Nitrogen fixing capacity of eleven clover cultivars modulated by native rhizobia

Berseem clover, Trifolium alexandrinum, is the main winter forage legume in Egypt. A national breeding and selection program is under way in order to upgrade the productivity of this crop. 11 clover cultivars were evaluated for their N-fixing capacity when nodulated by native rhizobia. 2 cultivars, Giza 2 and Seds 5 gave small nodular tissue, dry matter yield and low nitrogen content. Some other cultivars, Upper Egypt 1 and Giza 52 were distinguished by exhibiting high N-fixation and dry matter yield. The response of different cultivars to N-fertilization was different. However, most of the tested cultivars benefited from N-fixation in the second and third cuts rather than the first cut