The diversity of head-scab resistance in Triticeae and their relation to ecological conditions
Abstract1507 accessions from 93 species of 18 genera in Triticeae were screened for resistance to initial infection and resistance to pathogen spread with multi-floret and single-floret injection inoculation methods respectively. The accessions with high resistance were mainly found in perennial genera: Roegneria, Hystrix, Agropyron, Kengyilia and Elymus. Based on differences in resistance, 18 genera screened in Triticeae could be classified into five groups. The species with high resistance were mainly distributed in humid ecological environments.
Genetic variation for resistance to Fusarium head blight in bread wheat
SummaryDuring a four year period, a total of 258 winter and spring wheat genotypes were evaluated for resistance to head blight after inoculation with Fusarium culmorum strain IPO 39-01. It was concluded that genetic variation for resistance is very large. Spring wheat genotypes which had been reported to be resistant to head blight caused by Fusarium graminearum were also resistant to F. culmorum. The resistant germplasm was divided into three gene pools: winter wheats from Eastern Europe, spring wheats from China/Japan and spring wheats from Brazil. In 32 winter wheat genotypes in 1987, and 54 winter wheat genotypes in 1989, the percentage yield reduction depended on the square root of percentage head blight with an average regression coefficient of 6.6. Heritability estimates indicated that for selection for Fusarium head blight resistance, visually assessed head blight was a better selection criterion than yield reduction.
HYBRIDIZATION OF TRITICUM AND AGROPYRON: I. CROSSING RESULTS AND DESCRIPTION OF THE FIRST GENERATION HYBRIDS
Two species of tetraploid (2n = 28) and three varieties of hexaploid (2n = 42) wheat were crossed with A. glaucum (2n = 42), and A. elongatum (2n = 70), with an average crossing success of 18%. The seed obtained from tetraploid wheat × A. glaucum was slightly plumper and germinated better than that obtained from tetraploid wheat × A. elongatum. On the other hand, hexaploid wheat × A. elongatum gave decidedly plumper and better germinating seed than hexaploid × A. glaucum.Grown under greenhouse conditions the F1 hybrids proved to be self-sterile and perennial in habit, with hybrid vigor strongly marked. The hybrids were, in general, intermediate in morphological characters, but with somewhat more resemblance to Agropyron than to wheat. This dominance, whole or partial, was more noticeable in the A. elongatum than in the A. glaucum crosses. Dominance phenomena are discussed in relation to current theories.