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The effects of NaCl salt (EC = 16 dS m -1 ) on water potential, and accumulation of proline, Na + and K + in leaves on the main stem of 30 wheat cultivars (Triticum aestivum L.) at awn appearance and 20 days after anthesis (20 DAA) were evaluated in a greenhouse experiment. Plants were arranged in a according to a randomized complete block design with factorial treatments in three replications. Proline accumulation at 20 DAA increased with increasing salt stress. This increase was 27.4-fold with the salt-sensitive cultivar ''Ghods,'' while the mean was 5.2-fold for 19 salt-resistant cultivars. Positive correlations between proline, and K + + Na + concentrations associated with higher sensitivity to salt stress indicated that proline may not have a protecting role against salt stress. No correlation was observed between leaf proline and water potential. Almost no contribution to the osmotic adjustment seems to be made by proline. The contribution made by proline to the osmotic adjustment of plants at 20 DAA was 0.69 bar, whereas that made by K + and Na + was 2.11 and 4.48 bar, respectively. The 30 wheat CV s used in this experiment showed different performances regarding the traits observed. Eleven of them showing the higher stress sensitivity indices had the highest level of proline and Na + concentrations. They were considered to be salt-sensitive cultivars. Among the others, nine cultivars showed salt tolerance with almost the same Na + and proline concentrations, but a higher K + /Na + selectivity of ions from leaf to grains. In 10 of the cultivars, Na + and proline concentrations were low, indicating the presence of a salt avoiding mechanism.

In order to evaluate the effect of different levels of drought stress on some physiological parameters in strawberry, one experiment with potted strawberry cultivars 'Kurdistan' and 'Selva' was conducted in summer 2008. The experiment was performed with four drought stress treatments [control (75% of field capacity), S1: mild drought stress (50% of field capacity), S2: severe drought stress (25% of field capacity) and R: one day after rewatering]. Physiological parameters such as: leaf relative water content (RWC), membrane stability index (MSI), net CO2 assimilation rate (A), stomatal conductance (gs), transpiration (E), water use efficiency (A/gs), chlorophyll, proline and soluble carbohydrate contents were measured in leaves of strawberry subjected to different drought stress conditions as well as one day after rewatering. The results showed that RWC, MSI, A, gs, E, and chlorophyll of two cultivars decreased as soil water content was reduced. A/gs was highest under mild water stress for both cultivars. 'Kurdistan' had lower A, gs and E than 'Selva'. RWC, MSI and A/gs of 'Kurdistan' were higher than 'Selva'. Recovery of these parameters was faster for 'Kurdistan' than 'Selva'. Chlorophyll contents of 'Kurdistan' was higher than 'Selva'. Chlorophyll recovery didn't occur one day after rewatering. Amount of proline and soluble carbohydrates increased under severe drought stress. 'Kurdistan' had higher proline content compared to 'Selva' under severe drought stress. Amount of proline and soluble carbohydrates were reduced in both the cultivars one day after rewatering. This study revealed that moderate drought stress affects gas exchange while severe drought stress affects chlorophyll, proline and soluble carbohydrates levels.

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