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-producing desert plant ( Dierig et al., 1989 ; Ray et al., 1993 ; Thompson et al., 1988 ); consequently, selection for only one parameter may not always improve rubber yield. In guayule, single-plant selection for both root weight and rubber percentage increased
Abstract
Thirty random seedlings from each of 50 random parents of a sweet potato (Ipomoea batatas (L.) Lam.) mass selected population were evaluated in the greenhouse and their subsequent field performances were recorded. Simulated selection sequences were also studied. A sequence with mass selection first on maternal hill weight, high seed set, and high seed weight followed by a 50% culling level within families on the basis of low greenhouse seedling vigor resulted in average progeny field yields 45% above that of no selection. The results showed seed weight to be a potentially useful selection criterion for root yield. Individual seedling root weight in the greenhouse was not a good predictor of field yield.
for genetic gains using recurrent selection methodologies. However, these studies also suggest that heritability estimates are characteristic of individual populations and environments. Furthermore, genetic parameters may change over time as
achieved by shortening the ear rather than actually lengthening the husk. The goals of this research were to determine the feasibility of selecting a sweet corn population for longer husks without shortening the ears, to determine whether direct selection
recurrent selection at −0.8 MPa increased germination of sand bluestem ( Andropogon hallii ) nearly 2-fold in vitro ( Springer, 2011 ; Springer et al., 2014 ). In the field, establishment increased 16.4% compared with the base population ( Springer et al
Turkey and the Caucasus. Most of the world's production is based on selections from local wild populations with different cultivars grown in each zone. Most cultivars are single clones, although some, including a few leading Turkish types (e.g., Tombul
commercial traits are needed to be combined into one plant. The use of a selection index approach as described by Falconer and Mackay (1996) for such multiple-trait selection could offer a solution. This approach, designed to give the most rapid improvement
Agricultural Research Service, nor criticism of similar ones not mentioned. We gratefully acknowledge the technical assistance of Rufus R. Horton, Jr., and the advice on recurrent selection methods of Robert H. Moll. The cost of publishing this paper was
Thermal degradation of fractions from sweetpotato roots (`Jewel') was conducted with gas chromatographymass spectrometry to identify precursors of critical flavor volatiles. Upon heating (200 C), sweetpotato root material that was insoluble in methanol and methylene chloride produced similar volatile profiles to those from sweetpotatoes baked conventionally. Volatiles derived via thermal degradation of the nonpolar methylene chloride fraction and the polar methanol fraction did not display chromatographic profiles similar to those from conventionally baked sweetpotatoes. Initial reactions in the formation of critical volatiles appear to occur in the methanol and methylene chloride insoluble components. Maltol (3-hydroxy-2-methyl-4-pyrone) was found to be one of the critical components making up the characteristic aroma of baked sweetpotatoes. Integration of an analytical technique for the measurement of flavor into sweetpotato breeding programs could potentially facilitate the selection of improved and/or unique flavor types.
Breeders of horticultural crops and agronomic crops have often adopted different strategies and systems of selection. Breeders of grain crops have a long tradition of quantitative approaches and of collecting objective data from large populations