Aphis glycines Matsumura (Hemiptera: Aphididae) can reduce the yield of aphid-susceptible soybean (Glycine max (L.) Merrill) cultivars. The Rag1 and Rag2 genes conferresistance to some biotypes of A. glycines. These genes individually can limit population growth of A. glycines and prevent yield loss. The impact of these genes when combined is not known. We compared the development of A. glycines on soybean with Rag1 alone (R1/S2), Rag2 alone (S1/R2), both genes combined (R1/R2), or neither gene (S1/S2). In addition, we determined the impact of different levels of aphid infestation on seed yield. The genotypes were grown in cages and artificially infested with A. glycines to achieve five treatment levels: aphid-free, 675 aphids per plant, 25,000 cumulative aphid days (CAD) (25K), 50,000 CAD (50K), and 75,000 CAD (75K). The S1/S2 line reached the 50K treatment, but did not reach the 75K treatment. Aphid development on R1/S2 and S1/R2 soybeans after two infestations reached a maximum of 25K. The maximum treatment reached on R1/R2 was only 675 aphids per plant after two infestations, at which there was no significant yield reduction when compared with the aphid-free treatment. The maximum yield reduction of S1/S2 was 27% at 50K treatment compared with 2% for R1/S2 and 12% for S1/R2 at the 25K treatment. Our results indicated that for A. glycines used in our study, cultivars with both Rag1 and Rag2 had less aphid exposure and less yield reduction than soybeans with only one resistant gene.

ABSTRACTGenetic modification of the fatty acid composition of soybean [Glycine max (L.) Merr.] oil has been successful in better meeting the needs of end users than is possible with conventional oil. Three modified oils are or have been sold commercially. Oil in which the linolenic acid (18:3) content has been reduced from 8 to 1% makes it possible to reduce or eliminate the need for chemical hydrogenation to achieve the stability and shelf life necessary for some food applications. Elimination of chemical hydrogenation and the trans‐fatty acids produced by the process is important for human health. Oil in which the oleic acid (18:1) has been increased from 25 to >80% also have increased its stability and shelf life. An oil with palmitic acid (16:0) reduced from 11 to <4% makes it possible to achieve a low content of saturated fatty acids, which is desirable for cardiovascular health. The genetic changes in soybean oil were achieved by conventional breeding and genetic engineering. Mutagenesis was the conventional breeding method used to develop the major genes for reduced palmitic and linolenic acids that are in the cultivars currently grown for commercial production. Genetic engineering was used to elevate oleic acid to >80%. The purpose of this paper is to review the methods that have been used to develop the fatty acid modifications, the inheritance of the modifications, the impact of the trait on agronomic and seed characteristics, the methods of phenotypic and genotypic selection, and the commercial status of the modified oils.

ABSTRACTSoybean [Glycine max (L.) Merr.] cultivars have been developed with reduced palmitate content that is controlled by the fap1 and fap3 alleles. One objective of our study was to compare the tocopherol content of reduced and normal palmitate lines with similar genetic backgrounds. A second objective was to compare the agronomic and seed traits of the two types of lines. Three single‐cross populations segregating for palmitate content were developed from which 20 reduced and normal palmitate lines were selected for evaluation at three environments during 2004. The mean total tocopherol of the reduced palmitate lines was 15% greater than the normal palmitate lines, and the line with the greatest total tocopherol in each population contained reduced palmitate. The mean seed yield of the reduced palmitate lines was 5.5% lower than the normal palmitate lines. There were significant differences between the two types of lines for other agronomic and seed traits; however, the significant genetic variation among lines of each type would permit the selection of reduced palmitate lines that were similar to normal palmitate lines for those traits. Use of the reduced palmitate trait would be advantageous to maximize the tocopherol content of soybean oil.

About 75% of the total P in conventional soybean [ Glycine max (L.) Merr.] seed is phytate P, which cannot be readily digested by nonruminant livestock, such as swine and poultry. The phytate P in soybean lines homozygous for the recessive alleles pha1 and pha2 is reduced to about 25% of the total P. The objective of this study was to determine the influence of low phytate (LP) on agronomic and seed traits of soybean. Three populations were developed by crossing three cultivars with normal phytate (NP) to the LP line CX1834‐1‐6. From each population, 10 LP and 10 NP lines were selected and grown in replicated tests at three Iowa environments during 2003. The mean total P of the LP and NP lines was not significantly different, but the mean phytate P, inorganic P, and other P were significantly different for the two types of lines in the three populations. The mean seedling emergence of the LP lines was 45% compared with 68% for the NP lines. The mean differences between the LP and NP lines for the other agronomic and seed traits were not significant in one or more of the populations. On the basis of these results, reduced seedling emergence will be a major factor to consider in the development of commercially viable cultivars with the pha1pha1pha2pha2 genotype for LP.

Crop ScienceVolume 45, Issue 4 p. 1671-1672 Registrations of Germplasm Registration of LDX01-1-65 Soybean Germplasm with Soybean Cyst Nematode Resistance Derived from Glycine soja B.W. Diers, Corresponding Author B.W. Diers bdiers@uiuc.edu Dep. of Crop Sciences, Univ. of Illinois, Urbana, 61801 Corresponding author (bdiers@uiuc.edu)Search for more papers by this authorP.R. Arelli, P.R. Arelli USDA-ARS, 605 Airways Blvd., West Tennessee Exp. Stn., Jackson, TN, 38301Search for more papers by this authorS.R. Carlson, S.R. Carlson Dep. of Crop Sciences, Univ. of Illinois, Urbana, 61801Search for more papers by this authorW.R. Fehr, W.R. Fehr Dep. of Agronomy, Iowa State Univ., Ames, IA, 50011Search for more papers by this authorE.A. Kabelka, E.A. Kabelka Horticultural Sciences Dep., Univ. of Florida, Gainesville, FL, 32611Search for more papers by this authorR.C. Shoemaker, R.C. Shoemaker USDA-ARS, Dep. of Agronomy, Iowa State Univ., Ames, IA, 50011Search for more papers by this authorD. Wang, D. Wang Dep. of Crop and Soil Sciences, Michigan State Univ., E. Lansing, MI, 48824Search for more papers by this author B.W. Diers, Corresponding Author B.W. Diers bdiers@uiuc.edu Dep. of Crop Sciences, Univ. of Illinois, Urbana, 61801 Corresponding author (bdiers@uiuc.edu)Search for more papers by this authorP.R. Arelli, P.R. Arelli USDA-ARS, 605 Airways Blvd., West Tennessee Exp. Stn., Jackson, TN, 38301Search for more papers by this authorS.R. Carlson, S.R. Carlson Dep. of Crop Sciences, Univ. of Illinois, Urbana, 61801Search for more papers by this authorW.R. Fehr, W.R. Fehr Dep. of Agronomy, Iowa State Univ., Ames, IA, 50011Search for more papers by this authorE.A. Kabelka, E.A. Kabelka Horticultural Sciences Dep., Univ. of Florida, Gainesville, FL, 32611Search for more papers by this authorR.C. Shoemaker, R.C. Shoemaker USDA-ARS, Dep. of Agronomy, Iowa State Univ., Ames, IA, 50011Search for more papers by this authorD. Wang, D. Wang Dep. of Crop and Soil Sciences, Michigan State Univ., E. Lansing, MI, 48824Search for more papers by this author First published: 01 July 2005 https://doi.org/10.2135/cropsci2005.001Citations: 13 Contribution from the Illinois Agric. Exp. Stn., Urbana. Research supported in part by the Illinois Soybean Checkoff Board. Registration by CSSA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume45, Issue4July–August 2005Pages 1671-1672 RelatedInformation

Soybean [Glycine max (L.) Merr.] oil with elevated oleate content would be useful for food and industrial applications that require increased oxidative stability. The first objective of this study was to determine if molecular selection for the Fad2‐1 deletion associated with the ol allele in the mid‐oleate mutant line M23 could be used to identify mid‐oleate individuals in a breeding program. The second objective was to determine if modifying genes affect phenotypic expression of oleate content in individuals homozygous for the deletion from a cross between M23 and Archer, a cultivar with normal oleate content. The segregation among 88 F2 plants from the cross satisfactorily fit a ratio of 1:2:1 homozygous normal (OlOl)/heterozygous (Olol)/homozygous (olol) for the Fad2‐1 deletion on the basis of Southern analysis. A PCR‐based marker Fad2‐1‐ol identified the same olol individuals as the Southern analysis. The PCR‐based marker would be a more rapid and less labor intensive method for molecular selection of olol individuals than Southern analysis. The olol individuals had the highest mean oleate content, the Olol individuals were intermediate, and the OlOl individuals had the lowest mean oleate content. There was significant variation among the olol individuals and their distribution overlapped that of the OlOl and Olol individuals, which indicated that modifying genes had an important influence on the trait. It would be necessary to test the fatty acid profile of olol individuals to select those with the highest oleate content.

Increased oleate content of soybean [Glycine max (L.) Merr.] oil may be useful for food and industrial applications requiring increased oxidative stability. The objective of this study was to determine if transgressive segregates for oleate content could be found in crosses between three mid‐oleate lines: FA22 from Iowa State University, N98‐4445A from the USDA‐ARS/North Carolina State University, and M23 from Saga University, Japan. Single‐cross populations of FA22 × M23, FA22 × N98‐4445A, and N98‐4445A × M23 were developed. Plants with significantly greater oleate than the highest oleate parent were observed in the three populations in the F2 and F3 generations. For the F3:4 lines grown in Puerto Rico, there were four lines with significantly greater oleate than the highest parent in the cross FA22 × M23, one line in FA22 × N98‐4445A, and 27 lines in N98‐4445A × M23. The F3:4 line with the greatest oleate content had 689 g kg−1 in the population FA22 × M23, 672 g kg−1 in FA22 × N98‐4445A, and 730 g kg−1 in N98‐4445A × M23 compared with 542 g kg−1 for FA22, 589 g kg−1 for N98‐4445A, and 583 g kg−1 for M23. Transgressive segregates from the populations should be useful as parents in a breeding program to develop cultivars with elevated oleate content.

Monogastric animals cannot readily digest the raffinose and stachyose in soybean [Glycine max (L.) Merr.], which reduces the amount of metabolizable energy that can be obtained from soybean meal. Soybean cultivars homozygous for the recessive allele stc1a from PI200508 have a reduced content of raffinose and stachyose and an increased content of sucrose. The objective of our study was to evaluate the influence of the stc1a allele on agronomic and seed traits. Two populations were developed by crossing two high‐yielding cultivars to a donor with the stc1a stc1a genotype. Lines from each population with the stc1a stc1a genotype (stc1a lines) and Stc1a Stc1a genotype (Stc1a lines) were grown in replicated tests at three Iowa locations during 2002. There were no significant differences in the mean performance of stc1a and Stc1a lines in one or both of the populations for field emergence, seed yield, maturity, lodging, height, protein, oil, palmitate, stearate, oleate, linoleate, or linolenate. It should be possible to develop stc1a stc1a cultivars with reduced raffinose and stachyose that perform as well as conventional Stc1a Stc1a cultivars for all the agronomic and seed traits evaluated.

Genetic improvement for yield in soybean [Glycine max (L.) Merr.] has been accomplished by breeding within a narrow elite gene pool. Plant introductions (PIs) may be useful for obtaining additional increases in yield if unique and desirable alleles at quantitative trait loci (QTL) can be identified. The objectives of the study were to identify QTL for yield in elite and PI germplasm and to determine if the PIs possessed favorable alleles for yield. Allele frequencies were measured with simple sequence repeat (SSR) markers in three populations, designated AP10, AP12, and AP14, that differed in their percentage of PI parentage. AP10 had 40 PI parents, AP12 had 40 PI and 40 elite parents, and AP14 had 40 elite parents. Four cycles of recurrent selection for yield had been conducted in the three populations. Allele frequencies of the highest‐yielding C4 lines in the three populations were compared with the parents used to form the populations of the initial cycles. Allele flow was simulated to account for genetic drift. Fifty‐four SSRs were associated with 43 yield QTL. Seven of the QTL had been identified in previous research. Sixteen favorable marker alleles were unique to the PI parents. The genes associated with the unique PI alleles merit further investigation for their potential to increase yield of soybean cultivars.

Improving seed yield of soybean [ Glycine max (L.) Merr.] is an important breeding goal. The objective of this study was to evaluate two soybean PIs as sources of alleles for the enhancement of seed yield in North American cultivars. A population of 167 F 5 –derived lines was developed from a cross between ‘BSR 101’ and the experimental line LG82‐8379. BSR 101 has nine of 10 major ancestral lines contributing to the commercial gene pool of North America, while LG82‐8379 was selected from a cross between PI 68508 and FC 04007B. The F 5 –derived lines, divided into three sets based on maturity, were evaluated for 145 polymorphic simple sequence repeat (SSR) marker loci and for seed yield and other agronomic traits in 12 environments. Fifteen quantitative trait loci (QTL) were significantly [ P < 0.05, likelihood of odds (LOD) > 2.5] associated with seed yield in at least one set with two significant across all sets. For nine of the yield QTL, the LG82‐8379 alleles were associated with yield increases of 1.7 to 5.4% while the BSR 101 alleles increased yield 2.4 to 4.4% at six yield QTL. Four yield QTL were associated with significant changes in R8, eight with plant height, and three with seed protein concentration. Additional QTL were identified for R8, plant height, lodging, and seed protein and oil concentration. These results indicate that soybean PIs have the genetic potential for improving seed yield of U.S. soybean cultivars.

Soybean [Glycine max (L.) Merr.] oil is an important source of the tocopherols (vitamin E) used as a dietary supplement and as an antioxidant in foods. Previous research studies have indicated that genotypes with lower linolenate than that of conventional soybean genotypes have less tocopherols and that the relative amounts of α‐ and γ‐tocopherol may change as linolenate content is reduced by genetic modification. Those studies have utilized a limited number of genotypes with diverse genetic backgrounds and with greater linolenate content than that of currently available genotypes. The purpose of our study was to evaluate the tocopherol content of 20 lines with reduced linolenate of about 10 g kg−1 and 20 lines with normal linolenate of about 70 g kg−1 derived from each of three single‐cross populations segregating for the trait. The lines were grown in replicated tests at Isabela, PR, and at two locations near Ames, IA, during 2002. The mean total tocopherol content of the lines with reduced linolenate was 6.0% less than for the normal‐linolenate lines averaged across populations and environments. There was significant variation for total tocopherol among the lines of each type in each population, and some reduced‐linolenate lines were not significantly different from normal‐linolenate lines for the trait. Lower total tocopherol in reduced‐linolenate lines was due to a proportionate decrease in α, γ, and δ tocopherol, and the mean percentages of the three tocopherols in the total tocopherol were not significantly different in the reduced‐ and normal‐linolenate lines. It should be possible to develop cultivars with about 10 g kg−1 linolenate that have an acceptable content of total tocopherol and with the same proportions of α, γ, and δ tocopherol as conventional soybean cultivars.

Nonruminant animals fed soybean [Glycine max (L.) Merr.] meal cannot metabolize the P that is in the form of phytate. A soybean line CX1834-1-6 was developed that had a major reduction in phytate P and a concomitant increase in the inorganic P that is available to nonruminants. The objective of this study was to determine the impact of low phytate (LP) on agronomic and seed traits of lines with reduced palmitate in the seed oil. A population of soybean was developed by crossing CX1834-1-6 to a reduced-palmitate line B01769B019 and backcrossing the F-1 plants to B01769B019. Twenty BC1F2-derived lines with LP and reduced palmitate and 20 lines with normal phytate (NP) and reduced palmitate from the population were evaluated at three Iowa environments in 2003. The LP lines had a mean seedling emergence that was 22.3 percentage units less than the NP lines. Although the plant density of the LP lines was less than the NP lines, the mean yield of the two types was not significantly different. The palmitate and stearate content of the LP lines was significantly greater than that of the reduced-palmitate parent. The reduced emergence and greater saturate content of the LP lines may make it difficult to develop acceptable cultivars for production of LP soybean meal and low-saturate oil.

A reduction in the phytic acid (phytate) content of soybean [Glycine max (L.) Merr.] seed would improve the bioavailability of P in rations of nonruminant animals containing soybean meal. A soybean mutant with low phytate and increased inorganic P was developed by the USDA‐ARS and Purdue University. The objective of this study was to determine the inheritance of low phytate in a line derived from the mutant. The low‐phytate line was crossed reciprocally to a line with normal phytate. The F1 seeds from the reciprocal crosses had normal phytate, indicating complete dominance for the wild‐type alleles and no maternal effects. The segregation of 210 F2 seeds satisfactorily fit a phenotypic ratio of 15:1 normal to low phytate. The F2–derived lines satisfactorily fit a ratio of 7:8:1 homogeneous normal phytate to segregating to homogeneous low phytate. The segregation ratios indicated that low phytate was controlled by recessive alleles designated pha1 and pha2 at two independent loci that exhibited duplicate dominant epistasis. Both of the alleles must be homozygous to obtain low‐phytate seed.

Soybean [Glycine max (L.) Merr.] lines homozygous for the mips allele (mips lines) have reduced phytate P and raffinose saccharides in the protein meal. Less phytate is desirable for reducing the P content of manure from nonruminant animals and less raffinose saccharides increases the amount of metabolizable energy available to them. Field trials indicated that seedling emergence percentage of mips lines was less for seed produced in a subtropical environment than a temperate environment. The objective of this study was to determine if field emergence of mips lines is influenced by the environment used for seed production. Seed of six mips lines and four commercial cultivars (Mips lines) produced in four temperate and 12 subtropical environments during 2 yr was evaluated for field emergence percentage, seed viability percentage, and germination percentage in warm germination, cold vigor, and accelerated aging tests. The field emergence percentage of mips lines was significantly less than Mips lines for all seed sources. The mips lines had a mean field emergence of 63% for temperate sources and 8% for subtropical sources while Mips lines had a mean field emergence of 77% for temperate sources and 83% for subtropical sources. The mean seed viability percentage for the mips lines based on the tetrazolium test of 88% for temperate sources and 70% for subtropical sources accounted for only part of the differences in field emergence. Differences in field emergence between the mips and Mips lines were not consistently predicted by the warm germination and cold vigor tests for temperate sources. The accelerated aging test effectively differentiated the field emergence potential of the mips and Mips lines for all seed sources. Seed source should be a consideration when evaluating the field emergence of mips lines in a breeding program or for obtaining acceptable plant populations in commercial fields.

The quality of some soybean [Glycine max (L.) Merr.] food products has been associated with the content of some components of the protein fraction of the seed. The objective of this study was to determine the role of genotype, environment, and genotype × environment interactions on the components of β-conglycinin (βc) and glycinin (G). The traits were measured on 14 cultivars of Maturity Group II grown in three replications at each of eight locations throughout Iowa in 1998, 1999, and 2000. Cultivars were significantly different for all traits, except the A3 subunit of G. No significant interactions were found for cultivars with years or locations for βc, G, or the G/βc ratio, which indicated that the relative performance of cultivars across environments was consistent. No significant differences were expressed among years or locations for βc, G, and the G/βc ratio; however, there were significant differences for the three traits among the 24 environments. There was a significant phenotypic correlation of −0.92 between the βc and G contents of the 14 cultivars averaged across environments, but no significant correlations of βc, G, or the G/βc ratio with protein and oil content. It should be possible to breed for desired levels of the protein components in a cultivar development program and to select among cultivars for the traits in commercial grain production.

Seed size is an important attribute of soybean [Glycine max (L.) Merr.] for some food uses. The objectives of this study were to identify simple-sequence-repeat (SSR) markers associated with quantitative trait loci for seed size (SSQTL) and to compare the effectiveness of phenotypic selection and marker-assisted selection for seed size among individual F-2 plants. Three small-seeded lines were crossed to parents with normal seed size to form three two-parent populations. The parents of the populations were screened with 178 SSR markers to identify polymorphism. Population 1 (Pop 1) had 75 polymorphic SSR markers covering 1306 centimorgans (cM), Pop 2 had 70 covering 1143 cM, and Pop 3 had 82 covering 1237 cM. Seed size of each population was determined with 100 F-2 plants grown at Isabela, Puerto Rico, and their F-2-derived lines grown in two replications at three environments. Single-factor analysis of variance and multiple regression were used to determine significant marker-SSQTL associations. Population 1 had 12 markers that individually accounted for 8.1 to 14.9% of the variation for seed size combined across environments, Pop 2 had 16 markers that individually accounted for 7.8 to 36.5% of the variation, and Pop 3 had 22 markers that individually accounted for 8.6 to 28.8% of the variation. Three marker loci that had significant SSQTL associations in this study also were significant in previous research, and 13 markers had unique SSQTL associations. The relative effectiveness of phenotypic and marker-assisted selection among F-2 plants varied for the three populations. Averaged across the three populations, phenotypic selection for seed size was as effective and less expensive than marker-assisted selection.

ABSTRACTSoybean [Glycine max (L.) Merr.] cultivars with large seed size and high protein content are desirable for the production of tofu and other food products. The objectives of this study were to evaluate the amount of genetic variability and the effectiveness of single‐plant selection for seed size and protein in two‐ and three‐parent soybean populations. Two parents with large seed and high protein (LSHP) and one parent with normal seed size and protein (N) were used to produce three population types: LSHP × N, LSHP × LSHP, and LSHP × (LSHP × N). Four sets of the three population types were evaluated with different parents in each set. For each of the populations, 100 random F2 plants and 10 plants of each parent were harvested at Ames, IA, and their seed size and protein were measured. The F3 progeny of the 100 F2 plants and 10 entries of the three parents of each set were evaluated in replicated tests at two Iowa locations. The percentage of F2:3 lines with seed size greater than or equal to the smallest LSHP parent and protein greater than or equal to the lowest LSHP parent in the set averaged 4% for the LSHP × N, 88% for the LSHP × LSHP, and 31% for the three‐parent crosses. Single‐plant selection was not considered cost effective in the LSHP × N populations because the percentage of acceptable segregates was so small or in the LSHP × LSHP populations because the percentage of acceptable segregates was so high. For the three‐parent populations, single‐plant selection was most effective when the F2 plants were ranked for the two traits and those with the most favorable rank were selected for evaluation as F2:3 lines. LSHP × LSHP and three‐parent populations should be the most useful for developing LSHP cultivars.

Soybean [Glycine max (L.) Merr.] genotypes with elevated palmitate content in the seed oil have been developed for food and industrial applications. The objective of the study was to determine the association of elevated palmitate with agronomic and seed traits of soybean. Two high‐yielding cultivars with normal palmitate content of ≈110 g kg−1 were crossed to lines with the genotype fap2‐b fap2‐b fap4 fap4 that had an elevated palmitate content of ≈250 g kg−1. From each of the two segregating populations, 27 F3‐derived lines with elevated palmitate content and 27 with normal palmitate content were selected for replicated testing at two locations in Iowa in 1993 and 1994. The elevated palmitate lines had significantly reduced yield; later maturity; reduced lodging; elevated height; reduced seed weight, protein, oil, stearate, oleate, and linoleate; and elevated palmitate and linoleate than the normal‐palmitate lines. The magnitude of the negative association between elevated palmitate and seed yield was different between the crosses, which indicated that multiple high‐yielding parents with normal palmitate should be considered for developing cultivars with the fap2‐b fap2‐b fap4 fap4 genotype. The distributions for oil content of the elevated‐ and normal‐palmitate lines did not overlap; therefore, the oil content of cultivars with elevated palmitate is likely to be less than that of normal cultivars. The magnitude of the differences between the elevated‐ and normal‐palmitate lines for the other characteristics was not sufficient to preclude the development of acceptable cultivars with the fap2‐b fap2‐b fap4 fap4 genotype.

Plant‐row‐yield tests (PRYT) are used by soybean [Glycine max (L.) Merr.] breeders for the initial evaluation of experimental lines. The highest yielding lines in the PRYT are advanced for additional testing in replicated tests. The objective of this study was to determine the reliability of selection for seed yield in unreplicated plots by the family and line methods of selection. Four F3‐derived lines from each of 21 F2 families from four populations were grown in a PRYT during 1995 and in replicated tests at four environments in 1996. For the family method, the mean seed yield of the four F3‐derived lines of each F2 family was used to identify superior families from which to select individual lines. For the line method, lines were selected without regard to the family structure. The seed yield of the selected and unselected lines on the basis of data from the PRYT was compared with their mean seed yield in the 1996 environments. The total number of lines selected by the family method was less than for the line method in all populations. The percentage of selected lines that were correctly classified was similar for both methods. There was a greater percentage of lines incorrectly rejected by the family method than by the line method. The use of replication at an individual location did not improve the selection of lines by the family or line methods of selection. For the selection of lines for seed yield in unreplicated plots, breeding methods that rely on family performance would not be more effective or efficient than methods that ignore family structure. To obtain lines for yield tests at multiple locations, selection of lines by the line method on the basis of their performance in a PRYT would be better than the use of random lines.

Development of soybean [Glycine max (L.) Merr.] cultivars with reduced palmitate and stearate will lower the total saturated fatty ester content of the seed oil, and reduction of linolenate will improve its oxidative stability. The objective of this study was to compare the family and line methods of selection for reduced palmitate, palmitate + stearate (saturates), and linolenate in four populations segregating for the major alleles fap1 and fap3 for reduced palmitate or the fan1(A5) and fan2 for reduced linolenate. Four random F3‐derived lines from 21 F2 families from each population were evaluated in a plant‐row‐yield test in 1995 and replicated trials at four locations in 1996. For the family method, the mean palmitate, saturates, and linolenate of the four F3‐derived lines of each F2 family was used to identify families from which to select individual lines. For the line method, lines were selected without regard to the family structure. The fatty ester contents of the selected and unselected lines based on data from one environment were compared with their mean fatty ester contents in the other environments. The number of lines selected for each of the traits by the family method was less than for the line method in all populations. There was a greater percentage of lines incorrectly rejected by the family method than by the line method. For development of cultivars with reduced palmitate, saturates, and linolenate, breeding methods that rely on family performance would not be more effective or efficient than methods that ignore family structure.