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A Division of the Alfalfa Cross‐Inoculation Group Correlating Efficiency in Nitrogen Fixation with Source of Rhizobium Meliloti 1
Author(s) -
Burton Joe C.,
Erdman Lewis W.
Publication year - 1940
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1940.00021962003200060004x
Subject(s) - nitrogen fixation , chemist , rhizobium , inoculation , nitrogen , library science , horticulture , chemistry , biology , computer science , organic chemistry
A nitrogen-fixation relationship between leguminous plants and Rhizobia is known to be dependent upon the plant as well as the root nodule bacteria. The qualities or requisites for either have as yet been undefinable from a biochemical or physiological standpoint. Studies to date have dealt primarily with demonstrations of the phenomenon and the extent of its existence within the plant groups. Previous studies have shown that a strain of bacteria efficient in nitrogen fixation on one leguminous plant within a cross-inoculation group is not necessarily efficient on other plants in the same group. They have also shown that there are all gradations in efficiency among strains of legume bacteria causing nodule formation on any one host plant. These studies demonstrate a group specificity with respect to the legume bacteria isolated from alfalfa (Medicago sativa) and sweet clover (Melilotus sp.), and their nitrogen fixation efficiency on burr clover (Medicago hispida, arabica) and fenugreek (Trigonella Foenum-Graecum), which belong to the same cross-inoculation group. When all, or the majority of all, strains of bacteria isolated from a particular leguminous plant fail to cause nitrogen fixation, although producing excellent nodulation on another plant within the same group, it reflects a change in the bacteria produced by the physiology or the chemistry of the plant itself. This phenomenon is demonstrated in these studies with R. meliloti isolated from Mfalfa and sweet clover. It can not be demonstrated with strains of R. meliloti isolated from burr clover or fenugreek on the plants now included in the alfalfa cross-inoculation group.