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dc.contributor.authorGreen, Andrew Justinen_US
dc.date.accessioned2014-03-14T20:49:22Z
dc.date.available2014-03-14T20:49:22Z
dc.date.issued2011-11-15en_US
dc.identifier.otheretd-12122011-112349en_US
dc.identifier.urihttp://hdl.handle.net/10919/36086
dc.description.abstractPeriodic evaluation of improvements in yield and disease resistance is necessary to assess breeding progress over time, and the elucidation of underlying traits responsible for yield gains can help direct future breeding. Objectives of this study were: 1) to determine the rate and magnitude of yield progress in eastern soft red winter (SRW) wheat (Triticum aestivum, L.) cultivars released from 1950 to 2009 relative to a historical cultivar Red May (1919) and; 2) to determine effects of leaf rust (Puccinia triticina f. sp. tritici) and powdery mildew [Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal] on grain yield components and agronomic traits. Replicated yield trials were grown at Warsaw, VA in 2010 and 2011, and at Holland and Blacksburg, VA in 2011. For objective 1, the genetic progress experiment: flag leaf angle, kernel weight, spikes m-2, lodging, flowering date and harvest index collectively explained the most yield variation in multiple environments on the basis of linear regression analysis. Rate of genetic yield improvement ranged from 0.56% yr-1 at Holland in 2011 to 1.4% yr-1 at Blacksburg in 2011. For objective 2, the disease loss experiment: yield losses ranged from 1% at Holland in 2011 to 21% at Warsaw in 2011. Losses primarily due to powdery mildew and leaf rust were as high as 14% and 33%, respectively. Powdery mildew had the largest negative correlation with harvest index and seeds spike-1, while leaf rust had the largest negative correlation with plant biomass and harvest index.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartGreen_AJ_T_2011.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectyielden_US
dc.subjectwheaten_US
dc.subjectgeneticsen_US
dc.titleYield Improvement in Eastern Soft Red Winter Wheat from 1919 to 2009en_US
dc.typeThesisen_US
dc.contributor.departmentCrop and Soil Environmental Sciencesen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
dc.contributor.committeechairGriffey, Carl A.en_US
dc.contributor.committeememberBalota, Mariaen_US
dc.contributor.committeememberParrish, David J.en_US
dc.contributor.committeememberThomason, Wade E.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12122011-112349/en_US
dc.date.sdate2011-12-12en_US
dc.date.rdate2011-12-22
dc.date.adate2011-12-22en_US


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