bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection for Caryopsis Percentage in Oats1
Authors: Stuthman D. D. , Granger R. M.
Published: July 2010

Three populations of oats (Avena saliva L.) were developed to study caryopsis percentage, the proportion of whole kernel that is caryopsis. Information was obtained on the heritability of the character, the relative importance of component changes in effecting changes in caryopsis percentage, and the relationship of the character to other important agronomic characteristics. F2‐derived F4 families were grown in the field in 1970 and bi‐directional selection was practiced for caryopsis percentage. A group of random lines also was used to provide an estimate of the unselected population mean. Selected and random lines were evaluated at two locations in 1971. Effectiveness of selection was measured by comparing selected with random line means. Realized heritability estimates were calculated for caryopsis percentage, and correlated responses were calculated for several important agronomic traits. Selection for caryopsis percentage was effective in all three populations. Differences in the magnitude of response among populations agreed well with theoretical expectations. Small but significant genotype × location interactions were detected. Realized heritability estimates for caryopsis percentage ranged from 0.34 to 0.72, all statistically significant. Genetic variability for caryopsis percentage was considerably reduced by a single cycle of selection. Progress in selection for caryopsis percentage could be attributed to changes in either caryopsis weight or hull weight or to changes in both. Correlated responses of agronomic characters were not consistent across populations and were not of sufficient magnitude to be a serious consideration when selecting for high caryopsis percentage.
Genotypic Influences on in vitro Fertilization and Kernel Development of Maize1
Authors: Gengenbach B. G.
Published: July 2010

A study was conducted to determine the performance of maize (Zea mays L.) genotypes in a procedure for in vitro fertilization and kernel (caryopsis) development. The influence of sampling and crossing methods on in vitro fertilization and kernel development were examined as part of a continuing effort to improve the procedure for use in genetic and developmental studies. Segments of maize ears containing 10 unfertilized intact pistillate spikelets were pollinated after placement on a defined agar‐based medium in petri dishes. Fertilization percentage, frequency and extent of kernel development, and germination percentage were obtained for 31 female genotypes each sibbed and crossed by four inbred‐line males. Average percent fertilization of 11 single‐cross females (42%) was higher than for 20 inbred‐line females (18%). Fertilization ranged from 0 to 84% and significant effects were attributable to female genotype; male genotype; female ✕ male combinations; crossing date interactions with females, males, and female ✕ male combinations; age of ears (from silking); and the time of day that pistillate spikelets and pollen were collected in the field for crossing. Full kernel development lot crosses involving single‐cross females averaged 12% of the initial ovary number and was influenced mainly by female genotype. For a 10‐ovary block, differences in development were evident among fertilized ovaries beginning 10 to 15 days after pollination. Two fully developed kernels was the average maximum per 10‐ovary block. Germination of full kernels developed from single‐cross and inbred‐line females was 95 and 85%, respectively. The above effects should be considered when designing in vitro fertilization studies with maize.
Genetic Variances and Hybrid Predictions of Maize at Two Plant Densities1
Authors: Stuber C. W. , Moll R. H.
Published: July 2010

Six quantitative traits were compared within and between two plant densities in two sets of maize (Zea mays L.) crosses (one set showing a high proportion and one small proportion of epistatic variance) for: 1) estimates genetic parameters, 2) genotype by environmental interactions, and 3) predictions of hybrid performances. Significance levels for partitions of genetic variation were similar, irrespective of plant density. However, total genetic variance of yield per unit area increased with increased plant density. When the data were transformed to yield per p!ant, genetic variances increased in the set with a high proportion of epistatic variance and decreased in the other set as plant density increased. Differences in epistatic variation may have contributed to this finding. Accurate predictions of hybrid performances within plant densities were highly improbable when a large proportion of epistatic variation was present. Predictions between plant densities were poor for yield and ear number, even with a small proportion of epistatic variation.
Combining Ability and Yield Component Analyses in a Five‐Parent Diallel Cross in Sugarcane1
Authors: Miller J. D.
Published: July 2010

A combining‐ability analysis of a five‐parent diallel cross in plant crop of sugarcane (Saccharum spp.) seedlings showed that estimates of mean squares of general combining ability for stalk weight, stalk number, stalk diameter, stalk length, density, cane yield, Brix, and kg‐Brix were not significantly different from zero. Estimates of mean squares of specific combining ability were significant for all characters. Path‐coefficient and regression analyses of l0 crosses showed that stalk number, stalk diameter, stalk length, Brix, and density, i n that order, were important in determining kg‐Brix on a per‐plant basis. This information suggests that a small number of seedlings of each of many crosses among adapted clones should be examined to identify combinations with high specific combining ability. A large number of seedlings of these superior crosses could then be grown in subsequent years.
Association of Seedling Respiratory Metabolism and Adenylate Energy Charge with Seed Weight of Panicum antidotale Retz.1
Authors: Abernethy Rollin H. , Wright L. Neal , Matsuda K.
Published: July 2010

Seed from selections of blue panicgrass, Panicum antidotale Retz, for heavy and light seed‐weight from six cycles of recurrent selection were evaluated for association between seed weight, seedling vigor, and several aspects of seedling energy metabolism. Seed and seedling fresh weight, respiration rate, free sugar levels, mitochondrial protein content, adenosine triphosphate (ATP), and total adenylate phosphates content were sampled after 0, 6, 12, 24, 36, 48, 60, and 72 hours of germination and initial growth. Dry weight of seed decreased about 2% during the first 72 hours of germination and fresh weight of all seedlings increased about 60% in 72 hours Respiration rates were higher for heavy seed‐weight selections through the first 72 hours Content of free sugar (mg per seed) was significantly greater for heavy seed‐weight selections. Pools for adenylate phosphates were larger for heavy seed‐weight selections on the basis of nmoles per seed. Energy charge values were not significantly different during germination; however, energy charge values for unimbibed seed were greater for heavy seed‐weight selections. Heavy seed contained more free sugars for respiratory substrate and more adenylate phosphates for further phosphorylation. The enhanced respiratory metabolism resulted in increased rates of ATP formation, and larger seedlings resulted.
Relationship of Stalk Morphology and Chemical Composition to Lodging Resistance in Sorghum1
Authors: Esechie H. A. , Maranville J. W. , Ross W. M.
Published: July 2010

Lodging reduces grain yields significantly in most grain crops. Therefore, selection of lodging‐resistant lines might alleviate the lodging problem. Several factors are associated with lodging resistance, but attempts to quantitate these factors are either very few or lacking for grain sorghum (Sorghum bicolor (L.) Moench). Morphological and stalk composition measurements were made in 2 consecutive years using 30 lodging‐resistant and 30 lodging‐susceptible lines in order to quantify these factors and to assess their value as an index of selection.

Lodging resistance was associated with larger diameters of basal internodes and peduncles, shorter peduncles, shorter plant height, higher weight of 5‐cm basal and peduncle stalk sections, and a thicker rind. When external force was artificially applied in the field, those lines classified as lodging resistant required more force to effect stalk failure.

Lodging‐resistant sorghums contained higher total nonstructural carbohydrates (TNC) and lower stalk potassium and protein concentrations. The resistant types also appeared to be more perennial in habit and thus were resistant to senescence of cell tissues after freezing. High TNC was directly associated with resistance to post‐freeze senescence and/or with longer maturity, and indirectly with lodging. Resistant types were generally later maturing, and the results indicated that resistance probably can be obtained without sacrificing yield.
Combining Ability Effects for Resistance to Four Insects in Selected Alfalfa Clones1
Authors: Kugler J. L. , Kehr W. R. , Ogden R. L.
Published: July 2010

Diallel cross progenies, including reciprocals, of six alfalfa (Medicago sativa L.) clones that differed in miridinduced leaf malformation and aphid resistance were studied to obtain estimates of combining ability effect for characters associated with resistance to the spotted alfalfa aphid (SAA), Therioaphis maculata Buckton; the peaaphid (PA), Acyrthosiphon pisum Harris; and two mirids: the alfalfa plant bug (APB), Adelphocoris lineolatus Goeze, and the tarnished plant bug (TPB), Lygus lineolaris Beauv. The responses to mirid feeding were measured in the field with controlled APB and TPB infestations under cages. Aphid tests were conducted on seedlings in the greenhouse. The hypothesis that the same genetic system controlled feeding by APB and TPB was supported by the absence of significant genotype ✕ mirid species interactions. Forage yield and stem length were reduced 5 and 20%, respectively, whereas percentages of dry matter were unchanged and protein percentages increased 4% due to mirid infestation. Resistance to mirid‐induced forage yield reduction and stunting was not found. Leaf malformation, a symptom of mirid feeding, appeared to be a highly heritable trait, but was not correlated with forage yield reduction, stunting, forage quality, or aphid resistance. General combining ability effects were far more important than specific combining ability effects among single crosses for forage yield, stem length, and leaf malformation under mirid infestation, and for PA and SAA resistance.
Effects of Two Diverse Environments on Seed Production Characteristics of the Parent Clones of ‘Vantage’ Reed Canarygrass1
Authors: Rincker C. M. , Carlson I. T. , Garrison C. S.
Published: July 2010

Differences in pollination and seed yield among clones of forage grasses may alter genetic composition of seed lots. Eight characteristics of the six parent clones of ‘Vantage’ reed canarygrass (Phalaris arundinacea L.) were investigated at Prosser, Wash., and Ames, Iowa, in 1973 and 1974 in relation to the genetic composition of breeder seed lots produced at the two locations. Similarities among location‐year combinations in rankings of the clones were evident for each trait. Range among clones in the date pollen shedding began was 3 or 4 days except at Prosser in 1973 when it was 8 days. Pollen shedding periods of the six clones always overlapped. In 1973, range among clones for panicle number and florets per panicle was 2.6 and 2.1 times greater, respectively, at Prosser than at Ames. In 1974, ranges were similar at the two locations. Range among clones in percentage seed set was greater at Prosser both years. Overall means at Ames and Prosser were, respectively, 213 and 280 panicles/ plant, 645 and 896 florets/panicle, 79 and 70% seed set, 88 and 92 mg/100 seeds, and 42 and 102 g of seed/plant. Except for percentage seed set and weight of 100 seeds, all location differences were significant. Seed yield per plant at Prosser was 2.4 times that at Ames. Breeder seed lots produced in the 2 years at the two locations may not be similar in genetic composition.
Reaction of Reed Canarygrass Genotypes to the Leafspot Pathogens Stagonospora foliicola and Helminthosporium catenarium1
Authors: Zeiders K. E. , Sherwood R. T.
Published: July 2010

Our objectives were to determine the range of reactions to tawny blotch (caused by Stagonospora foliicola (Bres.) Bubak) and Helminthosporium leafspot (caused by H. cateranium Drechs.) among diverse genotypes of reed canarygrass (Phalaris arundinacea L.), to assess the relationships among lesion size, lesion frequency, leaf size, and tawny blotch severity ratings, and to assess the feasibility of selecting for resistance as a means of improving this highly productive forage species.

The 24 clones varied from resistant to highly susceptible to S. foliicola or H. catenarium in artificial inoculations. Differences among disease severity means for both pathogens were significant at P < 0.01. Resistance to S. foliicola was controlled independently from resistance to H. catenarium. One clone was resistant to both pathogens. There was a wider range of reaction among clones to S. foliicola than to H. catenarium.

Differences in lesions per leaf, lesions per cm2, and lesion size rating for S. foliicola were significant at P < 0.01. There was a significant negative correlation (r = −0.60) between leaf area and lesions per cm2. Lesions per leaf and lesion size were correlated (P < 0.01) with disease severity ratings (r = 0.69), thus supporting the validity of our disease severity evaluations. The results indicate that the prospects for developing lines with resistance to either or both pathogens are good.
Injury in Mungbean from Natural Infection with Cucumber Mosaic Virus1
Authors: Purivirojkul Watchara , Poehlman J. M.
Published: July 2010

Five mungbean (Vigna radiata (L.) Wilczek) strains susceptible to cucumber mosaic virus (CMV) and one resistant strain were grown with three treatments: unprotected control; systemic insecticide; and screen cages to exclude insects. Virus was spread by natural agents. The susceptible strains were damaged severely in the control and systemic insecticide plots but were free of virus symptoms when grown in the screen cages. The resistant strain was free of virus symptoms in all plots. Absence of virus symptoms in susceptible strains in the cages indicated that the virus was spread by an insect vector. A systemic insecticide to control the vector provided slight protection to mungbeans from the virus. In the unprotected plots, the mungbean strain with greatest virus injury had only 16% of the height, 9% of the branch length, 9% of the leaf size, and 5% of the dry weight index of the resistant strain. In the cages the same susceptible strain had 91% of the height, 106% of the branch length, 65% of the leaf size, and 114% of the dry weight index of the resistant check.
Histological Evidence for a Cotton Genotype with Opposite Leaves and Fruiting Branches at a Main Stem Node1
Authors: Gausman H. W. , Namken L. N. , Heilman M. D. , Dilday R. H.
Published: July 2010

Cotton (Gossypium hirsutum L.) usually has one fruiting branch emerging at each main stem node. ‘Tamcot SP‐37’ plants often have two branches emerging opposite each other. Frequency of plants with two fruiting branches per node increased following selection of Tamcot SP‐37 plants that had opposite leaves at nodes five or six, rather than the conventional spiral (alternate) leaf arrangement. We sought histological data concerning this previously unreported anomaly in phyllotaxis and fruiting emergence.

We compared the main‐stem apical meristems and vascular systems of anomalous Tamcot SP‐37 plants with those of ‘Stoneville 213’, a standard cultivar that does not exhibit this phenomenon. Comparative anatomy indicated no internode at the level(s) where Tamcot SP‐37's two leaves and two fruiting branches emerge and develop. This anomaly in Tamcot SP‐37 has not been reported previously and may be useful in the future for developing earlier maturing and higher yielding cotton cultivars.
Diallel Analysis of Resistance to Air Pollutants in Alfalfa1
Authors: Campbell T. A. , Devine T. E. , Howell R. K.
Published: July 2010

The inheritance of resistance to air pollutants in alfalfa (Medicago sativa L.) was studied in two diallels in greenhouses at Beltsville, Md. Progenies were exposed to polluted ambient air that was cooled and moistened by a wet‐pad cooling system, since such an environment appears to enhance pollution damage. Oxidants were often present at levels known to cause foliar damage in alfalfa. Other pollutants were not monitored. General combining ability constituted most of the genotypic variation indicating that resistant populations might be developed using simple recurrent selection, or recurrent full‐sib family selection. Nonadditive genetic variation may be sufficient so that progress might also be made using hybridization. Maternal and reciprocal effects were relatively unimportant.
Effect of the Nectariless Trait on Cottonseed Protein and Amino Acid Composition1
Authors: Elmore C. D. , Meredith W. R. , King E. E. , Ranney C. D.
Published: July 2010

Nectariless cottons (Gossypium hirsutum L.) are potentially useful agronomic strains of cotton. This experiment was conducted to compare the percent N of seed from nectariless cottons with that of seed from their nectaried recurrent parents. Two nectariless lines (‘DES DK he’ and ‘DES SL ne’) compared in 1969 and 1970 had higher seed percent N than their normal counterparts and one (‘DES 7A ne’) did not. In another experiment where eight BC5F4 ectariless lines were compared with their nectaried recurrent parents in 1974‐75, there was no effect of the nectariless trait on seed percent N. There was, however, a significant cultivar by location interaction, indicating considerable influence of the environment on seed percent N. Aspartic acid, threonine, serine, glycine, and alanine contents were significantly higher in the seed from nectariless cotton lines than in seed from normal cotton. The increases in absolute percentage values were, respectively, 0.10, 0.04, 0.03, 0.05, and 0.04. While these values were statistically significant, they would be of little consequence in affecting the quality of protein in seed from nectariless cotton plants.
A Plant Pathologist's View of Germplasm Evaluation and Utilization1
Authors: Hooker A. L.
Published: July 2010

Plant diseases represent important preventable hazards to crop production. Genetic or cytoplasmic uniformity greatly increases vulnerability to disease when the crop is a) widely grown, b) has resistance to an aggressive pathogen that has an efficient means of dispersal and the potential for frequent genetic shifts from avirulence to virulence, and c) is grown in an environment favorable for disease. While there are risks to crop uniformity, the advantages to agriculture outweigh the disadvantages. Since epidemics are rare, present germplasm evaluation and utilization schemes are quite good but improvements are possible. Better monitoring of pathogens and germplasm relative to genes and cytoplasms for resistance is needed. Many germplasm collections have not been adequately evaluated for disease reaction and the available genes for resistance have not been transferred to plant types suitable for agriculture. Stable resistance to most diseases can be achieved by means of breeding and gene deployment. General resistance, multicomponent resistance, zonal deployment, and multilines are alternatives, each with advantages and limitation relative to plant breeding and agricultural objectives. International testing against a diversity of pathogen biotypes in a range of environments is a powerful tool in breeding for disease resistance. Germplasm diversity affords some protection against the unknown.
Relationship of Ribonucleic Acid Degrading Enzymes to Survival Levels of Winter Barley Phenotypes1
Authors: Kenefick D. G. , Kolp B. J. , Whitehead E. I.
Published: July 2010

The ribonuclease and phosphodiesterase enzyme activities of 18 lines of barley (Hordeum vulgare L.) were compared to their winter survival ratings. These lines, selected in Wyoming, were obtained from a composite cross derived from 18 original parents using male sterility. Enzyme analysis on the soluble extract from 4‐day seedlings showed, in general, that the rihonuclease activity in the hardiest phenotypes was depressed to a greater extent by 0.50 M KCI. These extracts contained the lowest amounts of an enzyme tentatively identified as ribonuclease L Usually the extracts of the hardiest phenotypes also contained the highest phosphodiesterase activity, as determined with thymidine 3′‐(p‐nitrophenyl) phosphate.
Frequency Distribution of Maize Yield Before and After Reciprocal Recurrent Selection1
Authors: Moll R. H. , Bari Abdul , Stuber C. W.
Published: July 2010

Reciprocal recurrent selection in populations of Zea mays L. will be of great value if the increase in mean performance is accompanied by a corresponding increase in performance of hybrids found in the upper tail of the genotypic distribution. We examined the frequency distributions for yields of two populations of single‐cross hybrids. A population of 192 intercultivar single crosses among inbreds was derived from two cultivars, ‘Jarvis Golden Prolific’ and ‘Indian Chief’, after six cycles of reciprocal recurrent selection. This population of single crosses was compared with a control population of 185 single crosses among unselected inbreds from the original cultivars. Frequency distribution of average single‐cross yields over replications and locations showed no significant deviations from normal distributions. A small but statistically significant estimate of skewness was found for average yields of single crosses from the selected cultivar. Mean yields of single crosses from the selected cultivars averaged 12.5% greater than those from the unselected cultivars. Variances among the selected single crosses were smaller than among the unselected single crosses, but the differences were small and not statistically significant. Reciprocal recurrent selection apparently had little effect on the distribution of single‐cross yields other than an increase in mean performance. This implied that the shape of the distribution had not changed but that the distribution had been shifted to the right, with an increased probability of outstanding hybrids in the upper tail. The best 10 single crosses from the selected population averaged 8.6% more yield than the 10 best single crosses from the original population. Five single crosses from the selected population exceeded the yield of the best single cross from the control population.
A Method of Transferring Genes from Tetraploid to Diploid Crested Wheatgrass1
Authors: Dewey Douglas R.
Published: July 2010

Gene flow between diploid crested wheatgrass, Agropyron cristatum (L.) Gaertn., and tetraploid crested wheatgrass, A. desertorum (Fisch. ex Link) Schult., largely “one‐way”, from diploid to tetraploid. A method is presented by which genes can be transferred from the tetraploids to the diploids via colchicine‐induced tetraploids. The procedure involves hybridizing natural‐tetraploid A. desertorum with induced‐tetraploid A. cristatum followed by repeated backcrossing to diploid A. cristatum. By using this procedure, a recessive gene for absence of anthocyanin pigments was transferred from tetraploid A. desertorum to diploid A. cristatum. This method can be used to transfer other genes from the genetically variable crested wheatgrass tetraploids to improve the genetic and breeding potentials of diploid A. cristatum. The same method may also apply to other species‐complexes with a ploidy series and one‐way gene flow, e.g., DacCylis g/omerata L.
Vascular Anatomy of Cotton Carpels as Revealed by Digestion in Ruminal Fluid1
Authors: Simpson M. E. , Marsh P. B.
Published: July 2010

The vascular anatomy of cotton (Gossypium hirsutum L.) carpels was revealed when cracked fresh bolls were incubated in bovine ruminal fluid, rinsed, dried, and examined without further preparation. Radially‐oriented club‐shaped terminal vascular elements surmounted a roughly cuboidal middle meshwork which arose from a tangentiallyoriented inner layer. The above anatomy may be associated with the reflexing of the carpels at boll opening by causing greater shrinkage during dehydration in the outer layer than in the middle and inner ones.
Inheritance of Gossypol Level in Gossyplum. III. Genetic Potentials of Two Strains of Gossypium hirsutum L. Differing Widely in Seed Gossypol Level1
Authors: Lee Joshua A.
Published: July 2010

Genetic potentials for the production of terpenoid aldehydes (gossypol in the present material) were compared in two stocks of Gossypium hirsutum L. differing widely in their capacities to produce these substances. In the line, 3‐T, the dimeric genotype, Gl2Gl2Gl3Gl3, averaged 2.78% gossypol in dried seed meal, whereas the same genotype in ‘Acala 4‐42’ averaged 0.90%. Most of the genetic variance generated by the substitution of mutant for normal alleles at the two loci was additive for both cottons.

In 3‐T, the monomerics, Gl2Gl2gl3gl3 and gl2gl2Gl3Gl3, produced an average of 3.03 and 1.18% gossypol, respectively, whereas the same genotypes in Acala 4‐42 averaged 0.69 and 0.24%. Thus the ratio of gossypol production for the monomerics was nearly the same for both cottons.

In 3‐T, the Gl2 monomeric proved to be duplex sufficient; that is, monomeric plants produced as much seed gossypol as dimerics. The Gl2 allele in Acala 4‐42 was not duplex‐sufficient, but became so after transfer to the 3‐T background.

Analysis of individual seed lots from 84 dimeric F2 plants from a cross of the two cottons produced a symmetrical curve of gossypol value spanning the distribution between the parents. This result was interpreted to mean that potentials for the alleles, Gl2 and Gl3, are similar in high and low gossypol cottons, and that observed differences in recovery of seed terpenoids results from variation in numbers, or effectiveness, or modifier alleles.
Genes for Low Reaction to Puccinia graminis tritici in Aegilops and Triticum1
Authors: Gerechter‐Amitai Z. K. , Loegering W. Q.
Published: July 2010

Bulk and single‐plant accessions of Aegilops longissima Schweinf. and Muschl. and Ae. sharonensis Eig from Israel were tested for reaction to Puccinia graminis Pers. f. sp. tritici Erikss. and E. Henn. Forty‐four lines from these accessions and 23 wheat (Triticum sp.) lines monogenie for different Sr genes were inoculated with 20 cultures of P. graminis tritici. Data were recorded as infection types (IT) and by the low‐high (L‐H) system of interorganismal genetics. The data were processed by internal, external, and boxing computer programs as well as visual analysis. Internal correlations placed the 44 Aegilops lines in 18 groups with different L‐H patterns, indicating a minimum of five different genes for low reaction (LR). Eight different genes for LR were postulated by the boxing program. Visual analysis differentiated five additional LR genes. External correlation demonstrated that four Aegilops lines carried genes for LR which were not present in any of the monogene wheat lines. Analysis of the comparisons between IT's on the Aegilops and monogene wheat lines suggested the presence of several more LR genes in the Aegilops lines that are different from those in the monogene wheat lines as well as some that are the same. It was concluded that there are available in Aegilops sp. many genes for low reaction to P. graminis tritici that could be used effectively in wheat breeding programs.
Genetic Behavior of Five Induced Dwarf Mutants in an Indica Rice Cultivar1
Authors: Padma A. , Reddy G. M.
Published: July 2010

The genetic control of dwarfism was studied in the mutants induced by the chemical mutagen ethyl methanesultanate in a tall indica rice (Oryza sativa L.) cultivar, ‘Tellakathera’. The five dwarfs were, dwarf‐6(d0), dwarf‐ 7(d7), dwarf‐8(d8), dwarf‐9(d9), and dwarf‐10(d10). In crosses of the dwarfs with the tall parent, F1 plants were tall and the F2 plants segregated three tall to one dwarf, suggesting that each of these dwarfs is controlled by a single recessive gene. Crosses among the dwarfs produced tall F1, plants and a dihybrid segregation pattern of nine tall to seven dwarf plants in F2, indicating these five dwarfing gene loci were nonallelic to each other.
Location of Genes Conditioning Resistance to the Corn Stunting Disease Complex in Maize1
Authors: Scott Gene E. , Rosenkranz Eugen E.
Published: July 2010

Reciprocal chromosomal interchanges were used to determine which chromosome arms of the resistant corn (Zea mays L.) inbred Mp412 carried genes for resistance to the corn stunting disease complex. The material was evaluated at Mississippi State, Miss., and Hurricane Mills, Tenn., under conditions of natural infections. Genes for resistance in inbred Mp412 were found on the short arm of chromosome 1 and on the long arm of chromosome 3. One year's data indicated the presence of another resistance gene(s) on the short arm of chromosome 4.
Comparative Cold Hardiness of Several Triticum species and Secale cereale L.1
Authors: Fowler D.B. , Dvorak J. , Gusta L.V.
Published: July 2010

Cold hardiness, fresh weight, dry weight, and water content were determined for cold acclimated crowns of 44 strains representing Triticum boeoticum Boiss., T. urartu Tum., T. tauschii (Coss.) $chmal., T. timopheevii (Zhuk) Zhuk. var. araraticum Jakubz., T. turgidum L. var. turgidum, T. turgidum L. var. durum, T. turgidum L. var. dicoccoides (Korn) Bowden, T. aestivum L. and Secale cereale L. Significant differences due to strains and species were observed for all variables. Correlation coefficients based on these differences were significant for all comparisons except cold hardiness with fresh weight.
Response of Resistant and Susceptible Alfalfa Cultivars to Regional Isolates of Stem Nematode1
Authors: Elgin J. H. , Evans D. W. , Faulkner L. R.
Published: July 2010

Nine stem nematode [Ditylenchus dipsaci (Kühn) Filipjev] isolates were collected from different nematodeinfested regions of the United States and Canada. They were tested for variations in pathogenicity at 15, 20, and 25 C on ‘Ranger’ and ‘Moapa’ (susceptible and ‘Lahontan’ and ‘Caliverde 65’ (resistant) alfalfa (Medicago sativa L.) to determine if variations in plant responses to different nematode isolates should be considered when breeding for resistance to stem nematode. All isolates were generally capable of parasitizing alfalfa; however, a difference in virulence was detected among isolates. Isolates did not demonstrate an interaction with temperature or with alfalfa cultivars. We concluded that a resistant alfalfa developed in a breeding program using one pathogenic isolate would probably be resistant to stem nematode isolates from other regions.
Screening of Flax Species for New Sources of Genes Resistant to Melampsora lint (Ehrenb.) Lev.1
Authors: Wicks Z. W. , Hammond J. J.
Published: July 2010

The control of rust (Melampsora lini (Ehrenb.) Lev.) in flax (Linum usitatissimum L.) has been by development of rust resistant cultivars. Because genes for rust resistance are continually being rendered ineffective by new races of rust, the isolation of new genes is essential.

Hybridization of the common flax cultivar ‘Bison’ was attempted with available species of flax with chromosome numbers of n = 15. Ten accessions representing four successfully hybridized species were immune to cultures of race 371. Of these, two were immune to all known races of rust in North and South America. Inv munity of each of these accessions was conditioned by a single gene located at or near the L locus. Because the genes for rust resistance were both found at the L locus and both conditioned immunity to all known North and South American races of rust, it was impossible to determine if they were the same or different alleles located at the same locus. These genes have not been reported previously in the literature, and we propose to designate them L12‐l and L12‐2.
Differential Iron Chlorosis of Oat Cultivars1
Authors: McDaniel M. E. , Dunphy D. J.
Published: July 2010

Iron chlorosis symptoms of varied severity were observed among oat (Avena byzantina C. Koch) cultivars in field trials at Beeville, Tex., during the 1975 and 1976 seasons. A cultivar exhibiting severe iron chlorosis and one having no apparent chlorosis symptoms in the field were grown in the greenhouse in two different soils known to have low levels of available iron. Growth of the "resistant" cultivar was relatively normal in both soils, whereas leaves of the "susceptible" cultivar were chlorotic, and plant growth was severely retarded. The addition of iron to either soil corrected the chlorosis symptoms of the susceptible cultivar. Plants of the susceptible cultivar grown in iron‐treated soil produced more than three times as much aboveground dry matter and more than twice as much crown and root weight as plants grown in untreated soil. Shoot and root yields of the resistant cultivar were influenced only slightly by iron treatment. Knowledge of the sensitivity of oat cultivars to iron chlorosis should be useful in developing new cultivars for areas where iron chlorosis is a problem.
Influence of an Extra Pair of Fragment Chromosomes on Grain Yield in a Hexaploid Oat
Authors: Brinkman M. A. , Frey K. J. , Browning J. A.
Published: July 2010

Three hundred panicles were selected from a population of CI 9192, a hexaploid oat (Arena sativa L.) with 42+2 fragment chromosomes. When panicle progenies were treated as lines and tested for uniformity of crown rust reaction, 258 lines were found resistant to race 264B of the crown rust fungus (Puccinia coronata Cda. avenae Fraser and Led.), and the remaining 42 were susceptible. The susceptible lines had lost both chromosome fragments and were normal hexaploids. All lines were grown in rust‐free conditions in a hill‐plot test. No differences betweent he rust‐resistant and rust‐susceptible groups were detected for plant height and heading date, but the susceptible group was significantly higher yielding than the resistant group.
Adaptation of Reciprocal Full‐Sib Selection in Sunflower Breeding Using Gibberellic Acid Induced Male Sterility1
Authors: Miller J. F. , Fick G. N.
Published: July 2010

Gibberellic acid (GA3) was evaluated for pollination control in branched sunflower (Helianthus annuus L.) male‐fertility restorer lines. A 50 ppm concentration of GA3, applied directly to the main head flower bud, reduced self‐fertility to 2.4, 3.0, and 3.8% of the checks. Self‐pollinated seed was obtained from secondary heads of treated plants. These results indicated that reciprocal full‐sib selection can be adapted to develop and improve sunflower breeding populations.
Fine Structure of Sugarcane (Saccharum sp.) Callus and the Role of Auxin in Embryogenesis1
Authors: Nadar H. M. , Soepraptopo S. , Heinz D. J. , Ladd S. L.
Published: July 2010

Histological examination of callus of sugarcane cultivar H50‐7209 (Saccharum sp. hybrid) revealed all stages of embryoid development when the callus was cultured on modified Murashige and Skoog medium containing 3.0 mg 2,4‐D/liter. It is suggested that the process of dedifferentiation and embryogenic‐cell initiation required relatively high auxin concentrations. Lower auxin concentrations may be required for advanced embryogenesis stages. Plantlet differentiation occurred only in the absence of auxin. Callus on auxin‐free medium showed no dedifferentiation or embryogenesis. We suspect that the origin of the individual sugarcaue plants in this study is from single cells. If so, mutant induction and selection could yield true mutant plants.
Water Relations of Tall and Short Cultivars of Winter Wheat1
Authors: Kirkham M. B. , Smith E. L.
Published: July 2010

Water potential, osmotic potential, stomatal resistance, and leaf temperature were measured for 8 weeks in spring under field conditions, on the top and bottom green leaf of eight cultivars of winter wheat (Triticum aestivum L.). Four cultivars were adapted for the Southern Great Plains (‘Payne,’ ‘Scout 66,’ ‘Sturdy,’ and ‘Turkey’) and four for Europe (‘Burgas 2,’ Bulgaria; ‘David,’ Austria; ‘F23‐71,’ Romania; ‘Odesskaya 51,’ U.S.S.R.). Four cultivars were tall (F23‐71, Odesskaya 51, Scout 66, and Turkey) and four were short (Burgas 2, David, Payne, Sturdy). Soil was moist and plants were not under moisture stress.

Tall and short cultivars reached a maximum height of 114 and 84 cm, respectively. Water potential and osmotic potential of top leaves of tall cultivars averaged 4.8 and 3.3 bars less (more negative), respectively, than those of top leaves of short cultivars. Water potential and osmotic potential of bottom leaves of tall cultivars were similar to those of bottom leaves of short cultivars (about _7 and _16 bars for water and osmotic potentials, respectively). Stomatal resistance of the upper surfaces of top leaves of tall cultivars (5.8 sec/cm) was similar that of upper surfaces of the top leaves of short cultivars (5.3 sec/cm). Stomatal resistance of the upper surfaces of bottom leaves of tall cultivars (9.1 sec/cm) was less than that of upper surfaces of bottom leaves of short cultivars (13.2 sec/cm). Because plants were not water stressed, temperature of all leaves was always cooler than air temperature (0.4 to 0.9 C cooler than air). Average yields of short and tall cultivars were 3,260 and 2,950 kg/ha, respectively. The better yield of short cultivars appeared to be related, in part, to the lower tension with which water was held in the top leaf of the short plants compared to the top leaf of the tall plants.
Influence of Intergenotypic Competition on Seed Yield of Heterogeneous Soybean Lines1
Authors: Gedge D. L. , Fehr W. R. , Cox D. F.
Published: July 2010

Two experiments were conducted to determine if overcompensation or undercompensation due to intergenotypic competition is preferentially associated with high or low‐yielding heterogeneous soybean (Glycine max (L.) Merrill) lines. In Experiment 1, yield of 40 random F2‐derived lines, four F5‐derived lines from each F2 line, and a blend of the four F5 lines (F5 blend) were evaluated for two crosses. Linear regression was used to compare the yield of the F2 lines and F5 blends with the mean yield of the four F5 lines. In Experiment 2, four F5‐derived lines were selected from each of six high and six low‐yielding F2‐derived lines in the two crosses. The four F5 lines were evaluated for yield in pure stands, in the six possible two‐component blends, and in a four‐component blend. Yields of the blends were compared with average performance of the components in pure stands.

In both experiments, overcompensation or undercompensation was not preferentially associated with high or low‐yielding heterogeneous lines. The results indicated that early generation testing for yield in soybeans should not be biased significantly by intergenotypic competition within heterogeneous lines.
Heterosis, Inbreeding, and Line Performance in Crosses of Adapted Spring Wheats1
Authors: Cregan P. B. , Busch R. H.
Published: July 2010

Eight adapted high‐yielding spring wheat (Triticum aestivum L.) parents were crossed in a diallel to produce 28 hybrid populations. The F1, F2 through F5 bulks, and a varying number of F5 lines/cross were grown at two locations. The F1 yields exhibited midparent heterosis from 5 to 58% (x̄ = 20%) and highparent heterosis from _17 to 41% (x̄ = 8%). Compared to the respective highest yielding line (HL) from each cross, F1 yields ranged from 75 to 119% (x̄ = 99.4%). The three highest yielding entries were Fl's even though the average HL and F1 over all crosses were similar.

Significant general combining ability (GCA) mean squares for yield were noted in the combining ability analyses of the F1, F2 through F5 bulks, HL, and the x̄ of F5 lines from each cross (x̄F5L). Significant specific combining ability (SCA) mean squares were detected the analyses of the F, and x̄F5L. The significant SCA mean square for x̄F5L suggested the presence of additive ✕ additive epistasis. The GCA effects generally were positively correlated across the various hybrid generations, which indicated consistent performance of the parents when measured by bulks or F5 lines.

The regression analysis of F1 and F2 through F5 bulk yields on heterozygosity detected a highly significant mean square (r2 = 0.947). The mean yield of the 28 crosses decreased at a linear rate of 0.23% per 1% decrease in heterozygosity with a maximum rate of 0.4% in one cross. Even this maximum rate was less than the lowest reported in maize (Zea mays L.) suggesting lesser amounts of dominance genetic variance in these materials.

The significant F1 heterosis and SCA for yield and the significant inbreeding depression indicated the possible desirability of F1 hybrids to maximize yield in these materials. However, since no F1 hybrid significantly outyielded the best F5 line tested, it was unclear if increased yield would best be obtained via pureline or F1 hybrid development.
Physiological Response of Three Alfalfa Cultivars to One Chilling Night1
Authors: Peoples T. R. , Koch D. W.
Published: July 2010

Most studies involving photosynthetic efficiency have compared species or cultivars that were grown under fixed day/night temperature regimes. Researchers attempting to improve photosynthetic efficiency and productivity of a crop may also need to consider genotype response to adverse factors, such as temporary chilling, which have been shown to reduce subsequent photosynthetic rates.

Three alfalfa (Medicago sativa L.) cultlvars, representing a range of environmental adaptation, were grown in a greenhouse at 22/18 C (day/night), and then were exposed for one night to 5 or 18 C to determine the effect of low temperature on physiological processes the following morning. The CO2 exchange rate (CER) of all three cultivars was reduced following a 5 C night. A greater reduction in CER occurred in ‘Mesa‐Sirsa’ and ‘Saranac’ (69.1 and 60.2% less than 18 C, respectively) than in ‘Kane’ (36.7% less than 18 C). Transpiration rates were significantly reduced following chilling exposure of Mesa‐Sirsa only (75.5% less than 18 C). This reduction in transpiration was associated with a 50% increase in leaf diffusive resistance and a 4.3 bar decrease in xylem water p6tential. Increased leaf diffusive resistance was not observed in Saranac and Kane following a chilling night. A greater leaf carbohydrate concentration and reduced l4C‐photosynthate translocation from leaf tissue was noted in all cultivars following a 5 C night.

These data suggest a feedback inhibition of CER in alfalfa following one 5 C chilling night. A water stress inducing an increased leaf diffusion resistance and decreased transpiration was found in Mesa‐Sirsa only.
Diallel Analysis of Ear Height and Associated Characters in Corn1
Authors: Harville B. G. , Josephson L. M. , Kincer H. C.
Published: July 2010

Early and late low ear corn (Zea mays L.) synthetics were developed by sib‐mating for lower ear height over 12 cycles of selection. Cycles 1, 3, 5, 7, 8, 9, and 10 were crossed in a diallel set for a study on inheritance of ear height and associated characters.

Ear height was reduced an average of 3.20 cm per cycle in the early synthetic and 2.98 cm in the late synthetic. Plant height remained fairly constant in both synthetics. The plant‐to‐ear height ratio increased from 3.03 to 4.84 in the early synthetic and from 2.96 to 4.56 in the late synthetic.

Lower ear placement was associated with a change from a fewer number of nodes below the ear to a greater number of nodes above the ear in both synthetics. Over 12 cycles of selection, ears were lowered more than one node in each synthetic. Therefore, the lower ear heights were due to placement on the stalk as well as shorter internodes.

Large general combining ability mean squares indicated that the characters were controlled by additive gene action. Significant changes of the estimate of the general combining ability effects were less with each succeeding cycle of selection, indicating less progress in lowering ear height with each succeeding cycle.
Inheritance of Subcrown Internode Length, Crown Depth, and Crown‐Tissue Regrowth in a Winter Wheat Cross1
Authors: Gul Azam , Allan R. E.
Published: July 2010

Forty‐two randomly selected wheat (Triticum aestivum L.) lines from the cross ‘Gaines’/‘Nord’ were studied for inheritance of subcrown internode length, crown depth, and crown tissue regrowth at three exposures to cold temperature [0 C for 20 hours (control), and −18 for 4 and 8 hours]. Heritability estimates calculated by the progeny‐parent (F5, F4) regression method for subcrown internode length and crown depth were 74 and 79%, respectively, suggesting that inheritance of the two criteria is not complex and should permit adequate selection progress. Subcrown internode length and crown depth were closely genetically related with one another, whereas both of these traits were expressed independently of crown tissue regrowth at the three exposures. Use of subcrown internode length and crown depth as selection criteria would not enhance crown tissue regrowth after exposure to cold temperature. The heritability coefficients for crown tissue regrowth of the control, and the 4 and 8‐hour exposures to −18 C were 31, 36, and 49%, respectively. This indicated that screening for this trait in the F4 generation is feasible but may be less successful than selection for subcrown internode length and crown depth. Except for subcrown internode length of F4 lines, all three traits were expressed independently of the short plant stature gene (Rht2) of Gaines.
Gas Exchange of Finger Millet Inflorescences1
Authors: Tieszen Larry L. , Imbamba Simeon K.
Published: July 2010

The growth and development of finger millet [Eleusine coracana (L.) Gaertn.] inflorescences is described. The respiration rate on a dry weight basis remained uniform until it decreased during the later stages of seed filling and drying. On an inflorescence basis, the respiratory production of CO2 increased until the “mature” stage because of the large increase in the mass of the inflorescence with time.

The inflorescence was photosynthetically active at all stages and at “early an thesis” accounted for about 41% of the C reguirements. The photosynthetic contribution of C was less in both later and earlier stages of development. Inflorescences possessed low resistances to mass transfer, were a significant source of water loss, and appeared to possess poor stomatal control. The quantitative importance of this source of CO2 for grain filling and yield remains to be established.
Combined Effects of Genes for Appressed and Decumbent Branching in Safflower1
Authors: Fernandez‐Martinez José , Knowles P. F.
Published: July 2010

Safflower (Carthamus tinctorius L.) with appressed branches (angle with main stem is 20° or less and genotype apap) was crossed to a type having decumbent branches (angle with main stem is 80 to 90° and genotype decdec) to determine the association of the genes in inheritance and their combined effects on the phenotype. F1, F2, and F3 populations were studied. The genes ap and dec were inherited independently. Because the genes had opposite effects on branching, the genotype apapdecdec had normal branching (angle with main stem is 40 to 70°).