The fixation of atmospheric nitrogen in some Fabaceae species

In two replications performed on different dates the fixation of atmospheric nitrogen was measured in some species of the family Fabaceae. The first replication involved 48 species and the second 49 species. On the basis of the results obtained the species were divided into four groups. Besides Lathyrus sativus the best nitrogen fixers were Trifolium incarnatum, Lotus corniculatus, Trifolium hybridum, Trifolium pratense, Trifolium repens, Trifolium ambiguum and annual species of Trifolium resupinatum and Trifolium alexandrinum. In the first replication the tested species of the genus Lupinus were very good nitrogen fixers. However, in the second replication these species formed no nodules on the roots. To make the comparison of the species tested more effective it is recommended to calculate nitrogenase activity per 1 g of root dry matter. On the basis of the calculations Lathyrus sativus, Trifolium pratense 4 n, Trifolium repens and Vicia cracca were good nitrogen fixers in both replications.