Investigations on the root nodule bacteria of leguminous plants. XVII. Continued investigations on the effect of air content of the medium on the development and function of the nodule

Abstract

The effect of the air content of the medium on the development and function of the nodule was studied with sterile cultures of peas inoculated with their appropriate strain of nodule bacteria.In water cultures the plant grows well without added nitrogen, even though all nodules are submerged, if air is bubbled through the medium during the period of growth. Abundant nodulation occurs also in nonaerated liquid cultures; the nodules, however, are much smaller than in aerated cultures, and the plant grows poorly. Subsequent aeration of such cultures results in a distinct increase in the size of the nodules and improvement in the growth of the plant.Nodulation is completely prevented by passing a stream of gaseous N through the medium. That oxygen is indispensable for the function of the nodules is shown also by the fact that the peas grow excellently on added nitrogen in non-aerated cultures.

Haemoglobin and the oxygen uptake of leguminous root nodules

“…was accompanied by a proportional decrease in the uptake of gaseous and combined nitrogen. Their experiments, however, are not directly comparable with those of Golding (1903) and Virtanen & von Hausen (1935, 1936, in which the P02 would probably be much lower than 0-012 atm. and the green parts of the plants were in an atmosphere containing 20 % oxygen.…”

“…Thornton (1930) has shown that such nodules fix little nitrogen. The effect of depriving normal mature nodules of their oxygen supply has been studied by Golding (1903) and by Virtanen & von Hausen (1935, 1936, who found that uptake of gaseous nitrogen in nutrient solution cultures ceased in the absence of an oxygen supply to the nodulated roots, while uptake of combined nitrogen was independent of root aeration. Wilson & Fred (see Wilson, 1940) have produced quantitative results demonstrating the effect of growing entire clover plants in partial pressures of oxygen (PO2) varying between 0-012 and 0*6 atm.…”