IMPACT OF INSECT ROOT HERBIVORY ON THE GROWTH AND NITROGEN AND CARBONCONTENTS OF WHITE CLOVER (TRIFOLIUM-REPENS) SEEDLINGS

The impact of root herbivory by larvae of the weevil Sitona flavescens (Marsh.) on the growth and carbon and nitrogen economies of seedlings of white clover (Trifolium repens L.) and the nature and extent of ni trogenous compounds found in the root exudates taken from the rhizosph ere were investigated. The seedlings were grown in sand culture in a s ystem of microlysimeters that enabled sequential sampling of root exud ates. Weevil infestation significantly reduced foliar biomass and tota l N and C contents and impaired N-fixation. The C:N ratios of the infe sted plants were significantly increased compared with those of uninfe sted seedlings. The most abundant amino acids in the exudates were asp artic acid and serine.