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The perennial halophytes, Batis maritima L., Sesuvium portulacastrum L., and Portulaca rubricaulis H.B.K. which inhabit the extreme environment on parts of the salt plain and at the edges of the vegetation islands of Ciénega el Ostional were examined to determine their strategies for growth and survival in the rainy and dry seasons. All of the three species are leaf‐succulents. High leaf‐sap osmotic pressures, xylem tensions and Na+ and Cl− levels indicated that S. portulacastrum and B. maritima are salt‐accumulating halophytes. Succulence, leaf‐sap osmolalities and Na+ and Cl− levels increased in the dry season in B. maritima by a factor of 1.5‐2.0 and in S. Portulacastrum by a factor of 1.9–2.7. B. maritima also accumulated sulphate with a two‐fold increase of concentrations in the dry season. In S. portulacastrum Na+ accumulation much exceeded Cl− accumulation and oxalate synthesis was found to serve charge balance. In this species the compatible solutes, proline and pinitol, were clearly detectable in both seasons; their levels increased by a factor of about 6 in the dry season. Exchange of water vapour and CO2 was measured with a portable steady‐state porometer. Photosynthesis in B. maritima showed little response to the transition from the rainy to the dry season while S. portulacastrum was severely impaired in the dry season, showing pronounced midday depressions of gas exchange and about 40% inhibition of light‐saturated rates of CO2 uptake. P. rubricaulis shed its leaves in the dry season. According to carbon isotope ratios (δ13C), B. maritima (δ13C =−26.4‰) and S. portulacastrum (δ13C =−25.8 ‰) are C3 plants while P. rubricaulis (δ13C =−12.3‰) performed C4 photosynthesis. Copyright © 1989, Wiley Blackwell. All rights reserved

Original publication

DOI

10.1111/j.1469-8137.1989.tb00692.x

Type

Journal article

Journal

New Phytologist

Publication Date

01/01/1989

Volume

111

Pages

283 - 291