Download or read book Evaluation of Ten Generations of Divergent Mass Selection for Ear Length in Iowa Long Ear Synthetic of Maize Zea Mays L written by Hernan Cortez-Mendoza and published by . This book was released on 1977 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this investigation was to study the direct and correlated responses to divergent mass selection for ear length in Iowa Long Ear Synthetic. Two phases were involved: (1) estimation of the genetic parameters in the base population to predict direct and correlated responses from selection; and (2) evaluation of direct and correlated responses in ear and other agronomic traits after ten generation of divergent mass selection. A biparental, or Design I, mating scheme was imposed on Iowa Long Ear Synthetic to develop 84 half-sib and 336 full-sib families which were evaluated at three locations in Iowa (Kanawha, Ames, and Ankeny) in 1966. From these types of relative, the pertinent estimates of genetic parameters to make predictions were obtained. Theresults from the combined analysis of Design I indicated that for yield, ear length, ear diameter, ear-row number, and 300-kernel weight, the additive genetic variance accounted for all or most of the total genetic variance, under the assumption of no epistasis. For silking date and ear height the estimates indicated that the greatest proportion of the total genetic variance was due to dominance effects. Since all estimates of dominance genetic variance for yield and its components were negative, it was suggested that either the assumptions necessary for the estimation of the genetic parameters were nos satisfied or sampling errors and geneotypes x environment interaction biased the estimated obtained. it was found that the most likely source of (...).

Download or read book Divergent Mass Selection for Ear Length in the Iowa Long Ear Synthetic Maize Cultivar After Twenty seven Cycles of Selection written by Jose de Jesus Lopez-Reynoso and published by . This book was released on 1997 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hence, improvement in grain yield in the longer-ear subpopulation was canceled by a significant reduction of the kernel-row number and ear diameter. The rate of inbreeding depression of ear length and yield remained constant during the course of selection in the longer-ear subpopulation, but it was gradually reduced with continued selection in the shorter-ear subpopulation. No heterosis was observed in the crosses between corresponding cycles of selection. Estimates of genetic variability among S1 progenies showed no evidence that genetic variance is been exhausted. Hence, further progress in selection is expected in both short- and long-ear subpopulations.

Download or read book Quantitative Genetics in Maize Breeding written by Arnel R. Hallauer and published by Springer Science & Business Media. This book was released on 2010-09-28 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is used in an endless list of products that are directly or indirectly related to human nutrition and food security. Maize is grown in producer farms, farmers depend on genetically improved cultivars, and maize breeders develop improved maize cultivars for farmers. Nikolai I. Vavilov defined plant breeding as plant evolution directed by man. Among crops, maize is one of the most successful examples for breeder-directed evolution. Maize is a cross-pollinated species with unique and separate male and female organs allowing techniques from both self and cross-pollinated crops to be utilized. As a consequence, a diverse set of breeding methods can be utilized for the development of various maize cultivar types for all economic conditions (e.g., improved populations, inbred lines, and their hybrids for different types of markets). Maize breeding is the science of maize cultivar development. Public investment in maize breeding from 1865 to 1996 was $3 billion (Crosbie et al., 2004) and the return on investment was $260 billion as a consequence of applied maize breeding, even without full understanding of the genetic basis of heterosis. The principles of quantitative genetics have been successfully applied by maize breeders worldwide to adapt and improve germplasm sources of cultivars for very simple traits (e.g. maize flowering) and very complex ones (e.g., grain yield). For instance, genomic efforts have isolated early-maturing genes and QTL for potential MAS but very simple and low cost phenotypic efforts have caused significant and fast genetic progress across genotypes moving elite tropical and late temperate maize northward with minimal investment. Quantitative genetics has allowed the integration of pre-breeding with cultivar development by characterizing populations genetically, adapting them to places never thought of (e.g., tropical to short-seasons), improving them by all sorts of intra- and inter-population recurrent selection methods, extracting lines with more probability of success, and exploiting inbreeding and heterosis. Quantitative genetics in maize breeding has improved the odds of developing outstanding maize cultivars from genetically broad based improved populations such as B73. The inbred-hybrid concept in maize was a public sector invention 100 years ago and it is still considered one of the greatest achievements in plant breeding. Maize hybrids grown by farmers today are still produced following this methodology and there is still no limit to genetic improvement when most genes are targeted in the breeding process. Heterotic effects are unique for each hybrid and exotic genetic materials (e.g., tropical, early maturing) carry useful alleles for complex traits not present in the B73 genome just sequenced while increasing the genetic diversity of U.S. hybrids. Breeding programs based on classical quantitative genetics and selection methods will be the basis for proving theoretical approaches on breeding plans based on molecular markers. Mating designs still offer large sample sizes when compared to QTL approaches and there is still a need to successful integration of these methods. There is a need to increase the genetic diversity of maize hybrids available in the market (e.g., there is a need to increase the number of early maturing testers in the northern U.S.). Public programs can still develop new and genetically diverse products not available in industry. However, public U.S. maize breeding programs have either been discontinued or are eroding because of decreasing state and federal funding toward basic science. Future significant genetic gains in maize are dependent on the incorporation of useful and unique genetic diversity not available in industry (e.g., NDSU EarlyGEM lines). The integration of pre-breeding methods with cultivar development should enhance future breeding efforts to maintain active public breeding programs not only adapting and improving genetically broad-based germplasm but also developing unique products and training the next generation of maize breeders producing research dissertations directly linked to breeding programs. This is especially important in areas where commercial hybrids are not locally bred. More than ever public and private institutions are encouraged to cooperate in order to share breeding rights, research goals, winter nurseries, managed stress environments, and latest technology for the benefit of producing the best possible hybrids for farmers with the least cost. We have the opportunity to link both classical and modern technology for the benefit of breeding in close cooperation with industry without the need for investing in academic labs and time (e.g., industry labs take a week vs months/years in academic labs for the same work). This volume, as part of the Handbook of Plant Breeding series, aims to increase awareness of the relative value and impact of maize breeding for food, feed, and fuel security. Without breeding programs continuously developing improved germplasm, no technology can develop improved cultivars. Quantitative Genetics in Maize Breeding presents principles and data that can be applied to maximize genetic improvement of germplasm and develop superior genotypes in different crops. The topics included should be of interest of graduate students and breeders conducting research not only on breeding and selection methods but also developing pure lines and hybrid cultivars in crop species. This volume is a unique and permanent contribution to breeders, geneticists, students, policy makers, and land-grant institutions still promoting quality research in applied plant breeding as opposed to promoting grant monies and indirect costs at any short-term cost. The book is dedicated to those who envision the development of the next generation of cultivars with less need of water and inputs, with better nutrition; and with higher percentages of exotic germplasm as well as those that pursue independent research goals before searching for funding. Scientists are encouraged to use all possible breeding methodologies available (e.g., transgenics, classical breeding, MAS, and all possible combinations could be used with specific sound long and short-term goals on mind) once germplasm is chosen making wise decisions with proven and scientifically sound technologies for assisting current breeding efforts depending on the particular trait under selection. Arnel R. Hallauer is C. F. Curtiss Distinguished Professor in Agriculture (Emeritus) at Iowa State University (ISU). Dr. Hallauer has led maize-breeding research for mid-season maturity at ISU since 1958. His work has had a worldwide impact on plant-breeding programs, industry, and students and was named a member of the National Academy of Sciences. Hallauer is a native of Kansas, USA. José B. Miranda Filho is full-professor in the Department of Genetics, Escola Superior de Agricultura Luiz de Queiroz - University of São Paulo located at Piracicaba, Brazil. His research interests have emphasized development of quantitative genetic theory and its application to maize breeding. Miranda Filho is native of Pirassununga, São Paulo, Brazil. M.J. Carena is professor of plant sciences at North Dakota State University (NDSU). Dr. Carena has led maize-breeding research for short-season maturity at NDSU since 1999. This program is currently one the of the few public U.S. programs left integrating pre-breeding with cultivar development and training in applied maize breeding. He teaches Quantitative Genetics and Crop Breeding Techniques at NDSU. Carena is a native of Buenos Aires, Argentina. http://www.ag.ndsu.nodak.edu/plantsci/faculty/Carena.htm

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1977 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Iowa State Journal of Research written by and published by . This book was released on 1977 with total page 878 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Iowa State Journal of Research written by Iowa. State College, Cedar Falls and published by . This book was released on 1977 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1976 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plant Breeding Reviews Volume 15 written by Jules Janick and published by John Wiley & Sons. This book was released on 2010-04-22 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant Breeding Reviews is an ongoing series presenting state-of-the art review articles on research in plant genetics, especially the breeding of commercially important crops. Articles perform the valuable function of collecting, comparing, and contrasting the primary journal literature in order to form an overview of the topic. This detailed analysis bridges the gap between the specialized researcher and the broader community of plant scientists.

Download or read book Agronomy News written by and published by . This book was released on 1997 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sept.-Oct. issue includes list of theses and dissertations for U.S. and Canadian graduate degrees granted in crop science, soil science, and agronomic science during the previous academic year.

Download or read book Plant Breeding Abstracts written by and published by . This book was released on 1980 with total page 1282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Genetic Analysis of Ear Length and Correlated Traits in Maize written by Andrew Jon Ross and published by . This book was released on 2002 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) ear length is positively correlated with grain yield. Thirty generations of selection for increased ear length, however, failed to increase grain yield in Iowa Long-Ear Synthetic (BSLE). Negative correlations between ear length and other yield-related traits complicated indirect selection for grain yield. The main objective of this investigation was to identify quantitative trait loci (QTL) that affect the variation of ear length, grain yield, and other ear traits, and the correlations among traits. Secondary objectives were to validate QTL by comparing their genetic positions across generations, environments, and other populations. QTL were mapped in the F2 and F[subscript 2:3] generations of a bi-parental population. The inbred parents differed in ear length by 14 cm, and were derived from the divergent sub-populations of BSLE. More QTL were detected for ear length (16), kernel-row number (12), and kernel depth (6) than detected in prior QTL studies. Eighty percent of the alleles for increased trait values originated from the parent with the higher trait value. Most QTL were validated by one of the three methods. More than 67% of the QTL were identified in at least two F[subscript 2:3] environments. Forty-three percent of the QTL from the F[subscript 2:3] mean environment were previously identified in the F2. Seven QTL for ear length, one for kernel-row number, and two for grain yield seemed to coincide with QTL in other populations. Traits with higher heritabilities generally had more coincidental QTL, and traits with lower heritabilities generally had fewer coincidental QTL. QTL positions and the parental origin of alleles agreed with the direction of the genetic correlation coefficients. The magnitude of the correlations was generally explained by the frequency of QTL that coincided or were genetically linked. Repulsion-phase linkage between ear length and grain yield QTL near the centromere of chromosome 5 may have caused the failure of ear length selection in BSLE to increase grain yield. QTL on chromosome 6 exemplified the genetic basis for the positive correlation between ear length and grain yield.

Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1984 with total page 1086 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1973- include the following subject areas: Biological sciences, Agriculture, Chemistry, Environmental sciences, Health sciences, Engineering, Mathematics and statistics, Earth sciences, Physics, Education, Psychology, Sociology, Anthropology, History, Law & political science, Business & economics, Geography & regional planning, Language & literature, Fine arts, Library & information science, Mass communications, Music, Philosophy and Religion.

Download or read book Comprehensive Dissertation Index Agriculture written by and published by . This book was released on 1984 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Crop Science written by and published by . This book was released on 1987 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Mass Selection for Grain Yield and Estimation of Genetic Variability in Three Selected Maize Zea Mays L Populations written by Mulamba Ngandu-Nyindu and published by . This book was released on 1981 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Divergent Mass Selection for Time to Anthesis in a Maize Zea Mays L Population written by Pedro Justino Jasa-Vega and published by . This book was released on 1984 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study was to determine the correlated and direct responses to divergent mass selection for days-to-antheis (DTA) in a Mecican land-variety belonging to the race Chalqueno. Ten cycles of selection and evaluations were conducted at Chapingo. The tenth (final cycle) also was evaluated at College Station. Also, a combined general analysis involving all data collected over the six evaluation in Chapingo, was done. The response of DTA to selection was significant in both directions in all evaluations from 1976 to 1982. However, there was asymmetry in response, the later direction being about three times that of the earlier. The total response in DTA over six evaluation in Chapingo, was: 42.5% at a rate of 4.04% +- 0.21 per cycle in the later direction and, -11.7% at a rate of -1.38% +- 0.21 per cycle in the earlier direction. In addition, response of F1 crosses (between later by earlier selection) to DTA was found to be exactly intermediate between parents. The high linear response to selection in both directions and the intermediate F1 value, suggested and average additive effect of the genes controlling DTA. Realized heretability for DTA was calculated as the coefficient of linear regression between the cumulative response on DTA against cumulative calculated differential selection, which were 0.25 +- 0.03 in the later direction, 0.19 +- 0.02 in the earlier direction, and 0.24 +- 0.02 for divergence (later - earlier) values. All b1 coefficient were different from zero at P=0.01 level. (...).

Download or read book Effects of Mass Selection for Ear Length in Maize written by Artemio Manto Salazar and published by . This book was released on 1985 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: