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Pak. J. Bot., 45(3): 725-736, 2013.

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INTERACTIVE EFFECT OF SALT, LIGHT AND TEMPERATURE ON SEED GERMINATION AND RECOVERY OF A HALOPHYTIC GRASS - PHRAGMITES KARKA

AFSHEEN ZEHRA¹, BILQUEES GUL¹, RAZIUDDIN ANSARI¹, A. A. ALATAR², A. K. HEGAZY² AND M. AJMAL KHAN^{1, 2,3*}

Abstract: The effect of chloride and sulfate salts of Na⁺, K⁺ and Mg²⁺ on seed germination of a halophytic grass Phragmites karka was studied under different dark/light conditions and a range of temperature regimes. Seeds germinated better at 20/30ºC and their germination decreased with increases in salinity. This reduction in germination could be attributed to specific ion toxicity as well as variable osmotic stress due to the composition of salts. Among cations, K⁺ was generally most toxic followed by Mg²⁺ and Na⁺ but such generalizations could not be made in case of anions. Potassium sulfate was inhibitory than Mg²⁺ salts for seed germination. A better germination recovery from salt stress was found in 10/20ºC. More seeds recovered when transferred from NaCl to distilled water at all temperature regimes. Seeds treated with magnesium sulfate showed better recovery at 10/20 ºC, while recovery in Na₂SO₄ and MgCl₂ treated seeds was better in moderate temperatures. The salts did not affect viability of seeds which probably entered into dormancy.

¹Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi-75270, Pakistan

²Department of Botany & Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia

³Qatar Shell Professorial Chair for Sustainable Development, Department of International Affairs, College of Arts and Sciences, Qatar University, P O Box 2713, Doha, Qatar

^*Corresponding author’s e-mail: ajmal.khan@qu.edu.qa;  Ph: +974 4403 4952, Fax: +974 4403 4931