The cereal cyst nematode (Heterodera avenae) on oats. I. Identification of attributes useful in early screening for tolerance to H. avenae

Abstract

Variation in morphology, development, and water relations of four oat cultivars inoculated with a range of densities of Heterodera avenae larvae was assessed during early growth to identify distinguishing traits for tolerance. Experiments were performed under glasshouse conditions on cultivars previously rated for tolerance. Cultivar differences were found in the effects of H. avenae on final leaf length, and on root and shoot mass within 20 to 30 days of planting. These differences corresponded to cultivar differences in tolerance to H, avenae at maturity. Differences between cultivars in their sensitivity to root stunting by H, avenae were also related to their final tolerance ratings. Tiller removal generally enhanced tolerance but had little effect on the overall tolerance ranking of the four cultivars examined. H. avenae infection had the least effect on the water use efficiency (WUE) of the most tolerant cultivar and the greatest effect on the least tolerant cultivar. In the absence of nematodes, intolerant cultivars used water more efficiently than did tolerant cultivars. Results suggest that oats can be screened for tolerance to H. avenae during early plant development.