Publication Date
1985
Location
Kyoto Japan
Description
The intercellular relationships between leaves and stems for pathways of CO2 and nitrate assimilation were investigated in Portulaca oleracea growing under the natural environmental conditions. The number of stomata was 3,275cm-2 in leaves, while the stomata could not be observed in stems. Stomata! resistance in leaves of the young purslane was high at night and low in daytime. The difference between the highest and the lowest acidity was the greatest at the 2nd node of the intact plant. The order of the node having the highest acidity was changed as the leaves were detached from the top to the bottom. The stem tissues of P. oleracea showed high activity of Crassulacean acid metabolism(CAM) but no CAM activity was seen in the leaves. The rapid acidification was seen in the intact stems at dawn but defoliated stems showed only a gradual increase. RuBP carboxylase activity was very high at 2:00 P.M. in both leaves and stems. However, its activity at 1:00 A.M. and 5:30 A.M. was hardly detected. Particularly, activity of PEP carboxylase in leaves was very high in the early morning, though that in stem tissues was little. Those results indicate that CO2 passed through open stomata at dawn may be assimilated by PEP carboxylase in leaves and then C4 products move to stems. The levels of nitrate concentration and of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase were higher in stems than in leaves. The levels were also higher in the light than in the dark. It would be suggested that cosiderable amount of nitrate absorbed from roots be assimilated in stems and nitrate transferred to leaves via stem tissues be reduced there.
Citation
Chang, N K. and Kim, H B., "Adaptive CO2 Fixation and Nitrate Assimilation in Portulaca oleracea" (1985). IGC Proceedings (1985-2023). 7.
(URL: https://uknowledge.uky.edu/igc/1985/ses3/7)
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Adaptive CO2 Fixation and Nitrate Assimilation in Portulaca oleracea
Kyoto Japan
The intercellular relationships between leaves and stems for pathways of CO2 and nitrate assimilation were investigated in Portulaca oleracea growing under the natural environmental conditions. The number of stomata was 3,275cm-2 in leaves, while the stomata could not be observed in stems. Stomata! resistance in leaves of the young purslane was high at night and low in daytime. The difference between the highest and the lowest acidity was the greatest at the 2nd node of the intact plant. The order of the node having the highest acidity was changed as the leaves were detached from the top to the bottom. The stem tissues of P. oleracea showed high activity of Crassulacean acid metabolism(CAM) but no CAM activity was seen in the leaves. The rapid acidification was seen in the intact stems at dawn but defoliated stems showed only a gradual increase. RuBP carboxylase activity was very high at 2:00 P.M. in both leaves and stems. However, its activity at 1:00 A.M. and 5:30 A.M. was hardly detected. Particularly, activity of PEP carboxylase in leaves was very high in the early morning, though that in stem tissues was little. Those results indicate that CO2 passed through open stomata at dawn may be assimilated by PEP carboxylase in leaves and then C4 products move to stems. The levels of nitrate concentration and of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase were higher in stems than in leaves. The levels were also higher in the light than in the dark. It would be suggested that cosiderable amount of nitrate absorbed from roots be assimilated in stems and nitrate transferred to leaves via stem tissues be reduced there.
