bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Regulation of Linolenic Acid Concentration in Rapeseed1
Authors: Diepenbrock Wulf , Wilson Richard F.
Published: July 2010

Rapeseed (Brassica napus L.) contains a relatively high level of linolenic acid. The flavor and nutritional quality of rapeseed oil could be improved by reducing linolenic acid content through plant breeding. Therefore, a study was conducted to show whether genetic regulation of linolenic acid concentration in two rapeseed mutants, M43 and M364, was determined by the genotype of the embryo, maternal influence, or cytoplasmic factors. Reciprocal crosses were made between the mutants. The reciprocal F1 plants and the mutants were mated in all possible two‐way combinations. The concentration of linolenic acid was measured in triacylglycerol and monogalactosyl diacylglycerol from F1 seed. These glycerolipids were synthesized by different pathways and accounted for 95% of the linolenic acid in the rapeseed mutants. It was found that the concentration of linolenic acid in triacylglycerol was determined by nuclear and cytoplasmic gene interaction, whereas linolenic acid in monogalactosyl diacylglyceroi was determined by cytoplasmic factors. Therefore, it appeared that at least two different genetic mechanisms governed linolenic acid synthesis in these seed. Although the control of linolenic acid synthesis may be complex, a more complete understanding of the genetics of this trait should aid the development of improved cultivars with low levels of linolenic acid.
Effects of Chilling on Photosynthetic Capacity, and Leaf Carbohydrate and Nitrogen Status of Soybean1
Authors: Purcell L. C. , Ashley D. A. , Boerma H. R.
Published: July 2010

When soybean [Glycine max (L.) Merr.] is exposed to cool temperatures (5 to 10°C) during late reproductive development, photosynthetic rates and duration are decreased. This limits the amount of available assimilate, shortens the seed‐fill period, and potentially decreases yield. Greenhouse experiments were conducted to describe the photosynthetic, leaf carbohydrate, and leaf N responses of three soybean cultivars (Cobb, Davis, Tracy) exposed to cool temperature treatments (5 to 7°C) at the flowering (R2) or full seed (R6) stage of development. Plant photosyntheticapacity (PPC) and leaf photosynthetic capacity (LPC), expressed as a percentage of control, were measured before treatments began (Day 1) and each day thereafter through Day 5. Cooling the entire plant one night dropped PPC nearly 100% on the following day (Day 2) and the drop in LPC ranged from 60 to 80% at R2 and from 80 to 100%. at R6. Relatively low PPC and LPC rates were maintained until the day following one night of recovery at 19°C. Cooling the entire plant had a greater effect on photosynthesis than cooling only the roots. The decrease in photosynthesis was associated with a chill‐induced water stress that was moderate to severe when the entire plant was cooled, and slight to moderate when only the roots were cooled. At R2, all cultivars recovered more than 90% PPC by Day 5, whereas at R6, Cobb and Tracy recovered about 80% PPC and Davis about 70% PPC. The latter responses imply genotypic differences in chilling stress responses. Plant recovery from chilling did not appear to be associated with carbohydrate level. The greater photosynthesis recovery of plants cooled at R2 than at R6 appeared to be related to a conservation of leaf N at R2, and a decrease in leaf N at R6.
Effect of Early and Late Flowering on Agronomic Traits of Soybean at Different Planting Dates1
Authors: Pfeiffer T. W. , Pilcher D.
Published: July 2010

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.
Tolerance of Weed Competition Associated with High Leaf‐Area Expansion Rate in Tall Fescue1
Authors: Forcella F.
Published: July 2010

Crop traits that confer competitive ability and/or tolerance to interference by weeds have not been documented well. Such documentation requires comparisons of competitive abilities of isogenic lines of crop cultivars. To determine the value of leaf‐area expansion (LAE) rates as a competitive trait, two near‐isogenic lines of tall rescue (Festuca arundinacea Schreb.) with high and low LAE rates were grown in pots in monoculture and in mixture with velvetleaf (Abutilon theophrasti Medik.) in a greenhouse. In monoculture, shoot dry matter production of the two genotypes was equal. However, when competing with velvetleaf, the high‐LAE genotype produced 38 to 73% more dry matter (in two experiments) than the low‐LAE genotype. Furthermore, velvetleaf growth was suppressed 14 to 24% (in two experiments) when grown with the high‐LAE genotype than when grown with the low‐LAE genotype. Thus, high‐LAE rate confers weed tolerance and competitive ability to tall rescue. This trait also maybe a valuable inclusion to breeding programs for other crops that currently suffer from weed interference.
Interrelationships among Three Major Loci Controlling Heading Date of Spring Barley when Grown under Short Daylengths1
Authors: Gallagher L. W. , Belhadri M. , Zahour A.
Published: July 2010

Early maturing cultivars of barley (Hordeum vulgare L.) would enhance yield stability in lowland, low rainfall areas of Morocco. The objective of this work was to study the inheritance of heading date in crosses involving six spring barleys developed in the Sacramento Valley of California, USA and the Yaqui Valley of Sonora, Mexico. Data were gathered under short daylengths at 32° 15′ N Lat with December sowing in Morocco. Frequency distributions of parental, F1, F2, and backcross generations indicated a three‐locus model with recessive and duplicate dominant epistasis accounting for most of the phenotypic variability. Recessive gene interaction resulted in plants that were about 19 to 35 days earlier than later counterparts with the dominant allele present. Among the later genotypes, the presence of a dominant allele at either of the duplicate loci in the genotypes not homozygous for extreme earliness resulted in increased earliness of 5 to 14 days over the duplicate double recessive depending upon modifiers. A genotype for each parent was suggested; however, the three‐locus model did not account for the 4‐ to 6‐day differences between two pairs of parents. Apparently, modifying loci or different alleles were present in some parents.
Morphological Changes Associated with Three Cycles of Recurrent Selection for Grain Yield Improvement in Oat1
Authors: Bregitzer P. P. , Stuthman D. D. , McGraw R. L. , Payne T. S.
Published: July 2010

To assess the potential for improving grain yield via indirect morphological trait selection, the original and third cycle parents from a recurrent selection program for grain yield in oat (Avena sativa L.) were compared. Evaluation was based on hill plots grown in three field environments. This selection increased grain yield 13.5% and total dry matter 15.9%; thus, there was no increase in harvest index. All morphological structures measured increased in size. Grain yield was not closely or consistently related to any individual morphological trait, nor to the photosynthetic area of the flag leaf and panicle. Analysis of allometric relationships (the size of one plant structure relative to another) indicated that the size of morphological structures within a genotype tended to be proportional, but variability in allometric relationships was present. Therefore, selection for altered allometric relationships may be successful, but construction of an ideotype based on certain levels of expression of individual morphological traits, or photosynthetic areas, is not likely to be effective in increasing grain yield.
Genotype ✕ Environment Interaction and Stability Analysis of Protein and Oil in Grain Sorghum1
Authors: Saeed Mohammad , Francis C. A. , Rajewski J. F. , Maranville J. W.
Published: July 2010

Testing newly developed cultivars in different environments is important for evaluating stability of performance and range of adaptation. The objective of this study was to determine genotype ✕ environment (GE) interaction and stability of grain sorghum [Sorghum bicolor (L.) Moench] hybrids and lines for protein and oil, and effect of different environments on association of yield traits with protein and oil. Forty‐six hybrids and five lines of sorghum were evaluated at five locations across Nebraska and Kansas in 1978 and 1979. Hybrids and lines showed significant interaction with environments. The relative magnitudes of interaction variance components viz., genotype ✕ year (), genotype ✕ location (), and genotype year ✕ location () indicated that the relative performance of genotypes (hybrids and lines) for protein was more inconsistent across years than across locations. The opposite was true for oil. The results of stability analyses revealed that most of the high‐protein and highoil hybrids were more responsive to less favorable environments. Lines generally were more responsive to less favorablenvironments for protein and to more favorable environments for oil. The proteinyield correlation varied among environments. At three locations, this correlation was significantly negative, but at another location characterized as a low yielding environment with slow accumulation of growing degree days and delayed maturity, correlation of protein with yield, seed number, and seed weight was significantly positive. The oil‐yield relationship was positive at three locations. The results suggest that stability of high‐protein and high‐oil sorghum genotypes should be considered in breeding programs. Concurrent selection for high‐protein and high‐yield genotypes may be possible in less favorable environments where full yield potential of sorghum genotypes is generally not attained.
Yield Improvement in a Soybean Population by Utilizing Alternative Strategies of Recurrent Selection1
Authors: Piper Todd E. , Fehr Walter R.
Published: July 2010

Maximum genetic gain from recurrent selection requires an efficient and effective strategy for selection of superior individuals from a population and intermating these selections to form a new population. This research was conducted to compare genetic response to alternative strategies of recurrent selection for seed yield in soybean [Glycine max (L.) Merr.]. Four strategies initiated in the AP6 soybean population represented a factorial arrangement of one or two stages of replicated yield testing before selection of superior F4‐derived or S2‐derived lines and one or three generations of intermating between cycles. A fifth strategy, representing a conventional breeding program, was initiated in a population formed by sampling the first of three generations of intermating used to synthesize AP6. The conventional breeding strategy utilized a two‐stage yield test of F4‐derived lines obtained from a limited number of single crosses each cycle. The response to selection was determined by evaluating composites of the parents of each cycle at three locations during 2 yr. The number of cycles completed for the strategies varied from two to five. The average genetic gain per cycle was 9.6 ± 1.1 g m−2 for the conventional breeding strategy, 6.0 ± 1.1 g m−2 for the twostage test and one intermating, 5.5 ± 1.8 g m−2 for the two‐stage test and three intermatings, 1.8 ± 0.6 g m−2 for the one‐stage test and one intermating, and 0.3 ± 1.1 g m−2 for the one‐stage test and three intermatings. The ranking of the five strategies for genetic gain per year was the same as for genetic gain per cycle. The results indicated that multiple generations of intermating did not enhance genetic gain and that the two‐stage test, as conducted in this study, was superior to the one‐stage test for yield improvement.
Genetics of Field Resistance of Rice to Brown Planthopper1
Authors: Velusamy R. , Heinrichs E. A. , Khush G. S.
Published: July 2010

The brown planthopper [Nilaparvata lugens (Stal)] is one of the most serious insect pests of rice (Oryza sativa L.) in South and Southeast Asia. Because cultivars with vertical resistance to brown planthopper have “broken down” due to brown planthopper biotype selection, field resistant cultivars with horizontal resistance are being evaluated. The inheritance of field resistance to brown planthopper in two traditional rice cultivars, ‘Utri Rajapan’ and ‘Triveni’, was investigated. Twenty‐day old seedlings were infested with second and third‐instar brown planthopper nymphs. Reactions of F1, F2, and F3 populations from the crosses of resistant cultivars with the susceptible parent ‘TN1’ revealed that two independently segregating recessive genes govern resistance in both cultivars. Allelism tests revealed that the two cultivars have the same genes for resistance.
Seed Yield of Soybean Bulk Populations Grown for 10 to 18 Years in Two Environments1
Authors: Degago Yohannes , Caviness C. E.
Published: July 2010

The bulk method of plant breeding has been used extensively by breeders working with various self‐ and cross‐pollinated plant species, but the value of this breeding technique as a means of improving gene frequency for seed yield is not well‐documented in soybean [Glycine max (L.) Merr.]. The objective of this research was to determine the effect of two diverse locations, where bulk populations had been grown for 10 to 18 yr, on seed yield. Seed of these bulk populations were harvested in 1981 and evaluated for seed yield in 1982 and 1983 at the two locations (Rohwer and Marianna, AR), where the bulks were developed and at a neutral location (Stuttgart, AR). The soil series at the three locations are: Rohwer—Perry clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquepts); Marianna—Loring silty loam (fine‐silty, mixed, thermic Typic Fragiodalfs); and Stuttgart—Crowley silty loam (fine, montmoriilonitic, thermic Typic Albaqualfs). Three of the four bulks developed at Rohwer produced significantly higher seed yields at this location than the same bulks developed at Marianna. The bulk population that did not show a yield increase was derived from parents that are resistant to Phytophthora rot (caused by Phytophthora megasperma Drechs. p. glycinea Kuan and Erwin), whereas the other bulks contained segregates that were resistant and susceptible to this disease. Seed yields at Marianna and Stuttgart were not significantly different for the two seed sources of the bulk populations, although there was a trend for the bulk populations developed at Rohwer to produce slightly higher yields at Stuttgarthan those developed at Marianna. Damage from Phytophthora rot was evident each year the bulks were grown at Rohwer, whereas damage from this disease was not observed at Marianna during the development of the bulk populations. Greenhouse tests also indicated there was a significantly greater number of plants resistant to Phytophthora rot in the Rohwer seed source than in the seed source of the bulks developed at Marianna. These results indicate that the bulk method of breeding for soybean is moreffective where there is constant year‐to‐year selection pressure from a disease or other stress factors.
Inheritance of Resistance to Race 3 Downy Mildew in Sunflower1
Authors: Miller J. F. , Gulya T. J.
Published: July 2010

Lines of sunflower (Helianthus annuus L.) resistant to race 3 of downy mildew, incited by Plasmopara halstedii (Farl.) Berl. et de Toni, were developed and inheritance of this resistance was determined. The same single, dominant gene controlled resistance in selections developed from two open‐pollinated sources, ‘Novinka’ and ‘Progress’, in crosses with the breeding lines, HA 89 and RHA 274. This gene did not impart resistance to race 2. A breeding line, RF‐S11‐5566‐74‐10, obtained from Romania was reported to have a new gene, Pl5, imparting resistance to downy mildew. Selections of this line were resistant to race 3. The F2 seedlings of crosses between RF‐S11‐5566‐74‐10 and the selections of Novinka and Progress did not segregate when plants were inoculated with race 3, indicating that all three sources possess the same gene, Pl5, imparting resistance to race 3 downy mildew. The findings have implications for sunflower breeding in the USA, as hybrids must have the gene Pl2, controlling resistance to race 2, and the new gene, Pl5, to provide resistance to both races.
Reliability of Two Laboratory Techniques to Predict Bread Wheat Protein Quality in Nontraditional Growing Areas1
Authors: Lorenzo A. , Kronstad W. E.
Published: July 2010

This investigation was undertaken to evaluate the reliability of two laboratory techniques, sodium dodecyl sulphate sedimentation (SDSS) test and SDS‐polyacrylamide gel electrophoresis (SDSPAGE) of the high molecular weight (HMW) glutenin subunits, identify the protein quality factors from different sources of highprotein bread wheat (Triticum aestivum L.) selections. Spring wheat germplasm included high protein hexaploid derivatives from Triticum dicoccoides, and selections from Argentina with good bread milling and baking properties. Winter wheat materials were from the Oregon State University International Winter ✕ Spring Wheat Program. Electrophoretic analysis (SDS‐PAGE) of the HMW glutenin subunits was a reliable indicator of loaf volume at specific protein levels. Elevated protein levels were not always required for high loaf volumes, but usually gave slightly better expansion. The HMW glutenin banding patterns were independent of environment factors. Bands 5 and 10 contributed by the D genome, with either bands 1 or 2* from the A genome and bands 7 and 8 or 17 and 18 coded by the B genome, were correlated with high loaf volume. Fivegram wholemeai samples, suspended in 100 mL of a solution containing 0.96 g lactate L−1 and 20 g SDS L−1 and a reading time of 30 min gave the best sedimentation values to discriminate between wheat lines giving high or low loaf volume. For the experimental materal used, SDSS values were found to be dependent upon variations in protein content.
Selection for Bacterial Blight Phytotoxin Resistance in Wheat Tissue Culture1
Authors: Pauly Michael H. , Shane William W. , Gengenbach Burle G.
Published: July 2010

Bacterial blight (caused by Pseudomonas syringae pv. syringae) is a foliar disease that occasionally reduces wheat (Triticum aestivum L.) yields in Minnesota and other northern states. Many strains of P. syringae pv. syringae produce a low molecular weight protein, syringomycin (SR), which has nonspecific toxic activity. This study was conducted to determine whether SR was toxic to wheat tissue cultures and whether selection in tissue culture could be a feasible approach for obtaining germplasm with increased bacterial blight resistance. Tissue cultures were established from immature embryos of ‘Angus’, a cuitivar susceptible to bacterial blight. Syringomycin was extracted according to established procedures, and conditions were determined to inhibit tissue culture growth. A bacterial mutant (no. 9‐25) incapable of producing SR was isolated from a producing strain (B359) via acridine orange mntagenesis. Polyacrylamide gel electrophoresis of partially purified extracts from B359 SR+, no. 9‐25 SR‐, and uninoculated control media indicated a single bioactive band inhibitory to Geotrichum candidum in only the B359 SR+ extract. Partially purified extracts from B359 SR+, but not no. 9‐ 25 SR‐ or control media inhibited the initiation and growth of tissue cultures from immature Angus embryos. The B359 SR+ extract concentrations that caused about 50% reductions in growth of initiating cultures were then used in attempts to select for resistance in established cultures. Cultures responded to SR selection by an increased tendency to form roots and shoots, but no stable resistant cultures were obtained during the period that regenerable cultures could be maintained. A total of 238 plants (R0) were regenerated from control and selected cultures during five subcultures. Eightyeight progeny plants (R1) from selected cultures were included in preliminary evaluation to compare their bacterial blight reaction to that of three noncultured reference genotypes. A suspension of P. syringae pv. syringae was introduced by pressure into leaf intercellular spaces and the increase in bacterial number was monitored in the leaf tissue. Phenotypic ratings of R1 plants were more variable than those of the three reference genotypes. Most R1 plants were as susceptible as Angus or L‐l, but five R1 plants had ratings within the range of the resistant cultivar, ‘Len’. Although increased variability is not unexpected in progeny of plants regenerated from tissue culture, tests of advanced generations will be required to establish whether R1 phenotypic differences are heritable.
Effect of a Modified Potato Medium on Anther Culture of Wheat1
Authors: Marburger J. E. , Sammons D. J. , Schaeffer G. W.
Published: July 2010

Modification of a potato extract medium was undertaken to increase pollen embryogenesis from anthers of a hard red spring wheat (Triticum aestivum L. cv. Chris). Whole potato tubers (Solatium tuberosum L. cv. Kennebec) were separated into peeled tubers and peel from which extracts were prepared. A 3 ✕ 3 latin square design with three replications in time was used to compare media prepared from: (i) extract of whole potato tubers, (ii) extract of the peel only, and (iii) extract of peeled tubers. A 60% increase in anther induction resulted from the peeled tuber extract medium compared to the whole potato medium. Removal of the peel from tubers probably reduces the concentration of compounds that may be inhibitory to wheat embryogenesis during anther culture. Anther source, defined by spike section (basal, middle, and distal), was a second variable in the experiment but did not significantly affect embryogenesis.
Effects of Mepiquat Chrloride on Natural Plant Resistance to Tobacco Budworm in Cotton1
Authors: Graham Charles T. , Jenkins Johnie N. , McCarty Jack C. , Parrott William L.
Published: July 2010

The effects of mepiquat chloride (1,1‐dimethyl‐piperidinium chloride) (Pix®) on natural plant resistance to the tobacco budworm (TBW), (Heliothis rirescens F.) in cotton (Gossypium hirsutum L.) was studied in 1984 and 1985. A split plot randomized complete block experimental design with six replications was used. ‘Stoneville 213’ was grown in two row plots (2 ✕ 13.7 m) in a two‐planted oneskip row pattern on a Marietta sandy loam (fine‐loamy, siliceous, thermic Fluvaquentic Eutrochrepts) soil at Mississippi State, MS. Main plot treatments were with and without TBW and subplot treatments were three levels of mepiquat chloride (0, 50, and 100 g a.i. ha−1). The 100 g a.i. ha−1 level was split into 50 g at the recommended time of application and 50‐g 14 days later. Mepiquat chloride treatments caused significant yield increases at first harvest, but not in total yield, suggesting the typical induced earliness with this plant growth regulator. In the presence of an artificial infestation of TBW, no significant differences in yield were recorded either year among mepiquat chloride levels, indicating no increased plant resistance to artificial infestations of TBW.
Diploid‐Tetraploid Comparisons in Rye. IV. Grain Production1
Authors: Pfahler P. L. , Barnett R. D. , Luke H. H.
Published: July 2010

In the subtropical lower latitudes, rye (Secale cereale L.) is used primarily for late fall‐winter‐early spring forage and, secondarily, for grain. Diploid and tetraploid forms are available, with tetraploids having many advantages over diploids in the amount, distribution, and quality of forage. Information on grain production is essential to develop appropriate breeding strategies for forage and grain types at each ploidy level. Various grain production traits (grain yield GY, seed weight = SW, test weight = TW, percent fertility = %F) of five adapted diploid (2x) cultivars (‘Florida Black,’ ‘Gator,’ ‘Elbon,’ ‘Explorer,’ ‘Wrens Abruzzi’) and their colchicine‐derived tetraploid (4x) forms were examined. Tests were conducted in three seasons (1981–1982, 1982–1983, 1983–1984) at two Florida locations (Gainesville—29°4′0 N Lat; Quincy‐30°3′ 5N Lat) at two seeding rates (0.5 and 1.0 viable seeds per linear centimeter of row). Over all environment(ss easons, locations, seeding rates), highly significant differences amongc ultivars within each ploidy level were found for GY, SW, TW, and %F. The environmental stability values (means, b values, deviation mean squares) at each ploidy levels were inconsistent, indicating that ploidy level influenced the environmental response. Over all cultivars and environments, the tetraploid‐diploid relationship [(tetraploid/diploid ✕ 100)] was 59% for GY, 116% for SW, 89% for TW, and 84% for %F. However, substantial differences in this relationship resulting from genetic background( cultivars) were found for GY (range = 41–101%), SW (range = 98–134%), TW (range = 82–93%), and %F (range = 77–95%). Apparently, genetic background as well as environment influenced ploidy level differences. The results indicate that selection within each ploidy level should be effective in improving various grain characteristics, but testing and selection in a number of seasons and locations would be necessary.
Production and Reproductive Behavior of Monoploid Sugarbeet1
Authors: Yu M. H.
Published: July 2010

The rarity of sugarbeet (Beta vulgaris L.) monoploids has limited the usefulness of monoploids sugarbeet breeding. This study was conducted to evaluate the production and cytogenetical behavior of monoploid sugarbeets. The rate of occurrence of monoploids in three sugarbeet lines was 0.017%. Meiotic pairing in the monoploids indicated the presence of three or more duplications that involved at least six of the nine chromosomes in the basic genome. Chromosomes of monoploid sugarbeet usually were condense and seldom congregated at metaphase plates. Chromatid bridges and a centric fragments occurred in > 2% of microsporocytes. Only those gametes that developed from restitution nuclei and contained a complete set of sugarbeet chromosomes did not abort. Seed setting was rare, and not every monoploid sugarbeet produce viable seed. Sugarbeet monoploids gave rise to monoploid progeny through pollination with diploids at a rate of 1.49%, which was > 80 times higher than that from pollinating diploids. The progeny plants also contained 18, 19, 27, 36, and 18/36 chromosomes when monoploids were pollinated with diploids. A great majority (92.3%) of these progenies were diploids. The 19‐chromosome (trisomic) progeny was the only aneuploidy class recovered. It may not be possible to establish monosomic series of sugarbeet genotypes through conventiona pollination techniques because unbalance gametes (without an intact genome) do not survive. Although the monoploids exhibited morphologic dailvergence from diploid parents, the monoploid progeny resembled their respective maternal monoploids. This is the first reports howing the feasibility of recovering monoploid sugarbeet from monoploids.
Foundation Populations for Adapted by Exotic Crosses1
Authors: Bridges W. C. , Gardner C. O.
Published: July 2010

Introgression of exotic germplasm into adapted breeding populations is needed to reduce problems of genetic vulnerability and selection plateaus. Our objective was to determine whether the F2 or the first backcross to the adapted population (BC1) was the better foundation population in which to begin selection. Selection response was calculated in the foundation populations based on two different additive genetic models. The calculated selection responses were then used to compare the F2 and BC1. Results of the comparisons indicate (i) the F2 is better for both long‐term and short‐term selection goals when the adapted and exotic populations perform the same, (ii) the BC1 is better for short‐term goals when the adapted population is superior, (iii) the BC1 is better for long‐term goals when the adapted population is superior due to a greater number of loci with favorable alleles present, and (iv) the F2 is better for long‐term goals when the adapted population is superior due to the presence of favorable alleles at loci with large effects.
Assying for Linkage between Rps and Isozyme Loci in Soybean1
Authors: Rennie Brian D. , Beversdorf Wallace D. , Buzzell Richard I.
Published: July 2010

Linkage assays were run with soybean [Glycine max (L.) Merr.] lines differing for Rps and isozyme alleles, in an attempt to identify markers for Rps loci. The F2 seedlings were screened for resistance to specific races of Phytophthora megasperma (Drechs.) f.sp. glycinea (Hildeb.) Kuan & Erwin and cotyledon samples were assayed for isozyme patterns by means of starch gel electrophoresis. Alleles at the Rps1, Rps3, Rps4, Rps5, Rps6, and Rps? loci were assayed for linkage with isozyme alleles at the Aco4, Dial, Idhl, IdH2, and Pgm1 loci. No linkages were detected for the 18 Rps‐isoxyme pairs tested.
Crop‐Water Relations of Sunflower and Soybean under Irrigated and Dryland Conditions1
Authors: Cox W. J. , Jolliff G. D.
Published: July 2010

A field study was established on a Woodburn silt loam (fine‐silty, mixed mesic Aquultic Argixeroll) to study the physiological responses of sunflower (Helianthus annuus L.) and soybean [Glycine max (L.) Merr.] under irrigated and dryland conditions. Diurnal measurements of leaf water potential (ψL), stomatal resistance (Rs), leaf temperature (TL), and carbon exchange rates (CER) were made on individual leaves of both crops on four dates during a soil drying cycle that corresponded to bud formation through flowering in sunflower and flowering through pod formation in soybean. Soil water and leaf area index (LAI) measurements were also taken on the four dates. Dryland sunflower depleted soil water to a depth of 1.8 m, and maintained a minimum ψL (−1.6 MPa) of 0.4 to 0.6 MPa lower than that of irrigated sunflower on all dates. Although increased Rs of dryland sunflower did not occur until 50 days into the soil drying cycle, 33 and 15% reductions in LAI and CER, respectively, were observed 22 days into the cycle. The data suggested that nonstomatal effects were most responsible for the reduced CER in dryland sunflower. Dryland soybean depleted 45% less soil water than that of dryland sunflower; nevertheless, both dryland crops maintained the same minimum ψL on all dates. Stomatal closure, which occurred early in the soil drying cycle of dryland soybean, was accompanied by TL 4°C above ambient on occasion, a 50% reduction in CER, and a 68% reduction in LAI. A significant negative correlation (r = −0.80) was observed between CER and Rs of soybean, which suggests that stomatal closure was responsible for the reduced CER in dryland soybean.
Concentration of the Systemic Gametocide, TD‐1123, in Cotton Nectar, and Honeybee Response1
Authors: Loper Gerald M. , Olvey Jim , Berdel R. L.
Published: July 2010

The production of hybrid cotton (Gossypium hirsutum L.) seed requires both a system of sterilizing one parent in the crossing block and the effective use of a pollen vector. This paper reports results from studies in which a systemic gametocide was used to produce male‐sterile flowers and also reports behavioral responses of honeybees (Apis mellifera L.) to the gametocide. Field and greenhouse tests were conducted during 1984 and 1985 to determine the quantity of the foliar‐applied systemic gametocide, TD‐1123, that was translocated to the floral and bracteal nectar of cotton (G. hirsutum L. and G. barbadense L.). Field observations and a laboratory bioassay evaluated honeybee response to TD‐1123 in nectar or to TD‐1123‐ laced sucrose solutions. The gametocide was fonnd in floral nectar in the field (<1‐542 mg L‐1) (bracteal nectar not collected) and in both floral and bracteal nectar (11‐151 mg L‐1) in the greenhouse studies. The highest concentrations of TD‐1123 were found in the floral nectar of upland cotton sampled 1 day after spraying (542 mg L‐1). Honeybee consumption of 0.84 M sucrose solutions that included TD‐1123 was not significantly increased at 50 mg L‐1 but significantly increased at 75 mg L‐1 of the gametocide. Floral visitation by foraging honeybees as measured in the field was not affected by the gametocide. We concluded that although the gametocide occurs in the nectar of treated cotton plants, it should not pose a threat to adequate pollination activity by the honeybee.
Comparative Yields of Ratoon Cropped Temperately and Tropically Adapted Grain Sorghum Hybrids1
Authors: Duncan R. R. , Moss R. B.
Published: July 2010

With a growing season of + 230 frost‐free days and the need for additional double‐cropping alternatives in a subtropical environment, 10 tropically adapted (TA) and 10 temperately adapted (TE) sorghum [Sorghum bicolor (L.) Moench] hybrids were evaluated for ratoon cropping (two grain harvests from a single planting) performance in the southeastern USA from 1981 to 1983. The field study was conducted on a Greenville sandy clay loam (Rhodic Paleudults) and involved planting the crop in early April, harvesting the first grain crop in late July or early August, removal of the remaining stubble with a silage chopper, and harvest of the ratoon grain crop in early December. Tropically adapted hybrids produced 610 and 620 kg ha‐1 higher grain yields on the planted crop and on total combined yields, respectively, than TE hybrids. Ratoon‐crop yields were not significantly different between TA and TE hybrids, indicating that the adaptation characteristic was not a factor in ratoonability. Northrup King ‘Savanna 5’ (TE) and Douglass King ‘DK 788’ (TA) produced the greatest yields for the planted crop, ratooned crop, and total crop. However, the majority of hybrids apparently were not well adapted to ratoon cropping, and breeding efforts will be needed to stabilize yields in this alternative double‐cropping program, particularly for ratoon‐crop grain yields.
Larval Antiniosis Screening Technique for Mexican Bean Beetle Resistance in Soybean1
Authors: Rufener G. K. , Hammond R. B. , Cooper R. L. , St. Martin S. K.
Published: July 2010

Soybean [Glycine max (L.) Merr.] breeders and entomologists have primarily used field techniques to screen for insect resistance. Problems they have encountered include maturity variability among the host plants, variability in natural insect populations, and an inability to separate antibiosis from non preference. We developed a laboratory screening technique to breed for resistance to Mexican bean beetle (Epilachna varivestis Mulsant). Larval mortality and development are monitored to determine the level of antibiosis in individual plants. High mortality and/or slow larval development indicate high levels of antibiosis resistance. This laboratory technique allows the breeder and entomologist to control insect pressure while screening year‐round and to eliminate the problems associated with plant maturity differences in the field. Screening of the soybean lines is started at the V3 developmental stage; thus, resistant plants can be identified prior to anthesis. This allows for crosses among resistant lines to be accomplished the same growing season. These factors significantly reduce the time needed to develop Mexican bean beetle resistant lines.
Sex Expression in Buffalograss under Different Environments1
Authors: Huff D. R. , Wu Lin
Published: July 2010

Sex expression in buffalograss [Buchloe dactyloides (Nutt.) Engelm.] is considered to be complex and not always predictable from field observations. The objective of this study was to examine sex expression in buffalograss for predictable patterns. The distribution of sex forms was examined for two populations of buffalograss, Colorado common and Texas native. Frequency of monoecious plants was found to be higher in the Colorado common population than in the Texas native population. Sex expression was studied under different environmental conditions, including warm (day, 35°C/night, 27°C) and cool (day, 24°C/night, 15°C) temperatures, high (15.05 μmol photon m‐2 s‐1) and low (7.40 μmol photon m−2 s−1) light conditions, and high (181 kg ha−1) and low (45 kg ha−1) N fertilization levels. The sex expression of male and female plants (dioecious) remained constant over all environmental treatments. The trends of sex expression for monoecious sex forms, however, showed that conditions of warm temperature, high light, and low N were favorable for female sex expression, whereas conditions of cool temperature, low light, and high N were favorable for male sex expression. A significant effect on sex expression was only produced by the N treatment for predominately female monoecious sex form. In addition, sex expression was significantly different between genotypes within monoecious sex forms. This conclusion suggests that the stability of sex expression in buffalograss is genotype dependent.
Resistance to Phomopsis Stem Blight in Lupinus Angustifolius L.1
Authors: Cowling W. A. , Hamblin J. , Wood P. McR , Gladstones J. S.
Published: July 2010

Phomopsis leptostromiformis (Kühn) Bubák causes Phomopsis stem blight in narrow‐leafed lupin (blue lupine; Lupinus angustifolius L.). In southern Australia, Phomopsis stem blight appears on lupins during senescence when dark lesions and fruiting bodies develop on stems. P. leptostromiformis colonizes dead stems and produces a mycotoxin that is responsible for lupinosis in livestock that graze lupin stubble. We sought high levels of resistance to Phomopsis stem blight in wild L. angustifolius and attempted to transfer resistance to domesticated types by crossing with susceptible cultivars. Resistance was rated by estimating the proportion of mature, dry stems covered with stem blight lesions. Phomopsis stem ratings of 254 accessions of wild L. angustifolius ranged from < 1% (highly resistant) to 36% (highly susceptible) at two Western Australian field sites in 1977. Stem ratings of the wild lupins were subject to a large accession ✕ site interaction. Resistant accessions came from a range of habitats within several Mediterranean countries. Many accessions were crossed with susceptible cultivars, and F4‐derived progeny, reselected for domestic traits, were tested for resistance at up to five Western Australian sites from 1981 to 1983. Stem ratings of F4‐derived progeny ranged from 3 to 37% and susceptible cultivars from 26 to 38% when averaged across the 3 yr. Variance component estimates for line ✕ site and line ✕ year interactions were relatively small. Heritability of resistance was high (0.86‐0.92) when estimated on a line mean basis across sites in 1982. Heritability was reduced (0.49‐0.83) when estimated across years involving 1983, due to low average Phomopsis stem ratings (< 20%) in 1983, which inflated line ✕ year variance components. Resistance to Phomopsis stem blight was successfully transferred from wild to domesticated L. angustifolius.
Genomic and Phylogenetic Relationships among Rye and Perennial Species in the Triticeae1
Authors: Lapitan N. L. V. , Gill B. S. , Sears R. G.
Published: July 2010

Genomic and phylogenetic relationships among rye (Secale cereale L.) and eight perennial species representing the genera Pseudoroegneria, Thinopyrum, and Elymus were analyzed by in situ hybridization with two repeated DNA sequence probes from rye. The 120‐base pair (bp) sequence was observed to be present in all the perennial species, but only Thinopyrum elongatum showed an in situ hybridization pattern similar to that of rye. In both species, the 120‐bp sequence was distributed throughout the entire length of all seven pairs of chromosomes. The other species showed weak labeling or few sites of hybridization with the 120‐bp sequence. The 480‐bp sequence, which is specific to S. cereale, was detected in eight pairs of chromosomes of Thinopyrum intermedium and in one pair of chromosomes of Elymus trachycaulus. The labeled chromosomes in the hexaploid T. intermedium may have consisted of chromosomes from the ✕ genome, whose origin is unknown and is distinctly different from the two related genomes present in this species. This is the first report on the occurrence of the 480‐bp sequence (in the ✕ genome of T. intermedium) outside of the genus Secale and may indicate either a phylogenetic relationship or an independent amplification event. The results of the 120‐bp sequence confirm the widespread occurrence of this sequence in the Triticeae tribe. Both sequences provide valuable markers for molecular cytology (e.g., 120‐bp sequence for E genome and 480‐bp sequence for ✕ genome) for use in controlled introgression of useful traits from species containing these genomes into wheat.
Soybean Seed Coat Development1
Authors: Vaughan Duncan A. , Bernard R. L. , Sinclair J. B. , Kunwar Indra K.
Published: July 2010

The seed coat of mature soybean [Glycine max (L.) Merr.I has natural openings the micropyle and pits (pores). To determine when pits appeared during development of the seed coal scanning electron microscopic studies were made at weekly intervals after pollination. Pits appeared in the two accessions studied at about growth stage R7 (beginning maturity), 7 to 14 days before R8 (full maturity). micropyle developed before pollination and usually was an open structure. However, in ‘Union’, a micropylar plug was observed at 3 weeks after pollination. The micropyle was a well defined natural opening in the seedcoat from before pollination to maturity, whereas seed coat pits only began to form as the seed began to desiccate.
A Comparison of Methods for Moisture Determination of Forages for near Infrared Reflectance Spectroscopy Calibration and Validation1
Authors: Windham W. R. , Robertson J. A. , Leffler R. G.
Published: July 2010

Near infrared reflectance spectroscopy (NIRS) has gained widespread acceptance for the determination of nutritional quality in forages. However, little attention has been given to investigating its use in the analysis of moisture content of forages. Our objectives were to assess the use of Karl Fischer (KF) titration for the determination of the water content of forages and to compare this method with oven methods for use in NIRS calibration and validation. In the first experiment we assayed 68 samples of eight bermudagrass [Cynodon dactylon (L.) Pers.] cultivars. The methods of moisture analysis used were KF, forced‐air (FA) oven at 135 and 105°C for 2 and 24 h, respectively, and vacuum oven (VO) at 100°C for 24 h at 4 kPa laboratory vacuum. Moisture contents measured with the FA 105°C and VO methods were comparable but lower (P<0.05) than those obtained with the FA 135°C and KF methods, which were similar. The NIRS calibrations were developed within moisture methods from 48 bermudagrass samples and the remaining 20 samples used for validation. Calibrations within methods predicted the validation samples with a standard error of analysis (SEA) of 2.8 for FA 135°C, 3.2 for FA 105°C, 3.8 for VO, and 2.6 g kg‐1 for KF. In the second experiment, KF and FA 135°C based calibrations were tested on 30 samples composed of six different types of bermudagrasses, temperate grasses, legumes, silages, and silage‐based dairy cattle (Bos taurus) rations. Analysis with an FA 135°C calibration and validation with FA 135°C values resulted in large negative biases due to a loss of C‐containing substances as well as water, especially from the fermented materials. However, analysis with KF calibration and validation with KF values resulted in no bias and acceptable SEAs. The ability of the KF‐based calibration to accurately assess water content in more diverse populations is due to the specificity of KF for water and the very strong absorbance of water at 1930 nm regardless of the sample type.
Chitin as an Estimate of Mold in Hay1
Authors: Roberts C. A. , Moore K. J. , Graffis D. W. , Kirby H. W. , Walgenbach R. P.
Published: July 2010

Since studies with food products have shown that chemical quantification of mold is more reliable and repeatable than microscopic procedures, the objective of this study was to evaluate the quantification of mold in hay by the determination of chitin, a fungal cell wall polymer of glucosamine. Alfalfa (Medicago sativa L.) and alfalfa‐grass hay samples were collected and analyzed for spore count and chitin concentration. Spore counts ranged from 6.8 X 105 to 1.8 ✕ 107 spores g‐1 dry matter (DM) and were similar to spore counts previously reported. Chitin concentration ranged from 146 to 592 mg kg‐1 DM and was similar to those reported for contaminated food products. Chitin and spore count were not correlated (P>0.05). In a second study, core samples were taken from alfalfa bales in which various levels of mold were quantified using a relative mold index (RMI) of 1 = no visible mold to 5 = mycelial mat throughout the bale. Core samples were taken and chitin was quantified in each sample. The chitin concentration ranged from 75 to 464 mg kg‐1 DM and was similar to chitin concentrations reported in other agricultural products. Chitin and RMI were correlated (R = 0.81) and residual error was smallest when chitin concentrations were extreme. We conclude that chitin can accurately estimate level of mold infestation in hay.
Evaluation of in Vitro Propagated Sugarcane Hybrids for Somaclonal Variation1
Authors: Lourens A. G. , Martin F. A.
Published: July 2010

A study was conducted from 1982 to 1984 to assess the variability arising from in vitro regeneration and its vegetative transmission in two cultivars of Saccharum officinarum (L.) interspecific hybrids (‘CP 65‐357’ and ‘CP 72‐356’). Tissue was either regenerated directly from explanted apical meristems or maintained as callus for 6 weeks prior to plantlet regeneration. Several morphological characteristics of each plant were evaluated in the field at maturity in each of 2 years at one location. The frequencies of variants were compared to those found in each original cultivar. The tissue culture process resulted in slightly increased morphological variability in plant cane in both cultivars. This variability was manifested primarily in the form of abnormal plant growth habit, which included number of tillers, stalk length, leaf attitude, and stalk diameter. However, a reversion to the original phenotype characteristic of the parental cultivars was evident in the second year of the experiment, suggesting that the majority of the apparent variation from tissue culture was not under genetic control. Although conformity for plants derived from callus cultures increased n the second year, direct regeneration from explant tissue was more desirable for cloning in CP 65‐357, whereas CP 72‐356 tissue maintained up to 6 weeks as callus in culture also was suitable for clonal propagation. These results demonstrate that to successfully clone and mass propagate specific sugarcane cultivars for use as planting materials the effect of tissue culture technologies must be examined on a cultivar‐by‐cultivar basis.