The seasonal changes of symbiotic nitrogen-fixation activity and environmental factors of autumn olive (Elaeagnus umbellata Thunb.), which is an important constituent species of temperate vegetation and a non-leguminous root nodule plant interacting w...
The seasonal changes of symbiotic nitrogen-fixation activity and environmental factors of autumn olive (Elaeagnus umbellata Thunb.), which is an important constituent species of temperate vegetation and a non-leguminous root nodule plant interacting with Frankia sp., were quantitatively analyzed in the natural vegetations during the growing period from April through November 1992 and 1993.
Site 1'showed wetter condition than Site 2 in soil environments of habitat. The light conditions of Site 1 was partially shade, while Site 2 was sunny area. Soil pH of investigated area was weak acid ranging from 4 to 6.7. The nitrogenase activity showed two peaks in spring (58.6umole-CZH,-gfw-'-hr-') and autumn (47.8~emole-C,J-I,-gfw-'-hr-') but a significant drop in summer and nothing in winter. The plant grown in Site 1 showed higher chlorophyll contents than that in Site 2 and showed seasonal changes in the range of 16^-74 u g chl cm-. The maximum water content in each plant organ was 65.3, 321. 8, 365.3 and 697.7% respectively for stem, root, leaf and nodule. The optimum for nitrogen fixation activity was attained by 30 C, pH 7, 12Kpa of oxygen partial pressure, 2cm of nodule size and root attached conditions in the rhizosphere. The nitrogenase activity treated with salt and nitrogen sources for 30 minutes showed distiguisled decreases and nothing in 0.1 and 1M respectively.