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Hu Z.,University of Alberta | Yang R.-C.,Crop Research and Extension Division
Crop Science | Year: 2013

Nonparametric resampling bootstrapping approach to constructing confidence regions (CR) for genotypic and environmental principal component (PC) scores recently has been used to statistically assess the biplot analysis of genotype × environment interaction (GE). However, it is possible to generate "greater-than-expected" CR due to nonunique singular value decomposition (SVD) of two-way GE data from bootstrap samples. The objective of this study is to improve the current bootstrapping procedure to correct for the "systematic bias" due to the nonuniqueness of SVD through the use of Procrustes rotation. The Procrustes rotation is to compare the genotypic and environmental PC scores from bootstrap samples and original (target) data, with the comparison being done by rotating and then stretching and/or shrinking the PC scores from bootstrap samples such that the sum of squared distances between the corresponding elements of bootstrap and target scores is minimized. The bootstrapping and Procrustes rotation are implemented in an R package, bbplot/R. The analysis of two data sets from wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivar trials shows that the CR for rotated genotypic and environmental scores are up to 10 times smaller than the CR for the corresponding unrotated scores. The shrunk CR constructed using the rotated scores for the biplot analysis reveal more definite delineations of mega-environments than the assessment based on mere visual inspection of biplots. Thus, the improved bootstrapping approach will construct the more precise CR for the genotypic and environmental PC scores, thereby facilitating the correct use of biplot analysis for critical decisions on genotype selection or mega-environment delineation. © Crop Science Society of America. Source

Raatz L.L.,University of Alberta | Yang R.-C.,Crop Research and Extension Division | Yang R.-C.,University of Alberta | Eudes F.,Agriculture and Agri Food Canada | Hall L.M.,University of Alberta
Crop Science | Year: 2014

Harvesting volunteer genetically modified (GM) crops is a likely source of adventitious presence (AP) that could preclude coexistence with conventional crops. Spring triticale (×Triticosecale Wittm. ex A. Camus) is proposed as a biofuel and, with genetic modifications, as a platform crop for bioindustrial products. We investigated seed production of simulated volunteer triticale in four western Canadian cropping systems: glyphosate-resistant (GR) canola (Brassica napus L.); glufosinate-resistant (GLUR) canola; field pea (Pisum sativum L.); and imidazolinone-resistant (IR) wheat, in 2006 and 2007 at two locations, and quantified crop yield losses, triticale seed viability, and AP of triticale in harvested crops. Fecundity of volunteers in the absence of herbicides varied between locations, from 3506 to 9280 seeds m-2, and with crop: GLUR canola = GR canola < IR spring wheat < field pea. Herbicides applied preseeding (PRE) reduced triticale densities between 30 and 80%, and survivors produced between 178 and 2052 seeds m-2. Herbicides applied in-crop (POST) were more effective and reduced triticale densities between 8 and > 99% and fecundity between <1 and 1231 seeds m-2. The combination of PRE and POST applications reduced fecundity below that of PRE or POST alone in 3 of 16 crop years. The AP was >1% of the crop (weight/weight) in 3 of 13 crop years when both PRE and POST herbicides were applied. Volunteer triticale is a probable source of AP in subsequent crops that may reduce acceptability in some GM sensitive markets. © Crop Science Society of America. Source

McKenzie R.H.,Crop Research and Extension Division | Bremer E.,Symbio Ag Consulting | Middleton A.B.,Crop Research and Extension Division | Beres B.,Agriculture and Agri Food Canada | And 6 more authors.
Canadian Journal of Plant Science | Year: 2014

Triticale (×Triticosecale Wittmack) is an attractive crop for biofuel production due to its high grain yield potential, weed competitiveness, and drought tolerance. Field plot studies were conducted at seven locations across Alberta from 2008 to 2010 to determine optimum agronomic practices (seeding date, seeding rate andNfertilizer rate) for grain and starch production of spring triticale. The yield penalty from delayed seeding was variable, with an average yield decline of only 0.1% per day. Significant yield benefits from increasing seeding rates from 100 to 500 viable seedsm-2 were obtained at site-years with more than 200 mm of growing season precipitation, but were inconsistent or negligible at site-years with less than 200 mm of growing season precipitation. Optimum N fertilizer rates for grain production increased with growing season precipitation, but were not correlated with pre-seeding soil extractable NO3-N levels. Starch concentrations were either unaffected or only slightly affected by seeding date, seeding rate or N fertilizer rate. Thus, agronomic practices that were optimum for triticale grain production were also optimum for starch production. Under good growing conditions, grain production of spring triticale was optimum when seeded at 350 to 450 seeds m-2 and N fertilizer rates of 90 to 150 kg N ha-1. Source

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