Effects of elevated CO2 on leaf area dynamics in nodulating and non-nodulating soybean stands
- 366 Downloads
The effects of elevated CO2 on leaf area index (LAI) vary among studies. We hypothesized that the interactive effects of CO2 and nitrogen on leaf area loss have important roles in LAI regulation.
We studied the leaf area production and loss using nodulating soybean and its non-nodulating isogenic line in CO2-controlled greenhouse systems.
Leaf area production increased with elevated CO2 levels in the nodulating soybean stand and to a lesser extent in the non-nodulating line. Elevated CO2 levels accelerated leaf area loss only in nodulating plants. Consequently, both plants exhibited a similar stimulation of peak LAI with CO2 elevation. The accelerated leaf loss in nodulating plants may have been caused by newly produced leaves shading the lower leaves. The nodulating plants acquired N throughout the growth phase, whereas non-nodulating plants did not acquire N after flowering due to the depletion of soil N. N retranslocation to new organs and subsequent leaf loss were faster in non-nodulating plants compared with nodulating plants, irrespective of the CO2 levels.
LAI regulation in soybean involved various factors, such as light availability within the canopy, N acquisition and N demands in new organs. These effects varied among the growth stages and CO2 levels.
KeywordsLeaf area index (LAI) Leaf senescence Legumes Symbiotic N2-fixation Nitrogen demand Nitrogen retranslocation
We thank Meguru Inoue, Teruo Saito, Yukichi Satoh, and other members of NARCT, Chiho Kamiyama and Kay-May Miyagi of Tohoku University for technical assistance. Shoichiro Akao allowed us to use En1282. Makie Kokubun provided the seeds. We are also grateful to Elizabeth Ainsworth, Toshihiko Kinugasa and Toshinori Matsunami for comments. This work was supported by KAKENHI, a Grant-in-Aid for Young Scientists by Japan Society for the Promotion of Sciences (No. 23770027) and a Grant-in Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 21114001).
- R Development Core Team (2006) R: a language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing. ISBN 3-900051-07-0, URL http://www.R-project.org
- Hirose T (1971) Nitrogen turnover and dry-matter production of a Solidago altissima population. Jpn J Ecol 21:18–32Google Scholar
- Hirose T, Ackerly DD, Traw MB, Bazzaz FA (1996) Effects of CO2 elevation on canopy development in the stands of two co-occurring annuals. Oecologia 108:215–223Google Scholar
- Hirose T, Ackerly DD, Traw MB, Ramseier D, Bazzaz FA (1997) CO2 elevation, canopy photosynthesis, and optimal leaf area index. Ecology 78:2339–2350Google Scholar
- Killingbeck (1993) Inefficient nitrogen resorption in genets of the actinorhizal nitrogen-fixing shrub Comptonia peregrine: physiological ineptitude or evolutionary trade-off? Oecologia 94:542–549Google Scholar
- Killingbeck (1996) Nutrients in senesced leaves: keys to the search for potential resorption and resorption proficiency. Ecology 77:1716–1727Google Scholar
- Mae T, Ohira K (1981) The remobilization of nitrogen related to leaf growth and senescence in rice plants (Oryza sativa L.). Plant Cell Physiol 22:1067–1074Google Scholar
- Okada M, Hamasaki T, Sameshima R (2000) Pre-air-conditioned temperature gradient chambers for research on temperature stress in plants. Biotronics 29:43–55Google Scholar
- Rogers A, Fischer BU, Bryant J, Frehner M, Blum H, Raines CA, Long SP (1998) Acclimation of photosynthesis to elevated CO2 under low-nitrogen nutrition is affected by the capacity for assimilate utilization. Perennial ryegrass under free-air CO2 enrichment. Plant Physiol 118:683–689PubMedCrossRefGoogle Scholar
- Yasumura Y, Hikosaka K, Hirose T (2007) Nitrogen resorption and protein degradation during leaf senescence in Chenopodium album grown in different light and nitrogen conditions. Funct Plant Biol 34:409–417Google Scholar