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Variation in Nitrate Tolerance of Nitrogen Fixation in the Pea/ Rhizobium Symbiosis
Author(s) -
Jensen E. S.
Publication year - 1987
Publication title -
plant breeding
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.583
H-Index - 71
eISSN - 1439-0523
pISSN - 0179-9541
DOI - 10.1111/j.1439-0523.1987.tb01105.x
Subject(s) - nitrogen fixation , nitrogenase , biology , sativum , cultivar , pisum , nitrate , symbiosis , rhizobium , nitrite , rhizobium leguminosarum , nodule (geology) , agronomy , root nodule , horticulture , rhizobiaceae , botany , inoculation , bacteria , ecology , paleontology , genetics
The short‐term effects of nitrate on symbiotic nitrogen fixation were studied in six cultivars of pea ( Pisum sativum L.) using two strains of Rhizobium leguminosarum. Plants grown symbiotically for three weeks, in order to eliminate the effect of NO 3 on nodule formation, were exposed to nil, 5 or 15 mM NO 3 for a period of seven days. Nodule mass, nitrogenase activity by acetylene reduction and the NO 2 and NO 3 concentrations in nodules were determined. Exposure to nitrate reduced the total acetylene reduction activity (ARA) in all cultivars, and a significant cultivar × nitrate treatment interaction was found. Nitrate influenced the components of N 2 fixation, nodule mass and specific ARA (ARA/mg nodule), differently within and among cultivars. Nodule mass was reduced in all cultivars, but a variation among cultivars in the degree of reduction was found. Nitrate also reduced the specific ARA to different extents in the cultivars‐ The specific ARA of nodules from NO 3 ‐treated plants, expressed as per cent of the specific ARA of nodules from plants grown without NOT 3 was negatively correlated with the concentration of NO 3 in nodules. No relationship was found between the reduction of N 2 fixation and the nitrite concentration in nodules. The results indicate that it is possible to improve the nitrate tolerance of symbiotic N 2 fixation of the established pea/ Rhizobium symbiosis by selection of suitable host plants.