Breeding Methodology in Wheat. I. Determination of Characters Measured on F2 Spaced Plants for Yield Selection in Spring Wheat1
- P. B. E. McVetty and
- L. E. Evans2
Three crosses of spring wheat (Triticum aestivum L.) involving the cultivar ‘Glenlea’ as a common female parent were used to evaluate the use of physiological and/or morphological parameters alone or in combination on F2 plants as selection criteria to identify high-yielding F4 bulks. The F2 generation was grown as spaced plants in the field under two types of environmental regimes: (1) a regime and (2) a normal regime. Stress-free plants were given regular irrigation, optimum fertilization and complete weed control to minimize stress while the normal-regime plants were given no special treatment. Two hundred plants of each cross were measured for physiological, morphological, yield-component, and phenological traits. A random sample of 50 seeds from each of these plants was used to generate F4 bulks. For each cross, groups of 45 F4 bulks derived from stress-free F2's and 75 F4 bulks derived from normal F2's were tested for yield in the F4 in a six-replicate, partially balanced lattice design.
The results indicated that single F2 parameters which described source capacity, sink capacity or plant morphology all identified high-yield potential in the F2; however, at 15% selection intensity only 17 out of 53 high-yielding F4 bulks were retained. A multiple regression analysis was found to be better than a single parameter approach, retaining nearly half (24 out of 53) of the high-yielding lines. A combined-cross analysis indicated that yield, productivity, kernel number, peduncle length, and productivity per tiller were all significantly correlated with F4 bulk yields. A multiple regression analysis of the combined crosses indicated that productivity and peduncle length were the only significant common parametersPlease view the pdf by using the Full Text (PDF) link under 'View' to the left.
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