bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating Parental Cultivars for Use in Hybrids and Heterosis in Barley1
Authors: Gebrekidan Brhane , Rasmusson D. C.
Published: July 2010

Nine cultivars were crossed to ‘inbred’ and single cross testers in a study of methods of evaluating parental cultivars for potential use in hybrids of barley, Hordeum vulgare L. The cultivars were ranked in about the same order in testcrosses to inbreds, testcrosses to single crosses, and in the cultivar per se comparison for four of six characters — kernel number, kernel weight, days to heading, and height. The data did not provide a good basis for deciding among the three methods of evaluating potential parental cultivars for yield or number of heads. However, cultivar per se evaluation is recommended for initial screening of potential parental cultivars.

Twenty of the 27 hybrids that were evaluated in four environments exceeded their high parent in yield, and 16 of them exceeded ‘Traill,’ the highest yielding of the cultivars. Heterosis, on the high parent basis, ranged from –26 to 47% with a mean of 11%. Four hybrids had a mean yield 17% higher than Traill. High yielding cultivars produced a larger proportion of high yielding hybrids than did low yielding cultivars, whereas, maximum heterosis occurred in crosses among low yielding cultivars. Heterosis, on the high parent basis, was negligible for characters other than yield.
Breeding for Resistance to the Sorghum Shoot Fly1
Authors: Doggett H , Starks K. J. , Eberhart S. A.
Published: July 2010

Screening sorghum (Sorghum bicolor (L.) Moench) varieties for seedling resistance to the sorghum shoot fly (Atherigona varia, Meigen) gave inconsistent results, and “recovery resistance” (tolerance) proved a better character. When levels of pest attack were high, infestation levels exceeded 90%, indicating that there was little worthwhile seedling resistance in the sorghums being tested. In contrast, good recovery resistance was shown by the cultivars ‘Serena’ and ‘Namatare,’ and more than 70% of the infested plants recovered and yielded normally. Recovery resistance was associated with good yield from tillers, and heritability was fairly high. ‘Namatare’ proved a successful parent, and grain sorghums with a combination of good shoot fly recovery resistance and yield were developed from crosses between Namatare and susceptible sorghums.
Characterization of Photosynthesis in Cold Hardening Winter Wheat1
Authors: Barta A. L. , Hodges H. F.
Published: July 2010

Photosynthesis (net CO2 assimilation) was measured on two winter and one spring wheat cultivars (Triticum aestivum) at three stages of cold hardening. Photosynthesis during hardening was characterized by decreasing rates of CO2 assimilation and reduced response to light and temperature changes. The winter wheats, ‘Vermillion’ and ‘Seneca,’ had higher rates of photosynthesis at all stages of hardening than did the spring wheat, ‘Justin.’ Vermillion, the most winter hardy cultivar, had significantly higher photosynthesis than Seneca when rates were averaged over all variables. Treatment of the plants with (2‐chloroethyl) trimethylammonium chloride did not produce any significant changes in any of the photosynthetic parameters studied. No significant differences in specific rates of photophosphorylation or Hill reaction were noted among the cultivars, in contrast to the varietal differences found in whole plant CO2 assimilation rates.
Inheritance of a Self‐Compatibility Response to Temperature and the Segregation of S Alleles in Diploid Alsike Clover, Trifolium hybridum L.1
Authors: Townsend C. E.
Published: July 2010

Inheritance of a self‐compatibility response to temperature and the segregation of S alleles were investigated in I2, F1, F2, and BC1 progenies of diploid alsike clover, Trifolium hybridum L. I1 clones, 6‐5 (S3S4) and 7‐1 (S5S6), were the temperature‐sensitive parents and I1 clone 1‐5B (S1S1) was the temperature‐insensitive parent. Percentage of selfed florets setting seed after 3 to 5 days at 32 C was used to measure temperature‐sensitivity. The S alleles in the self‐progeny of clone 6‐5 segregated in a 1 S3S3:2 S3S4:1 S4S4 ratio. The S6S6 genotype was absent in the self‐progeny of clone 7‐1, but the other two genotypes (S5S5 and S5S6) segregated in a 1 : 1 ratio. The expected S genotypes (S1S3, S1S4, S1S5, and S1S6) were obtained equal frequencies in the F1 progenies (S1S1 ✕ S3S4, S1S1 ✕ S5S6, and reciprocals). In all F2 progenies, one homozygous and one heterozygous class (S3S3, S1S3; S4S4 S1S4; S5S5, S1S5 and S6S6, S1S6) were obtained in equal frequency. Only five of 202 F2 plants were S1S1.

Although other gene models were considered, the temperature‐sensitive data were interpreted best by a twogene model with an interaction between S allele genotype and temperature‐sensitivity. The proposed temperature‐sensitive genotypes of clones 6‐5 and 7‐1 were T1T1T2t2S3S4 and T1t1T2t2S5S6, respectively. The T gene(s) suppressed the action of the S alleles in the style when the plants were held at a 32 C temperature for 3 to 5 days. Dominance at one T locus was sufficient to give a temperature‐sensitive reaction with the S3, S5, and S6 alleles, but dominance at both T loci was required for such a reaction with the S, allele. Also, there was evidence for the interaction among certain S alleles in the presence of the T loci. The expression of the T loci was influenced by polygenes.

Apparently these data are the first from any species to establish the role that specific temperature‐sensitive genes have on the expression of specific S alleles and interactions thereof.
Comparison of Hill and Rod Row Plots in Common and Durum Wheats1
Authors: Baker R. J. , Leisle D.
Published: July 2010

Yields of 10 cultivars of common and durum wheat were studied in hill and rod row plots in two different years. Correlations between the two methods, when adjusted for attenuation, were high in all four tests. In all cases, the cultivars exhibited a greater range of yield in the hill plots than in the rod row plots. Hill plots appear to be very useful for genetic studies and for early generation selection.
Genetic Linkage in Soybeans: Linkage Group VII1
Authors: Weiss Martin G.
Published: July 2010

The genetic linkage between three loci in soybeans was determined, and established as Linkage Group VII. The loci involved arc Y13, y13 (normal, deficient chlorophyll); 0, o (brown, red‐brown seed coat pigmentation); and I, il, ik, i (multiple alleles determining the seed coat pattern of black and brown colors). The combined recombination value between the y13 and o loci was 31.3 ± 1.9%, between the o and i loci 17.8 ± 0.79%, and between the y13 and i loci 41.1 ± 0.9%. The order of genes was shown to be y13 ‐ o ‐ i.
Breeding Methods for Improving Pima Cotton and Their Implications on Variety Maintenance1
Authors: Feaster Carl V. , Turcotte E. L.
Published: July 2010

Three commercial varieties of cotton (Gossypium barbadense L.) = ‘Pima S‐1,’ ‘Pima S‐2,’ and ‘Pima S‐4’ = and selections from each variety were included in this study. Crosses among varieties and strains followed by selection resulted in greater improvement than selection within a variety. The potential of a strain was established in a few generations after a cross, making further selection ineffective. Thus, maintaining the established variety in the simplest manner possible, such as storing breeders seed for periodic release, and a separate program of improvement by hybridization and selection are suggested.
Rooting from SOD by Poa Pratensis L. and Agrostis Tennis Sibth.1
Authors: Madison John H.
Published: July 2010

The source was examined of roots which “knit” blue and bentgrass sods by emergence from the sod into the soil below. Sod was knit by new adventitious roots which emerged from the sod into the new soil in greater numbers as sod was more thinly cut. Regrowth of old roots was not a factor in knitting of sod. All bluegrass shoots initiated new roots. Only some bentgrass shoots initiated roots the first week, but the percent rooting increased with time.
Development of Subterranean Clover (Trifolium Subterraneum L.) at Very Early Stages1
Authors: Raguse C. A. , Fianu F. K. , Menke J. W.
Published: July 2010

Ten unique morphological stages of plant development from emergence to full expansion of the unifoliolate leaf were described for an annual clover (Trifolium subterraneum L.). This system of classification provides for precise morphological description of plant development when a high degree of experimental resolution is required at very early stages.
Analysis of Genetic Resistance to Maize Dwarf Mosaic Disease1
Authors: Johnson G. R.
Published: July 2010

Twenty maize diallel cross experiments, grown as part of a screening program for the isolation of resistance to maize dwarf mosaic virus disease, were analyzed to investigate the genetic basis for MDM resistance and to compare several methods for predicting three‐ and fourway hybrid performance.

General combining ability variance accounted for most of the variation among crosses; resistance appeared to be usually transmitted with nearly complete dominance; and midparent heterosis for resistance was observed. The performance of non‐parental single crosses predicted three‐ and four‐way cross performance most accurately.
Studies of Tiller Formation in Reed Canarygrass (Phalaris arundinacea L.) and ‘Climax’ Timothy (Phleum pratense L.)1
Authors: Horrocks R. D. , Washko J. B.
Published: July 2010

The greenhouse and growth chamber experiments reported herein were set up to investigate the influence of the following factors on tillering of ‘Climax’ timothy, Phleum pratense L., and reed canarygrass Phalaris arundinacea L., (a) stage of development at which the first harvest was removed; (b) clipping height; (e) nitrogen level; (d) day‐night temperature; and (e) shading. Stages of development at the time the first harvest was removed were as follows: for Stages 1, 2 and 3 the growing points were 5, 10 and 20 cm, respectively, above the soil surface; Stage 4 was 2 weeks after Stage 3. Tillering was affected as follows by these treatments: Climax timothy plants from Stages 1, 3, and 4 showed no increase in thc number of tillers formed between the 1st and 2nd harvests, but increased thereafter. Tillering under Stage 2 increased between the 1st and 2nd harvests, and declined between the 2nd and 3rd. Plants clipped leaving 10‐ vs 4‐cm stubble showed a 30% increase in the number of tillers formed. Tillering was increased significantly (18%) by the high rate of N (112 vs 28 kg/ha). Reed canarygrass plants clipped at Stages 1 and 2 demonstrated an increase in tillers of 2.6 times between the 1st and 3rd harvests. Those clipped at Stage 3 and 4 performed similarly to the above stages between the 1st and 2nd harvests, but showed no increase thereafter. Plants clipped leaving 10‐ vs 4‐cm stubble produced 26% more tillers. No N treatments were applied to reed canarygrass.

The number of tillers formed under high day‐night (32–27C) temperatures was less than the number under the 21–15.5C regime for both species. Climax timothy was more susceptible to injury when subjected to the higher temperature. Both species produced more tiller when shaded (40% of full light intensity received) regardless of whether the day‐night temperature was 32–27C or 21–15.5C

Dry matter production of reed eanarygrass was approximately equal regardless of whether the first harvest was removed at Stage I or Stage 4, or whether the clipping height was 4‐ or 10‐cm. Climax timothy produced less dry matter when the first harvest was removed at the two earlier stages of maturity, but no difference was found between the 4‐ and 10‐cm clipping heights.
Identification of Ocimene in Alfalfa Flower Aroma by Combined GC‐Mass Spectrometry1
Authors: Loper G. M. , Flath R. A. , Webster Janet
Published: July 2010

A component of the natural aroma of alfalfa (Medicago sativa cultivar ‘Mesa‐Sirsa’) flowers has been identified. The aroma of excised flowers was adsorbed and concentrated on Chromosorb 102 in stainless steel tubes. Combined capillary gas chromatography and mass spectrometry was used for component identification. An aroma component was identified as ocimene (a C10H16 terpene) on the basis of mass spectral comparisons and co‐chromatography with pure ocimene. The identification of this compound will facilitate studies of alfalfa pollination by honeybees.
Test Weight in High‐Amylose Corn1
Authors: Helm J. L. , Paez A. V. , Loesch P. J. , Zuber M. S.
Published: July 2010

Inheritance of grain test weight in high‐amylose corn (Zea mays L.) was studied by measuring the test weight performance of several inbred lines crossed on two singlecross testers and by a diallel mating system. Wider ranges in test weight were obtained with the low test‐weight tester than with the higher test‐weight tester. Rankings of entries for test weight were (1) highly correlated between years, (2) intermediate between locations, and (3) low between testers. The diallel analysis indicated a preponderance of additive genetic effects. Single‐cross hybrids involving inbred parents with low test weights had lower test weights than hybrids from Low by High and High by High inbred parents, with the latter group having the highest test weights. Likewise, inbred parents with low test weights gave lower top cross test weight performance than inbreds with higher test weights. Low test‐weight single‐cross testers had lower average test weights than testers with higher test weights. Breeding methods which take advantage of the large additive effects should be suitable in improving test weight of high‐amylose corn
Predicting Double‐Cross Sugarbeet Hybrid Performance1
Authors: Smith Garry A. , Hecker R. J.
Published: July 2010

Thirty‐five double crosses, 15 single crosses, and six red beet top crosses were developed from six inbred lines and used to tesl; five methods of predicting double‐cross sugarbeet (Beta vulgaris L.) hybrid performance. The mean of the four nonparental single crosses of any double cross was found to be the most consistent method for predicting root yield and percent sucrose. Percent purity was best predicted by the mean of all six single crosses of the parents iinvolved in any double cross. However, predictive capabilities of five methods studied were not greatly different. There was little relationship between the correlation cofficients and the percentage of accurately predicted top performing hybrids.
Methods for Evaluation of Soybean Hypocotyl Length1
Authors: Burris J. S. , Febr W. R.
Published: July 2010

We compared the effectiveness and efficiency of sand and paper‐towel methods for the evaluation of hypocotyl length of soybean (Glycine max (L.) Merrill) genotypes at 25C. Seeds planted in sand at 10 cm in containers covered with plastic bags had hypocotyl lengths that were reproducible and consistent, Sand methods made individual hypocotyl measurements difficult. When the seeds were planted on standard germination towels, the results equaled those in the 10‐cm sand if moisture was maintained at an adequate level. To obtain an adequate moisture level, it was necessary to use a 30‐ ✕ 30‐cm towel, and the containers had to be covered. Orientation of the seed with the mitropyle up on the paper towel prevented twisted hypocotyl~ which were difficult to measure. Seed treatment with a fungicide had no influence on hyocotyl length, but may be of value with diseased seed lots.
Relationships Between Yield and Its Components and Structures Above the Flag Leaf Node in Spring Wheat1
Authors: Hsu P. , Walton P. D.
Published: July 2010

The relationship of yield in spring wheat (Triticum aestivum) with its components and the morphological structures above the flag leaf node which contribute to the photosynthetic area were studied under both field and greenhouse conditions. Five varieties, with the F1, F2, and backcross progenies of a complete diallel set of crosses between them, were considered. Ear length, flag leaf sheath length and flag leaf breadth influenced yield and its components significantly. Ear number per plant was the most important component in determining yield per plant.
Cytological Studies of Four Diploid Dactylis Subspecies, Their Hybrids and Induced Tetraploid Hybrids1
Authors: Hu Wilma Wei‐Lin , Timothy David H.
Published: July 2010

To assess subspecies relationships within Dactylis glomerata L., chiasma frequencies and chromosome pairing of four diploids and their diploid and tetraploid hybrids were studied. Subspecies himalayensis, ibizensis, juncinella, and Smithii were chosen because of their extreme morphological, geographical, and ecological discontinuities. Pairing in parents and hybrids was generally normal and coincided with expected or published frequencies. Ssp. Smithii had more univalents and fewer chiasma than other parents. Chiasma frequencies of the diploid hybrids himalayensis ✕ juncinella, juncinella ✕ Smithii, and himalayensis ✕ Smithii were lower than those of the corresponding tetraploid hybrids. Chromosome structural differences, although minor, are most pronounced between ssp. juncinella and ssp. Smithii, and slightly less between ssp. Smithii and ssp. himalayensis. Ssp. ibizensis is the least structurally differentiated from the others and is probably the relict of a larger gene pool through which genetic exchange had previously occurred with the other subspecies or their ancestral forms.
Improvement of Seedling Vigor of Smooth Bromegrass (Bromus inermis Leyss.) by Recurrent Selection for High Seed Weight1
Authors: Trupp C. R. , Carlson I. T.
Published: July 2010

Three polycross populations of smooth bromegrass (Bromus inermis Leyss.) derived by recurrent phenotypic selection for high seed weight averaged higher in seed weight and seedling vigor and lower in fertility index than five check varieties. Selection for high seed weight had little effect on mean performance or variability for traits other than seed weight and seedling vigor. Seed and forage yields were maintained at high levels.

In average seed weight over 2 years, the three successive selected populations were, respectivdy, 6, 20, and 30% higher than the mean of two check clones selected to represent the mean of the initial material. Close agreement was obtained between space‐planted and seeded‐row tests for relative seed weight (r = .98). Phenotypic variance for seed weight increased with each successive cycle of selection.

Selection for increased seed weight resulted in superior seedling vigor as measured by ability to emerge from a 5‐cm planting depth, weight per seedling, and seedling yield per unit area. The seedling vigor advantage of large‐seeded strains was greatest during early stages of seedling growth. Topcross progenies of 50 plants selected for high seed weight and seed set from cycle 3 were 45% higher in average weight per seedling 1 month after planting in the field than were five check varieties.
Development of Cystine‐ and Cysteine‐rich Aleurone Grains in Bean Seeds1
Authors: Vogel Kenneth P. , Wood Donald R.
Published: July 2010

Histochemical techniques were used to study aleurone grains in developing cotyledons of four cultivars of Phaseolus vulgaris L. The ninhydrin‐Schiff's reaction and the 2,2′‐dihydroxy ‐ 6,6′ dinaphthyl‐disulfide (DDD) method were used to identify total protein and protein bound sulfhydryl and disulfide groups respectively. Aleurone grains of the subepidermal and adjacent mesophyll cells showed a more intense staining reaction to DDD 28 days after flower opening than the rest of the cotyledon, and the staining differentiation increased until the seed matured. The greatest concentrations of these deeply staining aleurone grains were in two areas, at the point where the embryo axis attaches to the cotyledons and adjacent to the hilum. A varietal difference was not demonstrated by these techniques.
Chromosome Numbers, Microsporogenesis, and Mode of Reproduction of Seven Paspalum Species1
Authors: Burson Byron L. , Bennett Hugh W.
Published: July 2010

Paspalum pumilum Nees had a chromosome number of 2n = 20. The chromosome number in P. arechavaletae Hack., P. cromyorhizon Trin. ex Doell., P. exaltatum F. & C. Presl, P. guenoarum Arech., and P. lividum Trin. ex Schlecht. was 2n = 40; and in P. mandiocanum Trin. it was 2n = 60. Meiosis was regular in P. pumilum, P. arechavaletae, P. exaltatum, and P. mandiocanum with primarily bivalent pairing. P. cromyorhizon and P. guenoarum had frequent quadrivalents, and meiosis in P. lividum was the most irregular with lagging chromosomes and micronuclei. A study of megasporogenesis and embryo sac development in each species showed that P. pumilum and P. arechavaletae were sexual and the other five species reproduced by apomixis. The type of apomixis was apospory and, with the exception of P. mandiocanum, species were pseudogamous.
Seasonal Nutrient Uptake and Accumulation Patterns in Soybeans1
Authors: Harper James E.
Published: July 2010

Field hydroponic gravel culture systems were used to determine nutrient uptake and accumulation in soybeans (Glycine max (L.) Merr.). Uptake of N, P, K, Ca, and Mg were low during the first 30 days after emergence. At initial flowering, nutrient uptake increased sharply, reaching maximum uptake rates between full bloom and midpod fill. Uptake of N, P, and K generally declined through later development stages while Ca and Mg uptake remained high or even increased. The difference in uptake patterns of the macronutrients during later development stages appeared to reflect differences in mobility and translocation of the nutrients.

Percent N in the total tops gradually declined from the seedling stage and leveled off shortly after full bloom. Phosphorus concentration increased during the first 30 days after emergence, peaked at initial flowering, declined until mid‐pod fill, and leveled off through the remaining sampling dates. Phosphorus toxicity symptoms were evident at initial flowering with the highest nutrient level imposed. Percent K increased slightly from the seedling stage until full bloom and then declined. Calcium concentration increased until initial flowering, then declined and leveled off during later growth stages while the Mg concentration decreased gradually from the seedling stage through the green bean stage. The concentration of micronutrients (Fe, Mn, Zn, Cu, and B) generally declined from the seedling stage through the green bean stage.
Intraspecific Hybridization as a Method of Breeding Kentucky Bluegrass (Poa pratemis L.) for Turf1
Authors: Pepin Gerard W. , Funk C. Reed
Published: July 2010

Four selections and one cultivar of Kentucky bluegrass were crossed in various combinations. The most vigorous of the resulting hybrids were selected for evaluation of turf performance. After 2 years of observation in turf trials, the 17 most promising turf‐type hybrids were studied in greater detail. Eight hybrids were highly apomictic, and were equal or superior to their parents in a number of characteristics reflecting vegetative and reproductive vigor, disease resistance and turf performance. Many of the most promising hybrids appeared to be triploids resulting from the fertilization of unreduced female gametes.
Seed Hydration‐Chilling Treatment Effects on Germination and Subsequent Growth and Fruiting of Cotton1
Authors: Thomas R. O. , Christiansen M. N.
Published: July 2010

Good and poor quality cottonseed (Gossypium hirsutum L.) were given the following pre‐planting treatments: (a) hydrated in water for 6 hr at 31 C; (b) hydrated as in (a) and chilled for 24 hr at 5 C in water; (c) chilled at 5 C for 24 hr in water; and (d) control no treatment. Field plantings of both good and poor seed were adversely influenced by chilling the seed. Preconditioning hydration prevented chilling injury and also improved performance of plantings of nonchilled poor quality seed. A hydration‐chilling treatment significantly increased yields of plantings from poor quality seed above the control.
Parenchyma Cell Death in Elongating Corn Cobs1
Authors: Katsanos R. A. , Pappelis A. J. , BeMiller J. N. , Tweedy J. A.
Published: July 2010

The pattern of cell death in the parenchyma tissue of the central portion of the corn cob was followed during ear elongation using a pith condition rating system based on the amount of white tissue observed in the cob when it was cut through the longitudinal axis. The white tissue was composed of dead cells. Cell death began in the central region and cells died more rapidly along the longitudinal axis than did those closer to the outer cylinder of vascular tissue surrounding the central parenchyma tissue. Although the pattern for cell death was similar in ears of plants grown on low or high N levels, ears grew longer and cells died earlier in the high N level.
Leaf Angles, Leaf Area, and Canopy Photosynthesis1
Authors: Duncan W. G.
Published: July 2010

For leaf area indices (LAI) of less than approximately 3.0, differences in leaf angle are predicted by computer simulation to have only small effects on canopy photosynthetic rates. For higher LAI values, layers of vertical and horizontal leaves can be arranged to give both the highest and lowest possible rates of canopy photosynthesis for the conditious assumed. These arrangements of leaf layers and angles are not much affected by leaf type or latitude within usual limits.

The ratio of highest to lowest photosynthetic rate varied from 1.14 at LAI 3.0 to 2.0 at LAI 10.0. Calculations with one set of corn (Zea mays L.) descriptions indicate that canopy photosynthetic rates may range from 92% of theoretical maximum at LAI 3.0 to 76% at LAI 7.0.
Size and Frequency of Leaf Stomata in Cultivars of Triticum aestivum and Other Triticum Species1
Authors: Teare I. D. , Peterson C. J. , Law A. G.
Published: July 2010

Lines of Triticum, representing diverse sources of germplasm, were characterized for stomatal frequency. Wheat leaf variation between the first, second, third, and fourth leaves on a tiller, sampling position at the base, center, and tip of each leaf, and sampling position in relation to adaxial or abaxial surface of the leaf were measured.

Stomatal frequency was always greater on the adaxial than on the abaxial surface. Mean ratios (abaxial/adaxial) were .748 for the first leaf and .728 for the second leaf on a culm. Frequencies ranged from 9,219 to 6,372 stomata cm‐2 for the adaxial and 8,024 to 3,487 for the abaxial surface of the first leaf. For the second leaf frequencies ranged from 8,875 to 4,597 for the adaxial and 8,172 to 3,487 for the abaxial surface. Stomatal frequency decreased in relation to position of leaf insertion on the culm. The first leaf had the greatest stomatal frequency, the second had the next greatest, and the fourth had the least. The leaf base contained the most, and the tip, the fewest stomata per unit of leaf area.

Plants grown on Cercosporella‐inoculated plots had more stomata per unit of leaf area than did those grown on the control plots.

No general relation was found between grain yield and number of stomata cm‐2 of leaf surface nor between grain yield and bn (the product of stomata length and stomata per unit of adaxial leaf area).
Advantages of Chromosomal Interchanges That Generate Haplo‐viable Deficiency‐duplications1
Authors: Phillips R.L. , Burnham C.R. , Patterson E.B.
Published: July 2010

Interchanges that produce haplo‐viable deficiency‐duplications have several possible uses. This paper reviews the behavior of these interchanges and relates that behavior to methods of determining linkage between a gene and an interchange breakpoint and their relative order merely by observing the segregation ratios of the unplaced gene in backcross or F2 populations. The method has the advantage that no additional marker gene or pollen classification is needed. Documented and predicted haploviable deficiency‐duplication generating interchanges of maize (Zea mays L.) are listed. A linkage‐detection tester set has been selected marking 19 of the 20 chromosome arms. Data are reported to substantiate the feasibility of the method. Additional uses of these interchanges include their employment in (1) inheritance studies on quantitative traits, (2) obtaining genetic markers for chromosome‐end segments, and (3) the production of duplications for terminal chromosome segments.
Plant Characteristics Affecting Field Drying Rate of Ear Corn1
Authors: Troyer A.F. , Ambrose W.B.
Published: July 2010

Two methods were employed to study field drying in corn Zea mays L.: First, a set of treatments (removal, enclosure, or other modification of plant parts) was imposed on a series of hybrids at the time of approximate physiologic maturity of the grain. Second, morphological differences among more than 150 plant introductions were evaluated. In both methods an attempt was made to determine cause and effect relationships between differences in plants (natural or imposed) and field drying rate of the ear. The results indicated the following: Premature death speeds rate of drying. Rate of drying is relatively independent of number of leaves or amount of green leaf area (including husks) available for transpiration. Husks limit air movement around the grain; loose, short husks, of a low number are conducive to fast drying.
Origin of Parthenogenetic Diploids in Maize and Its Implications for the Production of Homozygous Lines1
Authors: Sarkar K. R. , Coe E. H.
Published: July 2010

To study the production of diploid gametes in diploid maize (Zea mays L.) and their subsequent parthenogenetic development, we crossed males with dominant markers onto a female parent that was marked for identification of maternal embryos by scutellum color and a seedling marker, and for identification of chromosome reduction by heterozygosity for nine unlinked markers. The genotypes of maternal exceptions were determined by progeny tests; all derived from single fertilization. Heterozygosity at all loci, contributed by the female, would result frown failure of reduction at meiosis I; homozygosity at all loci except when gene‐centromere crossingover had taken place from failure of chromatid separation at meiosis II or from fusion of two adjoining megaspores; and complete homozygosity from doubling of reduced egg or fusion of two members of the egg apparatus. An analysis of about 50,000 kernels from the marked crosses failed to detect any cases of unreduced megaspores. However, it yielded two cases in which the diploid female contribution had complete homozygosity for all markers and two cases in which there was a high degree of homozygosity (possibly of megaspore fusion origin). Derivation of an unconventional parthenogenetic diploid individual from a diploid female does not always assure complete homozygosity. Hence, completely homozygous lines cannot be secured by this route.
Recurrent Selection for Bacterial Wilt Resistance in Alfalfa1
Authors: Barnes D. K. , Hanson C. H. , Frosheiser F. I. , Elling L. J.
Published: July 2010

A‐C4 and B‐C4, two unrelated populations of alfalfa, Medicago sativa L., were subjected to recurring cycles of phenotypic selection for resistance to bacterial wilt caused by Corynebacterium insidiosum (McCull) Jens. Thirty‐five hundred to 5,000 seedlings were inoculated in each population per cycle. About 150 plants in each population were intercrossed to initiate each new cycle of selection. The disease severity indices for wilt infection (0 = healthy, 5 = dead) for A‐C4 and after one and two cycles of selection were 3.72, 2.53, and 1.38, respectively. Comparable indices for B‐C4 and after each of four cycles of selection were 4.25, 3.94, 3.67, 3.13, and 2.63. Wilt indices for Narragansett,’ ‘Ranger,’ and ‘Vernal’ were 4.46, 3.04, and 2.17, respectively. Recurrent phenotypic selection was highly effective for developing resistance to bacterial wilt. Different genetic mechanisms for resistance in the two populations were postulated.
Monosomic Analyses of Genes for Stem Rust Resistance Derived from Marquis and Reliance Wheats1
Authors: Anderson M. K. , Williams N. D. , Maan S. S.
Published: July 2010

We determined the chromosomal locations of genes for resistance to culture 111‐SS2 of Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn. in Triticum aestivum L. em. Thell ssp. vulgare (Vill., Host) Mac Kay ‘Marquis’ and ‘Reliance’. Six wheat lines, Mq‐A, Mq‐B, Mq‐C, R1‐A, R1‐B, and R1‐C, which have monogenic resistance derived from Marquis/T. aestivum L. em. Thell ssp. compactum (Host) Mac Key ‘Little Club’ and Reliance/Little Club, were crossed with each of the 21 ‘Chinese Spring’ monosomics. F2 and backcross‐F1 seedlings from each of the crosses were tested for reaction to culture 111‐SS2. Significant deviations from disomic toward monosomic ratios in the F2 and backcross‐F1 were used to identify the chromosomes that had the genes for rust resistance. Mq‐A and R1‐A have a gene (Sr18) on chromosome 1D, Mq‐B has a gene (Sr19) on 2B, Mq‐C and R1‐C have a gene (Sr20) on 2B, and R1‐B has a gene (Sr16) on 2B for resistance to culture 111‐SS2.
A Rapid Method Based on Butanol Extraction for Selecting High‐Lysine Maize (Zea mays L.)1
Authors: Fromberg H. K. , Christ W. , Pollmer W. G.
Published: July 2010

Whole kernel samples from 48 selfed lines (S2, S3) of maize (Zea mays L.) were obtained from crosses involving normal and the mutant opaque‐2. Kernels from these samples were classified as translucent, semitranslucent, and opaque in appearance. All were treated with watersaturated n‐butanol at room temperature. The extraction resulted in losses of nitrogen ranging from 0 to 40%. The nitrogen compounds extracted were nearly free of lysine. The proportion of butanol‐insoluble nitrogen to total nitrogen was closely correlated with lysine content of the protein, with an r value of .817. Similarly, the insoluble nitrogen was closely correlated (r = .847) with the lysine content on a whole‐kernel basis. Since the method requires only the simple procedures of nitrogen determination and butanol extraction, it should be very suitable for screening a large number of maize samples for high lysine.
Ploidy Level Distribution of Tall Wheatgrass in Turkey1
Authors: Schulz‐Schaeffer Jurgen , Chapman S. R. , Yuan Margaret
Published: July 2010

A decaploid chromosome level (2n=70, 73) was predominant in 27 plants of Agropyron elongatum (Host) Beauv. from eight locations in Turkey. Octoploidy was detected at only two locations. Natural hybridization between octoploid and decaploid plants was evident for a collection site near Kayseri, Turkey, where one plant with 2n=73 and two plants with 2n=63 were detected. A hexaploid chromosome level detected earlier in collections of this taxon from Turkey was not found in this study.
Association between Genetic Factors for Crown Rust Resistance and Yield in Oats1
Authors: Frey K. J. , Browning J.A.
Published: July 2010

Through a backcrossing program two series of oat (Avena sativa L.) lines were created, one early and one midseason, that were isogenetic except for genes that conditioned crown‐rust reaction. The lines were tested under crown rust epiphytotic and rust‐free environments, and three of the resistance genes were found associated with sizable deviations in grain yield under the rust‐free conditions. In both early and midseason genetic backgrounds the crown rust reaction gene from C.I. 8079, an Avena sterilis line, was associated with an increase in grain yield. The crown‐rust reaction gene from C.I. 7171 was associated with an increase in yield in the early genotype, but not in the midseason. The crown rust reaction gene from C.I. 7232, a derived tetraploid, was tested only in the midseason genotype in which it was associated with a 9.6% reduction in grain yield.
Influence of Iron Supply on Peroxidase Activity and Peroxidase Isozymes in Corn (Zea mays)1
Authors: Ulmer R. L. , Haskins F. A. , Akeson W. R.
Published: July 2010

Plants of Oh43 ✕ Wf9 corn (Zea mays L.), grown in sand culture system, were watered daily with nutrient solution containing 0.025, 1.25, or 2.5 ppm Fe. Plants also were grown in a soil‐sand mixture. Leaf extracts were assayed quantitatively for peroxidase activity, and sampies of the extracts were subjected to gel dectrophoresis. A positive relationship was observed between Fe supply and proxidase activity. Numerous peroxidase isozymes were detected by gel electrophoresis. As judged by intensity of the hands, all isozymes appeared to be influenced by Fe supply.
Natural Cross‐pollination in Blue Lupine (Lupinus angustifolius L.) in Georgia and Florida1
Authors: Forbes Ian , Leuck D. B. , Edwardson J. R. , Burns R. E.
Published: July 2010

Natural cross‐pollination rates of blue lupine (Lupinus angustifolius L.) in Georgia and Florida ranged from 0 to 11.95% for different genotypes, test sites, test years, and honey bee population densities. The larger and fleshier‐flowered, earlier‐flowering biotype (common bitter blue lupine and ‘Rancher’ sweet blue lupine) had much lower cross‐pollination rates (0 to 3.45%) than the smaller and more fragile‐flowered, late‐flowering, elite winter‐hardy line 65G‐251. Nine other elite winter‐hardy lines were similar to 65G‐251 in floral, maturity, and cross‐pollination‐rate characteristics. We attribute the difference in natural cross‐pollination rates between the two major biotypes to their relative resistance to tripping by honey bees (Apis mellifera L.) or the flowering of the late type at temperatures more favorable for honey bee activity, or both.

Results from tests including treatments designed to prevent flower‐visitation by one or more of the possible insect vectors of cross‐pollination indicate that: (i) Bumble bees (Pyrobombus spp.) easily tripped all types of blue lupine flowers and are cross‐pollination vectors, but their numbers were too few to be the principal vector; (ii) Honey bees were the principal cross‐pollination vectors; (iii) Thrips (Frankliniella spp.) were not cross‐pollination vectors, although they may render some flowers male sterile hy eating all the pollen; (iv) Wild bees were not vectors; and (v) Blue lupine is highly self‐compatible, highly self‐pollinated, and fully capable of automatic self‐pollination, i.e., self‐pollination within the closed flower is independent of insect visitation.

In all tests at all locations cross‐pollination rates were positively correlated with honey bee population densities. Wind protection of the test site favored honey bee activity and higher cross‐pollination rates.

We made suggestions based on these findings for use in breeding, genetic, and variety seed production operations.
Further Studies on the Inheritance of a Self‐Compatibility Response to Temperature and the Segregation of S Alleles in Diploid Alsike Clover1
Authors: Townsend C. E.
Published: July 2010

Inheritance of a self‐compatibility response to a 32‐C temperature and segregation of S alleles were studied in the F1 and F2 progenies of a cross between two temperature‐sensitive I1 clones of diploid alsike clover (Trifolium hybridum L.). Temperature sensitivity (T) was inherited on a digenic banffs in the F1 progeny and was dominant to temperature insensitivity (t). The same two loci controlled temperalure sensitivity in both clones. The S alleles segregated in a l:l:l:l ratio. However, all temperature‐insensitive plants were of one S genotype.

Of 10 F2 progenies evaluated, segregation for temperature sensitivity was 3 T:I t in three progenies, 15 T:I t in five progenies, and 9 T:7 t in one progeny. One progeny with a very high frequency of temperature‐insensitive plants did not fit any acceptable ratio. Segregation ratios for the S allele genotypes were influenced by S allele combinations and individual F1 parents.

The data confirm the previously proposed two.gene model for the inheritance of temperature sensitivity in these two parent clones with an interaction between S allele genotype and temperature sensitivity.
Yield Components in Random and Selected Sugarcane Populations
Authors: James Norman I.
Published: July 2010

Path‐coefficient analyses indicated stalk number was the most important component of yield of millable stalks per unit area in three sugarcane (Saccharum spp.) populations. Stalk diameter ranked second in order of importance in all three populations; stalk length ranked third in two populations and fourth in one population. Stalk density contributed less to cane yield than the other three variables.

Stalk number, stalk diameter, and stalk length accounted for 82, 84, and 84% of the variation in yield in a random plant‐cane seedling population, random first ratoon clonal population, and selected plant‐cane clonal population, respectively.

A negative association between stalk diameter and stalk number, and between stalk diameter and stalk density resulted in a low frequency of large‐diameter highyielding clones in these populations. Thus, a compromise in stalk diameter may be desirable to increase the frequency of high‐yielding clones in selected populations
Changes in Stachyose, Raffinose, Sucrose, and Monosaccharides During Germination of Soybeans1
Authors: East Jerry W. , Nakayama T. O. M. , Parkman Sammie B.
Published: July 2010

The direct use of soybeans [Glycine max L., (Merrill)] for human food is limited due to the presence of undigestible factors. One of these is thought to be stachyose. The course of stachyose disappearance during germination was followed. Soybeans were germinated by a standard procedure and by the same procedure interrupted with a period of water steeping. The effect of hypochlorite addition to the steep water also was investigated. The contents of mono‐ and oligosaccharides changed similarly with all three methods of germination for a 144‐hour period. During the first 96 hours the monosaccharide content increased. Raffinose disappeared by the end of 96 hours of germination, and stachyose disappeared by the end of 144 hours of germination. Steeping resulted in a decrease in the rate of rootlet growth without a decrease in the rate of disappearance of stachyose or raffinose. Water steeping and hypochlorite treatment were valuable in retarding mold growth throughout the 144 hours of germination.
Linkage Tests in Upland Cotton, Gossypium hirsutum L. II.1
Authors: Kohel R. J.
Published: July 2010

Results of linkage analyses of cotton performed at College Station, Texas are presented, and linkage information reported by other workers is summarized. The mutants withering bract, accessory involucre, abnormal palisades, Ragged Leaf, round leaf, Red Dwarf, male‐sterile‐1, male‐sterile‐2, Male‐sterile‐4, and Ligon Lintless were tested for linkage with several marker loci and in various combinations among themselves.

Ragged Leaf and round leaf were found to be linked (R.C. = 32 %), and thus form a new linkage group, number X. Data are presented to document the simple dominant inheritance of Ligon Lintless; the symbol Li is assigned to the mutant allele.
C‐Labelled Photosynthate Translocation and Utilization in Cotton Plants1
Authors: Ashley D. A.
Published: July 2010

Cotton (Gossypium hirsutum L.) plant organs were exposed to 14CO2 under field conditions to quantitatively evaluate the relative contribution of these organs to fruit development and to obtain information on photosynthate translocation rates. From 87.5 to 91.0% of the photosynthate remained in the sympodia regardless of the vertical position of the sympodia on the main stem or the lateral position of the leaf on the reproductive branch. The primary source of photosynthate for a boll was its subtending leaf with some photosynthate supplied from the associated bracts and from leaves one node removed from the boll. A more rapid rate of photosynthate export was found for main stem leaves than from sympodia leaves. The rate of photosynthate translocation from leaves to other plant parts was slow relative to rates reported for other species with high photosynthetic rates.
Perennial Ryegrass Varietal Response to Maleic Hydrazide1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Maleic hydrazide applied as a soil drench to 13‐day‐old perennial ryegrass (Lolium perenne L.) caused leaves of many plants to become chlorotic. Varieties differed in percentage of chlorotic plants and conversely in percentage of green plants. ‘Manhattan’ had significantly fewer chlorotic plants than other varieties tested. Photoperiods (ranging from 9.5 to 14 hours) and concentrations (300 ppm compared to 600 ppm) did not alter varietal response greatly.
Effects of Leaf Area on Photosynthetic Rate, Light Penetration, and Grain Yield in Barley1
Authors: Berdahl J. D. , Rasmusson D. C. , Moss D. N.
Published: July 2010

Related barley (Hordeum vulgare L.) lines, with small‐ and large‐leaf areas were developed and used to study the effect of leaf area on photosynthesis, light penetration, and grain yield. An infrared gas analyzer was used to measurep hotosynthesis of flag leaves in the laboratory and photosynthesis of plant canopies in the field. Light penetration into plant canopies was measured with tube solarimeters. LAI, grain yield, and the components of yield were determined in field plots.

Photosynthetic rates per unit leaf area in the laboratory were similar in small and large flag leaves; thus, total photosynthetic activity per leaf was about twice as great in the large flag leaves. In field comparisons, however, no consistent differences in photosynthetic rates of small‐ and large‐leaf canopies could be detected, even though LAI's were greater in large‐ than in small‐leaf canopies by 19% in Population I and by 33% in Population II. Photosynthesis in the barley canopies as a whole was limited by lack of light throughout the entire range in intensity of solar radiation.

In yield trials large‐leaf lines exceeded small‐leaf lines in flag leaf area by 70% and in LAI by 25%. Lines with small leaves produced more heads and higher grain yields than lines with large leaves when plants did not lodge. Where lodging occurred, however, large‐leaf lines had higher kernel weights and were higher yielding. We postulate that large leaves favor higher kernel weights and that small leaves favor production of more culms.
Leaf Area‐Leaf Weight Relationships in the Soybean Canopy1
Authors: Koller H. R.
Published: July 2010

Leaf area (A) and leaf dry weight (LW) were determined throughout the growing season for lower, middle, and upper main stem segments and branches of a field soybean [Glycine max (L.) Merrill] community. The A/LW ratios were regressed on number of days after planting, using polynomial regression models. For the middle main‐stem segment, A was also regressed on LW.

Mean seasonal A/LW decreased from the base to the top of the canopy. Mean A/LW of branches was higher than that of any main‐stem segment.

The A/LW ralio of each main‐stem segment continually declined until just prior to leaf senescence. The trend subsequently reversed and A/LW increased rapidly during leaf abscission. The trend in A/LW of the branches differed in that there was an initial increase in A/LW, followed by a decline and then a second increase during leaf abscission.

Due to time related changes in A/LW, models for the prediction of soybean leaf area from leaf weight should also include time as a variable if observations are made at different growth stages.
Seed Size Effects Upon Seedling Vigor of Three Forage Legumes1
Authors: Carleton A. E. , Cooper C. S.
Published: July 2010

Seed size‐seedling vigor relationships were studied with birdsfoot trefoil (Lotus corniculatus L.), alfalfa (Medicago sativa L.), and sainfoin (Onobrychis viciaefolia Scop.). Differences in seed size were separated into those among plants and within plants. Seed weight distribution patterns were measured for each plant. An additional study measured the effect of varying number of seeds per raceme upon seed size of sainfoin.

Correlations among clones of seed size with seedling vigor were significant in birdsfoot trefoil, were not significant in alfalfa, and approached a significant level in sainfoin. Differences in seed size within plants were highly correlated with seedling vigor in all legume species. The degree to which seed size can be affected by regulating seed number per raceme was shown for five sainfoin plants.

Seed weight distribution patterns varied widely among plants within a species. The importance of these patterns in selecting for seedling vigor and in obtaining genetic equality in the contribution of plants to a composite variety is discussed.