CULTIVAR X RHIZOBIAL STRAIN INTERACTIONS IN PEAS WITH RESPECT TO EARLY SYMBIOSIS, NODULE INITIATION AND N UPTAKE

Sixteen pea cultivars differing in their phenotypic characteristics we re studied in order to characterize the cultivars' variability in symb iotic characters using three Rhizobium leguminoisarum biovar viceae st rains. The peas did not show any cultivar x strain interactions with t he rhizobial strains used with respect to root hair infection frequenc y or day of nodule initiation. Three cultivars had high root hair infe ction frequencies, and five had only a few infected root hairs. Four o f five leafless/semi-leafless varieties investigated and one cultivar with normal leaves formed nodules quickly, whereas three varieties wit h normal leaves formed nodules slowly. Ten of the cultivars showed cul tivar x strain interactions with respect to N uptake, indicating that the performance of the N-2-fixing symbioses depends on the rhizobial p artner. Six cultivars showed cultivar x strain interactions with respe ct to dry matter production and the nodule proportion of the dry matte r. Of the cultivars investigated, we conclude that some of the leafles s/semi-leafless varieties ('Capella','Filby' and `Solara') are suitabl e for inclusion in a future breeding programme, since these cultivars combined several important symbiotic characters.