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Wageningen Universiteit (1995)

Genetic variation between and within Ethiopian barley landraces with emphasis on durable resistance

Alemayehu, F.

Titre : Genetic variation between and within Ethiopian barley landraces with emphasis on durable resistance

Auteur : Alemayehu, F.

Université de soutenance : Wageningen Universiteit

Grade : PhD thesis 1995

Présentation
Landraces are known to be variable. Their resistance to diseases can be assumed to be durable. The durability of resistance in landraces can be due to the multiline principle or due to genetic durable resistance. To investigate the degree of variation both between and within landraces and what type of resistance is present 1800 single plant derived lines of IS Ethiopian barley landraces were studied for six traits among which resistance to two pathogens, Puccinia hordei, representing biotrophic fungi, and Rhynchosporium secalis, representing the hemi-biotrophic fungi.
The 1800 landrace lines were grown in 1991 and 1993 under field conditions a, Holetta Research Centre, Ethiopia and evaluated for scald (Rhynchosporium secalis) disease severity (DS) after infection from the naturally occurring inoculum. Earliness, plant height, leafiness and 1000 grain weight were also measured. All five characters varied greatly both between and within the landraces. The degree of association between DS and the other characters was investigated and earliness had an important effect on DS. The frequency of resistant genotypes within the landraces increased markedly with altitude. Complete resistance to scald occurred frequently. Lines fully resistant in one year could be fully susceptible in the other year indicating that the resistance of these lines was race-specific. It means, that for leaf scald at least a considerable part of the resistance found was race-specific. In this pathosystermthe multiline principle seems to operate to give durable resistance

Mots clés : hordeum vulgare / barley / plants / pest resistance / disease resistance / plant breeding

Résumé de la thèse

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