Competition and persistence of strains ofRhizobium trifoliiin relation to inoculation level and lime pelleting on white clover sown into cultivated soil

Abstract

Five strains of Rhizobium trifolii were assessed for their ability to compete with naturalised strains in nodulating white clover (Trifolium repens) sown in cultivated soil. At the initial assessment 5 months after sowing, the inoculant strains at the normal rate of slurry-inoculation had formed only a small percentage of the nodules present. Increasing the inoculation level to 10 times normal or lime pelleting increased the percentage of nodules formed by all strains apart from PDDCC 2163, which formed a low percentage of nodules irrespective of inoculation and pelleting treatments. The percentage of nodules formed by Strains 2153, 2666, and 2668 declined between the 5-and 18-month assessments so that the percentage of nodules formed by Strain 4144 after 18 months was about twice that of the other strains. Inoculating with Strain 4144 significantly increased %N and total N uptake in clover in spring, 10 months after sowing, compared with the other inoculant strains. However, there were no significant effects on clover dry matter production.

Nodule occupancy byRhizobium leguminosarumstrain WSM1325 following inoculation of four annualTrifoliumspecies in Canterbury, New Zealand

“…This work reinforces other work (using chromosomal and plasmid restriction fragment length polymorphism) done at the University of Otago, New Zealand, (Elliot 1997;Shah 2003) that demonstrated genotypic variation in rhizobia in New Zealand pastures. In previous surveys, a high titre of naturalized strains has been demonstrated (Greenwood 1965;Hale 1980;Rhys & Bonish 1981;Gaur & Lowther 1982) and this field site is typical of New Zealand lowland soils having a history of inoculation with commercially available strains of rhizobia.…”

“…It is unknown whether the dominant naturalized strains at the Canterbury site could fix N 2 at levels similar to strain WSM1325. Research has shown that the symbiotic effectiveness of naturalized strains varies widely, between 2 and 100% of that demonstrated by highly effective commercial inoculants (Gaur & Lowther 1980, 1982Rhys & Bonish 1981;Svenning et al 2001).…”

Establishment and persistence ofRhizobium trifoliiin a developed pasture soil

“…These populations of Rhizobium trifolii exhibit a wide range of effectiveness (ability to fix nitrogen) with white clover (Greenwood 1%0), and recent surveys (Bonish 1979;Hale 1980;Gaur & Lowther 1980) have shown that the effectiveness of field strains of R. trifolii in both North Island and South Island soils is generally 10-30% below that of commercially available inoculant strains.…”

“…The symbiotic effectiveness of Rhizobium trifolii strains isolated from an established white clover (Trtfolium repens L.)/ryegrass pasture over a 3-year period ranged from 24 to 130% of the effectiveness of a commercially recommended strain NZP561 (PDDCC 2163) when tested on 'Grasslands and the naturalised Rhizobium population for nodule formation (Brockwell et al 1980;Hale 1981;Gaur & Lowther 1982).…”

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AbstractThe symbiotic effectiveness of Rhizobium trifolii strains isolated from an established white clover (Trtfolium repens L.)/ryegrass pasture over a 3-year period ranged from 24 to 130% of the effectiveness of a commercially recommended strain NZP561 (PDDCC 2163) when tested on 'Grasslands and the naturalised Rhizobium population for nodule formation (Brockwell et al 1980;Hale 1981;Gaur & Lowther 1982).In this study, the symbiotic effectiveness of R. trifolii strains present in an established white clover/ryegrass pasture in the Manawatu region of the North Island was evaluated. The effects of 2 methods of inoculation of white clover seed on the establishment and persistence of a commercial inoculant strain and an effective field strain of R. trifolii in this soil were also compared.

Huia' white clover.

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