Stem photosynthesis in Psorothamnus spinosus (smoke tree) in the Sonoran desert of California

Erik T Nilsen; F C Meinzer; P W Rundel

doi:10.1007/BF00388478

Stem photosynthesis in Psorothamnus spinosus (smoke tree) in the Sonoran desert of California

Oecologia. 1989 May;79(2):193-197. doi: 10.1007/BF00388478.

Authors

Erik T Nilsen¹, F C Meinzer², P W Rundel³

Affiliations

¹ Department of Biology, Virginia Polytechnic Institute and State University, 24061, Blacksburg, VA, USA.
² Hawaiian Sugar Planters' Association, P.O. Box 1057, 96701, Aiea, Hawaii, USA.
³ Laboratory of Biochemical and Environmental Sciences, University of California at Los Angeles, 900 Veteran Avenue, 90024, Los Angeles, CA, USA.

PMID: 28312855
DOI: 10.1007/BF00388478

Abstract

Stem photosynthetic responses to environmental parameters were investigated with Psorothamnus spinosus in the Sonoran Desert of California. Light saturation of stem photosynthesis was equal to maximum midday summer irradance (1600-2000 μmol·m^-2·s^-1). The optimum temperature for stem photosynthesis was 39°C, and lower stem temperatures (27-35°C) caused significant decreases (up to 50%) in stem photosynthesis. Positive stem photosynthesis was maintained up to 51°C. Stem photosynthesis was relatively insensitive to increasing vpd up to 5 kPa; However, stem conductance decreased by 25% at a vpd of 5 kPa. At vpd greater than 5 kPa stem photosynthesis decreased relatively more than that of stem conductance causing a decrease in water use efficiency and an increase an intercellular carbon dioxide concentration. Maximum stem photosynthetic rates were low (6.2-10.6 μmol·m^-2·s^-1) on a stem surface area, but, stem photosynthetic rates of young shoots were substantially higher (19.5-33.3 μmol· m^-2·s^-1) on a projected area basis.

Keywords: Desert; Photosynthesis; Plant stress; Stem.