COSTS AND BENEFITS OF HYDROXAMIC ACIDS-RELATED RESISTANCE IN WINTER-WHEAT AGAINST THE BIRD CHERRY-OAT APHID, RHOPALOSIPHUM-PADI L

Estimations of infestation by the bird cherry-oat aphid (Rhopalosiphum padi) as well as measurements of grain yield in 26 Hungarian winter w heat cultivars under field conditions were correlated with the concent ration of hydroxamic acids (Hx) in seedlings of those cultivars. The s ignificant inverse relationship between infestation ratings and Hx lev els in wheat showed that Hx, despite their decreased accumulation at l ater plant phenological stages, may be able to confer resistance again st aphid infestation in the field. Since no significant relationship w as found between grain yield and Hx levels in plants it is suggested t hat Hx accumulation does not impose a cost to the plant in terms of yi eld. These findings support earlier claims stressing the potential of Hx as breeding targets for aphid resistance in wheat.