Observations on the Gaseous Exchanges which take place betweenMenyanthes trifoliataL. and its Environment

Publisher Website
Google Scholar
Abstract
As part of a general investigation into the exchange of gases between the bogbean, Menyanthes trifoliata , and its environment, determinations have been made of the composition of the internal atmosphere of the plant at five different levels, viz. leafy shoot, three successive portions of stem, and roots. Procedure is described for the analysis of small gas samples using a modification of the Bonnier and Mangin apparatus. In darkness with the lower part of the plant surrounded by an atmosphere of nitrogen, it has not been possible to show the presence of a regular downwards gradient of oxygen, such as would be expected on a basis of normal gaseous diffusion. Under these Air Top/Nitrogen Bottom conditions the roots are shown to contain between 12·5 and 17·5 percent, of oxygen in their intercellular gas system. The portion of stem immediately adjacent to the roots showed an oxygen level of from 14·0 to 18·0 per cent. In plants kept under Nitrogen Top/Air Bottom conditions in the dark for 48 hours, the concentration of oxygen in the roots fell to a level of 3·1 per cent, or below in three plants and to 6·o per cent, in a fourth. The oxygen concentration in the adjacent lowermost part of the stem was as high as 18·0 per cent., depending on the degree of aeration of the solution bathing the stem. It is suggested that this distribution of oxygen can be related to the relative impermeability of roots and of stem endodermis to gaseous diffusion from without, and it is thought that the major part of the oxygen supply to the roots is transported to them through the stelar air passages. Some evidence is presented to show that oxygen passes from the lower parts of the plant into the medium surrounding it.

This publication has 0 references indexed in Scilit: