Effect of cold stress on cell membrane stability, chlorophyll a and b contain and proline accumulation in wheat (Triticum aiestivum L.) variety

The aim of this research was to determine the effect of cold stress on chlorophyll content, proline accumulation and the cell membrane stability of 15 bread wheat (Triticum aestivum L.) at two stage of growth (2 leaf stage and 4 leaf stage). Experiment was carried out in complete block design with tree replications at year 2009 in west Azerbaijan Agriculture science and research center laboratory. 15 cultivar (five genotypes with types winters names Sayson, Martin, Gaskoghen, C-82-12, C-81-14, 5 genotype with type intermediate including Alvand, Mahdavi, Zarrin, Marvdasht, Toos and five genotypes with type spring names Shiraz, Pishtaz, M-79-7, M-81-13 and Kavir) were sown in lab condition . According to the results, cold stress had a significant effect on chlorophyll a and b, total chlorophyll, prolin content and cell membrane stability. At the other hand variety and growing stage have significant effect on treats (P>0.01). The result showed that the M-81-13 with 53.05 mΩ EC has the highest cell membrane stability and the lowest EC was obtaining from gaskoghen with 18.987 mΩ. Also M-79-7 with 2.315 mg chlorophyll a per 1 g leaf fresh weight has highest chlorophyll content. It was determining the ratio of maximal chlorophyll content after cold stress is reliable and a method to determine the frost hardness of wheat variety. The proline content of the leaf however increased in both growth stages in all variety of wheat. Gaskoghen with 0.340 (μg/0.5 g dwt) in 2 leaf growing stage had the highest rate of proline amino acid and Marvdasht variety from inter mediate type in 4 leaf growing stage with 0.003 (μg/0.5 g dwt) had the lowest rate of proline.   Key words: Wheat variety, chlorophyll content and proline.