biologia plantarum

Biologia plantarum 50:610-616, 2006 | DOI: 10.1007/s10535-006-0096-z

Water relations and photosynthesis in Cucumis sativus L. leaves under salt stress

P. Stępień^1,*, G. Kłbus¹

¹ Institute of Plant Biology, Department of Plant Physiology, University of Wroclaw, Wroclaw, Poland

Hydroponically grown cucumber plants were exposed to 14-d period of salinity (0, 50, 100 mM NaCl). NaCl caused reduction in the relative water content in the leaves. The Na⁺ content increased and the K⁺ content decreased. The net photosynthetic rate, stomatal conductance and transpiration rate were markedly decreased by all of the salt treatments. Salinity decreased also the maximum quantum efficiency of photosystem 2 (PS 2) determined as the variable to maximum fluorescence ratio, the photochemical quantum yield of PS 2 and the photochemical fluorescence quenching, while the non-photochemical quenching increased. Above results indicate that NaCl affects photosynthesis through both stomata closure and non-stomatal factors.

Keywords: chlorophyll fluorescence; NaCl; net photosynthetic rate; stomatal conductance; transpiration rate

Subjects: chlorophyll a,b; chlorophyll fluorescence; cucumber; Cucumis sativus; gas exchange; (photosynthetic) photon flux density; photosystem 2; relative water content (RWC); ribulose-1,5-bisphosphate carboxylase/oxygenase; salt, salinity stress; stomatal conductance; transpiration rate; water stress; water use efficiency (WUE)

Received: November 30, 2004; Accepted: August 15, 2005; Published: December 1, 2006  Show citation