Two soybean hybrids of high yielding varieties, Holladay/Hutcheson (Cross 1) and Brim/Boggs (Cross 2), were generated by hand pollinations. Succeeding generations were derived by bulk selfing pollinations. All generations were yield tested in multiple years and locations. The average yield of the Cross 1 hybrid was 16% greater than that of the highest yielding parent and the average yield of the Cross 2 hybrid was 5% greater than the highest yielding parent. Both crosses showed some depression in yield due to inbreeding. The existence of hybrid vigor in soybean two parent crosses may mean that superior gene combinations are possible in breeding lines derived from that cross. So when choosing among possible crosses which might produce high yielding varieties, a plant breeder may make the best selection by choosing the ones with the most hybrid vigor.

Technical Abstract: Heterosis generally is considered to be of little importance in soybean (Glycine max L. Merr.) and inbreeding depression is thought to be rare or non-existent. The F1 generations of two crosses, Holladay/Hutcheson (Cross 1) and Brim/Boggs (Cross 2), were generated by hand pollinations. Inbred generations were generated by bulk selfing. The F1, F2, F3, F4, and F5 generations were yield tested in replicated bordered single row plots in multiple years and locations. The average yield of the Cross 1 F1 was 16% greater than that of the highest yielding parent and the average yield of the Cross 2 F1 was 5% greater than the highest yielding parent. Both crosses showed inbreeding depression, when regressed on percent inbreeding. Possible genetic bases for heterosis in soybean include gene complementation or interaction of duplicate favorable loci in repulsion, linked dominant alleles that are inherited as a unit, a greater number of dominant alleles in the F1 than either parent separately, multiple dosage dependant regulatory loci and/or overdominance. The existence of heterosis is evidence that superior gene combinations are possible. The magnitude of yield heterosis should be a useful criterion for selection among biparental crosses. If there is evidence that dominance is important, early generation testing may also be a fruitful breeding strategy.