Evaluation of Density Classification as a Selection Technique on Breeding Soybeans for Protein or Oil¹

Abstract

PERCENTAGE protein and oil are important in evalu-•*• ating breeding lines of soybeans. The chemical method now used is costly, and if it were used on single plants grown at ordinary spacings, little or no seed would remain for planting. A reliable, low cost method for evaluating single plants for protein or oil content in a breeding program without destroying the seed for planting would have considerable value. The density of soybean oil is approximately 0.93 gram per cc. and the density of the non-oil portion of the seed is estimated to be within the range of 1.3 to 1.4 grams per cc. The oil and protein together will usually make up 60 to 65% of the dry matter in the soybean seed. On the basis of the differences in density of the oil and non-oil portions of the seed, it appears that it might be possible to classify seed from single plants in a segregating population according to density and thereby select plants with seed high in oil or high in protein. Laboratory studies have shown consistently that a lot of seed could be separated into density classes by subjecting the seed to a series of glycerol-water solutions with step

Mass Selection by Specific Gravity for Protein and Oil in Soybean Populations1

“…The phenotypic association for seed density with protein and oil reported in this study are in close agreement with those reported by Hartwig and Collins (1962) for specific gravity with protein and oil. The correlations reported in this study are measurements of association of the mean oil and protein performance for a line with the mean seed density value.…”

“…In experiments with rye from 1951 to 1959, Hoogland (1961) found that the leaf number per plant was increased considerably using mass selection. Romero and Frey (1966) practiced mass selection for height in oats for four generations beginning water solutions with step-wise-increasing specific gravities were used by Hartwig and Collins (1962) to stratify a lot of soybean seed into specific gravity classifications. Those lots of seed having a high specific gravity classification had a protein percentage above the mean of the original lot, and the lots having low specific gravity classifica tion had an oil percentage above the mean of the original lot of seed.…”

Selecting Increased Seed Density to Increase Indirectly Soybean Seed Protein Concentration

“…Burton, unpublished data, 1992). Because seed density has been used to evaluate seeds for protein content (Hartwig and Collins, 1962), it could potentially be used for indirect selection of protein content.…”

Mass selection by specific gravity for protein and oil in soybean populations

“…In experiments with rye from 1951 to 1959, Hoogland (1961) found that the leaf number per plant was increased considerably using mass selection. Romero and Frey (1966) practiced mass selection for height in oats for four generations beginning water solutions with step-wise-increasing specific gravities were used by Hartwig and Collins (1962) to stratify a lot of soybean seed into specific gravity classifications. Those lots of seed having a high specific gravity classification had a protein percentage above the mean of the original lot, and the lots having low specific gravity classifica tion had an oil percentage above the mean of the original lot of seed.…”