Identification of growth stage dependent expression of partial resistance of barley to powdery mildew

Abstract

Genotypic differences for growth stage dependent expression of partial resistance to barley powdery mildew have been identified on the basis of two components of resistance in the glasshouse and the pattern of epidemic development in the field.Differences for infection frequency and proportion of sporulating colonies were highly significant between the 16 genotypes investigated at four stages of plant development in the glasshouse. Both resistance components were significantly correlated mutually (r = 0.73 to 0.86) and with the infection level on leaves developed at comparable growth stages in the field (r = 0.52 to 0.73). The infection level of seedlings in the glasshouse was significantly correlated with the infection level of the leaves of the first until the third node in the field (r = 0.70 to 0.73). Adult plant resistance was predominantly expressed at the uppermost leaf. A clear genotype x growth stage interaction was apparent for infection level; some genotypes showed partial resistance predominantly at the seedling stage and others predominantly at the adult plant stage.

Nitrogen‐induced changes in colony density and spore production of Erysiphe graminis f.sp. hordei on seedlings of six spring barley cultivars

“…Results from glasshouse experiments cannot be applied directly to field conditions, although good agreement between field and laboratory methods have been found for assessment of PR (Knudsen et al, 1987;Mastebroek & Balkema-Boomstra, 1991). Under field conditions, plants are exposed to both virulent and avirulent inoculum which may result in induced resistance.…”

Powdery mildew resistance in Kentucky bluegrass genotypes regenerated from excised seed pieces

“…Therefore, their effect on DS of regenerated plants could not be fully determined . In some cereals, resistance to powdery mildew increases with age of plants (Mastebroek & Balkema-Boomstra, 1991) . This phenomenon was not determined in our study because leaves were mowed to permit new growth by vegetative means, and maintain a consistent range of leaf age.…”

Evaluation of sources of partial resistance to mildew in barley using enzyme-linked immunosorbent assay and other assessment methods

“…High correlation has been recorded between visual and ELISA field trial scores in other experiments using pathogen control treatments but it probably shows growth stage dependence. The correlation between seedling IF and field biomass may indicate the value of seedling assessments to predict field performance although Mastebroek & Balkema-Boomstra (1991) report a genotypex growth stage interaction for infection level. Similarly the correlation between seedling and adult plant IF confirms the value of seedling tests.…”

“…However, it is also important to limit infection at seedling stages to ensure that root establishment and tillering are not restricting and adversely affecting yield potential (Scott & Griffiths, 1980). Thus selection for partial resistance to mildew must involve good assessment of the components of partial resistance at all stages of development, especially as expression of partial resistance can vary with growth stage (Mastebroek & Balkema-Boomstra, 1991). In practice these assessments are not always possible using visual assessment in the field.…”