Effect of Temperature on Cell Membrane Stability and Solute Content of Leaves of Orchardgrass (Dactylis glomerata L.)

Abstract

The effect of environmental temperature on cell membrane stability (CMS) and solute accumulation in orchardgrass (Dactylis glomerata L. cv. Aberystwyth S 143) was studied in pot culture grown plants. The plants were subjected to three temperature treatments (25/20℃; 20/15℃; 15/10℃ day/night temperatures). Leaves were sampled 14 and 42 days after the commencement of the treatments. CMS was evaluated by the polyethylene glycol technique and subsequent measurement of electrolyte leakage. Osmotic potential and solute concentration in extracted leaf sap were measured. With decreasing temperature, CMS increased and osmotic potential decreased. Water soluble carbohydrates concentration in cell sap increased and K^+ concentration decreased with decreasing temperature, however, changes in concentrations of amino acid, organic acid, Ca^<2+>, Mg^<2+>, Na^+, SO_4^<2-> and C1^- were not observed. Water soluble carbohydrates and K^+ were the primary osmotic contributors in orchardgrass. Potassium played a major role in increasing osmotic concentration in plants under high temperatures, while plants exposed to low temperatures accumulated more water soluble carbohydrates, developed lower osmotic potential and maintained higher turgor. Water soluble carbohydrates concentration correlated positively with membrane stability.