Symbiotic effectiveness of root nodule bacteria isolated from white clover growing in North Island hill pastures

Abstract

Rhizobium trifolii isolates were obtained from nodules of white clover (Trifolium repens L.) growing within a grazing trial in steep, North Island hill country. The white clover was from each of 6 experimental treatments involving 2 fertiliser application regimes and 3 grazing managements. ‘Grasslands Huia’ and the resident Kentish-type white clover were present in pastures in variable proportions. Effectiveness of isolates, measured using Huia as the host plant and compared with a standard strain, ranged from 3 to 170%. Of 285 isolates tested, 9% were at least 20% more effective than the standard strain. Influence of experimental treatments on effectiveness of isolates appeared to be indirect, acting through effects on proportion of Huia and the resident white clover present at sample sites.

Keywords:

• Rhizobium trifolii
• hill country
• slope
• aspect
• Huia
• white clover
• grazing management
• fertiliser
• pasture