QTL mapping of root and leaf traits associated with drought tolerance in a canola (Brassica napus l.) doubled haploid population

2013 Fall. ; Includes bibliographical references. ; Drought stress is one of the major constraints to canola production in Colorado, therefore, improved understanding of the inheritance and genetic variation for drought tolerance will help to develop cultivars that are adapted to the state. To learn more about traits associated with drought tolerance in canola we focused on root pulling force and carbon isotope discrimination with the objectives of: • Detecting the location, number, and effects of quantitative trait loci (QTL) associated with root pulling force and carbon isotope discrimination • Understanding the association of root pulling force and carbon isotope discrimination with yield components in well watered and water limited environments We used 148 doubled haploid lines of the DHYB population developed from the cross of a black seeded (DH12075) and a yellow seeded (YN01-429) parent. The experiment was conducted as a split-plot design with three replications in the 2011 and 2012 summer seasons. Two moisture regimes (wet and dry) constituted the main plot factor, with genotype as the subplot factor. A single individual plant per replication represented each genotype. Days to flowering, leaf relative water content, δ13C (the ratio of 13C to 12C), plant height, lateral branch number, lateral root number, thousand seed weight, seed yield per plant, root pulling force, and proportion of aborted siliques were measured, though not every trait was evaluated in each treatment or year. Phenotypic correlation among all pairs of traits and heritability of the traits under both treatments were estimated. QTL analysis was conducted for each trait and environment with R/qtl software. Analysis of variance revealed significant differences (P<0.001) among genotypes for days to flowering, plant height, and δ13C in both treatments and years. Transgressive segregation was observed for root pulling force, δ13C, days to flowering and plant height in both treatments and years. Root pulling force was significantly ...