DIFFERENCES IN WINTER-WHEAT CULTIVARS IN APHID INFESTATION IN RELATIONSHIP TO BIOCHEMICAL CHARACTERISTICS

Four winter wheat cultivars of domestic origin (Hana, Regina, Viginta, Zdar) and foreign cultivar Sparta were tested in glasshouse condition s for suitability to cereal aphids Metopolophium (Walker), Rhopalosiph uin padi (L.) and Sitobion avenae (F.) in relationship to biochemical characteristics of plants. Suitability of cultivars for aphids was eva luated by aphid dry matter per tiller/spike 14 days from artificial in festation (three females M. dirhodum, R. padi per plant at the end of shooting phase - 49 GS, two females of S. avenae per spike at the begi nning of anthesis - 59 GS). The content of dry matter, free amino acid s and sugars in leaves and spikes of cultivars were determined in the control plants parallelly with infestation. Dry matter and basic metab olite contents in leaves of cultivars was in statistical significant p ositive correlation (P < 0.001) with reproduction of R. padi and in ne gative correlation (P < 0.05 to 0.005) with reproduction of M. dirhodu m on plants. Relationship between biochemical characteristics of culti vars' spikes and reproduction of S. avenae was not confirmed. Based on differences in reproduction of aphids, a certain level of antibiosis of the Regina cultivar to aphids was associated with the low content o f dry matter and metabolites, above all amino acids, in leaves and ant ibiosis in the Hana cultivar to M. dirhodum was connected with low lev el of water in leaves. The Sparta cultivar of a little development pre cocity, highest dry matter content, free amino acids and sugars in lea ves was the best host for R. padi and a little suitable for M. dirhodu m. The results obtained are discussed in relationship to differences i n requirements of cereal aphids for host and resistance of cereals to aphids.