Photosynthesis and Water Relations in Brazilian Sugarcane

Lauricio Endres1, *, José Vieira Silva2, Vilma Marques Ferreira1, Geraldo Veríssimo De Souza Barbosa1
1 Centro de Ciências Agrárias, Universidade Federal de Alagoas, Alagoas, CEP 57072-970, Brazil
2 Campus Avançado de Arapiraca, Universidade Federal de Alagoas, Alagoas, CEP 57072-970, Brazil

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© 2010 Endres et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Lauricio Endres, Condomínio Chácaras da Lagoa, G-20, Bairro Santa Amélia, Maceió, AL, CEP 57063- 260, Brazil; Tel: +55 82 32611676; Fax: +55 82 32611351; E-mail:


The expansion of sugarcane (Saccharum spp.) in Brazil has been boosted by the growing demand for bio-fuels all over the world and requires the occupation of new agricultural areas, including regions with unfavorable agro-climatic conditions. This observational study makes an analysis of the relationship between stomatal conductance, gas exchange and photosynthesis in sugarcane fields subject to different ambient conditions and growth phases. It was noted that the stomatal conductance had a much higher control on photosynthesis than on transpiration. Even under high stomatal conductance, photosynthesis maintained a high correlation to it. Sugarcane had an instantaneous water use efficiency of approximately 4.4 µmol of fixed CO2 for each mmol of H20 expended in transpiration. Lower leaf water potential, besides leading to an internal reduction of CO2, also reduced the instantaneous carboxylation efficiency, indicating that the photosynthesis apparatus was also affected. The variety RB92579, seems to have good water absorption system, because even under low leaf water potential, it maintained a good stomatal conductance, with a higher transpiration and photosynthesis than the others varieties. These results suggest that this variety has a tolerance mechanism to endure rather than avoid drought.

Keywords: Stomatal conductance, leaf water potential, instantaneous water use efficiency, Saccharum spp..