bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of Rice Composites Dimorphic for Plant Height and for Pubescence1
Authors: Dat Tran Van , Peterson M. L. , Rutger J. N. 
Published: July 2010

The effects on yield of two contrasting rice (Oryza sativa L.) plant characteristics (tall vs. short, pubescent vs. glabrous) were studied. These plant types were developed from a cross between a pubescent short cultivar and a glabrous tall one with related parentage. Four plant types, glabrous short, glabrous tall, pubescent short, and pubescent tall, were selected in the F2 and increased in panicle rows in the F3. These panicle rows were composited and evaluated in broadcast plots in the F4.The two short types produced grain yields about 10% greater than the two tall types at optimum N fertility levels. Differences were attributed to a combination of factors including greatly reduced lodging of short types, production of significantly more panicles per unit area, more grains per panicle, and a higher percentage of fertile florets (filled grains). The 100‐grain weight was similar for short and tall types.The pubescent and glabrous leaf and hull characteristics did not affect grain yields significantly but number of grains per panicle and percent of sterile florets were significantly less in the pubescent than in the glabrous types. The four plant types were evaluated at six N fertility levels applied as urea. Rates of application were from 33.5 to 201 kg/ha with 33.5 kg increments. Optimum yields were obtained at 167.5 kg/ha. A progressive increase, in internode length occurred with N rate increments. The lower internodes (fourth and fifth from the top) elongated relatively more than upper ones with increased nitrogen fertilizer applications. Internodes of tall types elongated more than short types with increased N rates.
Minimum Sample Size for Estimating Progeny Mean and Variance1
Authors: Wu Kuo Kao , Heinz Don J. , Meyer Hans K. , Ladd Sheldon L. 
Published: July 2010

Minimum sample size is defined as the minimum number of individuals necessary to estimate, with reasonable precision, mean and variance of a trait in a population.Repeated random samples for various sample sizes were taken for each of four yield components in five sugarcane (Saccharum sp.) hybrid populations grown in two contrasting environments over 2 years in three selection stages. Means and variances of the samples were compared with those of the populations. Forty individuals from a population were found to be the minimum sample size required to estimate mean and variance for refractometer solids, stalk number, stalk diameter, or stalk length.
Variability of Response to Low Levels of Inbreeding in a Population of Maize1
Authors: Burton J. W. , Stuber C. W. , Moll R. H. 
Published: July 2010

Variability of inbreeding response was studied in four sets of eight inbred lines chosen at random from the maize (Zea mays L.) cultivar, ‘Indian Chief’. The eight lines in a set were mated in balanced pedigrees to generate groups of material having expected inbreeding coefficients of 0, 2/16, 3/16, 4/16, and 5/16. (The pedigrees were balanced with respect to the relative contribution of each line). In each pedigree, 20 samples were taken from the generation in which genotypes began segregating, so that 20 subpopulationsw ered erived for each level of inbreeding within each set. This material was evaluated in four environments with respect to grain yield, ear number,and ear height.All four sets showed significant inbreeding depression in yield. None of the sets showed significant inbreeding depression in ear number, and only two sets showed significant depression in ear height. Inbreeding depression, when significant, was linearly rdated to the increase in F. Quadratic effects were not significant. The linear rate of inbreeding depression in yield was similar in all sets and averaged −0.36 q/ha per 1% increase in F. In all sets, there was much variability in response to inbreeding among the 20 subpopulations of a particular pedigree. The ranges of the 20 subpopulation means about each pedigree varied between 15 and 63% of the pedigree mean. Similar results were obtained with ear number and ear height. The variability was thought to be due to differences in genetic potential for inbreeding depression among the original genotypes sampled and genetic sampling error with inbreeding.
Relationships Among CO2‐exchange Rate and Plant Traits in Iowa Stiff Stalk S1ynthetic Maize Population1
Authors: Crosbie T. M. , Pearce R. B. , Mock J. J. 
Published: July 2010

We measured CO2‐exchange rates (CER), morphological traits, and yield traits of 64 maize (Zea mays L.) inbred lines randomly derived from Iowa Stiff Stalk Synthetic (BSSS). Our experiments were grown for 2 years at one location. Genotypic correlations among these traits were calculated to determine if selection for high CER would cause correlated responses in other traits. We also studied possible physiological limitations to grain and dry matter yield of these inbreds.Genotypic correlations between CER and plant traits were low, suggesting that one could develop high CER genotypes displaying various morphological traits. Nonsignificant correlations between CER and yield traits indicated CER was not the primary factor limiting yield of these inbreds. Correlations showed that dry matter yield was limited by amount of leaf area and by traits associated with efficient use of light energy. We concluded grain yield of these inbred lines was limited by sink size and by lack of a receptive sink because: 1) grain yield was highly correlated with ear length, ear diameter, 300‐kernel weight, and number of ears per plant and 2) potential dry‐matter production during grain filling was 208 g plant ‐1 compared with 49.6 g plant‐1 actually stored in the grain.
Heritability and Correlations of IVOMD, Maturity, and Plant Height in Rhodes Grass1
Authors: Quesenberry K. H. , Sleper D. A. , Cornell J. A. 
Published: July 2010

Little information is available on variability and heritability of forage quality and digestibility in Rhodes grass (Chloris gayana Kunth). In this study, variability and heritability of in vitro organic matter digestibility (IVOMD) at 2 and 6 weeks of regrowth of 82 randomly selected plant introductions of Rhodes grass were examined in two growing seasons. The genotypic source of variance for 2 and 6 week regrowth digestibility was significant for both years. Mean IVOMD for 2 and 6‐week regrowth over both years was 72 and 57%, respectively. Although years were a significant source of variation for IVOMD, entries that ranked high for 6‐week IVOMD in year 1 were also consistently high in year 2. Simple correlation coefficients between 2‐ and 6‐week IVOMD in year 1 (r = 0.13) and year 2 (r = 0.35) although statistically significant (P < 0.01), were rather low. However, when the data were combined over years the correlation between 2‐week and 6‐week IVOMD was r = 0.58. In addition the genetic correlation between 2‐ and 6‐week IVOMD from analysis of covariance of both years data was rg = 0.75 indicating that certain genes influenced both 2‐ and 6‐week IVOMD. Broad sense heritability estimates of 2‐ and 6‐week IVOMD over both years were 13.7 and 42.5% respectively.Significant variability was also found for maturity and plant height in both years. A highly significant positive correlation was found between maturity and plant height in year 1 (r = 0.76) and year 2 (r = 0.71). Heritability estimates for maturity and plant height derived from data averaged over both years were 74.3 and 66.3%, respectively. There was also a highly significant positive correlation (r = 0.71) between 6‐week regrowth digestibility and maturity.Our results indicate that sufficient variability exists in this random sample of unselected Rhodes grass plant introductions to make selection for improved IVOMD feasible. Broad sense heritability estimates for IVOMD, maturity, and plant height were sufficiently high to suggest that relatively rapid initial progress could be made in selecting for these traits. The high positive correlation between 6‐week IVOMD and maturity suggests that selection for late maturing genotypes with high IVOMD should be possible.
Studies of Inbreeding Depression, Breeding Behavior, and Heterosis with Inbred Lines of Buckwheat1
Authors: Marshall H. G. 
Published: July 2010

Homomorphic, self‐fertile inbred lines of buckwheat (Fagopyrum esculentum Moench) are a recent development, and little is known about their potential for improvement of the crop. My objectives were to determine the breeding behavior of several inbred lines and to measure the effects of inbreeding depression and heterosis on several characteristics of buckwheat.In polycross blocks during 2 years, all inbreds had reduced gross size, plant height, seed yield, and seed weight relative to an open‐pollinated parent. The percentage of hybrid plants in the polycross populations ranged from 0 to 93. All polycross hybrids exhibited heterosis for plant height and dry weight at the early blossoming stage compared to their seed parent and to all the possible inbred pollen parents. During 2 years, populations with the highest percentages of hybrids were the highest yielding, but none exceeded the yield of an open‐pollinated check strain.The four inbred lines with the least selfing in the polycross trials were paired in enclosed areas to produce single‐cross populations. ‘Kasho’, a cultivar with both compatible and incompatible pollen, also was paired with each of the inbreds. The percentage of hybrid plants in the inbred line combinations ranged from 5 to 72. Differences were found between reciprocal crosses for some combinations. When Kasho was the pollen parent, the percentage of hybrid plants ranged from 28 to 97. Regardless of the pollen parent, an inbred with the shortest style (0.58 vs. up to 1.16 mm) provided the fewest hybrids. The higher percentages of hybrids from Kasho pollinations apparently resulted from a differential rate of pollen tube growth that favored compatible pollen from thrum flowers. Differential pollen tube growth could provide pollen control to produce hybrid cultivars if thrum‐flowered inbred lines can be developed.Heterosis was studied in 10 of the single‐cross populations. Relative to the high inbred parent, all single‐crosses showed heterosis for plant height and total dry matter yield, eight showed heterosis for seed yield, and five showed heterosis for seed weight.
Flower Induction in Glycine Tomentella Hayata following Grafting onto G. Max (L.) Merr.1
Authors: Newell C. A. , Hymowitz T. 
Published: July 2010

An accession of Glycine tomentella Hayata, subgenus Glycine Willd. (P.I. 393567) from Northern Territory, Australia was induced to flower by grafting it onto a stem of the cultivated soybean G. max (L.) Merr., subgenus Soja (Moench) F. J. Herm. All previous attempts to obtain seed from P.I. 393567 by short photoperiods and ageing had failed. The G. tomentella scion grew vigorously and produced a large number of seed pods under a photoperiod regime conducive to flowering in the soybean. The parent plant from which the scion was obtained did not flower under the same conditions. These results indicated that flowering in the scion probably was induced by a floral stimulus from the soybean stock. Cytological examination showed P.I. 393567 to be tetraploid with 2n=80.Grafting was demonstrated to be a successful method of promoting seed production in a wild Glycine accession which did not otherwise flower under experimental conditions, thereby enabling conservation of germplasm which could not readily be replaced.
Spikelet Abscission in Guineagrass as Influenced by Auxin and Gibberellin1
Authors: Weiser Glen C. , Smith Rex L. , Varnell Ray J. 
Published: July 2010

Seed production of guineagrass (Panicum maximum Jacq.), an important pasture and forage crop in the tropics, is hindered by its heavy loss of seeds through spikelet abscission. A method whereby abscission could be delayed or arrested would be a great aid in seed harvest of this and other Panicum species.Auxin and gibberellin at three concentrations (10‐3, 5✕10‐3 and 10‐2M) were applied to the inflorescences of two experimental genotypes (PM285 and 68s‐5‐2) when the panicle was three‐fourths emerged from the flag leaf to inhibit spikelet abscission. Growth chamber and field experiments were conducted.Response was dependent on plant genotype and growth regulator concentration. In the growth chamber, panicle branch explants were inserted into semisolid agar solutions of growth regulators. The most responsive auxin treatment inhibited abscission by 32%. In the field, aqueous sprays of growth regulators were app.lied to entire inflorescences. The most responsive auxin treatment inhibited abscission by 40%, The two genotypes responded differently to IAA treatment with 68s‐5‐2 exhibiting significantly less abscission than PM285. Gibberellin treatments either stimulated abscission or had no influence under the conditions tested.Histological sections of pedicels of the genotype 68s‐5‐2 were made to follow the development of the abscission zone with and without applied auxin. The abscission zone exhibited no readily observable morphologlc or histologic response to auxin.
Recurrent Selection in Soybeans. II. Selection for Increased Percent Protein in Seeds1
Authors: Brim C. A. , Burton J. W. 
Published: July 2010

Recurrent selection for increased percent protein in seeds was conducted in two soybean (Glycine max (L.) Merrill) populations to test the utility of the selection procedure. Population I was derived from a cross of two highly adapted experimental lines. Population II was generated from backcrosses of nine unadapted plant introductions with high percent seed protein to a highly adapted experimental line. Each population was subdivided into an A and a B population. The effective population size of populations IA and IIA was about three times larger than that of IB and IIB. A cycle of selection involved intermating selected lines, testing S1 lines from the matings, and selecting those with highest percent seed protein as parents for the next cycle. Selection progress was evaluated in replicated field trials using composite popula. tions of the parents chosen from the testing generation in each cycle as entries.Percent seed protein increased significantly and linearly in all populations. Seed protein increased from 46.3 to 48.4% with six cycles of selection in population IA and from 46.4 to 47.6% with four cycles in population IB. In population IIA, protein increased from 42.8 to 46.1% with five cycles and from 43.2 to 45.9% with four cycles of selection in population IIB.Yield of the last cyde in both populations IIA and IIB. was significantly lower than that for C0, yet the change in total protein produced per unit area was nonsignificant. In population IA, however, both yield and total protein produced increased significantly from C0 to C8. There was no significant change from C0 to C4 for yield or total protein in population IB. Despite the significant linear decrease in percent seed oil, the total oil produced per unit area decreased significantly in populations IIA and IIB only.The results show that significant progress can be obtained from recurrent selection for protein in soybeans. Reduced effective population size and numbers of lines tested per cycle had little effect on progress.
Stormproof Boll in Upland Cotton. I. Development of Instrumentation and an Inheritance Study1
Authors: Dilbeck R. E. , Quisenberry J. E. 
Published: July 2010

The stormproof boll is a desirable trait for cultivars of cotton (Gossypium hirsutum L.) grown for once‐over stripper‐type harvest. The purpose of this study was to develop instrumentation to measure stormproofness (lock tenacity) and to determine the inheritance of the stormproof boll in a particular cross using this instrumentation. Parental, F1, F2, and backcross populations from a cross between ‘Acala 1517 Br‐2’ (non‐stormproof) and Z‐2557 (stormproof) were scored for visual appearance and measurement of lock tenacity to study qualitative inheritance patterns. Analysis of variance and joint scaling tests were conducted on the lock tenacity data for quantitative determinations of inheritance.The instrumentation developed was capable of detecting differences between stormproof and non‐stormproof boll types. Differences between combinations (pulls per boll ✕ number of bolls per entry) were not significant, while differences between entries were significant. Visual classification of segregating populations indicated that a single dominant gene controlled the stormproof character. However, data from lock tenacity determinations made on these same populations indicated a more complex mode of inheritance. Estimates from the joint scaling test suggested that additive, dominant, and epistatic genetic effects controlled the expression of lock tenacity.
Haploid Plant Development from Anthers and In Vitro Embryo Culture of Wheat1
Authors: Schaeffer G. W. , Baenziger P. S. , Worley J. 
Published: July 2010

Experiments were designed to identify cultivars of wheat (Triticum aestivum L., aestivum group) and culture media most suitable for successful in vitro anther culture and development of haploids. Anthers containing uninucleate pollen from 17 cultivars grown in the greenhouse and five lines grown in the field were excised and cultured on a potato (Solanum tuberosum L.) medium. ‘Kitt’, ‘Downy’, ‘Centurk’, and ‘GWO‐1809’ produced the highest number of embryoids from microspores.Calli removed from anthers cultured in vitro were differentiated into plantlets. Over 50 plants have been recovered. Preliminary cytological determinations proved that the plants were haploid. The results demonstrate the feasibility of the anther culture techniques for the development of haploids in agronomically important wheats.Embryos from presoaked and surface‐sterilized seed of 26 wheat lines were excised and planted on defined agar media to measure in vitro growth rates. Embryonic cells from mature wheat seeds divided and produced partially differentiated tissues on standard tissue culture media containing supplements of 2,4‐dichlorophenoxyacetic acid (2,4‐D), 2‐isopentenyladenosine, and naphthaleneacetic acid. Transfer of the calli to a medium with less 2,4‐D or to a medium with 1 mg/liter of indole‐3‐acetic acid and kinetin enhanced differentiation and the differentiated tissues ultimately produced whole plants. There were statistically significant differences in the growth rates, measured as fresh weight, among different lines. Among the promising lines for in vitro cultures were Kitt, GWO‐1809, ‘Baart’, ‘Coker 75‐6’, and others. Isolated embryos from some cultivars did not form calli in vitro. Kitt and GWO‐1809 grew well as partially differentiated calli.
Seedling Growth Responses of Oat Genotypes1
Authors: Murphy C. F. , Long R. C. 
Published: July 2010

The objectives of these investigations was to utilize a seedling growth technique to (i) verify previous reports on growth responses of germinating seedlings to nutrient additives; (ii) determine how soon seedling growth sponses occur; (iii) measure differences in genotypic respouses.A preliminary test with two F2 oat populations (Arena sativa L.) and their respective parents (‘Firecracker’ and ‘Goodand’; Goodland and N.C. 55) verified earlier observations of increased shoot growth and reduced root growth by 10‐lay‐old seedlings grown with a modified halfstrength Hoagland's solution, as compared to a growth medium of distilled water. Parental means were different and within‐parent variability was exhibited.Shoot and root lengths and dry weights, plus root volume, were measured on 4‐ to 10‐lay‐old seedlings of four oat genotypes (‘Carolee’, ‘Salem’, N.C. 2469‐3, and Firecracker) grown in distilled water and in modified half‐strength Hoagland's solution. Responses to the nutrient solution were apparent for shoot length and weight, and generally occurred after 6 to 8 days, depending upon the genotype. Hoagland's solution resulted in increased shoot length and shoot weight but reduced root length. Root weight and volume did not respond to the nutrient solution.Genotypic differences were evident for all five characters. The dwarf llne, N.C. 2469‐3, developed both shoots and roots more slowly than any of the other genotypes. Firecracker developed shoots and roots most rapidly while Carolee and Salem developed them at intermediate rates. Genotype ✕ growth medium interactions were evident for shoot length and weight and for root volume. A method for determination of root volume using the displacement technique is presented.
Application of a Modified Diallel Analysis to Evaluate Recurrent Selection for Grain Yield in Maize1
Authors: Smith O. S. 
Published: July 2010

The modified diallel analysis proposed by J. J. Hammond and C. O. Gardner in 1974 and the model proposed by O. S. Smith in 1979 to evaluate progress from recurrent selection were used ta evaluate half‐sib and S1 recurrent selection programs in the maize (Zea mays L.) cultivar, ‘BSK.’ Changes in the mean of selected populations and their crosses were found to be a function of inbreeding depression and changes in the frequencies of alkies with additive effects. Estimates of changes due to alleles with dominance effects were not significant. Terms involving changes due to alleles with dominance effects would be expected to be very small based on quantitative genetic theory and based on the way the terms were defined. Use of the modified diallel analysis for evaluating progress from recurrent selection may be limited to populations that have large effective population sizes and have undergone a large number of cycles of selection.Use of the analysis proposed by Smith showed that half‐sib and S1 selection increased the frequencies of alleles with additive effects and S1 selection was more affective than half‐sib selection. The analysis also provided an estimate of the rate of inbreeding depression and indicated that this rate was the same for both selection methods.
Inbred Lines vs. the Populations as Testers in Reciprocal Recurrent Selection1
Authors: Comstock R. E. 
Published: July 2010

In reciprocal recurrent selection (RRS) the change in the average value of genotypes in the cross between the selection populations is a function of allele frequency changes in the two selection populations; the change is not a function of the details of the selection process by which those changes are promoted. Thus, the proper criterion to employ in comparisons of variations of RRS is the expectation of change per unit tune in the frequency of an allele. Using this criterion and theory flowing from the genetic model that assumes linkage equilibrium and no epistasis but allows any number of alleles per gene, I found that the RRS populations are slightly superior, as testers for each other, to inbred lines extracted from those populations. This finding contrasts to the suggestion by Russell and Eberhart (1975) that such inbred testers should be superior. Their suggestion was based on evidence of greater genetic variance among test progenies when inbred line testers were used. The theory reported herein shows this is to be expected (unless gene action is completely additive) but that a corresponding increase in allele frequency changes is not to be expected.The results summarized above are discussed in relation to situations in which epistasis and linkage disequilibrium may be present. It is concluded that they are qualitatively correct in more general situations.