Toxicity of Arrowleaf Clover Seed to Rhizobium trifolii1
- L.A. Materon and
- R.W. Weaver2
Arrowleaf clover (Trifolium vesiculosum Savi.) needs to be inoculated when sown in many fields in the southeastern USA. Survival of rhizobia on the seed following inoculation is critical for successful nodulation of the seedling. The effect the seed has on survival of the rhizobia has not been determined and may potentially be important to the success of inoculation. Seeds of subclover (T. subterruneum L.) and different genotypes of arrowleaf clover were placed on inoculated yeast mannitol agar medium to determine if the seed contained diffusable substances toxic to rhizobia. A thermostable, watersoluble diffusate was released from autoclaved and nonautoclaved seeds that inhibited the growth of many strains of Rhizobium trifolii. Seed-coat disinfecting techniques that utilized aqueous solutions reduced toxicity of the seed and indicated that method of seed disinfection should be taken into consideration when conducting experiments on survival of rhizobia on seed. Two selections of ‘Amclo’ arrowleaf clover were demonstrated not to be toxic to R. trifolii. Additional research should be undertaken to identify the toxic substances in the seed and to determine their influence on survival of rhizobia applied to seed as an inoculant. The nontoxic seed would serve as a good control for such experiments and may prove to be useful to plant breeders in determining the genetic basis of the toxic substances.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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