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Effect of Rhizobium japonicum Mutants with Enhanced N 2 Fixation Activity on N Transport and Photosynthesis of Soybeans during Vegetative Growth 1
Author(s) -
Thomas Richard J.,
Jokinen Kari,
Schrader Larry E.
Publication year - 1983
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1983.0011183x002300030003x
Subject(s) - biology , photosynthesis , rhizobium , nitrogenase , xylem , mutant , nitrogen fixation , shoot , botany , rhizobiaceae , strain (injury) , inoculation , horticulture , symbiosis , bacteria , biochemistry , genetics , anatomy , gene
The effects of two mutant strains of Rhizobium japonicum with enhanced capacities N 2 fixation, on ureide transport, photosynthesis,root respiration, and growth in soybeans [ Glycine max (L.) Merr. ‘Wells’] were examined during vegetative growth. Three‐week‐old plants inoculated with the mutants were larger and had higher rates of acetylene reduction, photosynthesis, xylary ureide transport, leaf allantoinase activity and higher concentrations of ureides in shoot tissues than did plants inoculated with the wild‐type strain. The relative composition of xylem sap N was unaffected by Rhizobium strain. Ureides comprised over 90% of the sap N in all treatments. After 5 weeks growth, however, there were no statistically significant differences among treatments in rates of the physiological processes and growth parameters examined. Cross contamination of nodules containing the mutant strains with the wild‐type strain was not responsible for the apparent loss of the initial advantages to the host plant (in terms of N 2 fixation and growth) brought about by the use of the mutant strains. The use of modifications in Rhizobium genetics for improving the dependency of the host plant on N 2 fixation for its N requirements is briefly discussed.