Benchmarking symbiotic performance of white clover cultivars: Room for improvement?

Abstract

To gain insight into variation in white clover-Rhizobium interactions, we assessed symbiotic performance of 48 individuals each from 17 cultivars from a range of leaf size classes, and included a wild ecotype population and a T. repens × T. ambiguum hybrid cultivar. Measurements of symbiotic response were based on plant shoot and root biomass, pink nodule number, and symbiotic potential. This was determined using an effective and a partially-effective Rhizobium strain separately. The plant biomass and symbiotic potential traits were strongly linked, and also inversely correlated with the root:shoot ratio. T here were significant differences between cultivars for symbiotic interactions, with some performing equally well with both strains. Some cultivars exhibited extreme differences by performing very well with the effective strain, and very poorly with the partially-effective strain. Benchmarking symbiotic performance indicated clover population-specific genetic factors that may be explored as a breeding target for enhanced interaction with Rhizobium spp. to improve N-fixation.