Submitted to: Euphytica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/19/2007
Publication Date: 11/13/2007
Citation: Ortiz-Perez, E., Wiley, H., Horner, H.T., Davis, W.H., Palmer, R.G. 2007. Insect-mediated cross-pollination in soybean [Glycine max (L.) Merrill]:ii. phenotypic recurrent selection. Euphytica 152:1573-1595. Interpretive Summary: Soybean yields have increased at a slow pace for decades through breeding varieties with better pest resistance and with better adaptation over wider geographic areas. Most soybean varieties are pure inbred lines; a few are mixtures of pure lines. There are no commercially available soybean hybrids. Perhaps the most limiting factor in the production of soybean hybrids is the movement of pollen from the male parent to the female parent. One objective was to use insect pollinators to transfer the pollen from male to female parent. The second objective was to continually select the plants with the most insect-pollinated hybrid seed to use as parents the next generations to produce even more hybrid seed per female plant. This plant breeding technique was successful. After three generations of selecting for greater seed-set, some parent combinations were 80% of normal seed-set. Thus this technique can be used to increase hybrid seed production. Then more parental combinations can be made for agronomic performance tests. Hybrid combinations would be identified from the agronomic performance tests that might be commercially accepted. Hybrid seed should benefit the seedsman, the farmer, and the consumer with a consistent supply of soybean for food, fiber, or industrial applications.
Technical Abstract: Recurrent selection is a method for population improvement which has been used in soybean [Glycine max (L.) Merrill] to modify traits such as grain yield, seed-protein content, seed-oil content, iron-deficiency chlorosis, and seed size. Nuclear male-sterility with insect-mediated cross-pollination has been successfully used in recurrent selection schemes in soybean. However, little attention has been given to selection to increase the agronomic performance of male-sterile plants per se. The objective of this study was to evaluate the response of male-sterile lines segregating for male-sterile alleles ms2, ms3, ms6, ms8, and ms9 to phenotypic recurrent selection for increased seed-set, using a selected group of male parents. Bees were utilized as pollinator vector. The results indicated that recurrent selection in a favorable environment was successful to increase the number of seeds per male-sterile plant. Although a differential response was observed among populations, the seed-set observed would justify the use of some specific male-sterile selections as female parents in a hybrid soybean seed production system.