Effectiveness of three inoculation methods for lucerne (Medicago sativa L.) in two Canterbury soils

Abstract

The efficacy of ALOSCA^®, coated and peat seed inoculant treatments on the nodulation of lucerne sown in two soils in Canterbury, New Zealand was investigated. The commercial inoculant was Sinorhizobium meliloti strain RRI128. It was recovered from the nodules of lucerne plants grown from ALOSCA^®, peat and coated seed at both sites. Coated seed had the highest nodule occupancy with 45% and 47% of nodules containing S. meliloti strain RRI128 at the Ashley Dene and Lincoln University field sites, respectively. ALOSCA^® had only 9% and 16% of nodules from the Ashley Dene and Lincoln University field sites, respectively, containing S. meliloti strain RRI128. Naturalised Rhizobium strains were also recovered from the nodules of lucerne plants grown from ALOSCA^®, coated and peat seed inoculant treatments. A single genotype (genotype A) of a Rhizobium sp. was recovered more frequently than the inoculated S. meliloti strain in the nodules of plants grown from peat treated seed at Lincoln University (30% vs 22%) and in the nodules of ALOSCA^® treated seed at Ashley Dene (54% vs 9%). Bare seed was also nodulated by the Rhizobium sp. genotype A with 57% and 28% of nodules from plants grown from uninoculated seed at Ashley Dene and Lincoln University, respectively, containing this strain. This research shows delivery by an appropriate inoculation treatment is required to maximise occupancy by the commercial strain.

Keywords:

• alfalfa
• ALOSCA^®
• bare seed
• coated seed
• peat seed
• rhizobia