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Relationship between C 2 H 2 reduction, H 2 evolution and 15 N 2 fixation in root nodules of pea ( Pisum sativum )
Author(s) -
Skøt Leif
Publication year - 1983
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1983.tb06283.x
Subject(s) - pisum , sativum , nitrogenase , horticulture , nitrogen fixation , botany , analytical chemistry (journal) , chemistry , zoology , biology , nitrogen , chromatography , organic chemistry
The quantitative relationship between C 2 H 2 reduction, H 2 evolution and 15 N 2 fixation was investigated in excised root nodules from pea plants ( Pisum sativum L. cv. Bodil) grown under controlled conditions. The C 2 H 2 /N 2 conversion factor varied from 3.31 to 5.12 between the 32nd and the 67th day after planting. After correction for H 2 evolution in air, the factor (C 2 H 2 ‐H 2 )/N 2 decreased to values near the theoretical value 3, or in one case to a value significantly ( P < 0.05) below 3. The proportion of the total electron flow through nitrogenase, which is not wasted in H 2 production but used for N 2 reduction, is often stated as the relative efficiency (1‐H 2 /C 2 H 2 ). This factor varied significantly ( P < 0.05) during the growth period. The actual allocation of electrons to H 2 and N 2 , expressed as the H 2 /N 2 ratio, was independent of plant age, however. This discrepancy and the observation that the (C 2 H 2 ‐H 2 )/N 2 conversion factor tended to be lower than 3, suggests that the C 2 H 2 reduction assay underestimates the total electron flow through nitrogenase.