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Quantitative relationships in the infection cycle of seed-borne net blotch

Pinnschmidt, H.O.; Nielsen, B.J. and Hansen, H.J. (2005) Quantitative relationships in the infection cycle of seed-borne net blotch. In: Abstract booklet of the 5th ISTA - SHC seed health symposium 10-13 May, Angers, France, ISTA, p. 7.

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Summary

Seed-borne net blotch is a threat to organic barley seed production in Denmark because it often exceeds the recommended 15% contamination threshold in barley seed lots. This threatens the supply of organic barley growers with organically produced healthy barley seeds. The ORGSEED project aims at quantifying the links between initial seed contamination, primary seedling infection, disease severity during the growing season, yield parameters and new contamination of the harvested grains to improve decision support for handling net blotch contaminations in organic barley- and barley seed production. The harvested grains of spring barley varieties grown at several sites in Denmark in 2002 and 2003 were used as seed lots in subsequent trials in 2003 and 2004. The seed lots covered a range of contamination levels of seed-borne net blotch for each variety. Net blotch contamination level, 1000 grain weight and germination ability of the grains were determined and net blotch development during the growing season was visually assessed.
The net blotch contamination level of harvested grains was highly positively correlated with net blotch severity at growth stage 70 (beginning of grain filling, gs 70). A general linear model explained 72% of the variation of grain infection based on effects of [variety x year] and [variety x year x net blotch severity at gs 70]. Net blotch severity at gs 70 was highly positively correlated with the net blotch contamination level of the seeds and a general linear model explained 71% of the variation of net blotch severity at gs 70 based on effects of variety and seed contamination level. The results indicate that the transmission efficiency of net blotch from the epidemic on the foliage to the grains differs among varieties and that the effects of seed contamination on net blotch development later during the season may be variety-specific as well. Net blotch disease severity was highly negatively correlated with 1000 grain weight and explained, together with [site x year] effects, 58% of its variation.
Our results underline the importance of varietal resistance for seed health and suggest that the level of varietal resistance be included in considerations concerning the establishment of seed contamination thresholds.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Poster
Keywords:seed-borne barley net blotch, seed infection thresholds, disease propagation, epidemiology
Subjects: Crop husbandry > Crop health, quality, protection
Research affiliation: Denmark > DARCOF II (2000-2005) > VI.2 (BAR_OF) Characteristics of spring barley varieties for organic farming
Denmark > DARCOF II (2000-2005) > VI.1 (ORGSEED) Healthy seed for organic production of cereals and legumes
Deposited By: Pinnschmidt, Dr. Hans
ID Code:7932
Deposited On:04 Apr 2006
Last Modified:12 Apr 2010 07:33
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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