Canopy photosynthesis, evapotranspiration, leaf nitrogen, and transcription profiles of maize in response to CO₂ enrichment

Abstract

The effects of CO 2 enrichment on the growth and physiology of maize were investigated at the molecular, biochemical, leaf, and canopy levels. Maize plants were grown in sunlit soil-plant-atmosphere research (SPAR) chambers at ambient (370 lmol mol À1 ) or elevated (750 lmol mol À1 ) atmospheric carbon dioxide concentration (C a ) under wellwatered and fertilized conditions. Canopy gas exchange rates and leaf temperatures were monitored continuously during the growing season. CO 2 enrichment did not enhance the growth or canopy photosynthesis of maize plants. However, canopy evapotranspiration rates decreased by 22% and daytime leaf temperatures were increased about 1 1C in response to CO 2 enrichment. Leaf carboxylation efficiency and leaf nitrogen concentration also decreased at elevated C a . Transcription profiling using maize cDNA microarrays revealed that approximately 5% of tested genes responded to CO 2 enrichment. Of the altered transcripts, several were known to encode proteins involved in stomatal development or photosynthesis. For the majority of the altered transcripts, however, it was difficult to link their functions with specific physiological factors partly because many of these genes encoded unknown proteins. We conclude that maize did not exhibit enhanced growth or photosynthesis in response to CO 2 enrichment but a number of molecular and physiological processes including those involved in stomatal relations were affected by growth in elevated C a .

Plough Pan Impacts Maize Grain Yield, Carbon Assimilation, and Nitrogen Uptake in the Corn Belt of Northeast China

“…Pn of ear leaf in maize could partly indicate the photosynthetic capacity, thus it is the key factor to determine grain yield (Kim et al, 2006). The value of Pn were significantly reduced by plough pan in this study.…”

Modelling the impacts of weather and climate variability on crop productivity over a large area: A new process-based model development, optimization, and uncertainties analysis

“…Leakey et al (2004) showed maize growth at elevated [CO 2 ] significantly increased leaf photosynthetic CO 2 uptake rate by up to 41%, and 10% on average. Kim et al (2006Kim et al ( , 2007 (Fig. 5), g c and T T reduced by 26.6% (18.5%) and 44.5% (38.1%) on average, respectively, during the growing period in 2002 with total precipitation 476 mm (1997 with total precipitation 490 mm); L AI and crop yield increased by 0.96% (5.56%) and 3.25% (6.15%) on average, respectively, in 2002 (1997).…”

“…The important consideration is that experimentally observed crop physiological responses to climate change variables at plot and field levels (e.g. Kimball et al, 1995;Ainsworth et al, 2002;Leakey et al, 2004;Kim et al, 2006Kim et al, , 2007 are too simplified in current crop models (Tubiello et al, 2007a). As a consequence, the potential for negative surprises is not fully explored, thus reducing the level of confidence in regional and global projections (Tubiello et al, 2007a).…”

“…Extensive controlled-environment experiments such as the Free-Air Concentration Enrichment experiments (e.g., Kimball et al, 1995;Ainsworth et al, 2002;Leakey et al, 2004;Kim et al, 2006Kim et al, , 2007 have showed that increases in both mean and extremes of temperature and elevated [CO 2 ], under predicted climate change scenarios, can impact the growth and development of crops in several ways. Sustained temperature increases over the season will change the growing period of a crop (e.g., IPCC, 2001), whereas short episodes of high temperature during the critical flowering period of a crop can impact yield independently of any substantial changes in mean temperature (e.g., Matsui and Horie, 1992;Wheeler et al, 2000).…”

Decreases in Stomatal Conductance of Soybean under Open-Air Elevation of [CO2] Are Closely Coupled with Decreases in Ecosystem Evapotranspiration

“…Some studies in field and laboratory chambers have shown a decrease in ET with elevated CO 2 (Chaudhuri et al, 1990;Li et al, 2004;Kim et al, 2006), and others have not (Hileman et al, 1994). However, coupling to the atmosphere, humidity, radiation, and temperature are all altered by chambers, such that they may modify ecosystem response to CO 2 (McLeod and Long, 1999).…”