Investigations on the root nodule bacteria of leguminous plants. XVI. Effect of air content of the medium on the function of the nodule and on the excretion of nitrogen

Publisher Website
Google Scholar
Abstract
Experiments with sterile cultures of peas, inoculated with their appropriate strain of nodule bacteria, have given the following results:(1) In quartz sand the rate of excretion of nitrogenous compounds from the nodules was directly proportional to the capacity of the culture flask, i.e. to the supply of air to the roots.(2) In water cultures abundant nodules were formed within the liquid medium. However, when all nodules were submerged, the plants grew poorly and their nitrogen content was low. The growth was the better, the more the nodules were situated above the liquid surface. The submerged nodules were, however, fully capable of fixing nitrogen, since the removal of part of the liquid with the subsequent exposure of the nodules to air resulted in a profuse growth of the plants. Nevertheless, in water cultures the excretion of nitrogenous compounds from the nodules was very slight or nil. The nodule formation was completely in hibited when all air in the medium was replaced by nitrogen gas.