Quantitative-genetic analysis of leaf-rust resistance in seedling and adult-plant stages of inbred lines and their testcrosses in winter rye.
- Publication Type
- Journal contribution
- Authors
- Miedaner, T.; Gey, A.-K.; Sperling, U. and Geiger, H.H.
- Year of publication
- 2002
- Published in
- Plant Breed.
- Band/Volume
- 121/
- Page (from - to)
- 475-479
Leaf rust is the most frequent leaf disease of winter rye in Germany. All widely grown population and hybrid varieties are susceptible. This study was undertaken to estimate quantitative-genetic parameters of leaf-rust resistance in self-fertile breeding materials with introgressed foreign leaf-rust resistances and to analyse the relative importance of seedling and adult-plant resistance. Forty-four inbred lines and their corresponding testcrosses with a highly susceptible tester line were grown in the field in four environments (location-year combinations) with artificial inoculation. Plots were separated by a non-host (triticale) to promote autoinfections and minimize interplot interference. Leaf-rust severity was rated on three leaf insertions at three dates. The testcrosses showed a considerably higher disease severity than the lines. High correlations (r " 0.9, P=0.01) existed among leaf insertions and rating dates. Large genotypic variation for resistance was found in both inbred and testcross populations. Genotype-environment interaction and error variances were of minor importance, thus high entry-mean heritabilities were achieved. A tight correlation between inbreds and their corresponding testcrosses was found (r=0.88, P=0.01). Heterosis for resistance was significant (P=0.05), but not very important. In a seedling test with 20-30 single-pustule isolates, 34 out of the 44 inbreds reacted race-specifically. From the remainder inbred lines, three were medium and seven highly susceptible. In a further greenhouse test with 16 inbreds, seven were susceptible and five were resistant in both the seedling and the adult-plant stage. The remainder four lines had adult-plant resistance. In conclusion, race-specific leaf-rust resistance can be selected among inbred lines per se. Lines should also be tested in the adult-plant stage.