Wiley
Công bố khoa học tiêu biểu
Sắp xếp:
Mineral Concentration of Broccoli Florets in Relation to Year of Cultivar Release ABSTRACT It has been proposed that crop improvement through directed plant breeding has resulted in decreases in nutrient concentrations of harvested components over time. A few field studies wherein cultivars released over a period of years are evaluated for nutrient content provide the best evidence for nutrient changes over time; however, no such studies have been conducted with vegetable crops. To accomplish this with broccoli (Brassica oleracea L.), we grew 14 cultivars released over 50 yr in two field trials, and harvested florets were assayed for mineral concentration by inductively coupled plasma–optical emission spectroscopy. Results indicated significant cultivar differences in floret concentrations of Ca, Cu, Fe, Mg, Na, P, and Zn, but not of K, Mn, Mo, or S. With most minerals, there was no clear relationship between concentration and release year. Although the oldest cultivar exhibited some of the higher mineral concentrations, from 1975 to the present no significant changes appear to have occurred. Head mass was negatively correlated with concentrations of most minerals, but head mass was not correlated with year of release. We propose it most relevant to examine mineral nutrient changes for cultivars grown since 1975 when broccoli phenotypes changed dramatically and the vegetable grew in prominence as a component in the U.S. diet. Results provide a guide for mineral levels in broccoli that should be maintained as other characteristics are manipulated in the future.
Wiley - Tập 51 Số 6 - Trang 2721-2727 - 2011
Genetic Improvement for Yield and Fertility of Alfalfa Cultivars Representing Different Eras of Breeding Alfalfa (Medicago sativa L.) exhibits inbreeding depression for forage yield and also tends to set fewer seeds following self‐pollination than following cross‐pollination. The objectives of this study were to estimate changes in yield potential, inbreeding depression for yield, and self‐ and cross‐fertilities of alfalfa cultivars adapted to Wisconsin and representing different eras of breeding from 1898 to 1985. In addition, two University of Wisconsin‐Madison experimental cultivars with well‐known breeding histories were included in the study. The S0 and S1 populations derived from each cultivar were evaluated for 3 yr for forage yield. Self‐ and cross‐fertilities of some S0 populations were measured in a greenhouse study. Both S0 and S1 populations of modern (Era 3) cultivars yielded greater than those of the oldest (Era 1) cultivars. Era 3 S0 populations generally yielded more than those of cultivars released in the 1940s and 1950s (Era 2) but this was not true for S1 populations. These results suggest that favorable alleles have accumulated in modern alfalfa cultivars but that this mostly occurred between Eras 1 and 2. Inbreeding depression decreased between Eras 1 and 2 and increased between Eras 2 and 3. Increased heterozygosity or exploitation of nonadditive genetic effects may account for much of the improvement in cultivar yield potential that occurred between Eras 2 and 3. Era 3 cultivars had a significantly lower ratio of self‐fertility to cross‐fertility than Era 1 cultivars. Therefore, modern cultivars appear to have improved capacity to produce high proportions of cross‐pollinated seed when nonself pollen is available, compared with older cultivars.
Wiley - Tập 34 Số 4 - Trang 953-957 - 1994
Plant Genetic Resources Conservation and Utilization: The Accomplishments and Future of a Societal Insurance Policy Concerns about the genetic erosion of crop genetic resources (CGR) were first articulated by scientists in the mid‐20th century and have since become an important part of national policies and international treaties. The C‐8 (Plant Genetic Resources) section of the Crop Science Society of America (CSSA) was created in 1990 in response to these concerns. Over the last 50 yr, both ex situ and in situ conservation have been set up to maintain threatened CGR. During this period, a set of tools (core collections, molecular markers, and geographic information systems) has been adopted to facilitate conservation and utilization by breeders. Current and future trends include characterization of the genotypic basis of phenotypic variation and the evolutionary, ecological, and human factors that have shaped CGR. The intellectual property regime to which CGR are subjected since 1980 has limited the exchange of germplasm. It remains to be seen if these regimes will evolve so as to achieve basic goals of conservation of genetic diversity and traditional knowledge associated with diversity, while at the same time reward breeders and farmers. Funding of biodiversity conservation remains a critical point. Finally, broadening the conservation circle to establish closer collaborations with grassroots conservation movements and community seed banks is necessary to better conserve the broad range of CGR and as an essential starting point for participatory breeding efforts.
Wiley - Tập 46 Số 5 - Trang 2278-2292 - 2006
Genotype × Environment Effects on Single‐Plant Selection at Low Density for Yield and Stability in Climbing Dry Bean Populations Breeders ought to consider the confounding effects of the environment and genotype × environment (G × E) interaction on response to early generation selection. To meet this requirement, honeycomb breeding was performed at a low density within two dry bean populations (Phaseolus vulgaris L.) under typical open‐field conditions and in an adjacent greenhouse. Nineteen progeny lines were formed through selection of nine and ten of the highest‐yielding plants in the greenhouse and the field, respectively. Honeycomb progeny testing at the low density in the two distinct environments showed up to 75% improvement in plant‐yield potential. Under farming‐density conditions in five environments, six of the lines outyielded the respective original population by 12 to 38% and exhibited the greatest stability according to the genotype and genotype × environment (GGE) biplot model. At low density, the greenhouse evaluation demonstrated less acquired variance than the field evaluation and was especially useful for selection and progeny evaluation. Three of the six outstanding lines originated from the greenhouse. Honeycomb progeny estimation on a single‐plant yield basis in the greenhouse, rather than in the field, gave a better prediction of yield potential on an area basis. The results showed that honeycomb breeding performed in two environments to address the G × E interaction may be successful for developing varieties that exhibit both high and stable productivity.
Wiley - Tập 50 Số 3 - Trang 775-783 - 2010
Assessment of Potato Breeding Progress in the USA over the Last Century Potato (Solanum tuberosum subsp. tuberosum ) production has increased six‐fold (per unit area) in the USA since the 1920s. Direct comparison of potato cultivars released during the past century can help us understand how potato breeding has contributed to these production improvements and to other important traits associated with marketing and utilization. Our objective was to study trends in potato genetic improvement during four subjective breeding periods (BP) (pre‐1900 = BP I; 1930 to 1949 = BP II; 1950 to 1969 = BP III; 1970 to present = BP IV), and also to compare performance between and within the three major cultivar types (round‐white, long, and red‐skinned). In field trials conducted from 1990 to 1992, under best management practices (with scheduled irrigation) in Michigan, the greatest total yield potential was observed in several cultivars released during BP I and II. These cultivars also had late vine maturities. On average, BP II had the greatest marketable yield. Cultivars released in BP III had the lowest total yield, earliest vine maturity, highest scab resistance and most favorable tuber appearance. General trends over periods were for earlier maturity and improved tuber appearance. Round‐white cultivars improved for chip‐processing ability and dry matter content over breeding periods, while long types increased in percent marketable yield only in BP IV. No trends were observed for scab resistance. When cultivars were grouped according to tuber type, there were no differences in total yield; however, the long types had the lowest marketable yield and the red‐skinned types had lowest dry matter content.
Wiley - Tập 36 Số 6 - Trang 1544-1552 - 1996
The Future of Plant Breeding A symposium was hosted 10 to 11 Mar. 2005 at Michigan State University to discuss the future of plant breeding education at public institutions. Plant breeding remains a vibrant, multidisciplinary science characterized by its ability to reinvent itself by absorbing and utilizing novel scientific findings and technical approaches. A contemporary breeding curriculum should include hands‐on experience with the inheritance and selection of complex traits in actual plant populations, basic biology of plants (reproductive biology, Mendelian genetics), principles of quantitative genetics and selection theory, principles and practice of plant breeding and related sciences such as genomics, applied statistics, experimental design, and pest sciences. Plant breeding education should also comprise several professional skills, including knowledge of other languages, business management, and intellectual property rights. The private sector should play an increased role in the plant breeding. There is also a need for alternative types of training in plant breeding geared toward working breeders and farmers. Additional support for plant breeding education programs may come from the private sector and the federal government. With regard to specialty crops, increased support for research and education may result from a focus on the unique features of these crops. Finally, it is important to cultivate public awareness of the accomplishments of plant breeding.
Wiley - Tập 46 Số 4 - Trang 1630-1634 - 2006
Intra‐Cultivar Variation for Seed Weight and Other Agronomic Traits within Three Elite Soybean Cultivars ABSTRACT Despite its importance, exploitation of intra‐cultivar variation has been very limited due to the belief that elite cultivars are highly homogeneous. The main objective of this study was to investigate the presence of exploitable intra‐cultivar variation for seed weight, maturity, and other agronomic traits within elite soybean cultivars released for their superior productivity and resistance to various diseases. Single‐plant progeny lines, selected at very low plant density from within these cultivars, were evaluated for seed weight, maturity, plant height, lodging, and seed yield in row‐plot replicated randomized complete block designs across years. For seed weight, the magnitude of intra‐cultivar variation across years between the largest‐ and the smallest‐seeded lines averaged 36 mg seed−1 for Benning, 22 mg seed−1 for Cook, and 45 mg seed−1 for Haskell. For maturity, the magnitude of intra‐cultivar variation was 5 d in Benning, 4 d in Cook, and 7 d in Haskell. Furthermore, we discovered intra‐cultivar variation for plant height within Cook and Haskell, and for lodging within Haskell. This study is the first one to report evidence of significant intra‐cultivar variation for seed weight, maturity, plant height, and lodging within soybean cultivars. The results suggest that cultivars may not be permanent records with nonexistent variation but genetic material that can be upgraded to maintain uniformity in the long term and further improve desirable agronomic or seed‐trait characteristics.
Wiley - Tập 47 Số 1 - Trang 367-373 - 2007
Yield Improvement in Temperate Maize is Attributable to Greater Stress Tolerance ABSTRACT A retrospective analysis of the physiological basis of genetic yield improvement may provide an understanding of yield potential and may indicate avenues for future yield improvement. Rate of yield improvement of maize (Zea mays L.) hybrids in Ontario, Canada has been ≈1.5% yr−1 during the last five decades. Comparison of short‐season hybrids representing yield improvement from the late 1950s to the late 1980s showed that genetic yield improvement was 2.5% per year and that most of the genetic yield improvement could be attributed to increased stress tolerance. Differences in stress tolerance between older and more recent hybrids have been shown for high plant population density, weed interference, low night temperatures during the grain‐filling period, low soil moisture, low soil N, and a number of herbicides. Yield improvement is the result of more efficient capture and use of resources, and the improved efficiency in resource capture and use of newer hybrids is frequently only evident under stress. Improved resource capture has resulted from increased interception of seasonal incident radiation and greater uptake of nutrients and water. The improved resource capture is associated with increased leaf longevity, a more active root system, and a higher ratio of assimilate supply by the leaf canopy (source) and assimilate demand by the grain (sink) during the grain‐filling period. Improvements of resource use under optimum conditions have been small, as leaf photosynthesis, leaf‐angle distribution of the canopy, grain chemical composition, and the proportion of dry matter allocated to the grain at maturity (i.e., harvest index) have remained virtually constant. Genetic improvement of maize has been accompanied by a decrease in plant‐to‐plant variability. Results of our studies indicate that increased stress tolerance is associated with lower plant‐to‐plant variability and that increased plant‐to‐plant variability results in lower stress tolerance.
Wiley - Tập 39 Số 6 - Trang 1597-1604 - 1999
Tổng số: 54
- 1
- 2
- 3
- 4
- 5
- 6