Symbiosis of Leguminous Plants and Nodule Bacteria

Publisher Website
Google Scholar
Abstract
A comparison has been made of the effect of oxygen concentration on the growth of nodulated red clover plants dependent on nodule-nitrogen and of non-nodulated plants provided with ammonium-nitrogen. Two techniques have been used, the first providing for the exposure of the root system only to adjusted oxygen supply, while in the second the whole plant was so exposed. Four levels of oxygen were employed, namely, 21, 12, 5, and 1 per cent. With the first method each step in the reduction of oxygen supply was attended by a significant curtailment of growth in nodulated plants. The responses of the ammonium plants were less marked. It is concluded that clover nodules function best when well supplied with oxygen. No clear effects of oxygen supply were obtained by the second method, this being due, it is considered, to the severe limitation imposed by the necessary experimental arrangement on the growth of the plants.