bluuebunny/crossref_metadata_2025 huggingface dataset:
EMS‐Induced Male‐Sterile Mutants in Euplasmic and Alloplasmic Common Wheat1
Authors: Sasakuma T , Maan S. S. , Williams N. D.
Published: July 2010

We studied 12 EMS‐induced male‐sterile mutants that were isolated from alloplasmic Triticum aestivum L. having T. tauschii (Coss.) Schmal. cytoplasm. Of these 12, four mutants had all empty pollen grains; the remaining eight mutants had small proportions of fertile pollen grains. Eleven of the male‐sterile lines were crossed to euplasmic ‘Chris’, and the F1 heterozygous male‐fertile plants were selfed or used as males in backcrosses to Chris. The BC1S1 male‐fertile plants were used as males in backcrosses to alloplasmic male‐sterile Chris to observe segregation for male‐sterility. Segregations in F1, F2, and BC1S1 progenies indicated that the inheritance of male‐sterility in the 11 mutants was controlled by single recessive genes, three of which were shown to be allelic. Eight of these mutant genes induced male‐sterility in euplasmic T. aestivum, and the same capability for the other three recessive mutants was not ruled out. One of the 12 mutants, FS6, had a dominant gene controlling male‐sterility. This dominant male‐sterile (FS6) produced segregating F1's from crosses with four common wheat cultivars and seven male‐fertility restorer (R‐)lines containing Rf genes from T. speltoides (Tausch) Gren. ex Richter, T. monococcum L., or 4x or 6x T. timopheevii (Zhuk.) Zhuk. The results indicated that the dominant gene for male‐sterility in FS6 was stable under different genetic backgrounds and did not interact with other gene(s) affecting male fertility.
An Evaluation of Control Plots and Moving Means for Error Control in Barley Nurseries1
Authors: Mak C , Harvey B. L. , Berdahl J. D.
Published: July 2010

Frequently repeated control plots and the moving mean of adjacent plots were compared as methods of controlling error in single‐row plots of barley, Hordeum sativum Jess. (H. vulgare L.) Adjustment by either technique was more effective for grain protein content than for grain yield. Covariance adjustment using either moving mean or control plots prevented overadjustment in several instances and was always more effective than percentage adjustment in reducing experimental error. Repeated control plots and moving means gave similar control of experimental error, but control plots had less practical application than moving means. A partially balanced lattice design accomplished superior control to both methods using percentage adjustment and similar control using covariance adjustment. In cases where the number of entries was too large to accommodate an incomplete block design, covariance adjustment using the moving mean would be advantageous.
Inheritance of a Soybean Seed Lectin1
Authors: Orf J. H. , Hymowitz T. , Pull S. P. , Pueppke S. G.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seed from the reciprocal crosses of ‘Amsoy’ and T102 were used to study the inheritance of the soybean seed lectin (SBL) having a molecular weight of 120,MH). Amsoy contains SBL while T102 lacks SBL. From data collected using polyarcylamide gel electrophoresis the presence of SBL is controlled by a single dominant gene designated Le. The homozygous recessive le le results in the lack of SBL. The availability of soybean lines lacking SBL may aid in determining the role and function of SBL.
Characterization of Cytoplasmic Diversity in Soybeans by Restriction Endonuclease Analysis1
Authors: Sisson V. A. , Brim C. A. , Levings C. S.
Published: July 2010

The limited geographic origin and paucity of maternal ancestors is a reasonable basis for suspecting that cytoplasmic uniformity exists among currently grown soybean (Glycine max (L.) Merr.) cultivars. Restriction endonuclease fragment analysis of mitochrondrial DNA (mtDNA) was used to assess the cytoplasmic diversity in soybeans. Ten sources of soybean germplasm including the predominant maternal ancestors of cultivated soybeans and their putative wild progenitor, G. soja Sieb. and Zucc., were examined. MtDNA isolated from each test genotype was digested with the restriction endonucleases BamI or SalI and the resulting fragments separated by gel electrophoresis. Comparison of the restriction patterns showed a high degree of homology among the mtDNAs from the test genotypes. The restriction patterns of the maternal ancestors were indistinguishable, with the exception of a single unique band present in the Sal‐restriction pattern of the cultivar ‘Lincoln’. Other intraspecies differences of one or two bands were noted among the banding patterns of the test genotypes. The fragment pattern of G. soja was readily distinguishable from the maternal ancestors when digested by either enzyme. Results of this study tended to substantiate the premise that cytoplasmic uniformity exists among currently grown soybean cultivars.
Inoculation of Detached Cotyledons For Screening Soybeans Against Two Races of Phytophthora Megasperma Var. Sojae1
Authors: Morrison R. H. , Thorne J. C.
Published: July 2010

A non‐destructive method was used to evaluate the resistance of soybean (Glycine max (L.) Merr.) to Phytophthora megasperma. Drechs. var. sojae Hildeb. based on the reaction of detached cotyledons inoculated with the pathogen. Cotyledons from soybean seedlings were placed on moist filter paper and inoculated with an agar culture homogenate of the pathogen using a hypodermic needle. Disease reactions were determined 72 to 96 hours after inoculation. Cotyledons of resistant genotypes showed only a slight discoloration at the inoculation site; cotyledons of susceptible genotypes became severely necrotic.

Similar results were obtained with cotyledon and hypocotyl inoculation when soybean genotypes differing in their reaction to races 1 and 3 were tested. The same plant could be tested simultaneously with both races by using a mixture of races, or by inoculating each cotyledon with a single race. The method was effective for greenhouse and field grown plants. Cotyledon inoculation is non‐destructive so that susceptible germplasm may be conserved and field‐grown plants can be tested without introducing the pathogen into an area.
Response to Selection for Yield in F3 of Four Wheat Crosses1
Authors: O'Brien L. , Baker R. J. , Evans L. E.
Published: July 2010

Four wheat (Triticum aestivum L.) crosses with the cultivar ‘Glcnlea’ as a common female parent were used to investigate response to selection for yield in the F3 generation. Selection was based on the mean performance of F3 lines (seed from a single F2 plant) grown in three replicate, three‐row plot yield tests in 1975. Response to selection in each cross was measured using F4 bulks, F5 bulks, and the family mean of eight random F5 lines. Significant response to selection was observed for Crosses I and II. These two crosses were characterized by wide yield range and a relatively high genetic variance among lines in the F3 yield test. In Crosses III and IV, which were characterized by less yield range and genetic variance among lines in the F3 yield test, response generally was not significant. The effectiveness of early generation yield testing was influenced by the amount of environmental variation among generation means and the amount of genotype and genotype ✕ environmental variation. Realized heritabilities were lower than those estimated from testing at one location in a single year in all four crosses.
Inheritance of Husk Numbers and Ear Insect Damage in Maize1
Authors: Brewbaker James L. , Kim Soon Kwon
Published: July 2010

Studies were made to determine the extent and genetic control of husk number variations in maize (Zea mays L.), and to test their association with ear insect resistance and response to environmental influences. Husk numbers were highly uniform within inbreds and single‐cross hybrids, ranging from 6 to 19. Twelve inbreds were chosen to represent this range for diallel and generation‐mean analyses. Analyses were made in Cali, Colombia, and in Waimanalo, Hawaii, of husk numbers from 10‐ and nine‐parent diallels. General combining ability (g.c.a.) mean squares were highly significant at both locations. Specific combining ability mean squares were also significant, but were exceeded by the g.c.a, values by ratios of 5.3 to 1 (Colombia) and 19.9 to 1 (Hawaii). Hybrids showed a significant positive heterotic effect of 11%, and array means correlated well with parental values (r = 0.93). Means and array means for the hybrids grown at both locations were also highly correlated (r = 0.94 and r = 0.86, respectively). F2 and backcross progenies of 10 crosses involving high ✕ low husk numbers were analyzed. Backcross progenies commonly reverted sharply toward parental means, and F2 and F1 means were quite similar. Environmental variability was high and narrow‐sense heritability estimates were low (average 24%). The Cuban Flint‐derived inbred CM111 (India) provided the best genetic source for increasing husk numbers, which is proposed as a practical and efficient alternative to selection for low insect injury for improved ear pest resistance.

Damage by the larvae of ear insects was evaluated for earwrm (Heliothis zea Boddie) and fall armyworm [Spodoptera frugiperda (J. E. Smith)] in relation husk numbers in Hawaii and Colombia. Resistance was notably higher in tropical lowland types of maize with high husk numbers. Ear damage in Hawaii (largely earworm) correlated significantly (r = −0.40) with husk numbers that ranged from 6 to 14 in a broad‐based composite. Ear insect damage in Colombia (largely fall armyworm) also correlated significantly (r = −0.68) with husk numbers that ranged from 8.0 to 14.9 in a 45‐entry diallel. Husk numbers were highest for lowland tropical races of maize and lowest for temperate and montane races, correlating significantly (r = −0.71) with elevation at which the race was indigenous. It was concluded that ear pests provided strong selection pressure for higher husk numbers during evolution of maize. Environmental effects on husk numbers appeared solely to relate to temperature during growth, and a reduction of one husk was observed for a corresponding increase of 4 C in growing temperature during early growth.
Effect of BASF 13‐338, a Substituted Pyridazinone, on Linolenic Acid Levels and Winterhardiness of Cereals1
Authors: St. John J. B. , Christiansen M. N. , Ashworth E. N. , Gentner W. A.
Published: July 2010

The substituted pyridazinone BASF 13‐338 [4‐chloro‐5(dimethylamino)‐2‐phenyl‐3(2H)‐pyridazinone] was tested in the field to evaluate its effect on linolenic acid levels and winter‐hardiness of small grains. Wheat (Triticum aestivum L. em Thell), barley (Hordeum vulgate I.,) and rye (Secale cereale L.) were sown in the fall in soil incorporated BASF 13‐338 at rates of 0, 2.8, 5.6, and 11.2 kg/ha. All concentrations of the compound reduced the linolenic acid content of polar lipids in the shoots of each of the test species. Treated plants showed early low temperature injury symptoms as evidenced by frost‐banding. Counts taken in the spring Indicated that BASF 13‐338 treatments reduced survival. Treated plants that did survive had fewer tillers than untreated plants. Plants grown in the greenhouse and treated with 11.2 kg/ha of BASIF 13.338 survived treatment with the chemical but were killed if subjected to −5 C. The collective data strongly support the hypothesis that accumulation of linolenic acid is an initial step in plant adaptation to low temperature although other factors may limit hardening and distinguish levels of hardiness among cultivars and species.
Cultivated Alfalfa at the Diploid Level: Origin, Reproductive Stability, and Yield of Seed and Forage1
Authors: Bingham E. T. , McCoy T. J.
Published: July 2010

Cultivated alfalfa (Medicago sativa L.) at the diploid level (CADL) was developed from cultivated tetraploids over a 10‐year period using haploidy, with breeding and selection. The goal was to produce a diploid form for research which was seed‐reproduced and stable in chromosome number. The 4x‐2x cross method was used to obtain 2x haploids, which, although relatively sterile, could be used as females in initial crosses with 2x M. falcata F1 hybrids thus obtained were fertile and were backcrossed as male parents to 2x haploids. CADL populations were selected for seed yield in between backcrosses. The proportion of cultivated germplasm increased by half with each backcross progressing from 50% in initial F1 hybrids with M. falcata to 98.44% in the fifth backcross to haploids, which is the current level. Selection for fertility was very effective and resulted in cross‐ and self‐fertility levels similar to tetraploid alfalfa in terms of seed number. Seven CADL populations and 2x M. falcata were screened for plants producing restitution (2n) gametes and for tetraploid plants in the diploid populations. Early populations contained a few plants producing 2n gametes and 2% tetraploids, while recent populations, which have had more selection for diploid fertility, contained no tetraploids. Hence, true breeding diploid CADL populations were obtained. A population with 87.5% cultivated germplasm was tested for forage yield and produced 72% as much as Vernal in three cuttings in the first 2 production years. Research applications of CADL were discussed.
Linkage Tests in American Pima Cotton1
Authors: Turcotte E. L. , Feaster Carl V.
Published: July 2010

The results of 42 linkage tests involving six American Pima cotton (Gossypium barbadense L.) mutants and 15 mutants of G. hirsutum L. are reported. Forty of the tests gave no significant evidence of linkage and two tests indicated linkage. A dominant Pima male‐sterile mutant (Msp) was found to be linked with one of a pair of duplicate factors for glandless (gl1) with 9.38 ± 0.98% recombination and with naked seed (N1) with 13.95 ± 1.89% recombination. Msp was not allelic with the dominant male‐sterile genes Ms4, and Ms7. The gene symbol, Ms11, is proposed for the character Pima male‐sterility in place of the currently used symbol Msp.
Identification of Soybean Germplasm Lines and Cultivars with Low Incidence of Soybean Mosaic Virus Transmission through Seed1
Authors: Goodman Robert M. , Bowers Glenn R. , Paschal E. H.
Published: July 2010

Soybean [Glycine max (L.) Merr.] cultivars and germplasm lines from the USDA soybean germplasm collections were tested to determine the incidence of soybean mosaic virus (SMV) transmission through seeds. Eighthundred ninety‐seven accessions were used, 400 from the tropical maturity groups (VIII, IX, and X) and 497 from temperate maturity groups II and III. Field‐grown soybeans at Isabela, Puerto Rico (18° N Lat) or Urbana, 111 (41° N Lat) were manually inoculated at the primary leaf stage with the “Illinois severe” isolate of SMV (SMV‐I1‐S). Seeds harvested from SMV‐I1‐S infected plants were planted in sand benches in a greenhouse and the incidence of virus infected seedlings was determined by observation of symptoms and by indexing. In 1976, all 897 lines were tested with 200 seeds per line. In 1977, 98 tropical lines and 35 temperate lines which had low incidence of transmission in 1976 were tested with 1,000 seeds per line. Nontransmitting lines from 1977 tests and their maturity group classification were FC 31678 (III), PI 60279 (II), PI 68680 (II), PI 70019 (III), PI 70036 (II), PI 88303 (II), PI 91115 (II), PI 92684 (II), PI 92718‐2 (III), PI 203406 (VIII), PI 240664 (X), PI 325779 (IX), PI 360835 (II), ‘Arisoy’ (VIII), ‘Cloud’ (III), ‘Manchu 2204’ (III), ‘Merit’ (0), ‘Mukden’ (II), and ‘Virginia’ (IV). Most temperate lines selected for absence of seed coat mottling in 1976 had a high degree of mottling when tested in 1977.
Cracked Root Mutant in Cotton: Inheritance and Linkage with Fertility Restoration1
Authors: Weaver J. B. , Weaver D. B.
Published: July 2010

A cracked root condition was observed in a line of upland cotton (Gossypium hirsutum L.) with G. harkenssii Brandegee cytoplasm. F1, F2, and testcross generations were grown to determine the inheritance of the cracked root condition. Observations indicate the character to be controlled by a single gene pair expressing complete dominance in upland stocks. In F1 hybrids between homozygous dominant cracked root upland plants and normal root G. barbadense L. plants, roots appear to be normal to slightly cracked, and inheritance is uncertain. Data indicate linkage of cracked root and fertility restoration with observed recombination values ranging from 6.7 to 14.5%.

The symbol Rc is proposed for the gene responsible for the cracked root phenotype and the symbol Rf is proposed for the fertility restoring gene.
Effects of Ploidy Level on the Components of Sucrose Yield and Quality in Sugarbeet1
Authors: Smith G. A. , Hecker R. J. , Martin S. S.
Published: July 2010

Comparisons of 2χ, 3χ, and 4χ sugarbeet (Beta vulgaris L.) lines and hybrids were made to determine the effects of ploidy level on sucrose yield and quality components in equivalent and non‐equivalent hybrid populations.

The relative order of importance for the components of recoverable sucrose was generally the same for all three ploidy levels, with root weight having the greatest path coefficient direct effect and juice purity the least.

Purity generally decreased as .ploidy level increased; this decrease was accompanied by increase in the quantity of non‐sucrose chemical components in the extract.

Significant differences were found between reciprocal equivalent 3χ hybrids for both yield and quality components. Recoverable sucrose yield of triploids produced from tetraploid female plants. [3χ(4χ ♀ )] averaged 17% greater than that of the reciprocal 3χ(4χ ♂ ) hybrids. The same 3X(4x ♀ ) triploid hybrids also were lower than their reciprocal equivalents in extract concentrations of Na. K, and total N, with decreases of 9, 17, and 12%, rcspectlvely. When components are expressed in rag/100 g sucrose, the corresponding decreases were 13, 20, and 16%, respectively.
Uniform Stage Descriptions in Upland Cotton1
Authors: Elsner J. E. , Smith C. Wayne , Owen D. F.
Published: July 2010

A systematic method of defining the developmental stages of upland cotton (Gossypium hirsutum L.) is described. The stages of growth are divided into two groups: vegetative and reproductive. The stage of growth of an individual plant is determined by the number of main stem nodes. The uppermost node immediately preceded by a 1.25‐cm internode is considered the latest developed node for staging purposes.

Use of these systematic growth stages should lead to more uniform application of agronomic research treatments, cultural practices, and the like.
Effect of Temperature on Rate of Leaf Appearance and Flowering Date in Maize1
Authors: Tollenaar M. , Daynard T. B. , Hunter R. B.
Published: July 2010

Classification of development in maize (Zea mays L.) based on temperature is important because of the need in agriculture to determine the adaptability of genotypes to particular environments and to predict flowering dates for breeding purposes. An equation predicting the effect of temperature on rate of development of maize was obtained by measuring the rate of leaf appearance of six short‐season maize hybrids. The hybrids were grown in growth cabinets at constant day/night temperatures ranging from 10 to 35 C, in 5 C increments, with a 15‐hour photoperiod. Rate of leaf appearance was also measured on plants grown under 16 regimes of differential day/ night temperature. The predictive value of the temperature vs. rate of leaf appearance curve was compared with calendar days from planting to silking and accumulated heat units from planting to silking, calculated by both the Degree Days and Ontario Corn Heat Unit (OCHU) methods, using date of flowering for 22 hybrids grown during 3 years at four locations.

Polynomial regression analysis of data for maize plants grown at constant day/night temperatures produced a cubic equation for rate of leaf appearance (leaves/day) vs. ambient temperature. This equation (Y = 0.0997 − 0.0360T + 0.00362T2 − 0.0000639T3) could be used to predict rate of leaf appearance in fluctuating temperature environments. For field‐collected data, the equation for rate of leaf appearance vs. temperature was superior to calendar days but similar to the Degree Days and OCHU methods in predicting dates of silking. Adjustment of the predicted time to silking by accounting for the effect of mean temperature during the first 30 days after planting on maximum leaf number (increase of 0.2 leaves/C increase in temperature) enhanced the precision of the derived equation in predicting date of silking.
Respiration and Concentration of Water Soluble Carbohydrate in Plant Parts of Contrasting Tall Fescue Genotypes1
Authors: Jones R. J. , Nelson C. J.
Published: July 2010

Little information is available concerning genotypic differences in dark respiration (RD) of plant tissues. The objectives of these studies were to determine if a gradient of RD (02 uptake) existed along the leaf blade and to compare maintenance respiration, growth respiration, and concentration of water‐soluble carbohydrate (WSC) leaf blades, terminal meristems areas, and root tips of seven genotypes of tall rescue (Festuca arundinacea Schreb.). Three genotypes had been selected for contrasting yield/tiller, and four genotypes had been selected for contrasting CO2 exchange rate (CER)‐yield relationships.

Center portions of mature leaf blades had the highest rate of RD and were used in subsequent leaf studies. Dark respiration of mature leaf blades probably reflected maintenance respiration since it was independent of measured carbohydrate levels and leaf growth had ceased. Rates of RD 3 hours after the photoperiod began were similar to those measured after 48 hours of darkness in elongating leaves and terminal meristems. Concentrations of WSC in these tissues were decreased during the dark period, but probably not enough to stop respiration associated with the growth component. Respiration of root tips was not significantly different among genotypes selected for contrasting yield/tiller, but was decreased to about 44% of the original rate by the 48‐hour dark treatment. That rate may have represented the maintenance component. Rates of RD of mature blades and terminal meristems of low, medium, and high yield/tiller genotypes corresponded to their yield/tiller classification. Conversely, among the four genotypes selected for their differential CER‐yield relationship, the low CER‐Iow yield genotype had the highest RD of mature leaf blades and terminal meristems.

In general, concentrations of WSC within tissues did not differ significantly among genotypes. Terminal meristems had a significantly higher concentration of WSC than did other plant tissues studied, and weights of WSC per terminal meristem were significantly different among genotypes. These data showed that genetic variation for RD existed in tall rescue, that RD was different for tissues within a plant, and that 48 hours in darkness was insufficient to decrease WSC enough to clearly separate the growth and maintenance components of RD in tall fescue.
Inheritance of Reaction to Soybean Mosaic Virus in Soybeans1
Authors: Kiihl Romeu A. S. , Hartwig E. E.
Published: July 2010

Eight soybean [Glycine max (L.) Merr.] cultivars previously identiifed as resistant to soybean mosaic virus (SMV) and three susceptible cultivars were used in a study to determine the inheritance of reaction to SMV. Field‐grown F2 and F3 populations were inoculated with virus strain SMV‐1. Greenhouse studies were also conducted in which the stock was inoculated and the reaction of homozygous and heterozygous scions determined. A variant of SMV‐1, designated SMV‐l‐B, was isolated and used to inoculate cultivars showing differential reactions to SMV‐1. Two types of resistance were recognized. The highest level of resistance gave complete protection against both SMV‐1 and SMV‐l‐B. The lesser level of resistance gave protection against SMV‐1 in the homozygous condition, but some of the heterozygous plants were necrotic. All homozygous plants became necrotic after inoculation with SMV‐l‐B. We proposed that the highest level of resistance be symbolized Rsv Rsv, the lesser level of resistance as rsvt rsvt, and the susceptible as rsv rsv. Rsv, rsvt, and rsv form an allelomorphic series with Rsv dominant to rsvt and rsv; and rsvt dominant to rsv.
A Temperature Sensitive Miniature Soybean1
Authors: Kilen T. C.
Published: July 2010

A miniature soybean [Glycine max (L.) Merr.] was grown in field and greenhouse environments in an attempt to find conditions that would favor the development of normal flowers for crossing and for seed production. A growth chamber study was also conducted to examine the effects of night, temperature upon the expression of the miniature trait.

When planted in the field in mid‐May, the miniature type grew about 3 cm tall, had cleistogamous flowers, and produced no seed. Planted in a greenhouse in mid‐May, miniature plants grew 21 times as tall as those in the field, had normal flowers and viable pollen, and had relatively good seed production. Average day temperature in the greenhouse was 10 C higher than that in the field, and the average night temperature was 4 C higher. When grown for 3 weeks in a growth chamber at a day temperature of 38 C and night temperatures of either 15, 20, or 24 C, minature plants were 5, 26, and 99% respectively, as tall as the cultivar ‘Hill’. The study showed that the summer greenhouse environment favored seed production in miniature plants, causing their highly cleistogamous flowers to develop, and open normally and permitting their use for crossing.
Variation in Stomatal Density with Leaf Position in Field‐Grown Soybeans1
Authors: Lugg D. G. , Sinclair T. R.
Published: July 2010

The objective of this study was to determine the stomatal density for all leaves of two soybean (Glycine max (L.) Merrill) cultivars and investigate the variation with leaf position. On the adaxial surface, stomatal density increased progressively from the lowest nodes to a maximum at node 7 and progressively declined to the uppermost nodes for both cultivars. On the abaxial surface a similar pattern existed for ‘Corsoy‖, but was not distinct for ‘Chippewa 64.’ The correlation coefficients between adaxial arid abaxial stomatal densities were 0.63 and 0.22 for Corsoy and Chippewa 64, respectively. The mean ratios of adaxial and abaxial stomatal density were 0.55 for Corsoy and 0.50 for Chippewa 64. This ratio was higher for leaves at the middle nodes than that for leaves at upper or lower nodes. Mean stomatal densities on the adaxial surface were 102.1 and 101.1 stomata/mm2 for Corsoy and Chippewa 64, respectively. On the abaxial surface, Chippewa 64 had greater stomatal density for all but two nodes and the means were 206.3 and 183.1 stomata/mm2 for Chippewa 64 and Corsoy, respectively. Chippewa 64 also had larger leaves than Corsoy at all nodes. It was concluded that a large variation in stomatal density makes it difficult to compare single measurements for different cultivars.
Cross‐Fertility Differentials in Birdsfoot Trefoil1
Authors: Schaaf H. M. , Hill R. R.
Published: July 2010

The flowers of 13 selected birdsfoot trefoil (Lotus corniculaius L.) genotypes were cross‐pollinated by hand in a complete diallel after emasculation to prevent selling. Fertility was measured by pods/flower pollinated (P/F), seeds/pod (S/P), and seeds/flower pollinated (S/F). The 156 crosses showed a continuous range in fertility from 0.98 P/F, 25.3 S/P, and 22.5 S/F to virtual sterility (no pods or seeds). All estimates of genetic variance (females, males, and females ✕ males) for cross fertility were highly significant (P < 0.01), except the interaction for S/P (P < 0.05). The genetics of male fertility appeared to differ from that of female fertility. Male effects were more important than female effects, especially for S/P. Although all these three measures of fertility ranked the plants similarly as females and males, S/F accentuated differences among plants owing to the accumulative effects of P/F and S/P on S/F. We concluded that genotypic differences in cross fertility can induce disproportionate genetic arrays in trefoil populations, even when other causes of nonrandom mating are absent.
Effects of the N Mosaic‐Resistance Factor on Agronomic and Chemical Traits in Burley Tobacco1
Authors: Legg Paul D. , Collins G. B. , Litton C. C.
Published: July 2010

Isogenic or near‐isogenic lines in eight cultivar backgrounds of burley tobacco (Nicotiana tabacum L.) were developed with the N. glutinosa L. factor for mosaic resistance. For each cultivar background, a resistant and a susceptible selection from the seventh backcross generation pins the recurrent parental cultivar were evaluated for several agronomic and chemical traits. Effects of the resistance factor or associated genetic material on characteristics other than response to the mosaic virus were not consistent over genotypes. The results, plns information from other studies, indicated that the genetic constitution of a recipient line influences the effects of the resistance factor.
Capacity for Proline Accumulation During Water Stress in Barley and Its Implications for Breeding for Drought Resistance1
Authors: Hanson A. D. , Nelsen C. E. , Pedersen A. R. , Everson E. H.
Published: July 2010

During controlled water stress applied at the threeleaf stage, the barley (Hordeum vulgare L.) cultivars ‘Proctor’ and ‘Excelsior’ showed different rates of free proline accumulation and leaf‐firing. Both processes were faster in Proctor (a drought‐susceptible cultivar) than in Excelsior (a drought‐resistant cultivar). The different rates of proline accumulation during stress in Proctor, in Excelsior, and in a wild barley (H. spontaneum C. Koch) could be attributed to differences in the rate of decline of leaf water potential (ψleaf); at the same ψleaf value, all three genotypes contained similar amounts of free proline.

After non‐destructive screening of the F2 generation from a Proctor ✕ Excelsior cross for proline‐accumulating capacity under controlled water stress conditions, F3 seed from plants selected for high and low proline accumulation was obtained. When F3 plants were tested for proline accumulation during controlled stress, the selection for proline accumulation was found to have been effective. Reselection among F3 plants and subsequent testing of the F4 generation confirmed this result.

Among individual plants of the F3 generation (which was segregating for the prollne accumulation trait) there was a positive association between the amount of free proline accumulated during stress and the severity of leaf‐firing.

Massive proline accumulation is a symptom of severe internal water stress in barley and apparently has no survival value during drought. Although there is heritable variation in the amount of proline accumulated during stress, it is not of practical value in breeding for drought resistance.
A Disomic‐5D‐Nullisomic‐5B Substitution Line of Durum Wheat1
Authors: Joppa L. R. , Williams N. D.
Published: July 2010

A disomic‐5D nullisomic‐5B (5D(5B)‐substitution‐disomic) line of durum wheat (Triticum turgidum L.) was produced by crossing a monosomic‐5B‐monosomic‐5D line with a 5D‐addition‐disomic line of ‘Langdon’ durum. This line is fertile, vigorous, and has homoeologous pairing because of the absence of the Ph gene on chromosome 5B. This line can be best maintained as disomic‐5D monosomic‐ 5B. The breeding behavior of this line is discussed. It should be useful for the introduction of alien genes from various species into durum wheat through pairing and exchange of genetic material between homoeologous chromosomes.
Inheritance and Association of Six Traits in Safflower1
Authors: Kotecha Ashok
Published: July 2010

The parents, F1 and F2 from four crosses of safflower (Carthamus tinctorius L. and C. palaestinus Eig.) were studied in field experiments. Data were taken on individual plants to estimate heritability, gene action, and mode of inheritance of plant height, time of flowering (TF), time to maturity (TM), time from flowering to maturity (TFM), leaf length, and stem diameter. In all crosses, F2 variability was largely genetic for all traits. Gene action was additive for plant height and leaf length, but nonadditive for TF, TM, and TFM. Gene action for stem diameter was additive in Cross 3 but nonadditive in Cross 4. The broad‐sense heritability estimates were high for all traits studied. Maternal effects were absent, except for TM and leaf length. In all F2's, continuous distributions were observed, suggesting multiple‐factor inheritance for plant height, TF, TM, TFM, leaf length, and stem diameter. Heritability estimates in the narrow sense for TF and plant height, calculated from the cross N4051 ✕ 830293, were 11 and 79%, respectively. In the same cross, the values for expected genetic advance for TF and plant height were 0.70 and 17.0%, respectively. On the basis of apparent gene action, heritability estimates and expected genetic advance, direct selection to improve plant height should be effective.

Plant height was not associated with striped hull or flower color; however, plant height was associated with anthocyanin pigmentation. Also, TF was not associated with striped hull, anthocyanin pigmentation, or flower color. Correlation coefficients of TF with TM and TM with TFM were high.
Selection Indices for Corn Grain Yield, Percent Protein, and Kernel Weight1
Authors: Kauffmann K. D. , Dudley J. W.
Published: July 2010

The objectives of this study were (i) to compare the effectiveness of a desired gain index, direct selection, and an estimated index for improvement of corn (Zea mays L.) grain yield and percent protein and (ii) to compare the effectiveness of mass selection and half‐sib family selection for increasing percent protein. Seven selection method‐index combinations were applied to two corn populations (RSSSC, a composite of four stiff‐stalk selections and RSL, a ‘Lancaster’ population) in each of 2 years. For half‐sib family selection, 200 families from each population were evaluated in three replications each year. For mass selection, 500 ears, 25 ears from each of 20 blocks, were analyzed for protein and kernel weight.

Selected progenies were evaluated in 20 replications in 1977. Indices compared were: (i) desired gain indices to (a) increase yield 20% and jprotein to 13% (HSPY) and (b) increase percent protean while holding kernel weight constant using half‐sib family means (HSPK) mass selection (MSPK); (ii) direct selection for grain yield (HSBY) or percent protein (HSBP); (iii) estimated indices to maximize gain in protein (HSEP) or grain yield (HSEY) using information on both traits.

Mass selection was as effective as half‐slb family selection for increasing percent protein; simultaneous improvement of grain yield and percent protein using a desired gain index was feasible; agreement with prediction of gains from an estimated index or a desired gain index was as good as for single‐trait selection; genetic variance and covariance estimates from 200 half‐sib families were sufficiently accurate to be useful in index development.
Comparison of Past and Recently Developed Soybean Cultivars in Maturity Groups VI, VII, and VIII1
Authors: Boerma H. R.
Published: July 2010

In the southeastern U.S., soybean [Glycine max (L.) Merr.] seed yields have increased due to improved cultivars, cultural practices, and general management. To determine the contribution of improved genotypes to this increase, 18 cultivars in maturity groups VI, VII, and VIII ranging in introduction or release date from 1914 to 1973 were evaluated in a common environment for 3 years. Other plant traits were evaluated to determine if differences existed among cultivars and if these differences were associated with year of release and seed yield. The regression of seed yield on year of release indicated significant genetic improvement in seed yield had occurred. Averagedo ver all maturity groups for the period 1942 to 1973, this increase was 0.7%/year. For cultivars in maturity group VIII, pods/m, plant height, and number of nodes were related to year of release. The differences in plant height and nodes/plant for cultivars in maturity group VIII were primarily due to the indeterminate growth habit of ‘Yelnanda’ and ‘Improved Pelican.’ The other cultivars in this experiment have the determinate growth habit. The differences for traits other than yield in cultivars within maturity groups VI and VII were not associated with year of release. The yield increase of recently developed cultivars was not consistently associated with any of the traits measured.
Seedling Selection for Morphological Characters Associated with Yield of Tall Fescue1
Authors: Jones R. J , Nelson C. J. , Sleper D. A.
Published: July 2010

Selection for herbage yield characters of forage grasses at an early stage of plant development would be desirable. Therefore, growth chamber and field experiments were conducted to determine if seedings selected for divergence in morphological characters associated with herbage yield remained consistent when plants were grown under field conditions. We also sought to determine the distribution of welght/tiller in field canopies.

Genotypes of tall fescue (Festuca arundinacea Schreb.), selected for a range in yield/tiller as seedlings, generally maintained similar rankings when grown under low competition conditions in a replicated pot experiment in a growth chamber and under sward conditions in the field. In all studiest he high yleld/tiller genotype had a higher proportion of large tillers and a lower proportion of small tillers than did the low yield/tiller genotype. Weight/tiller within a genotype was distributed neither normally nor log normally. Predominant morphological characters associated with high yield/tiller and high forage yield in these genotypes were low rate of tiller production and high rate of leaf elongation
Distribution of Total Non‐Structural Carbohydrates in Soybean Plants Having Increased Reproductive Load1
Authors: Streeter J. G. , Jeffers D. L.
Published: July 2010

The purpose of these experiments was to compare the distribution of total non‐structural carbohydrate (TNC) in soybean (Glycine max (L.) Merr.) plants with “normal” and with an increased reproductive load. This study included a comparison of methods for extraction and analysis of carbohydrates in soybean plant organs. Extraction with commercially available hydrolytic enzymes (“Clarase”) and analysis of extracts with ferricyanide method were chosen based on superior precision, accuracy, and recovery of standard added to samples.

Number of fruits and seed weight/plant were increased 30% or more by placing aluminum foil reflectors in plots for 2 weeks near the end of flowering. Beginning with the 2nd week of the reflector treatment period, plants were sampled twice weekly for analysis of TNC. Height, number of nodes, leaf blade dry weight, and stem + petiole dry weight of control and reflector‐treated plants were similar.

The initial effect of reflectors was to increase TNC concentration in all vegetative tissues. After reflectors had been removed for several weeks and throughout the period of rapid seed development, TNC concentration in pods and stems + petioles was almost always lower for reflector‐treated than control plants. There was a four‐fold decline in TNC concentration of pods and stems + petioles during seed development. However, leaf blades showed relatively little decline in TNC concentration during seed development, and senescent Ieaf blades contained 9% or more TNC. Also, increasing reproductive load by 30% appeared to have little effect on leaf blade TNC.

Based on this and other recent work, it is concluded that pods, stems, and petioles serve as major sources of stored carbohydrate for developing seeds while stored carbohydrate in leaf blades is relatively unavailable for supporting seed development. From the standpoint of TNC content, the soybean plant appears capable of maintaining higher reproductive loads.
Genetic Improvement of Soybeans in the Midwest1
Authors: Wilcox J. R. , Schapaugh W. T. , Bernard R. L. , Cooper R. L. , Fehr W. R. , Niehaus M. H.
Published: July 2010

Five group II and five group III soybean [Glycine max (L.) Merr.] cultivars released over a 50‐year period were grown at 12 location‐year combinations in the Midwest to evaluate genetic changes for seed yield, plant height, lodging, seed protein, and oil content and for phenotypic stability for seed yield. Current cultivars yielded 25% more seed than the original plant introductions in both maturity groups. Changes for the other characteristics were not consistent, however. Regression of cultivar means on environmental indices showed a consistent, linear increase in seed yield across the range of test environments, indicating equal stability for yield among the cultivars tested.
Ridge Regression for Extracting Soybean Yield Factors1
Authors: Williams W. A. , Qualset C. O. , Geng S.
Published: July 2010

In breeding crops to enhance yield, factors hypothesized to influence yield are often highly inter correlated. This condition is called multicollinearity when the intercorrelated variables are related to yield in a multiple regression equation. Ridge regression is a useful tool for untangling intercorrelated factors in multiple regression. The technique was applied to a set of soybean [Glycine max (L.) Merr.] data, involving a range of planting dates and cultlvars varying widely in maturity, to identify phenological variables associated with yield. Variables with highly unstable, estimated regressmn coefficients that were identified by the ridge technique were also shown to be highly correlated in the principal components with the smallest eigenvalues. The time from last flower to maturity was shown to be strongly associated with yield in this context.
A Survey of Soybean Cultivars for Variability in Specific Leaf Weight1
Authors: Lugg D. G. , Sinclair T. R.
Published: July 2010

The objective of this study was to determine the variability in specific leaf weight (SLW) of 373 soybean [Glycine max (L.) Merrill] lines, to examine the seasonal changes in SLW, and to determine the consistency in the ranking of selected lines over a 3‐year period. Consistency in these data would provide a basis for selecting lines for further, intensive physiological study. The SLW was sampled in the field with a leaf punch on the uppermost fully expanded leaf that was in full sunlight. For the whole collection, SLW was sampled at two growth stages, R2 (full‐bloom) and R5 (beginning to mid‐podfill). The mean SLW increased between these stages from 3.08 to 6.46 mg/cm2, while the standard deviations were 0.36 and 0.77 mg/cm2, respectively. Significant differences among lines were found at both growth stages. Chlorophyll deficient genotypes generally had low SLWs, while dwarf types were high. Cultivars derived from ‘Harosoy’ had significantly higher. SLWs at R5 with a mean of 7.12 than those derived from ‘Lincoln,’ mean of 6.24 mg/cm2, respectively. For 20 lines in 1976 and 10 in 1977, SLW was sampled on a weekly basis. We saw an increase in SLW from flowering to after mid podfill, and then a sharp decline. The SLW at R5 in 1975 correlated well with maximum SLWs in 1976 and 1977. Solar radiation levels influenced SLW. We found a linear relationship between the mean SLW at each sampling date and the radiation received in the week before sampling at R2 in 1975, and maximum SLW was significantly affected in 1976 and 1977.
Resistance to Root‐Knot Nematode in Control of Root‐Knot Nematode‐Fusarium Wilt Disease Complex in Cotton1
Authors: Hyer A. H. , Jorgenson E. C. , Garber R. H. , Smith S.
Published: July 2010

To determine the efficacy of resistance to root.knot nematode in the control of the root‐knot nematode‐Fusarium wilt disease complex in cotton (Gossypium hirsutum L.), the response to natural infections with root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, and wilt fungus, Fusarium oxysporum Schlecht. f. sp. vasinfectum (Atk.) Snyd. and Hans., was studied in four cottons that varied in resistance to both organisms. ‘Acala SJ‐l’ is susceptible to both organisms, ‘Auburn 56’ is tolerant to Fusarium and moderately resistant to root‐knot nematodes, ‘N6072’ is susceptible to Fusarium but highly resistant to root‐knot nematodes, and ‘Delcot 277’ is tolerant to Fusazium but susceptible to root‐knot nematodes. Control of Fusarium wilt and maintenance of stands were as good in N6072 as in Auburn 56 and Delcot 277. In unfumlgated plots, lint yield of N6072 exceeded those of Acala sJ‐1 and Delcot 277 by more than 60% and that of Auburn 56 by 18%. The superior performance of N6072 appea~ed to result from its ability to resist root‐knot nerdatodes, which helped prevent the develolpment of the wilt disease and subsequent stand and yield losses.
Influence of Sink Removal in the Senescence Pattern of Wheat1
Authors: Patterson T. G. , Brun W. A.
Published: July 2010

The influence of sink removal on leaf senescence was investigated in hard red spring wheat (Triticum aestivum L.). RuBP‐carboxylase (RuBPCase) and glucose‐6‐phosphate dehydrogenase (G‐6‐PDH) were measured in the flag leaf blade, sheath, and penultimate leaf blade. Heads were removed from field plots of wheat at weekly intervals starting at anthesis. Early sink removal caused a dramatic dry weight increase in the peduncle. Later treatments had smaller effects. Flag leaf blade and sheath were more responsive, in general, to sink removal treatments that the penultimate leaf. Chlorophyll content of the leaves and sheath declined during the postanthesis period. Sink removal treatments delayed the loss of chlorophyll slightly, but did not reverse the downward trend. RuBPCase activity declined continuously during the experiment, and was slightly maintained by early sink removal treatments. G‐6‐PDH activity, in contrast, was strongly maintained by sink removal. RuBPCase and G‐6‐PDH activity determinations detected a delayed senescence response in wheat and were deemed suitable as screening techniques for altered senescence patterns.
A Comparison of Replicated S1 per se vs. Reciprocal Full‐Sib Index Selection in Corn. I. Indirect Response to Population Densities1
Authors: West D. R. , Compton W. A. , Thomas M. A.
Published: July 2010

Two cycles of S1 per se selection have been completed in each of three corn (Zea mays L.) populations: Nebraska B Synthetic (NBS), Nebraska Stiff Stalk Synthetic (NSS), and improved Nebraska Krug variety (NKS). In addition, two cycles of reciprocal full‐sib recurrent selection (RFS) have been completed between NBS and NSS and between NBS and NKS. Each selection scheme was replicated three times. Selection was based on an index (resulting in a calculated value of yield on standing plants) and on yield trials generally grown at 51,666 plants/ha. Response at 68,888 and 17,222 plants/ha (called here indirect density response) is reported in this study. Each replicate of each selection procedure was grown as an S1, random mating (RM), or variety cross population. Index values of cycle 2 (C2.) were increased 20% or more over C0 in tests of bulked S1 populations selected by S1 per se performance while response to RFS selection varied from an increase of 9% in C2 of NKS to a negative response of −10% in NBS. Significant selection ✕ plant populaion density effects were found only in the random mating test of the NKS population. Response to S1 per se selection was significantly greater than response to RFS selection in the NBS random mating population, but response to the two methods did not differ in NSS or NKS grown as random mating populations.

Index means of variety crosses of C2 were approximately 12% above C0 variety crosses and there were no differences between selection methods. The evaluation of selection response indicated that in the early cycles of selection, response to selection at one plant density will be unchanged when selection products are grown at other plant densities. Response to S1 per se selection was greater than RFS selection response in bulk S1 and RM evaluations, but the RFS and S1 per se methods resulted in equal improvement of variety cross performance.