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1.
A tetraploid form of Phleum pratense from southwestern Europe was found to behave cytogenetically as an autotetraploid. Inheritance patterns in inbred seedlings artificially inoculated with stem rust agreed with this interpretation if chromosome and chromatid assortment are assumed.Results of cooperative investigations of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and former Graduate Assistant, Agronomy Department, Wisconsin Agricultural Experiment Station, Madison, Wisconsin. 相似文献
2.
Ten pentaploids were isolated from seedling populations developed from seed of tetraploid plants grown in association with hexaploid timothy. About 80% of the prophase sporocytes exhibited severe or moderate pycnosis. These pycnotic accumulations appear to arrest the meiotic processes and apparently result in sporocyte lethality. Surviving sporocytes at diakinesis possessed nuclei with configurations that varied from 1 VI+14 II+1 I to 9 II+17 I. It is suggested that the conventional sorts of irregularities (univalents, inversions and translocations) cannot account for the low percentages of stainable pollen. Pairing relations indicated that considerable duplication and/or autosyndesis occurred in the genomes combined, and suggest that even though the tetraploid (2n=28) and hexaploid (2n=42) forms of Phleum pratense are closely related they are not identical. A portion of the sterility observed may be due to nuclear-cytoplasmic interaction.Results of co-operative work of the Crops Research Division, A.R.S., U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wis.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and Graduate Assistant, Department of Agronomy, Wisconsin Agricultural Experiment Station. 相似文献
3.
Three hundred sixty-five S1 and 234 S2 seedling populations of timothy (Phleum pratense L.) were examined for their segregations for chlorophyll deficiencies. Arrays of both self-and open-pollination families indicated a lack of concentration at definite levels, with ratios expressed forming a continuous series from 4.6:1 to 572:1 for green: chlorophyll-deficient types in the S1 generation. The S2 populations examined ranged from 1.8:1 to 244:1. Arrays were very similar in their distributions.Sixty-three plants yielded chlorophyll-deficient types in both S1 and S0 populations. From these, it was calculated that 7 to 8 percent of natural self-pollination may occur in timothy.Except at two levels (28:1 and 143:1 tetradisomic) assumption of tetradisomic or simpler inheritance patterns resulted in lower calculated percentages of natural self-pollination than resulted from assumed hexasomic inheritance. No apparent explanation is available to account for these divergences from the regular pattern encountered.Results of cooperative work of the Crops Research Division, Agriculture Research Service, U.S. Department of Agriculture and the Wisconsin Agricultural Experiment Station, Madison.Research Agronomist, Crops Research Division, Agriculture Research Service, U.S. Department of Agriculture and Associate Professor, and Professor of Agronomy, Wisconsin Agricultural Experiment Station, respectively. 相似文献
4.
Progenies from 68 self-pollinated panicles of 10 somatically unstable sorghum-sudangrass hybrid sectors were grown. Data are presented for 25 progenies from three representative unstable plants. Highly uniform progenies were obtained from most panicles. Results indicate chromosome assortment was not always at random. Major distinctions between panicle progenies suggested that: (a) sorghum-like and sudangrass-like genomes functioned as units; (b) gene transfer and association were non-random further indicating that somatic chromosome substitution or somatic translocations, or other gross changes, may have occurred; and (c) other deviating behaviors implied genetic segregation.Results of cooperative work of the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wisconsin 53706 U.S.A. 相似文献
5.
Summary A hexaploid endosperm is regularly associated with a haploid embryo following 4x–2x crosses in potato. One explanation for this is that a single 24-chromosome restitution sperm nucleus fuses with the central cell of the megagametophyte. This suggests that a superior pollinator may be one that produces a high frequency of restitution sperm nuclei. To test this, a technique was developed for observing pollen tube mitosis in vitro following germination of potato pollen in a 20% lactose-50 ppm boric acid solution. A single 24-chromosome restitution sperm nucleus was found in up to 38% of the pollen tubes from a superior pollinator. Moreover, pollen from an inferior pollinator soaked in a sucrose-boric acid-colchicine solution produced 100% restitution sperm nuclei in vitro and a haploid frequency from a tetraploid cultivar comparable to that normally induced by an untreated superior pollinator. The data indicate that the effectiveness of a pollinator in inducing haploids in potato is determined by the frequency of restitution sperm nuclei it produces.Cooperative investigations of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station. Part of a thesis submitted by the senior author in partial fulfilment of the requirements for the Ph. D. degree. Published with the approval of the Director of the Wisconsin Agricultural Experiment Station.Research Assistant, Department of Horticulture, University of Wisconsin, and Research Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, Madison, Wisconsin 53706. 相似文献
6.
X-ray induced barley mutants and their prototype Hannchen were tested for their behaviour in evolutionary breeding (the term is used to indicate the application of population genetics to plant breeding). It was shown that only the better mutants survive. Eventually only the fittest mutants and recombinants will comprise the population.Contribution from the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Agronomy Departments of the University of California and of Arizona, co-operating. The mutants were selected from a culture grown for R. S. Caldecott at Brawley California in 1955.Research Agronomist and Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and Field Station, Supt., University of California, respectively at Davis, California, Tucson, Arizona, and Tulelake, California. 相似文献
7.
Intraplant variation in smooth bromegrass was examined by determining pollen stainability and size in 6 moderately self-compatible S-2, and 12 self-incompatible OP-3 plants. Statistically significant differences in pollen stainability occurred between panicles within plants, between plants, and between plants x within plant interactions. Pollen diameter distributions for OP-3 plants tended to be trimodal, and bimodal distributions occurred in S-2 plants. In trimodal distributions, peaks occurred at known diploid and tetraploid chromosome levels, and it is presumed that the peak between these represented the triploid gametic number.Results of cooperative investigations of the Crops Research Division, ARS, USDA, and the Wisconsin Agricultural Experiment Station, Madison. The statistical analyses were made by the Numerical Analysis Laboratory, University of Wisconsin. 相似文献
8.
Summary Approximately 85% of the S1, S2 and S3 plants in 142 smooth bromegrass progenies were morphologically similar within lines. Progenies developed from diallel crosses possessed greater uniformity than was expected from hybridization of S1 octaploid smooth bromegrass. Behaviors observed are interpreted on the basis of selective survival and functioning of gametes and can be explained by the fusion of like gametes.Results of cooperation between the Crops Research Division, Agricultural Research Service, US Department of Agriculture, and the Research Division, College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin 53706.Geneticist (deceased). 相似文献
9.
Summary Quantitative serological techniques were used to estimate the genotype relationships of six oat (Avena sativa L.) cultivars to a seventh. Reciprocal comparisons were made in which leaf, pollen, whole grain, and scutellum antigens were used. The reciprocal comparisons did not estimate genotypic relationships in the same order, but produced reciprocal results, i.e., when one method estimated lower relationships the other estimated higher, often above 100%. The reciprocal results were attributed to antigens common to each cultivar and these antigens masked and confounded the qualitative differences needed to estimate genotypic relationships. The different responses of common and qualitative antigens in the reciprocal comparisons made possible an analysis method that removed much of the masking effect of common antigen differences. In these tests, whole grain and embryo mean serological relationships agree well with best genetic estimates of genotypic relationships.1 Journal Paper No J-6291 from the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa, Project 1176. In cooperation with the Crops Research Division, Agriculture Research Service, U.S. Department of Agriculture. 相似文献
10.
Summary Allohexaploid (2n = 108) F2 and F3 interspecific hybrids ofHibiscus cannabinus × H. sabdariffa were intermediate in their resistance to the cotton root-knot nematode (Meloidogyne incognita acrita
Chitwood 1949) between their moderately resistant, tetraploid parent, roselle (Hibiscus sabdariffa L.) and their susceptible, diploid parent, kenaf (H. cannabinus L.). Whether or not this resistance, as measured by the amount of root galling, is sufficient to be of practical importance is not known at present. However, results were encouraging enough to suggest further testing of the hybrids for agronomic potential, stability, fertility, and response to root-knot, and other parasitic nematodes that attack this potentially important paper-pulp crop.Cooperative investigations of the Crops Research Division, Agricultural Research Service, US Department of Agriculture, and the Texas Agricultural Experiment Station. 相似文献
11.
M. W. Martin 《Euphytica》1970,19(2):243-252
Summary Developing high levels of resistance to curly top virus (CTV) and combining it with good horticultural type in tomato lines has been difficult. However genes for resistance from severalLycopersicon species have been obtained and combined by intercrossing and selection in extensive greenhouse and field tests. Several tomato breeding lines have been developed which contain these genes in combination with those giving good horticultural characteristics. The effective utilization of these resistant breeding lines in crosses with commercial types to develop finished varieties will necessitate severe exposure to CTV in several successive tests. Large F2 populations and large numbers of selections in the following filial generations must be screened. Horticultural selection should be done only in those tests in which disease exposure has been sufficient to eliminate the susceptible parent.Co-operative investigation of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Agricultural Experiment Stations of Utah and Washington, Logan, Utah, and Pullman, Washington, respectively. 相似文献
12.
Summary Genetic stability was evaluated in 11 long-time inbred lines of maize (Zea mays L.) by measuring 10 plant, ear, and seed characters in successive generations reproduced by self-pollination in ear-to-row progenies. The lines were reproduced through 10 generations, and the studies were made for generations 1, 3, 5, 7, 9, and 11. All lines had been inbred more than 10 generations before the start of the study. For 106 F-tests among generations, significant variation was observed for 40 tests (P<0.05). Major changes were observed in two inbred lines; in most other cases, the statistically significant changes were too small to be of practical importance.Joint contribution: Plant Science Research Division, Agricultural Research Service, U.S. Department of Agriculture, and Journal Paper No J-7245 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No 1897. 相似文献
13.
Summary Pollen germination and pollen tube growth after self- and intra- and interspecific pollinations of annual [M. scutellata (L.) Mill., M. disciformis DC., and M. rigidula (L.) All.] and perennial (M. sativa L.) Medicago species were studied using a Carl Zeiss microscope with a fluorescence filter attachment.Self-pollination of self-fertile annual and intraspecific pollination of cross-fertile perennials were characterized by high pollen germination and rapid normal pollen tube growth. In contrast pollen germination percentages were very low and many pollen tube growth abnormalities occurred following interspecific pollination and self-pollination of self-sterile plants. The time period from pollination to fertilization for interspecific crosses was about double that following self-pollination of the annual species. However, fertilization occurred frequently following interspecific pollinations. Much of the sterility was due to factor(s) operating after fertilization.Cooperative investigations of the Kansas Agricultural Experiment Station, Dept. of Agronomy and the U.S. Department of Agriculture, Agricultural Research Service. Contribution No. 82-582-J- Mention of a trademark name or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture, and does not imply its approval over other products that also may be suitable. 相似文献
14.
R. J. Hecker 《Euphytica》1972,21(1):106-111
Summary The effect of inbreeding on vegetative vigor, as measured by root yield, was evaluated in two diploid (2x) and equivalent autotetraploid (4x) sugarbeet strains, and one additional 2x and one 4x strain. Root yields of the 2x and 4x S1 progenies each averaged 86.7% of their comparable open-pollinated progeny. Inbreeding depression of root yield was variable from strain to strain. The selfed 4x populations, when compared with their 2x equivalents, suffered more yield depression than was expected on the basis of the theoretic approach to homozygosity associated with selfing in autotetraploids. The inbreeding depression was partly attributed to (a) the approach to homozygosity, and (b) the fact that partially homozygous 4x S1 individuals were probably unable to make compensating growth when located adjacent to a low vigor aneuploid plant. A major part of root yield depression remained unexplained. Sucrose content within strains and within ploidy levels was not significantly affected by one generation of selfing.Joint contribution of the Crops Research Division, Agricultural Research Service, US Department of Agriculture, the Colorado Agricultural Experiment Station, and the Beet Sugar Development Foundation. Published with the approval of the Director of the Colorado Agricultural Experiment Station as Scientific Series No. 1582. 相似文献
15.
K. J. Frey 《Euphytica》1965,14(2):196-208
From 1955 through 1963, approximately 300,000 hill plots have been used in various experiments in the Iowa small grain research program. When grain yield, plant height, and heading date were measured on the same varieties, the genetic correlations between rod rows and hills were 0.98, 0.96 and 0.96, respectively.The coefficients of variation for plant height, weight per volume, spikelets per panicle, panicles per plant, weight per 100 seeds were similar for rod rows and hills. However, the coefficients of variability for grain yield ranged from 2 to 5 times larger for hills than for rod rows. Competition between varieties in adjacent hills had little effect on the performance of varieties.The best method for planting hill plots is the conventional method opening a hole in the soil about 2 inches deep with a hoe, pouring the seed in the hole, and covering it with soil. Rates of planting influenced the expression of grain yield, panicles per plant, and spikelets per panicle, but not weight per 100 seeds and plant height. Approximately 30 seeds per hill appeared the most desirable planting rate.Journal Paper No. J-5064 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa. Project No. 1176. Received for publication Febr. 23, 1965. In cooperation with the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture.Professor of farm crops. 相似文献
16.
Summary Ten interspecific crosses of Avena sativa L. x A. sterilis L. were used to study associations of groat protein percentage with selected seed and agronomic traits. Each cross was grown in a replicated experiment, and the genetic material consisted of parents and F2-derived lines grown in the F4 generation.No close associations were found between groat protein percentage and plant height, heading date, or 10-groat weight. Individual crosses did show significant correlations, but none of the 3 traits was sufficiently associated with groat protein generally so as to be beneficial or inhibitory to combining high groat-protein percentage with the maturity, plant height, and 10-groat weight appropriate for good agronomic cultivars of oats.High groat-protein percentage was closely associated with abscission spikelet separation and jointed awn, both of which are A. sterilis traits. Shattering and dark seed color (A. sterilis traits) were also associated with high groat protein percentage, but kernel pubescence was not. Only a few segregates within each cross were A. sativa type for all 5 of the seed traits, but when A. sativa types from all crosses were grouped together, there was a large range for groat-protein percentages.Journal Paper No J-6950 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1752. In cooperation with the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture. Carried out with a grant from the Quaker Oat Co., Chicago, Illinois, USA. 相似文献
17.
Summary Barley powdery mildew was used as a model to evaluate the potential of barley composite cross populations for conservation of disease resistance. The objective was to determine if increases in resistance to powdery mildew could be detected over periods of time in composite cross populations developed in California, where the disease might have had a selective influence on the populations, and the same populations grown in Montana, where no selective influence of powdery mildew was expected. Four isolates of Erysiphe graminis f. sp. hordei were used to monitor the frequencies of plants with specific mildew resistances through early, intermediate and late generations of three composite cross populations (CCII, CCV, CCXII) grown at Davis, California, and Bozeman and Moccasin, Montana. Changes in frequencies of plants resistant to the four isolates were observed between generations in all populations from the three locations. Trends in the frequencies of resistance are discussed in relation to selection pressure applied by E. graminis. It is suggested that associations with gene complexes other than resistance to E. graminis might help to explain the increased resistance observed in these studies.This research was funded in part by U.S. Agency for International Development Contract No. AID/DSAN-C-0024. The authors are grateful to Dr A. L. Kahler for seed of the composite cross populations and to Dr J. G. Moseman for the powdery mildew cultures.Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture; the Department of Plant Pathology, Montana State University; and The Montana Agricultural Experiment Station. Journal Series Paper No. 1381 of the Montana Agricultural Experiment Station. 相似文献
18.
Summary A partial male sterility system in the soybean (Glycine max (L.) Merr.) germplasm population AP6(SI)CI was found to be controlled monogenically by a recessive allele, msp. Observations of msp msp plants in different environments suggested that environmental conditions significantly affect expressivity of the msp allele with respect to male sterility. We obtained no experimental evidence of cytoplasmic effects on msp expression. Background genotypes, however, seem to affect msp expressivity through their determination of flowering dates and resultant interactions with varying environmental conditions.Homogeneous populations of partially male-sterile plants can be generated by increasing families of msp msp plants in fertility-inducing environments, if measures are implemented to prevent the introduction and/or build-up of fertile genotypes that arise from natural cross-pollinations.Joint contribution: North Central Region, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, and Journal Paper No. J-9596 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011; Project 2107. 相似文献
19.
Summary We measured yielding ability and weight per 100 seeds in 7 populations of oat lines, each derived from a different cross. The association between these two traits was curvilinear, with maximum yields occurring when 100-seed weights were between 2.75 and 3.10 g.In a simulated selection experiment conducted on a bulk population of 150 oat lines (i.e. only lines with seed weight between 2.75 and 3.10 g per 100 seeds were saved), the proportion of superior yielding lines was increased from 16% in the original to 32% in the new one. In the 100-seed weight class below 2.75 g, the proportion of high yielding lines was only 5%.Journal Paper No. J-6102 of the Iowa Agricylture and Home Economics Experiment Station, Ames, Iowa, U.S.A. Project No. 1176. In cooperation with the crops Research Division, Agricultural Research Service, U. S. Department of Agriculture. 相似文献
20.
Summary The variation which persisted in interspecific aneuploids even after one or two generations of backcrossing prevented the morphological distinction of the aneuploids from their diploid sibs. An attempt was made to unmask the effects of aneuploidy by producing aneuploids within the more uniform genetic background of a single species.The procedure to produce trisomics and aneuploids of diploid species was to vegetatively double clones or seed of the species with colchicine, cross the induced tetraploids to diploids to produce triploids, and then cross the triploids to the original diploids. An attempt was made to use the same diploid clone and/or introduction of a species in all successive stages of the procedure in order to obtain as much uniformity as possible. This was largely unsuccessful because self-incompatibility and inbreeding reduced seed set. Seventy-three different tetraploids were obtained from seven species. Tuber treatments were noticeably unsuccessful in producing doubled plants. The two vegetative treatments were most successful and produced 41 different tetraploid clones while 30 doubled plants were obtained from four seed treatments.Morphologically the tetraploids resembled the diploid and there was no noticeable increase in size of leaflets and floral parts in the tetraploid. The average number of chloroplasts in ten pairs of guard cells was a distinctive feature which could efficiently be used in distinguishing the induced tetraploid plants from diploids. The tetraploids were generally less fertile than their diploid counterparts and the majority of them exhibited self-compatibility in comparison to self incompatibility of the diploids.Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture and the Wisconsin Agricultural Experiment Station. Supported in part by grants from the Research Committee of the Graduate School, University of Wisconsin. 相似文献