THE COMBINED EFFECT OF ARBUSCULAR MYCORRHIZAS AND SHORT-TERM COLD-EXPOSURE ON WHEAT

In order to investigate the effect of arbuscular mycorrhizal colonizat ion and short-term cold exposure on Triticum aestivum L., 7-wk-old see dlings of spring and winter cultivars (Glenlea and AC Ron) were submit ted to a 1-wk cold treatment when inoculated with Glomus mosseae (Nico l. & Gerd.) Gerd. & Trappe. The combined effect of arbuscular mycorrhi zas and low temperature on the two cultivars was determined for severa l physiological parameters including biomass and chlorophyll, protein, and sugar contents. The dry biomass was higher in Glenlea than AC Ron at week five and did not significantly change at week eight in both c ultivars with either the mycorrhizal or the cold treatment. The chloro phyll content was higher in mycorrhizal (M+) than nonmycorrhizal (M-) Glenlea at 5 degrees C but was unaltered in AC Ron or in either cultiv ar at 25 degrees C. The reducing and total sugar contents were higher in AC Ron than Glenlea. The non-reducing sugar level at 5 degrees C wa s higher in M+ AC Ron than M+ Glenlea and higher in M- than M+ Glenlea . The protein content was higher in Glenlea than AC Ron at 25 degrees C but remained constant regardless of the mycorrhizal or cold treatmen t. This study shows that the spring wheat seems to benefit more than t he winter wheat from AM association after a short-term exposure to low temperature.