Symbiotic adaptation in local strains of red clover and nodule bacteria

A study has been made of the response of a number of local strains of British and Swedish red clover in symbiosis with nodule bacteria isolated from the localities from which the plant strains were obtained. All combinations of bacterial isolate and plant type were examined under bacteriologically controlled conditions of plant culture on an agar medium.

In the Swedish material each local strain of clover responded most effectively with bacteria isolated from its own locality. This adaptation was detected at about 8 weeks from planting by scoring the seedlings for size and colour, and at harvest was reflected in a mean difference of 5% on a dry weight basis. No differences were found in nitrogen content.

No adaptation was found within the British material possibly because of the more uniform climatic conditions. A small intra-national adaptation was significant.
RESP-3059