Vol. 49 No: 4

Title:
Variation Studies in Carrots as an Aid to Breeding. II. Effect of Sites, Years and Densities on Some Quality Characters

Authors:
B.D. DOWKER, J.F.M. FENNELL and J.C. JACKSON

pp: 311-322

Abstract:
A series of experiments in which a set of eight genotypes (four Chantenay varieties, four Autumn King varieties) were grown at various sites and densities in successive years is described. A quantitative partitioning of the variance due to differences between varieties, between environments and to genotype-environment (GE) interaction is presented for the characters, skin quality and percentages of split, fanged and misshapen roots. The genetic variance between varieties for skin quality was shown to be small and of doubtful practical importance. The Chantenay type showed less susceptibility to fanging and production of misshapen roots, and the Autumn King type less susceptibility to splitting. Some potentially useful within-type variation occurred for splitting (both types) and for misshapen and fanged roots (within the Autumn King type). The main environmental effect on all characters was that of site × year combination. Density affected the proportion of blemished roots, low density giving the higher proportion for all three blemish characters. The GE interaction for splitting was described adequately by differences between regression slopes for types and varieties within types. The GE interaction found for fanged and misshapen roots could not, however, be described in these terms. Low densities gave the best predictable discriminating environment for blemished roots. For the plant breeder given a choice of four plots (any combination of replicates, densities and sites) within a single year, on which to base his selection, four sites would produce the highest expected heritabilities.

Full text: JHSB Subscribers     ISHS members & other users
(PDF 487082 bytes)

Translate:

Go back to previous page