The responses of gas exchange parameters and leaf chlorophyll content to elevated CO2 and diferent soil N availability in Pisum sativum leaves

Abstract

As both increasing atmospheric carbon dioxide and soil nitrogen play a pivotal role in plant growh and metabolism, there is in particular interest to study their interaction on plant performance, especially, when nitrogen, both extra N application and N deficiency, may play a role in the response of plant to elevated CO2. In order to study their interaction on photosynthetic and growh responses of plant, growth chamber experiments were performed with pea (Pisum sativum L.) plants grown in a controlled conditions at ambient (400 ppm) or elevated (700 ppm) CO2 levels under different soil N availability (3 and 12 g m-2 of nitrogen). The measurements of photosynthetic indices, chlorophyll content and dry total plant mass were performed at the end of an experiment after 10-days duration of treatment. The results showed that photosynthetic characteristics and growth of pea were significant affected by both elevated CO2 and nitrogen. At both N levels, leaves of pea plants grown under elevated CO2 had significant higher photosynthetic rate, lower stomatal conductance (gs), higher water-use-efficiency (WUE) and total chlorophyll content. The total dry mass of pea was significant higher at elevated CO2 by 41 and 35,2 % under 3 and 12 g m-2 of nitrogen in the soil, respectively. Although the gs reduced in elevated CO2, this by itself does not limited photosynthesis, because the ratio of intercellular to ambient CO2 concentration (ci/ca) at both nitrogen levels was higher under elevated than ambient CO2. The photosynthetic indices mostly differed significantly between two nitrogen levels with the lower values of photosynthetic rate and WUE and higer gs and ci/ca under nitrogen deficient at both CO2 concentrations, but the total dry mass and chlorophyll content do not doing so. [...]