Cell and Tissue Journal

Abstract

Abstract Aim: In this investigation the effect of salt stress on the early developmental stages of dark-grown wheat seedling was studied.
Materials and methods: Grains of the salt tolerant (Seds1) and the susceptible (Giza168) cultivars of wheat were germinated and grown in darkness in nutrient solution supplied with or without 200 mM NaCl. The protochlorophyllide content was determined. The fluorescence emission intensity ratio of 655/633 nm was measured. The ratio of newly formed Chlorophyllide to non-photoactive Pchlide was measured after irradiation of leaf sections with one single flash to estimate the degree of phototransformation. The chlorophyll a content was also determined after dark-grown leaf sections were irradiated.
Results: The salt stress treatment caused a marked increase in protochlorophyllide (Pchlide) content in dark-grown material and in Chlide content after irradiation of leaf sections of both varieties. The relative ratio of phototransformable to non-phototransformable pchlide and of newly formed chlorophyllide (Chlide) was influenced by salt stresse. The results were influenced by the different growth rates found for stressed and unstressed seedlings. Leaf sections from seedlings grown under salt stress in darkness accumulates more chlorophyll a than leaf sections from unstressed seedlings when floating on nutrients or on a 200 mM NaCl solution in continuous white light.
Conclusion: The increased accumulation of the long-wavelength form of Pchlide is suggested to be an expression for the mobilization of a part of the protective mechanisms against salt stress.
 

Abstract Aim: In this study we have used two wheat varieties with different tolerance to salt in different concentration of solt.
Material and Methods: Giza 168, Seds 1 plants have been grown for seven days in Hoagland solution and some of them were grown in Hoagland solution supplemented with 200 mM extra salt. Cutted leaf segments from these plants incubated with 600 mM salt. Dark-grown pre-adapted, with 200mM extra salt, plants were illuminated to determine the chlorophyll accumulation in two varieties.
Results: The maximum photochemical efficiency, Fv/Fm, stayed the same for all measurements. Measurement of relative ETR showed that the tolerant variety, Seds 1, had higher values for ETR than the susceptible variety (Giza 168). Also the measurement showed that the salt adapted samples of both varieties better withstood the excess of salt applied than the non-adapted samples.
The chlorophyll content was higher for the tolerant variety compared to the susceptible. The chlorophyll accumulation of the tolerant samples pre-adapted with or without salt showed no dramatic differences. The susceptible sample, Giza 168, however, accumulated more chlorophyll if pre-adapted to salt before being exposed to high salt concentration.
Conclusion: PSII seems to be stable and unaffected at the functional level by salt stress. The tolerant variety is better adapted to salt stress. It seems to be due to the advantage of having a more efficient photosynthetic apparatus.