bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of Ergoline Alkaloids during In Vitro Ruminal Digestion of Tall Fescue Forage
Authors: Moyer Joseph L. , Hill Nicholas S. , Martin Scott A. , Agee Christopher S.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) is an important forage grass in the USA, but most is infected with an endophytic fungus, Acremonium coenophialum Morgan‐Jones & W. Gams. The endophyte mediates production of ergopeptine alkaloids, the compounds implicated in fescue toxicosis of cattle (Bos taurus L.). Alteration of pyrrolizidine alkaloids has been demonstrated in the rumen, but the fate of ergoline alkaloids associated with tall fescue remains to be investigated. This experiment was performed to gain information as to the extent and rate of in vitro ruminal degradation of such alkaloids. Endogenous ergovaline (EV) and exogenous ergonovine (EN) were measured in fractions of the digest using HPLC. Soluble (SOL) and insoluble (INSOL) fractions before (0 h) and after 6, 12, 24, 48 h of in vitro tall rescue forage digestion were lyophilized, extracted, and assayed. Most (> 72%) of the EN measured in the digest was found in the SOL fraction, where it declined in concentration to 35% of the initial 1105 µg kg−1 in 24 h, but decreased little thereafter. Ergonovine in the INSOL fraction declined linearly throughout the incubation period, such that only 5% of the initial concentration was present after 48 h. Endogenous EV concentration in the SOL fraction declined linearly from 272 to 32 µg kg−1 during the 48‐h incubation. The concentration of EV in the remaining dry weight of the INSOL fraction exhibited an apparent increase, possibly because EV was sequestered in fungal or plant cell walls. Thus, both alkaloids studied were susceptible to ruminal degradation when exposed to the liquid phase. Application of these results depends on the location of the primary site of ergoline alkaloid absorption.
Epistasis of rj1 Nonnodulation of Soybean to Nodulation by Sinorhizobium fredii
Authors: Rasooly Avraham , Isleib T. G.
Published: July 2010

Utilization of highly efficient N‐fixing, improved strains of Bradyrhizobium japonicum in soybean [Glycine max (L.) Merr.] inoculants has been hampered because these strains cannot compete in the rhizospbere with indigenous strains. Development of host genotypes that selectively nodulate with introduced strains could improve the field response of soybean to inoculation. Our objective was to determine whether Sinorhizobium fredii USDA 205 could overcome the nodulation block in soybean plants homozygous for the rj1 gene. The rj1 gene produces a nonnondulating phenotype with most strains of B.japonicum. ‘Peking’ is homozygous for the recessive allele conferring the ability to nodulate with S. fredii. Peking was crossed with an isoline of ‘Harosoy’ bearing rj1. We identified F2 plants homozygous for the recessive allele for S. fredii nodulation by selecting for the ability to form nodules with S. fredii. F3 progeny of these F2 selections segregated for the ability to nodulate with B. japonicum 110, indicating segregation for rj1. The results indicate that the two traits are controlled by different loci that are not tightly linked. In a separate test, F2 plants homozygous for rj1 were selected and allowed to self. Ten seeds from each of four F2 rj1 plants were inoculated with S. fredii, but none formed nodules, showing that rj1 nonnodulation is epistatic to nodulatlon by S. fredii. We surmise that rj1 cannot be used in conjunction with an S. fredii inoculum to overcome the problem of bacterial competition for nodule occupancy.
Fructan and Sugars in 273 Oat Accessions
Authors: Livingston David P. , Elwinger Gerald F. , Weaver Joan C.
Published: July 2010

Oat (Avena sativa L.) reportedly accumulates less fructan during hardening than other winter cereals. Little is known about the variability for fructan concentration after hardening in the genus Avena, however. To investigate genetic variability, fructan was measured in 273 oat accessions grown under controlled conditions. Dicktoo barley (Hordeum vulgare L.) was included as a high degree of polymerization (DP) fructan check. After 3 wk of hardening, plant stems (1 cm above the crown) were ground and extracted with water. Carbohydrates were separated by high performance liquid chromatography (HPLC) and quantified by comparison of peak areas in known standards to that in unknowns. On a fresh weight basis more than half the accessions had total fructan (DP > 2) levels not significantly (P < 0.05) different from Dicktoo barley, however, all but one accession had less (P < 0.05) high DP fructan (DP > 4) than Dicktoo. Based on percentages of five carbohydrates, the accessions were grouped into eight clusters. One of the five species analyzed was alone in a cluster; the remaining species were spread across several clusters. Genetic variability for fructan concentration is apparently high enough in the accessions analyzed in this study to permit more detailed physiological studies with fewer accessions with a wide range of fructan content.
Inheritance of Resistance to Mexican Bean Weevil in Common Bean, Determined by Bioassay and Biochemical Tests
Authors: Kornegay Julia , Cardona Cesar , Posso Carmen E.
Published: July 2010

Arcelin, a seed protein discovered in wild Phaseolus vulgaris L. accessions, gives high levels of resistance to the Mexican Bean Weevil [MBW; Zabrotes subfasciatus (Boheman)]. Five arcelin variants have been described. To better understand the genetic control of arcelin and MBW resistance, an inheritance study was conducted. Bioassay tests for insect response, and biochemical lasts to detect the presence‐absence of arcelin, were performed on the same individual seed. Accessions G12952 (arc‐4) and G02771 (arc‐5) had the highest level of resistance to MBW with no adults emerging from infested seed. Resistance was also found in G12882 (arc‐1) and G12866 (arc‐2), while G12922 (arc‐3) and the commercial cultivar, Pijao, were susceptible to the insect. The genetic study confirmed that all arcelin variants were inherited as a single dominant gene based on biochemical evaluations for presence‐absence of arcelin. Nevertheless, in bioassay tests with MBW, only crosses with arc‐1 and arc‐5 showed a single, completely dominant gene mode of inheritance, with the presence of arcelin being highly associated with resistance to the insect. For arc‐1 and arc‐5, biochemical tests can be reliably used to select for MBW resistance. For arc‐2, a combination of biochemical and bioassay tests is needed. As arc‐4 segregated few resistant individuals, and arc‐3 gave only intermediate to susceptible offspring, the use of these two arcelin variants is not recommended in a routine resistance breeding program. Electrophoretic patterns and bioassay tests of F1 and F2 generations showed that arc‐5 and arc‐1 variants are inherited as a single unit and are codominant.
Barley Yellow Dwarf Virus Resistance in a Wheat × Wheatgrass Population
Authors: Goulart Luiz R. , Mackenzie Sally A. , Ohm Herbert W. , Lister Richard M.
Published: July 2010

The barley yellow dwarf viruses (BYDVs) constitute an important group of plant viruses of cultivated cereal crops in which only tolerance and/or low levels of resistance are known. High levels of resistance, which we here define as low concentrations of virus in plant tissues, have been discovered in Thinopyrum spp. (formerly. Agropyron). In this study we have characterized such resistance in BC2 and BC3 populations, derived by crossing cultivated wheat (Triticum aestivum L. emend. Thell.) with Th. ponticum (Podp.) Barkw. & D.R. Dewey Agropyron elongatum [Syn (Host) P. Beauv.] and backcrossing to wheat. The objectives were to evaluate the levels of resistance genetically transferable to wheat lines using both enzyme‐linked immunosorbent assay (ELISA) and cDNA dot‐blot hybridization for the detection of low levels of virus in plant tissues. Uniformity in results using both techniques depends on procedural uniformity, but a high correlation (0.93) between ELISA values and densitometry scans was obtained. A range in resistance was observed among the BC2 and BC3 populations from highly resistant to moderately resistant to susceptible. Lines classified as resistant had densitometry absorbance values of 0.25 to 0.60 and ELISA values from 0.03 to 0.30. The low values for both ELISA and dot‐blot assays indicate that significant resistance can be maintained in more advanced generations. Such low virus levels also suggest that inhibition of virus replication or cell to cell movement may occur in resistant Thinopyrum spp.
Chromosome Transmission and Meiotic Stability of Sugarcane (Saccharum spp.) Hybrid Derivatives
Authors: Burner David M. , Legendre Benjamin L.
Published: July 2010

Efficiency of selection in sugarcane (Saccharum spp. hybrids) breeding may be influenced by the type of chromosome transmission. Our objectives were to determine chromosome transmission and meiotic stability among and within sugarcane families derived from crosses of elite, interspecific clones with four S. spontaneum L. clones. The cytological behavior, pollen stainability, and seed yield were measured for 23 nonrecurrent clones in parental, F1, and BC1 to BC3 generations. Chromosome number was determined for 13 recurrent parents. Chromosome transmission was strictly n + n, although meiotic irregularity, aneuploidy, and chromosomal mosaicism resulted in aneuploid gametes. Chromosome number increased quadratically with generations from 2n=60.5 in S. spontaneum parents to 2n=84.0 at F1, 97.5 at BC1, 106.1 at BC2, and 108.0 at BC3. Chromosomes paired primarily as bivalents, although variable numbers of univalents and multivalents were observed. The frequency of trivalents increased linearly with generations, and was greater in hybrid derivatives than in parental S. spontaneum clones. Multivalent pairing indicated that autosyndesis was incomplete. Meiotic irregularities also included multiple nucleoli, anaphase bridges and laggards, asynchronous meiosis, chromosome fragments, pseudobivalents, first and second division restitution nuclei, and syncytes. One clone, ‘CP 33‐224’, was partially desynaptic. Results suggest that sugarcane cultivars and S. spontaneum share a common endosperm balance number unlike S. officinarum L. and S. spontaneum. Transmission by n + n may indicate that additional cycles of random mating among hybrid derivatives, relative to that with 2n + n transmission, may be necessary to recover desirable recombinants in sugarcane populations.
Consistency of Rank Correlations of Peanut Breeding Lines for Market Grade Characteristics and Yield
Authors: Knauft D. A. , Gorbet D. W.
Published: July 2010

The genetic potential of peanut (Arachis hypogaea L.) breeding lines for pod yield can only be determined after testing in several environments. Limited data are published on the influence of the environment on peanut market grade characteristics. The objective of this study was to determine the amount of evaluation needed to rank market‐grade characteristics in peanut. Rank correlations for pod yield, 100‐ seed weight, shelling percentage, and total sound mature kernel (TSMK) proportion were calculated between replications, between harvest dates, and between locations for a range of genotypes in 60 tests. Rank correlations for pod yield between locations ranged from −0.48 to 0.77 and were not significant in more than half the tests. Shelling percentage correlations ranged from 0.69 to 0.96 and 100‐seed weight correlations ranged from 0.78 to 0.98 and were all highly significant. The TSMK correlations were less frequently significant and ranged from 0.39 to 0.90. Similar observations were made between replications and between harvest dates. Thus, relative genotypic expression in peanut for seed weight and shelling percentage is consistent in different environments. Decisions to discard or retain peanut lines in a breeding program may be based on acceptable seed size or shelling percentage after limited testing.
F2 Hybrids of Host Plant Germplasm and Cotton Cultivars: II. Heterosis and Combining Ability for Fiber Properties
Authors: Tang Bing , Jenkins Johnie N. , McCarty J. C. , Watson C. E.
Published: July 2010

Estimates of combining ability and heterosis for fiber properties among pest‐resistant cotton (Gossypium hirsutum L.) gene pools and cultivars are necessary for efficient F2 hybrid development. Four cultivars were crossed as female with 16 pest‐resistant germplasm lines in a North Carolina Design II to evaluate combining ability and potential heterosis of F2 hybrids for six fiber characteristics. The 20 parents and 64 F2 hybrids were evaluated in four environments at Mississippi State, MS. Environment × hybrids interactions were significant for strength and micronaire, but not for length, uniformity, or elongation. Parent populations generally were more sensitive to the environment than were their F2 hybrids for most characteristics. General combining ability (GCA) effects were more importan than specific combining ability (SCA) effects. Except for 2.5% span length, GCA effects for ‘DES119’ were significant, positive, and consistent for all characteristics. ‘C315’, MHR10 and ‘Deicot 344’ had significant, positive GCA effects for strength, 50% span length and 2.5% span length. In general, fiber traits of F2 hybrids were similar to mid‐parental values. Very few F2 hybrids wre superior in fiber properties to their high parent, but approximately 50% of the F2 hybrids were not significantly different from their high parents for most fiber traits except micronaire. These results are encouraging for the potential of utilizing pest‐resistant germplasms as parents with cuitivars to produce F2 hybrids that combine acceptable yield and fiber properties.
Inheritance of Red‐Buff Seed Coat in Soybean
Authors: Seo Y. W. , Specht J. E. , Graef G. L. , Graybosch R. A.
Published: July 2010

In soybean [Glycine max (L.) Merr.], five loci ((I/i‐K/i‐i/i, R/r‐m/r, T/t, W1/wl, O/o) interact to produce seed coat and/or hilum color phenotypes of gray (G), yellow (Y), black (BI), imperfect black brown (Br), striped brown‐black, red‐brown (Rbr), or buff (Bf). The T/t and Wl/wl loci also condition tawny/gray pubescence and purple/white flowers, respectively. T236, a white‐flowered gray‐pubescence accession in the soybean genetic collection, has an unusual red‐buff (Rbf) seed coat. The genetic relationship of Rbf to the other seed coat colors was not known. To evaluate this relationship, T236 was mated to six soybean lines of known genotype relative to the five loci. F2 individuals were classified as to flower, pubescence, seed coat, and hilum color. In all crosses, only F2 plants with white flowers, gray pubescence, and an R_ genotype produced Rbf seed coats or hila. The F2 segregation ratios were not compatible with an inheritance model for Rbf that invoked allelic segregation at a sixth locus. Indeed, Rbf seed coat seemed to be conditioned by a new allele at the T/t locus, symbolized as t‐r. While there was no perceptible difference in the gray pubescence phenotypes conditioned by the t and t‐r alleles, the t‐r allele was detectable in an R_w1wl genetic background, where the allelic series T/t‐r/t produced the seed coat color phenotypes of B1/Rbf/Bf (in left‐to‐right dominance‐recessiveness order). In all other backgrounds (i.e., R_Wl_, rrWl__, and rrwlwl), the seed coat colors produced by t and t‐r were identical. The currently accepted model for the inheritance of anthocyanidin pigments in the soybean seed coat is that: (i) R is necessary for anthocyanidin production,( ii) T is needed for dihydroxylation of the B‐ring, (iii) Wl is needed for trihydroxylation of the B‐ring. Our postulation that the Rbf seed coat phenotype requires an R_t‐r_wlwl genotype is consistent with this theory. It is also consistent with the report that pelargonidin, a monohydroxylated B‐ring anthocyanidin, is the predominant pigment in the Rbf seed coats of strain T236.
Field Response of Soybean to Increased Dinitrogen Fixation
Authors: Vasilas Bruce L. , Fuhrmann Jeffry J.
Published: July 2010

A number of studies have shown an association between soybean [Glycine max (L.) Merr.] seed yield and plant N accumulation, suggesting that yield could be increased by nodulation by superior strains of Bradyrhizobium japonicum. Attempts to evaluate the response of field‐grown soybean to bradyrhizobia‐mediated increases in N accumulation have been hindered by an inability of introduced strains to compete successfully with indigenous strains. Therefore, to determine the effect of increased N2 fixation on soybean growth and seed yield, an experiment was conducted using soybean seedlings that were nodulated under greenhouse conditions and then transplanted to the field. Two inoculation treatments, USDA 122 and a mixture of bradyrhizobia indigenous to the field site (control), were applied to the seed and seedlings were developed for 21 d in the greenhouse. Prenodulated seedlings were then transplanted to 1.8 m2 field microplots on a Matapeake silt loam (fine‐loamy, mixed, mesic Typic Hapludult) with a most probable number of indigenous bradyrhizobial population of 6.1 × l08 cells kg−1 soil. Relative to the control, nodulation by USDA 122 increased both N2 fixed and total shoot N by a 2‐yr average of 29%. Plants nodulated by USDA 122 also assimilated more soil N. The increase in N2 fixation and total N accumulation occurred prior to, but not during, seedfill. The USDA 122 treatment increased seed yield by an average of 31% (90 g m−2). The yield increase was associated with increases in pod number, seedfill rate, remobilized dry matter, remobilized N, and vegetative biomass.
Agronomic Performance of Sulfonylurea‐Resistant Transgenic Flue‐Cured Tobacco Grown under Field Conditions
Authors: Brandle J. E. , Miki B. L.
Published: July 2010

Field testing of transgenic crops is an essential step towards commercialization. This study was conducted to assess the agronomic performance of herbicide‐resistant transgenic tobacco (Nicotiana tabacum L.) lines relative to untransformed controls and to evaluate their sensitivity to sulfonylurea herbicides in a field situation. Two transgenic flue‐cured tobacco lines harboring the csr1‐1 gene for sulfonylurea resistance were evaluated after application of three rates of two sulfonylurea herbicides [chlorsulfuron (2‐chloro‐N[(4‐methoxy‐6‐methyl‐1,3,5 triazin‐2‐yl) aminocarbonyl]‐benzenesulfonamide) and DPXR9674, a 2:1 mixture of thifensulfuron (methyl‐3‐[[4‐methoxy‐6‐methyll, 3,5‐triazin‐2‐yl aminocarbonyl]aminosulfonyl]‐2‐thiophenecarboxylate) and tribenuron (methyl‐2[[[|4‐methoxy‐6‐methyl‐l,3,5‐triazin‐2‐yl]carbonyl]amino]sulfonyl]benzoate)]. We showed that one of the lines was resistant to 10 g a.i. ha−1 of chlorsulfuron but not to 20 g a.i. ha−1 and that both lines were susceptible to DPX‐R9674. Comparison of transgenics to an untransformed control in the absence of herbicide treatment showed that both transgenics were lower yielding than the controls. This impairment of agronomic performance could be attributed to any of a number of factors. Resistance to chlorsulfuron was adequate, but margins of safety need to be increased before any farm level use of these transgenic lines can be considered. Selection among lines for maximum expression of the transgene and selection or backcrossing to recover the parental phenotype may further improve agronomic performance.
Selection of a Core Collection from the U.S. Germplasm Collection of Peanut
Authors: Holbrook C. Corley , Anderson William F. , Pittman Roy N.
Published: July 2010

The U.S. germplasm collection for peanut, Arachis hypogaea L., consists of 7432 accessions and contains a great amount of genetic diversity. Information on economically important traits does not exist for most accessions due to the time and labor required for evaluation. The development of a core collection for peanut would provide a subset of accessions that are representative of the entire collection and that, could be extensively examined. The objective of this research was to select a core collection for peanut. Data for the U.S. peanut germplasm collection were obtained from the Germplasm Resources Information Network (GRIN). The entire germplasm collection was then stratified by country of origin and by the amount of available morphological data. When information was available for at least four of the same morphological variables for at least 16 accessions from the same country of origin, then the data for these accessions were analyzed using multivariate statistical analysis. Results allowed the accessions to be clustered into groups which, theoretically, are genetically similar. Random sampling was then used to select ≈ 10% from each group. Accessions with inadequate data for multivariate analysis were selected using a 10% random sample from each country of origin. Accessions from countries having few (≤5) entries in the collection were pooled and a 10% random sample was selected. The resulting 831 accessions form a core collection for peanut. Examination of data for six phenotypic traits indicated that the genetic variation expressed for each trait in the entire collection has been preserved in this core collection. This peanut core collection has many potential uses and should increase the utilization of peanut germplasms resources.
Recurrent Selection in Oat: Stability of Yield and Changes in Unselected Traits
Authors: Reysack J. J. , Stuthman D. D. , Stucker R. E.
Published: July 2010

Recurrent selection, primarily for grain yield in oat (Avena sativa L.), has been practiced at a single location for four cycles. Previous evaluations of this program had indicated that grain yield had been increased and that correlated changes, some undesirable, had also occurred. In some studies in other species, yield increases have come at the expense of stable productivity. The objectives of this study were to evaluate the stability of grain yield and to assess changes in nine unselected traits to determine the potential of lines from this program for cultivar development. Grain yield was measured in 23 trials during a 5‐yr period to evaluate gain from selection and compare the average yield stability of the 12 initial parents with that of the 21 fourth cycle parents (lines selected from the third cycle). Seven agronomic and seed quality traits (days to heading, plant height, resistance to lodging, test weight, groat percentage, percentage groat protein, and percentage groat oil) were evaluated in 12 trials to examine correlated response to yield selection. Barley yellow dwarf (BYD) and loose smut reactions were evaluated in inoculated disease nurseries. Gain from four cycles of yield selection ranged from ✕2.0 to 44.6% in the individual environments, and was usually significantly positive. Also, based on regression stability statistics, selection for grain yield increased the ability of the selected materials to respond to more favorable environments. Finally, there were significant correlated responses for all but two of the unselected traits, groat percent and BYD reaction; however, even though most of the changes were undesirable they were relatively small and should not detract from the potential of the fourth cycle parents in a cultivar development program.
Effects of Recurrent Selection for Grain Yield on Oat Kernel Morphology
Authors: De Koeyer D. L. , Stuthman D. D. , Fulcher R. G. , Pomeranke G. J.
Published: July 2010

Kernel size, as it is related to kernel weight, is an important yield component in oat (Avena saliva L.). The main objective of our research was to evaluate the changes in kernel morphology following five cycles of recurrent selection for grain yield. Parents of Cycles 0, 1, 3, and 5 and seven check cultivars were grown in row and hill plots at St. Paul and Rosemount, MM, in 1989. Kernel area, perimeter, length, and width were measured on 100‐kernel samples from each plot using digital image analysis (DIA). Grain yield, kernel weight, and kernel number were also evaluated in these experiments. Grain yield was enhanced by 26.8 and 55.3% following five cycles of recurrent selection as measured in row and hill plots, respectively. Kernel area increased by 9.8 and 10.1% in row and hill plot samples, respectively. Kernel perimeter, length, and width increased by 4.8, 5.7, and 4.6%, respectively, in row plot samples. In hill plot samples, kernel perimeter, length, and width increased by 5.5, 6.8, and 3.7%, respectively. There were no significant difference among cycles for two derived shape factors, FCIRCLE (4 π [kernel area]/[kernel perimeter]2) and kernel width/length ratio. Values for kernel area, perimeter, length, and width from hill plot samples were significantly larger than those from row plots; however, selection responses in the two plot types were quite similar. In this study, environmental influences on kernel morphology were minor. Kernel weight was positively correlated with the two size measurements, kernel area and width. Results from our study indirectly suggest that increased kernel size, and not kernel density, largely accounts for the observed increases in kernel weight. These experiments also demonstrate the utility of DIA in agronomic research.
Genetic Analysis of Resistance to Fusarium solani in Soybean
Authors: Stephens P. A. , Nickell C. D. , Kolb F. L.
Published: July 2010

Sudden death syndrome caused by highly pathogenic strains of Fusarium solani (Mart.) Appel & Wollenw. emend. Snyd. & Hans., can cause severe foliar necrosis and yield reduction in soybean [Glycine max (L.) Merr.]. The soybean cultivar Ripley is resistant to foliar disease symptoms caused by F. solani. To determine the genetic control for F. solani resistance in Ripley, Ripley was crossed reciprocally to Spencer, a cultivar that develops severe foliar chlorosis and necrosis when infected with F. solani. Progeny from these crosses were evaluated in the greenhouse for reaction to F. solani using an infested‐oat inoculation technique. Reaction to F. solani in segregating F2 and F3 generations indicated that the ability for Ripley to resist foliar disease symptoms caused by F. solani is conditioned by a single dominant nuclear gene (Rfs).
Spatial Heterogeneity Affects Variety Trial Interpretation
Authors: Ball Shane T. , Mulla David J. , Konzak Calvin F.
Published: July 2010

Observations in neighboring plots of variety trials are often spatially dependent. This may reduce the utility of applying the classical analysis of variance (ANOVA) due to trends and correlated errors. Identifying the presence, magnitude, and pattern of spatial heterogeneity is useful for assessing the utility of ANOVA. Our objectives were to estimate the effects of spatial heterogeneity on the independence of errors, and appraise a nearest‐neighbor analysis (NNA) to improve the analysis of a variety trial experiment. A semivariogram for organic C at one field site showed a substantial soil spatial dependence and was consistent with the semivariogram for residuals in grain yield. Semivariograms of classical residuals for grain yield had large nugget variances and exhibited spatial structure. Similarly, semivariograms of the nonclassical residuals showed large spatial dependence, accounting for 40 to 80% of the sample variance. Genotype effects were not alwaystatistically significant when the raw data were analyzed using ANOVA. The NNA was used to adjust data for the effects of large‐ and small‐scale spatial dependencies in the variety trial experiment. The ANOVA on NNA‐adjusted data showed highly significant P ≤ 0.01) genotypic effects. The improved analysis also showed reduced error variance (from 57–78%), and dramatically increased 2 values compared with the ANOVA on unadjusted data. The estimates of variance between genotypes from ANOVA on unadjusted data were from 99% smaller to 63% larger than the error variance. On the other hand, the variance component estimates between genotypes from ANOVA on adjusted data ranged from 0 to 300% larger than the error variance. The spatial heterogeneity can have serious effects on the interpretation of variety trials experiments. In general, nonclassical deviations appear more sensitive to the effects of spatial heterogeneity than classical residuals, and are more useful as a test for violations in the classical assumption of spatial independence.
Recurrent Selection for Seed Size in Soybean: III. Indirect Effects on Seed Composition
Authors: Tinius C. N. , Burton J. W. , Carter T. E.
Published: July 2010

In soybean [Glycine max (L.) Merr.], correlations between seed yield and seed composition are often significant, while correlations between seed size (a component of yield) and seed composition are usually low. In addition, selection for changes in seed composition have often resulted in seed yield changes but usually not changes in seed size. The objective of this research was to examine the indirect effects of recurrent selection for increased seed size on protein and oil concentration in a random mating population that segregates for male sterility. The intermating population N79‐1500 was divided into three subpopulations designated SS1, SS2, and SS3. Male‐slerile (MS) plants were selected for large seed size through four cycles in SS1 and SS2 and three cycles in SS3. Parental composites of each cycle were tested at four locations in North Carolina in 1987 and 1988. In MS seeds of SS1 and SS2, the concentration of protein decreased linearly across cycles of selection. Oil concentration increased in MS seeds of SS1. There was no change in protein or oil concentration in MS seeds of SS3. In male‐fertile (MF) seeds, protein decreased and oil increased in SS1 and SS2, while SS3 was unchanged for both constituents. On a weight per seed basis, there was a linear increase in protein and oil concentration of both MS and MF seeds of all three subpopulations. Total protein (protein concentration × seed yield) increased only SS3 while total oil (oil concentration × seed yield) increased in SS2 and SS3. The identification of a subpopulation (SS3), which did not decrease significantly in protein or oil percentage as seed yield increased and therefore increased in total protein, suggests that selection as practiced in this study can be useful to improve these important traits.
Inheritance of Photoperiod Response in Andean and Mesoamerican Common Bean
Authors: Kornegay Julia , White Jeffrey W. , Dominguez Jerson R. , Tejado Gerardo , Cajiao Cesar
Published: July 2010

In the tropics, the majority of common bean (Phaseolus vulgaris L.) landraces are photoperiod sensitive to long daylengths, yet, within certain bean gene pools, significant numbers of photoperiod insensitive cultivars are present. The effect of photoperiod response on common bean adaptation and yield potential in the tropics is not known, nor is the inheritance of photoperiod response well understood. In this study, the inheritance of photoperiod response in common beans was investigated in two environments differing in mean temperature. Five common bean lines from each of two gene pools—Mesoamerican and Andean—were crossed in all combinations within each group. Under 12.3‐h natural and 18‐h artificially extended daylength treatments in field studies at Palmira and Popayan, parental lines, F1 and F2 generations, and random F3 lines (Palmira) were evaluated for days flower (DTF). In a second study, allelism tests were done to determine whether the genes controlling photoperiod‐induced delay of flowering were the same in the Mesoamerican and Andean gent pools. The parental lines in all evaluations showed three distinct responses to long daylengths: day‐neutral, intermediate, and sensitive. At Palmira, under warmer temperatures, photoperiod response was maximized with DTF ranging from 30 to 100 d. At Popayan, under cooler temperatures, photoperiod response was reduced and DTF ranged from 37 to 74 d. Neutral lines flowered about 5 d later at Popayan than at Palmira, while sensitive lines flowered about 12 d earlier. Under both environments, photoperiod sensitivity was inherited as two dominant genes (AABB), while the neutral response was conditioned by recessive epistasis (aabb or aaBB). An intermediate response occurs when the first gene is dominant, but the second gene is recessive (AAbb). All insensitive lines used in these studies were aabb, but the possible existence of insensitive aaBB genotypes is addressed. Crosses between Mesoamerican × Andean genotypes showed that the genes controlling photoperiod response in the two gene pools are the same.
Genetic Improvement in Agronomic and Physiological Traits of Oat Since 1914
Authors: Lynch P. J. , Frey K. J.
Published: July 2010

The breeding of oat (Avena saliva L.) cultivars in the midwestern USA has not resulted in dramatic yield increases for this crop. To determine what changes breeding of oat has brought about in agronomic and physiological traits, nine cultivars and one experimental line of oat released over the past eight decades were tested in 1987 and 1988 at the Iowa State University Agronomy and Agricultural Engineering Research Center, near Antes, IA. Grain yield, test weight, heading date, plant height, biomass, harvest index, accumulation of leaf area, plant dry weight, and crop and relative growth rates were determined. Under favorable growing conditions (1987) plant height (0.3 cm yr−1) and harvest index (0.2% yr−1) were positively correlated with year of cultivar release; under stress conditions (1988) such correlations were observed for grain yield (0.02 Mg ha−1yr−1), test weight (1.0 Mg m−3yr−1), and harvest index (0.3% yr−1) increased with year of cultivar release. No change occurred in either crop or relative growth rate. More recent oat cultivars had a slower rate of postanthesis leaf senescence. It was concluded that oat breeding primarily has improved the ability of oat cultivars to perform in stressful environments.
Freezing Tolerance and Carbohydrate Content of Low‐Temperature‐Acclimated and Nonacclimated Centipedegrass
Authors: Fry J. D. , Lang N. S. , Clifton R. G. P. , Maier F. P.
Published: July 2010

Little is known about environmental and physiological factors affecting centipedegrass [Eremochloa ophiruoides (Munro) Hackell winter survival. Stolons of common and ‘Oklawn’ centipedegrass were sampled from field‐ or growth chamber‐grown turf in three separate experiments to (i) determine freezing tolerance of acclimated and nonacclimated turf; (ii) identify and quantify nonstructural carbohydrates (NSC) in acclimated and nonacclimated turf, and (iii) relate levels to freezing tolerance. Lethal temperatures for common and Oklawn were similar throughout all studies. Freezing tolerance estimated by electrolyte leakage for turf sampled from the field in winter 1988–1989, indicated that lethal temperatures ranged from about −7 to −8 °C in February and March, to −9 °C in December and January. In a 1990–1991 field and growth chamber studies, injury was estimated by stolon recovery growth in the greenhouse after freezing at −2, −4, −6, −8, and −10 °C for 1 h. Lethal temperatures in mid‐winter were −2 °C lower than in fall or spring during active growth. In stolons, starch and sucrose were the primary NSC ranging from ≈2 to 13 mg (100 rag)−1 dry weight. Sucrose was higher in acclimated than pre‐ or post‐acclimated turf. In a growth chamber study, 47% more sucrose was present in acclimated vs. preacclimated turf. Sixty‐nine percent more acclimated stolons survived −4 °C than preacclimated stolons, and a positive correlation (r = 0.78) was observed between sucrose level and number of surviving stolons. Higher sucrose concentrations in low‐temperature‐acclimated vs. nonacclimated common centipedegrass stolons may be a component of improved freezing tolerance.
Weed Management and Tall Fescue Quality as Influenced by Mowing, Nitrogen, and Herbicides
Authors: Dernoeden P. H. , Carroll M. J. , Krouse J. M.
Published: July 2010

A 3‐yr field study was conducted to determine the influence of N level (98 and 196 kg ha−1 yr−1), mowing height (3.2,5.5, and 8.8 cm), and three herbicides on weed encroachment and overall quality of tall fescue Festuca arundinacea Schreb. cv. Rebel II. The major objective of this study was to identify cultural methods of excluding weed development in tall fescue. Dithiopyr [3,5‐pyridinedicarbothioic acid, 2‐(difluoromethyl)‐4‐(2‐metbylpropyl)‐6‐(trifluoromethyl)‐S,S‐dimethylester] and pendimethalin [N‐(l‐ethylpropyl)‐3, 4‐dimethyl‐2,6‐dinitrobenzenamine] were applied preemergence for smooth crabgrass [Digitaria ischaemum (Schreber) Schreber ex Muhlenb.] control, and fenoxaprop [(±)‐2‐[4‐[(6‐chloro‐2‐benzoxazolyl)oxy]‐ phenoxylpropanoic acid] was applied postemergence for crabgrass control. Rates of dithiopyr and pendimethalin were reduced or eliminated on selected plots in the last 2 yr of the study to determine if reduced herbicide inputs would continue to provide effective crabgrass control. Tall fescue mowed at 8.8 cm resisted smooth crabgrass invasion, exhibited best visual summer turf quality in 1990 and 1991, had poorest winter turf quality, and had highest white clover (Trifotium repens L.) populations. Other environmental factors and lower mowing height (3.2 or 5.5 cm) reduced summer turf quality in 1990 and 1991. High N improved fall and winter turf quality, but not summer quality. Nonherbicide‐treated plots receiving high N had less smooth crabgrass than low N plots, but high N provided no additional crabgrass reduction in herbicide‐treated plots. High mowing (8.8 cm) was the best cultural management strategy for reducing smooth crabgrass encroachment and maintaining tall fescue cover. Results indicated that smooth crabgrass control with label use rates of herbicides was warranted when mowing tall fescue at 3.2 or 5.5 cm.
Forage and Grain Yields of Wheat and Triticale as Affected by Forage Management Practices
Authors: Miller G. L. , Joost R. E. , Harrison S. A.
Published: July 2010

Most research on the effects of grazing cereal grains has been conducted on hard red winter wheat (Triticum aestivum L.) and little information exists concerning the influence of forage harvest on the subsequent grain yield of other cereal crops. The objectives of this study were to evaluate the effects of forage harvest management on subsequent grain yields of triticale (× Triticosecale Wittmack) and wheat to determine the growth stage for cessation of forage harvest to optimize grain and forage production. The effect of defoliation until Feekes Growth Stage (GS) 5.0, 6.5, or 8.0 on forage production and grain yield components of ‘Terral 817’ wheat, ‘Jenkins’ triticale, and ‘Morrison’ triticale was investigated for two growing seasons at Baton Rouge, LA. Plots harvested up to GS 8.0 produced the greatest forage yield both years. There were no significant differences in mean grain yield of the three cultivars between undipped check plots and plots harvested until GS 5.0 either year. A favorable combination of forage and grain yields in 1987–1988 was achieved if the final forage harvest was made at GS 5.0, but the highest yield combination in 1988–1989 was produced by continuing forage harvest until GS 8.0. Clipping significantly reduced lodging and disease incidence during the 1988– 1989 growing season. Defoliation until GS 8.0 resulted in reductions in number of stems m−2, number of spikelets per head, and weight per seed by 37, 11, and 18%, respectively, resulting in a grain yield reduction of 44% compared with the undefoliated plants. Forage utilization should be terminated by the first node stage to minimize grain yield reductions due to tiller mortality, shortened heads, and poor kernel fill.
Use of Morphological, Developmental, and Plant Nitrogen Traits in a Selection Scheme in Soybean
Authors: Zeinali‐khanghah H. , Green D. E. , Shibles R. M.
Published: July 2010

A 3‐yr study was conducted to determine the response in seed yield from a tandem selection scheme in which the first step was to select desirable lines from each of two single‐cross populations of soybean [Glycine max (L.) Mew.] for morphological and developmental traits, by using independent culling. The second step was to select for greater plant N content at the R5 developmental stage. The genetic material was 213 F6‐derived indeterminate lines from three maturity groups (79 lines early, 93 medium, and 41 late) from a single‐cross population (IX139) and 102 lines from three different stem‐termination types (28 determinate lines, 40 semideterminate, and 34 indeterminate) from different cross (IX149). Yield increase from the first part of the selection scheme was 2.2% in the early, 1.8% in the medium, and 5.5% in the late maturity groups of IX139, with a mean of 3.2%. Selection for morphological and developmental traits decreased seed yield by 4.4% in the determinate group of IX149 and increased the seed yield in the semideterminate and indeterminate groups of IX149 by 1.0 and 4.7%, respectively. In the second portion of the tandem selection scheme, selection for greater plant N content at R5 decreased seed yield by an average of 0.06% across the maturity groups of IX139 and increased the yield by an average of 1.1% across the three stem‐termination types of IX149. The average yield increase across the groups, locations, and years was 0.5%. In assessing the overall response to tandem selection in all groups within IX139 and IX149, most groups responded positively, but the determinates decreased in seed yield by 3.8%. Plant N content at the R5 stage, because of its poor association with seed yield and the inconsistent seed‐yield response to selection, did not seem to play a significant role in determining the final yield of F6‐derived lines of soybean.
Inbreeding and Yield Prediction in Synthetic Cultivars of Maize: II. Alternative Methods
Authors: Márquez‐Sánchez Fidel
Published: July 2010

The first generation (Syn‐l) of synthetic cultivar is obtained by making the possible crosses among the components or parental inbred lines (Syn‐0). The second generation (Syn‐2) is the result of randomly mating Syn‐l. When the number of inbred lines is large, it is difficult to make the total number of possible crosses. Thus, in order to facilitate the hand pollination work, a smaller number of crosses among the inbred lines is desired. The yield of a synthetic cultivar depends on its inbreeding coefficient. Therefore, for an alternative method of obtaining Syn‐I to be valid, the inbreeding coefficient of its Syn‐2 has to be equal to the inbreeding coefficient of the synthetic obtained by the conventional method, in which all possible crosses are made. In this paper the inbreeding coefficient of Syn‐2 is calculated for five alternative methods of crossing to obtain Syn‐l. Results show that the inbreeding coefficient of Syn‐2 is the same for the five methods as long as each component line has the same chance of contributing to Syn‐l. In practice, choosing the method will depend on the purpose of the synthetic, the number of lines, the availability of skilled hand labor to make pollinations, and whether there is an even number of lines. It is shown that with any of the methods yield of Syn‐2 is always the same.
Variation in Seed Protein among Nodes of Normal‐ and High‐Protein Soybean Genotypes
Authors: Escalante Eduardo E. , Wilcox James R.
Published: July 2010

Current analytical techniques permit the determination of protein, nondestructively on 20‐ to 25‐seed samples, or destructively on individual seeds of soybean [Glycine max (L.) Merr.]. When these small seed samples are analyzed, within‐plant variability in seed protein may affect accuracy of single plant protein values. Objectives of this study were to: (i) determine variability in seed protein among nodes of normal‐ and high‐protein genotypes, and (ii) determine variability in protein of seeds from different positions within pods. Seeds from a single pod at all fruiting nodes and from three positions within pods of normal‐ and high‐protein genotypes were analyzed for protein content in each of 2 yr. Seed protein content increased linearly from the 6th, lowest fruiting node, to the 17th, highest fruiting node, of both normal‐ and high‐protein strains. The range in seed protein across nodes averaged 344 to 432 g kg−1 for normal and 420 to 509 g kg−1 for high‐protein genotypes. No differences were detected in protein content among seeds within pods for any strain. The data demonstrate that analyses of seed samples representative of the entire plant are essential to accurately determine seed protein of individual plants. Although non‐destructive analyses of 20‐seed samples is possible, we recommend non‐destructive analyses of all seeds from an individual plant to determine seed protein on a single‐plant basis.
Changes in Yield and Seed Growth Traits in Soybean Cultivars Released in the Southern USA from 1945 to 1983
Authors: Salado‐Navarro L. R. , Sinclair T. R. , Hinson K.
Published: July 2010

The successive release of new cuitivars over time implies that crop yield, and perhaps the physiological traits which influence it, have been improved or altered. For soybean [Glycine max (L.) Merr] cultivars released in the southern USA, there is little information on the impact of cultivar improvement on physiological traits. The objectives of our studies were to (i) estimate the genetic change in seed yield relative to year of cultivar release for a set of cultivars released over nearly a 40‐yr period, and (ii) assess what concomitant changes occurred in the above‐ground biomass at the beginning of seed growth, dates of reproductive stage R5 (beginning seed‐fill) and R7 (physiological maturity), final harvest index, dry matter allocation during seed growth, and seed filling duration. Eighteen determinate soybean cultivars of Maturity Groups (MG) VI through VIII released in USA from 1945 to 1983 were field tested in eight environments, four in Florida and four in Argentina. Annual rates of genetic gain in seed yield were significant and positive in only two U.S. environments (1.59 and 1.87 g m−2 yr−1). The newest cultivars exhibited superior yields over the oldest cultivars only within MG VII and VIII, when the analysis included all four USA environments. In Argentina, no increase in yield was observed in relation to year of cultivar release, even in an environment where the mean seed yield exceeded 4000kg ha−1, which was 73% higher than the best USA trial. In fact, some of the oldest released cultivars were found to have the highest yields in the Argentina environments. None of the physiological traits measured at the USA locations were found to change appreciably with year of cultivar release. In fact, seed yield within and across environments was not found to be consistently associated with any of the measured seed growth traits. Seemingly, a number of alternatives for combining seed growth traits have been used in the succession of released soybean cultivars.