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Green A.J.,Kansas State University | Berger G.,Virginia Polytechnic Institute and State University | Griffey C.A.,Virginia Polytechnic Institute and State University | Pitman R.,Eastern Virginia Agricultural Research and Extension Center | And 3 more authors.
Crop Science | Year: 2012

Periodic evaluation of breeding progress is necessary to assess genetic gains over time, and underlying traits responsible for yield gains can direct future breeding. This study was conducted 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). The effects of agronomic, morphological, and yield component traits on grain yield were studied in 50 widely grown historic and current cultivars in replicated yield trials at Warsaw, VA, in 2010 and 2011 and at Holland and Blacksburg, VA, in 2011.Genotype × environment interactions were significant (p < 0.01) for most traits. Linear regression models for yield were constructed for each environment, with r 2 values ranging from 0.62 to 0.76 among environments. The traits flag leaf angle, kernel weight, spikes per square meter, lodging, flowering date, harvest index, normalized difference vegetative index (NDVI), and green leaf retention, respectively, explained the most yield variation in multiple environments. The rate of genetic yield improvement ranged from 0.56% yr -1 at Holland in 2011 to 1.4% yr -1 at Blacksburg in 2011. Traits that consistently increased in magnitude over time were spikes per square meter, erect flag leaf angle, harvest index, seeds per spike, seeds per spikelet, and yield. Traits that decreased over the time period studied were flowering date and plant height. © Crop Science Society of America. Source


Berger G.,University of Arkansas | Green A.,Kansas State University | Brooks W.,Virginia Polytechnic Institute and State University | Vaughn M.,Eastern Virginia Agricultural Research and Extension Center | And 3 more authors.
Crop Science | Year: 2013

Determining what factors contribute to the yield difference that exists between hulled and hulless winter barley (Hordeum vulgare L.) is necessary for continued yield improvement in the hulless barley germplasm pool. This yield difference is a major factor limiting the acceptance and production of hulless barley as an alternative to traditional hulled barley. Experiments were conducted in Warsaw, VA, during 2010/2011 and 2011/2012 and in Blacksburg, VA, during 2011/2012. Seedling emergence, plants per square meter, normalized difference vegetative index, heading date, spikes per square meter, plant height, lodging, yield, grain volume weight, 1000 kernel weight, spikelets per spike, seeds per spike, seed weight per spike, ash, crude fiber, fat, protein, and starch were measured. Grain volume weight and protein concentration were significantly (p ≤ 0.05) higher for hulless genotypes while seedling emergence and grain ash concentration were significantly (p ≤ 0.05) higher for hulled genotypes. Other traits measured in the study varied by population and environment. On the basis of linear regression analysis, none of the traits explained yield variation in all populations and environments. Before adjustment for hull weight, hulless genotypes yielded significantly (p ≤ 0.05) less than hulled genotypes on average in all populations at Warsaw and for population 1 at Blacksburg during the 2011/2012 growing season. After adjustment for hull weight, yield potential of select hulless genotypes was statistically similar to that of hulled genotypes. Therefore, it is possible to identify hulless genotypes having yield potentials equal to those of their hulled sibs. © Crop Science Society of America. Source

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