Study of some tolerance mechanisms to water dificit stress in bread wheat genotypes (Triticum aestivum L.)

To assess the physiological characteristics of wheat genotypes under water deficit conditions, a pot experiment was carried out as factorial based on completely randomized design with three replications in greenhouse and laboratory of Mohaghegh Ardabili in 2012. Treatments were consisted of water deficit in three levels (85%, 60% and 35% of field capacity) and five wheat genotypes (Mihan, C-88D-7, C-88D-17, C88D-19 and C88D-20). Results showed that stomatal conductance, proline content, soluble sugar, primary florescence and maximum florescence increased significantly in most of the genotypes due to an increase in drought stress intensity. It seems that enhancing the lysine and methionine breakdown under stress, leads to increase synthesis of proline for osmotic adjustment. The genotype C-88D-17 showed minimum biomass loss during stress which may be due to increase stomatal resistance, membrane stability by reducing the osmotic potential in severe stress. The maximum amount of proline and soluble sugars produced by Mihan genotype so it showed better resistance to water stress and the less biomass reduction under stress. According to these results the Mihan and genotype C-88D-17 can introduced resistant genotypes and genotype C-88D 19 and C- 88D-7 Semi resistant to water stress. Also, since the genotype C-88D-20 showed lowest proline accumulation, biomass production and soluble sugars accumulation than other genotypes it is sensitive to water stress compared to the other genotypes.