POLLINATION OF MS2 MALE-STERILE SOYBEANS: EFFECT OF POLLINATOR DENSITY AND VARIABILITY OF DERIVED POPULATIONS

MICHAEL LYNN MAY, Purdue University

Abstract

The objective of this research was to characterize the ms(,2) gene for genetic male-sterility for use in a recurrent selection program in soybeans {Glycine max (L.) Merrill}. Information was collected about the effect of pollinator seeding density on the incidence of pollination by that pollinator, about the relative variability of four populations that were developed with the use of the ms(,2) gene, and about the effects of sparsely-podded male-sterile plants on yields of adjacent male-fertile plants in a space-planted nursery. For the pollinator density tests, a population that was segregating for ms(,2) genetic male-sterility was interplanted with two pollinators, the cultivar 'Century' and the breeding strain CX602-107-1-2, at four pollinator seeding densities for two years. Seeds harvested from individual male-sterile plants were grown and scored for percent pollination using pubescence color as the genetic marker. The response to changes in pollinator seeding density was predominately linear. Observed pollination was greater when CX602-107-1-2 was a pollinator. There was a significant pollinators by pollinator densities interaction, but this interaction did not affect the useability of the ms(,2) gene as a means of eliminating tedious hand-pollination of soybean populations in the intermating phases of recurrent selection schemes. Families of seeds from male-sterile plants from the pollination tests were space-planted in a total of four progeny tests over two years. Records for maturity, harvest index, seed yield, and seed protein percentage were kept for individual plants. Estimates of between-family variances, within-family variances, and intraclass correlation coefficients were computed for each of the measured traits in each progeny test. Yields of male-fertile plants adjacent to male-sterile plants in the progeny tests were compared with yields of male-fertile plants not adjacent to male-sterile plants and no difference was found. It was concluded that the ms(,2) gene was suitable for inclusion in breeding populations as a means of achieving random intermating for the recombination phases of recurrent selection programs for soybean improvement.

Degree

Ph.D.

Subject Area

Agronomy

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