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Interactive effects of growth‐limiting N supply and elevated atmospheric CO 2 concentration on growth and carbon balance of Plantago major
Author(s) -
Den Hertog Jeroen,
Stulen Ineke,
Posthumus Freek,
Poorter Hendrik
Publication year - 1998
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1998.1030402.x
Subject(s) - photosynthesis , dry matter , shoot , relative growth rate , carbon dioxide , plantago , growth rate , nutrient , nitrogen , specific leaf area , zoology , botany , dry weight , chemistry , horticulture , biology , geometry , mathematics , organic chemistry
To assess the interactions between concentration of atmospheric CO 2 and N supply, the response of Plantago major ssp. pleiosperma Pilger to a doubling of the ambient CO 2 concentration of 350 µl l −1 was investigated in a range of exponential rates of N addition. The relative growth rate (RGR) as a function of the internal plant nitrogen concentration (N i ), was increased by elevated CO 2 at optimal and intermediate N i . The rate of photosynthesis, expressed per unit leaf area and plotted versus N i . was increased by 20‐30% at elevated CO 2 for N i above 30 mg N g −1 dry weight. However, the rate of photosynthesis, expressed on a leaf dry matter basis and plotted versus N i , was not affected by the CO 2 concentration. The allocation of dry matter between shoot and root was not affected by the CO 2 concentration at any of the N addition rates. This is in good agreement with theoretical models. based on a balance between the rate of photosynthesis of the shoot and the acquisition of N by the roots. The concentration of total nonstructural carbohydrates (TNC) was increased at elevated CO 2 and at N limitation, resulting in a shift in the partitioning of photosynthates from structural to nonstructural and, in terms of carbon balance, unproductive dry matter. The increase in concentration of TNC led to a decrease in both specific leaf area (SLA) and N i at all levels of nutrient supply, and was the cause of the increased rate of photosynthesis per unit leaf area. Correction of the relationship between RGR and Ni for the accumulation of TNC made the effect of elevated CO 2 on the relationship between RGR and N i disappear. We conclude that the shift in the relationship between RGR and N i was due to the accumulation of TNC and not due to differences in physiological variables such as photosynthesis and shoot and root respiration, changes in leaf morphology or allocation of dry matter.