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 were studied in order to characterize the cultivars' variability in symbiotic characters using three Rhizobium leguminoisarum biovar viceae strains. The peas did not show any cultivar x strain interactions with the rhizobial strains used with respect to root hair infection frequency or day of nodule initiation. Three cultivars had high root hair infection frequencies, and five had only a few infected root hairs. Four of five leafless/semi-leafless varieties investigated and one cultivar with normal leaves formed nodules quickly, whereas three varieties with normal leaves formed nodules slowly. Ten of the cultivars showed cultivar x strain interactions with respect to N uptake, indicating that the performance of the N-2-fixing symbioses depends on the rhizobial partner. Six cultivars showed cultivar x strain interactions with respect to dry matter production and the nodule proportion of the dry matter. Of the cultivars investigated, we conclude that some of the leafless/semi-leafless varieties ('Capella','Filby' and `Solara') are suitable for inclusion in a future breeding programme, since these cultivars combined several important symbiotic characters.