Symbiotic nitrogen fixation in two species in Leguminosae: Lathyrus maritimus (L) Bigel. and Oxytropis campestris (L) DC

The symbiotic association of Rhizobium strains and two species of legumes, Lathyrus maritimus (L.) Bigel. and Oxytropis campestris (L.) DC found in subarctic regions of Newfoundland were investigated. The isolate of L. maritimus was found to resemble fast-growing Rhizobium leguminosarum biovar vicia, except in its ability to tolerate a wide range of pH and a high concentration of NaCl. The isolate of O. campestris exhibited characteristics which resembled those of both slow-growing and fast-growing strains.;Growth patterns and external morphology of the symbiotic root nodules were studied. The beaded structure of field-collected nodules indicate that they resume growth after overwintering annually. The results of laboratory-grown specimens showed that nodules of both species attain a maximum size after which no growth occurs. The two species showed highest nitrogenase activity at 20;Nodules possessed lipid bodies which may be involved in the protection of the nitrogen-fixing tissue from the cold environment by forming an insulating jacket around it. (Abstract shortened by UMI.).;An isolate of O. campestris could not infect any of the hosts used while that of L. maritimus could infect Vicia cracca.