Elevated CO2 increases water use efficiency by sustaining photosynthesis of water-limited maize and sorghum

2011 ◽  
Vol 168 (16) ◽  
pp. 1909-1918 ◽  
Author(s):  
Leon Hartwell Allen ◽  
Vijaya Gopal Kakani ◽  
Joseph C.V. Vu ◽  
Kenneth J. Boote
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Use Efficiency

Does Elevated CO2 Affect the Physiology and Growth of Quercus Mongolica under Different Nitrogen Conditions?

2005 ◽  
Vol 277-279 ◽  
pp. 528-535
Author(s):  
Oh Hyun Kyung ◽  
Yeonsook Choung
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Physiological Activity ◽  
Photosynthesis Rate ◽  
Total Biomass ◽  
High Nitrogen ◽  
Quercus Mongolica ◽  
Use Efficiency ◽  
Nitrogen Conditions

The response of Quercus mongolica, one of the major tree species in Northeast Asia and the most dominant deciduous tree in Korea, was studied in relation to elevated CO2 and the addition of nitrogen to soil in terms of its physiology and growth over two years. Plants were grown from seed at two CO2 conditions (ambient and 700 µL L-1) and with two levels of soil nitrogen supply (1.5 mM and 6.5 mM). Elevated CO2 was found to significantly enhance the photosynthesis rate and water use efficiency by 2.3-2.7 times and by 1.3-1.8 times, respectively. Over time within a growing season, there was a decreasing trend in the photosynthesis rate. However, the decrease was slower especially in two-year-old seedlings grown in elevated CO2 and high nitrogen conditions, suggesting that their physiological activity lasted relatively longer. Improved photosynthesis and water use efficiency as well as prolonged physiological activity under high CO2 condition resulted in an increase in biomass accumulation. That is, in elevated CO2, total biomass increased by 1.7 and 1.2 times, respectively, for one- and two-year-old seedlings with low nitrogen conditions, and by 1.8 and 2.6 times with high nitrogen conditions. This result indicates that the effect of CO2 on biomass is more marked in high nitrogen conditions. This, therefore, shows that the effect of CO2 is accelerated by the addition of nitrogen. With the increase in total biomass, the number of leaves and stem diameter increased significantly, and more biomass was allocated in roots, resulting in structural change. Overall, the elevated CO2 markedly stimulated the physiology and growth of Q. mongolica. This demonstrates that Q. mongolica is capable of exploiting an elevated CO2 environment. Therefore, it will remain a dominant species and continue to be a major CO2 sink in the future, even though other resources such as nitrogen can modify the CO2 effect.

Responses of CO2 Assimilation, Transpiration and Water Use Efficiency to Long-Term Elevated CO2 in Perennial C3 Xeric Loess Steppe Species

1996 ◽  
Vol 148 (3-4) ◽  
pp. 356-361 ◽  
Author(s):  
Zoltán Tuba ◽  
Kálmán Szente ◽  
Zoltán Nagy ◽  
Zsolt Csintalan ◽  
Judit Koch
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Co2 Assimilation ◽  
Steppe Species ◽  
Use Efficiency

Plant Responses to Salinity Under Elevated Atmospheric Concentrations of CO2

1992 ◽  
Vol 40 (5) ◽  
pp. 515 ◽  
Author(s):  
MC Ball ◽  
R Munns
Keyword(s):  
Water Use Efficiency ◽  
Elevated Co2 ◽  
Water Use ◽  
Water Loss ◽  
Salt Flux ◽  
Carbon Gain ◽  
Salt Balance ◽  
Salt Uptake ◽  
Use Efficiency ◽  
Atmospheric Concentrations

This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of halophytic and non-halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be regulated to protect sensitive metabolic sites from salt toxicity. Salt-tolerant species exclude most of the salt from the transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concentrations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt storage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and the expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one of the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies coupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevated CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient and elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in both C3 and C2 non-halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust to environmental factors affecting the availability of water and ions at the roots (salinity) and those affecting carbon gain in relation to water loss at the leaves (atmospheric concentrations of water vapour and carbon dioxide).

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