Agronomic Traits In Soybean Research Articles

Breeding strategies for early soybeans in Belarus

AbstractYield and other agronomic traits in soybean depend on the growth habit. The best maturity group, 00 indeterminate cultivars, compared with semi determinate cultivars for 3 years, out yielded the latter by 9%, possessed greater height and node number but somewhat stronger lodging and better lower bottom pod set. Maturity did not differ significantly within the samples. Correlations were recorded between the yield, growth type and node number. Indeterminate cultivars, in general, require fewer days to start flowering than determinate cultivars. This character is useful in the development of cultivars tolerant to a moderate drought in the second half of the summer. Thus, the most likely model of maturity group 00 variety for Belarus may be an indeterminate, early flowering, full season cultivar.

Expression of the narrow leaflet gene for yield and agronomic traits in soybean.

Genes that affect plant form and function may be used to enhance the yield of soybean [Glycine max (L.) Merr.]. Most soybean cultivars have broad (ovate) leaflets. A single gene, ln, controls inheritance for the narrow leaflet characteristic. Narrow leaflet cultivars (ln/ln) also tend to have a higher percentage of four-seeded pods than ovate (Ln/Ln) leaflet cultivars. Heterozygous (Ln/ln) plants have a leaflet shape intermediate between narrow and ovate. Determining the agronomic effects of the narrow leaflet allele (ln) in the heterozygous (Ln/ln) condition in soybean may have applications in practical plant breeding. We studied an ovate leaflet and a narrow leaflet cultivar, crosses between them in the F(1) and F(2), and backcrosses to both cultivars. The ratio of leaflet width to leaflet length accurately distinguished among narrow, ovate, and intermediate leaflet plants in the F(2) and backcross generations. In the F(2) generation, differences occurred among plants with different leaflet morphology. Narrow leaflet plants produced more seeds per pod and lower seed weight than ovate leaflet plants. Narrow and ovate leaflet plants produced comparable numbers of pods per plant and plant yield. Compared to ovate leaflet plants, intermediate leaflet plants produced similar numbers of seeds per pod and seed weight. Intermediate leaflet plants produced significantly more pods per plant and plant yield than plants with either ovate or narrow leaflets. The heterozygous condition at the locus for leaflet morphology resulted in heterosis for plant yield and may be of benefit in association with commercialization and development of hybrid soybean.

Genetics of Soybean Agronomic Traits: I. Comparison of Three Related Recombinant Inbred Populations

ABSTRACTMolecular markers provide a rapid approach to breeding for desired agronomic traits. To use them, it is necessary to determine the linkage between quantitative trait loci (QTLs) and such markers. The objective of this research was to determine such linkage in recombinant inbred (RI) soybean [Glycine max (L.) Merrill] populations. To do this, RI soybean segregants were characterized for molecular genetic markers and traits measured in several different environments. QTLs then were identified by interval mapping. Agronomic traits were measured and compared in large (about 240 segregants) RI populations derived from crosses between the cultivars Minsoy and Noir 1 (MN population), Minsoy and Archer (MA population), and Noir 1 and Archer (NA population). The MA and NA populations were grown together as two replications in each of four environments. Measurements from the MN population were reported previously and were taken from three replications grown in four environments. Traits measured were plant height, lodging, date of flowering, reproductive period, maturity, yield, seed weight, seed oil, seed protein, leaf length, and leaf width. Additional traits were derived from these primary measurements. Each of the three RI populations was also characterized by a large (>400) number of molecular genetic markers including RFLP (restriction fragment length polymorphism) and SSR (simple sequence repeat polymorphisms). QTLs were identified for all of the primary and derived traits at a significance level ≥LOD 3 on 17 of the 20 linkage groups and tended to be clustered on three. QTLs with major effects (R2 > 10%) were identified for all traits, and for many, these explained more than half of the heritable variation. Comparison of QTLs between the three RI populations established that for the majority of the traits, only two alleles could be identified. In only a few instances could a third allele be detected. Many of the significant QTLs identified in one population were confirmed in another. However, an almost equal number were found in only one population, suggesting that a dependence on the genetic background for expression (epistasis) was common.

Genetics of Soybean Agronomic Traits: II. Interactions between Yield Quantitative Trait Loci in Soybean

ABSTRACTIn order to breed efficiently, it is necessary to identify individual quantitative trait loci (QTLs) as well as interactions between these loci and to determine which QTLs produce phenotypes that are environment specific. This can be done by linking QTLs to molecular markers. The objective of this research was to carry out such an analysis for yield, one of the most complex agronomic traits. To do this, recombinant inbred lines of soybean [Glycine max (L.) Merrill] were characterized for molecular genetic markers and analyzed for yield in different environments. Interactions between QTLs were identified by subdividing the segregants into four sub‐populations defined by molecular alleles at pairs of unlinked loci. Differences in the mean yields of these sub‐populations defined interactions between QTLs. Measurements of yield in genotyped, recombinant inbred populations derived from crosses of ‘Minsoy’ with ‘Archer’ (MA population) and ‘Noir 1’ with Archer (NA population) have identified a pair of interacting yield QTLs whose effect was independent of environment as well as a pair of loci whose interaction was environment specific. Each example of epistasis, involved an allele specific interaction between the two QTLs. In the NA population, a pair of QTLs was identified in which Noir 1 alleles interact to specify a significant increase in yield that is not environment specific. These loci, located on linkage groups (LG) U3 and U9, do not affect either height or maturity. In all environments, the interaction between the QTLs was significant. In the MA population, a pair of QTLs was identified in which the Minsoy alleles interact to specify a significant increase in yield. However, this significant interaction is environment specific. One of the loci (on LG U14) is also associated with effects on height, seed weight, and maturity that are found in other environments, but these latter effects do not appear to involve any interactions with other loci. The data from the MA population support the concept that interactions between QTLs also can result in location‐specific effects on quantitative traits.

Effects of Innoculation, Planting Dates and Imbibition Duration on Some Agronomic Characters and Seed Yields of Soybean (Glycine max L.)

This study was conducted to determine the effects of inoculation, planting dates and imbibition duration on the seed yield and agronomic traits of soybean (cv. P-9292) under Bafra (Samsun) climatical condition. Four planting dates (6, 17, 27 May and 6 June) were assessed in 1993. For imbibition, the seeds were soaked in wet towels for 0, 3, 6, 12, 24 or 48 hours. Then, either inoculated (With R. japonicum) or non inoculated seeds were planted. A split-split randomized block design with three replicates was used. Emergence, flowering, pod filling and the maturity prolonged when the seeds were early planted. But at the last two planting dates (27 May and 6 June), when the seeds were soaked for 24 and 48 hours, the emergences hastened for 2 to 3 days. The growing period of plants ranged from 124 to 113 days depending on the planting dates. The plant height, number of pod/plant, number of seed/plant, number of nodule/plant, nodule dry weight/plant and 1000 seeds weight were increased with the inoculation. However, in the last planting date, all the values for the same characters were decreased. The oil content of seed was decreased, but the protein content was increased by inoculation. The oil and protein contents of seed were 23.04 and 36.96 %, respectively, when the seeds were not inoculated. Similarly, 22.86 and 38.33 % values for oil and protein contents, respectively, were obtained when the seeds were inoculated. The effect of inoculation on the protein content was highly significant (P

Pink Flower Color Associated with Increased Protein and Seed Size in Soybean

Most soybean [Glycine max (L.) Merr.] cultivars and plant introductions have either purple (Wl) or white (wl) flowers. Pink (wp) flower color results when the homozygous wp alleles are combined with Wl. This study was conducted to determine the effect of pink flower color on agronomic traits in soybean. Pink and near‐isogenic purple‐flowered lines were derived from an F4 plant. Seven homozygous pink‐flowered, three homozygous purple‐flowered, and two lines segregating for pink and purple flower color were evaluated at three locations in Illinois for 2 yr. When pink‐flowered lines were compared to purple‐flowered lines no differences were found for yield, maturity, height, lodging, or seed quality, while significant (P < 0.05) differences were found for seed weight, protein, and oil concentration. Pinkflowered lines averaged 22% higher in seed weight, 4% higher in protein, and 3% lower in oil compared to the purple‐flowered lines. The pink flower trait represents unique germplasm in soybean that can be used in the development of high yielding cultivars with increased seed protein.

Relationships between the fan Allele and Agronomic Traits in Soybean

Normal levels of linolenic acid (70‐80 g kg‐1) in soybean [Glycine max (L.) Merr.] oil adversely affect oil flavor and stability. The mutation‐induced line C1640 has half the normal level of linolenic acid (37 g kg‐1), but is 24% lower yielding than ‘Century’, from which it was selected. This study was conducted to determine if there are genetic relationships betweena gronomictr aits and the fan allele for low linolenic acid identified in C1640. Century and ‘Harper’, both with the FanFan alleles for normal 18:3, were crossed with C1640 containing the fanfan alleles for low 18:3. Both FanFan and fanfan segregates from the two crosses were evaluated for agronomic traits and linolenic acid in replicated tests over a 2‐yr period on a Chalmers soil (fine‐silty, mixed, mesic Typic Haplaquoll) at the Purdue University Agronomy Research Center near West Lafayette, IN. The fanfan segregates in the Century × C1640 cross averaged slightly higher in seed yield and taller in plant height than the FanFans egregates. In the Harper × C1640 cross, fanfan segregates averaged 1 d later in maturity than FanFan segregates. Mean values for FanFan and fanfan segregates for other traits in both crosses were essentially the same. These data indicate that there are no associations between the fanfan alleles and those agronomic traits needed in commercial soybean cultivars with low levels of linolenic acid. Apparently the low yield of C1640 is controlled by genetic changes independent of the mutation for low 18:3. Regression of linolenic acid level on maturity dates for both FanFan and fanfan segregates in the Harper × C1640 cross show that segregates of both genotypes tended to have increased linolenic acid at later maturity dates. This could be attributed to the cooler temperatures during seed maturation to which the later maturing segregates were exposed.

Effect of Inoculant Rate on Nodulation and Various Agronomic Traits of Soybean

In a soil lacking indigenous Bradyrhizobium japonicum, soybean (Glycine max [L.] Merr.) nodulation depends upon the number of rhizobia applied with the inoculum. This field study reports the effect of different rates of applied rhizobia on nodulation, dry matter and nitrogen content in soybean in a Mediterranean soil lacking B. japonicum. Treatments included six rates of B. japonicum, ranging from 2.5 × 104 to 6.075 × 106 rhizobia cells per seed applied to the seed as peat inoculant at planting, 100 kg N ha−1 and an uninoculated control. The experiment was conducted in an Entisol soil. Regression analysis showed linear relationship between the rate of applied rhizobia and the number of the nodules per plant or the dry weight per nodule. In early stages of development (32 and 68 days after planting) plant dry weight was not affected by inoculation rate. At harvest a rate of 7.5 × 104 rhizobia cells per seed was necessary for maximum total and stover dry weight. A higher rate, 6.75 × 105 rhizobia cells per seed, was required to obtain maximum grain yield, total N content in plant tops and grain N content. Grain percentage N was increased up to 2.025 × 106 rhizobia cells per seed. Nitrogen application increased grain yield, total N content and grain N content at the same level as the lower inoculation rate.

Effect of Early and Late Flowering on Agronomic Traits of Soybean at Different Planting Dates1

Double‐cropping soybean [Glycine max (L.) Merr.] after a winter small grain crop often forces planting to be delayed beyond the date when maximum yield, plant height, and vegetative mass can be attained. The objective of this study was to evaluate soybean plant introduction (PI) lines selected for differing flowering dates, but with a constant maturity, for differences in vegetative size and yield reduction due to delayed planting. Two groups, each consisting of 12 PI lines, were compared in the field at Lexington, KY for 3 yr (1982–1984) in early (15 May) and late (21 June) planting on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) soil. The early flowering group (group EF) flowered 10 days and matured 1 day earlier than the late flowering group (group LF). Group LF was taller with more nodes at Rl, R4, and R7 in both planting dates. The flowering and pod initiation (R1–R4) and seed filling (R4–R7) periods were shorter in group LF than in group EF. Yields averaged over all 3 yr were 1510, 1520, 1370, and 1380 kg ha−1 for group EF early planting, group LF early planting, group EF late planting, and group LF late planting, respectively. Both groups showed a 9% decrease in yield due to delayed planting. The planting date effect was highly significant, while the group effect and the planting date ✕ group interaction were nonsignificant for yield. In 1983 and 1984, group LF had smaller yield reductions in delayed plantings than group EF (6 and 17% reductions for each group, respectively). Although the planting date ✕ flowering group interaction for yield was highly significant in 1983 and 1984, group LF did not yield significantly more in late plantings. In 1982, the two groups did not differ in yield in late plantings. Thus, in this sample of soybean Pis, delayed flowering increased height and vegetative size but did not provide a yield benefit in late plantings.