Author: Morakinyo Abiodun Bamidele Fakorede
Publisher:
ISBN:
Category :
Languages : en
Pages : 678

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Author: M.A.B. Fakorede
Publisher:
ISBN:
Category :
Languages : en
Pages : 326

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Dr. G. F. Sprague initiated recurrent selection programs during the 1940' and 1950' to improve the grain-yield performance of several maize (Zea mays L.) population at the Iowa Agriculture and Home Economics Experiments Station. Seven cycles of reciprocal recurrent selections (RRS) in Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic #1 (BSCB1), and six cycles of recurrent half-sib selection (HS) in the open-pollinated variety 'Alph'(i.e., BS12) have been completed. Inbred B14 was the tester in the HS program. My objectives were to (1) evaluate progress that resulted from the RRS and HS programs and (2) evaluate changes in several other traits associated with recurrent selection for grain yield. I evaluated the CO x CO, C5, and C7 x C7 of the RRS program, and CO and C6 of the HS program, each testcrossed to B14A. Estimated gain from seven cycles of RRS was 2.06 q/ha (or 5.21%) per cycle and observed difference in mean yield between CO and C6 of the program was 2.25 q/ha (or 6.00%) per cycle. Improved hybrids outyield their unimproved counterparts at all levels of nitrogen (0, 90, 180, and 270 kg N/ha) and plant density (39,000; 59,300; 79,000; and 98,800 plants/ha) investigated. Each hybrid displayed a positive, curvilinear response to nitrogen and a negative, linear response to plant density. Stability and adaptation-reaction analysis revealed that improved hybrids consistently demonstrated greater adaptation to high-nitrogen environments, but their unimproved counterparts did not take (...).

Author: Paulo Nelson Rehn
Publisher:
ISBN:
Category :
Languages : en
Pages : 166

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Author: M. A. B. Fakorede
Publisher:
ISBN:
Category : Corn
Languages : en
Pages : 31

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Experiments were conducted in there field environments with the following objectives: (1) to evaluate the progress from seven cycles of reciprocal recurrent selection in Iowa Stiff Stalk Synthetic (BSSS(R) and Iowa Corn Borer Synthetic #1 (BSCB(R) and six cycles of half-sib family selection in 'Alph' (i.e. BS12) maize (Zea mays L.) populations, (2) to compare the response of unimproved and improved maize variety hybrids to different levels of nitrogen fertilizer and plant density, and (3) to evaluate the influence of nitrogen and plant density on the morphological and physiological traits associated with recurrent selection for grain yield in maize. Each experiment was grown in randomized complete blocks with a split-split-plot arrangement and two replications. Nitrogen fertilizer levels (0,90,180, and 270 kg N/ha) were main plots, plant densities (39,500; 59,300; 79,000; and 98,800 plants/ha) were subplots, and five variety hybrids, BSSS(R)CO x BSCB1(R)CO, BSSS(R)C5 x BSCB1(R)C5, BSSS(R)C7 x BSCB1(C7, BS12C0 x B14A, and BS12C6 x B14A, were randomized as sub-subplots. We obtained data on grain yield and grain-yield components, flowering traits, plant traits, leaf area, leaf orientation, lodging, dry-matter productivity, and harvest index.(...).

Author: Arnel R. Hallauer
Publisher: Springer Science & Business Media
ISBN: 1441907661
Category : Science
Languages : en
Pages : 669

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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

Author: Eduardo J. Graterol M.
Publisher:
ISBN:
Category :
Languages : en
Pages : 128

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Author: Benjamin Aaron Ford
Publisher:
ISBN:
Category :
Languages : en
Pages : 374

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Increases in grain yield, the primary trait for selection, include a direct response of 2.2 percent per cycle in the population cross, and indirect responses of 3.3 and 1.2 percent per cycle in BS10 and BS11, respectively, but only the response for BS11 fits a linear model. Linear trends through the first nine selection cycles, however, indicate a 4.6 percent per cycle increase for the population cross, as well as increases of 1.6 percent in BS10 and 1.6 percent in BS11 parent populations. Evaluations of random S1 line performance for BS10CO, BS10C13, BS11CO, and BS11C13 indicate decreasing trends in genetic variability over 13 cycles of FR. Exceptions are grain yield in BS10 and BS11 and plant height in BS11. While genetic variance estimates for grain yield are nearly equal for BS11CO and BS11C13, a nearly significant increase in variability is evident from BS10CO to BS10C13. Variability estimates suggest FR for grain yield in BS10 and BS11 will be effective in future selection cycles.

Author: M. Bänzinger
Publisher: CIMMYT
ISBN: 9706480463
Category :
Languages : en
Pages : 69

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Introduction - why breed for drought and low N tolerance?; Conceptual framework - breeding; Conventional approaches to improving the drought and low N tolerance of maize; Conventional approaches challenged; The challenge of breeding for drought and low N tolerance; Maize under drought and low N stress; Conceptual framework - physiology; Water and the maize plant; Nitrogen and the maize plant; Maize under drought and low N stress - consequences for breeding; Stress management; Drought; Low N stress; Statistical designs and layout of experiments; Increasing the number of replicates; Improved statistical designs; Field layout; Border effects from alleys; Secondary traits; Why use secondary traits?; How do we decide on the value of secondary traits in a drought or low N breeding program?; Secondary traits that help to identify drought tolerance; Secondary traits that help to identify low N tolerance: Selection indices - Combining information on secondary traits with grain yield; Combining information from various experiments; Breeding strategies; Choice of germplasm; Breeding schemes; Biotechnology: potential and constraints for improving drought and low N tolerance; The role of the farmer in selection; What is farmer participatory research and why is it important?; What is new about farmer participatory research?; Participatory methodologies.

Author: Daryl Keith Hexum
Publisher:
ISBN:
Category :
Languages : en
Pages : 132

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Author: Gregory John Holland
Publisher:
ISBN:
Category :
Languages : en
Pages : 238

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