|Allen, Leon - Hartwell|
Submitted to: Journal of Plant Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/6/2009
Publication Date: 6/18/2009
Citation: Vu, J.C., Allen Jr, L.H. 2009. Stem juice production of the C4 sugarcane (Saccharum officinarum) is enhanced by growth at double-ambient CO2 and high temperature. Journal of Plant Physiology. 166:1141-1151. Interpretive Summary: Research on rising atmospheric carbon dioxide (CO2) and climate changes has focused mainly on C3 crops such as soybean and rice. Few tests have been done on C4 crops such as sugarcane and maize. In this study, by ARS scientists with the CMAVE Chemistry Research Unit in Gainesville, FL, four sugarcane cultivars were grown for 3 months under ambient and double-ambient CO2 and at temperatures (T) of 1.5 and 6C higher than outside ambient, and leaf area, stem juice, plant biomass and leaf photosynthesis were determined at harvest. On a main stem basis, leaf area, leaf biomass, stem biomass, juice volume and whole plant biomass were increased by growth at doubled CO2 or high T. Such increases were even greater, ranging from 110 to 493% higher, under doubled CO2/high T combination than at ambient CO2/near-ambient T combination. In addition, plants grown at doubled CO2/high T were 2.6-fold higher in stem sucrose. Although leaf photosynthesis was hardly affected by doubled CO2 or high T, the increase in stem juice and sucrose for sugarcane grown at doubled CO2 and high T was primarily the outcome of an increase in whole plant leaf area. Such increase would enhance the photosynthetic capability and thus sugar production of sugarcane.
Technical Abstract: Four sugarcane cultivars were grown for three months in sunlit greenhouses under [CO2] of 360 (ambient) and 720(doubled) ppm and at temperatures (T) of 1.5 (near ambient) and 6.0C higher than outside ambient T. Leaf area, stem juice, plant biomass, leaf CO2 exchange rate (CER) and activities of PEP carboxylase (PEPC) and Rubisco were determined at harvest. On a main stem basis, leaf area, leaf biomass, stem biomass, juice volume and whole plant biomass were increased at doubled [CO2] or high T. Such increases were even greater at doubled [CO2]/high T combination. Plants grown at doubled [CO2]/high T were 132, 110, 493, 468 and 324% greater in leaf area, leaf biomass, stem juice, stem biomass and whole plant biomass, and 2.6 to 3-fold higher in stem soluble solids and sucrose, compared with plants grown at ambient [CO2]/near-ambient T. Doubled [CO2] but not high T reduced PEPC, while Rubisco was not affected by doubled [CO2] but was reduced by high T. Under doubled [CO2] and/or high T, the greater production in stem juice and sucrose was the outcome of an increase in whole plant leaf area, although CER of mature leaves was hardly affected. Such increase would enhance the whole plant ongoing and cumulative photosynthetic capability.