Author
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Vu, Joseph |
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Submitted to: Environmental and Experimental Botany
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/8/2004 Publication Date: 2/5/2005 Citation: Vu, J.C.V. 2005 Acclimation of peanut(Arachis hypogaea L.) leaf photosynthesis to elevate growth CO2 and temperature. Environmental and Experimental Botany 53: 85-95 Interpretive Summary: Peanut, a subtropical pulse or oil crop, has been widely grown under various climatic conditions in Africa, Asia, and North and South America. Yield of peanut, similar to other crops, is the net result of photosynthesis, a process by which green leaves absorb carbon dioxide (CO2) from the air to make the basic compounds required for plant growth and development. Photosynthesis is greatly influenced by environmental factors. Assessment of the regulatory mechanisms of peanut photosynthesis in response to future global climate changes is, however, limited. In this study, by USDA, ARS, scientists at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL, peanut was grown season-long under ambient or twice-ambient CO2, and at near ambient and 6C above ambient temperatures, to assess leaf photosynthesis with rising air temperature at high CO2. The results indicate that peanut plants grown at twice-ambient CO2 acclimated and exceeded their ambient-CO2 counterparts at both growth temperatures in most aspects of leaf photosynthesis, including CO2 uptake rates, water-use efficiency and accumulation of carbohydrates. Thus, in the absence of other stresses, peanut should perform well photosynthetically under rising CO2 and temperature conditions as predicted for this century. Technical Abstract: Peanut was grown for under 360 and 720 ppm CO2 and at 1.5 and 6C above ambient temperature to characterize leaf photosynthesis response to high CO2 and temperature, and to test if leaf photosynthetic capacity, in terms of Rubisco activity and protein content, was down-regulated at high CO2. Leaves of plants grown at high CO2 had higher photosynthetic rate (Pn), lower transpiration and conductance, higher water-use efficiency and lower Pn response curve initial slope, compared to those of plants grown at ambient CO2. Both activity and protein content of Rubisco were reduced at high CO2. Declines in Rubisco under high CO2 were up to 30% for activity and 20% for protein content. Although Rubisco was down-regulated at high CO2, Rubisco photosynthetic efficiency, the ratio of midday Pn to Rubisco activity, of the high-CO2 plants was 1.3- to 1.9-fold greater than that of the ambient-CO2 plants at both growth temperatures. Leaf soluble sugars and starch of plants grown at high CO2 were 1.3- to 2-fold higher than those of plants grown at ambient CO2. Leaf soluble sugars and starch were not affected by high temperature under elevated CO2, but were reduced at ambient CO2. Thus, in the absence of other stresses, peanut photosynthesis would perform well under rising atmospheric CO2 and temperature as predicted for this century. |
