Variation characteristics of chlorophyll fluorescence of a typical Eremophyte (Smirnovia Iranica (Sabeti)) during phenological stages in the sand drift desert (Case study: In Kashan Region)

Smirnovia iranica, a native valuable woody species from Fabaceae, is an adaptable plant of central sandy areas of Iran. Changes in chlorophyll fluorescence and photosynthetic pigments characteristics were analyzed in the course of phenological stages including vegetative, flowering, seed ripening, and seed falling stages, respectively (VS, FS, SRS, and SFS). The results obtained from analysis of variance indicated that there was a significant difference among different phonological stages of S. iranica in terms of the mentioned characteristics. Extending phenological stages along with increasing water deficiency resulted in significant reduction in Fv /Fm ratio in SRS and SFS. A significant effect of progression in phenological stages on thermal dissipation of light energy (D) value was observed in SRS and reached to the highest value in SFS. In all evaluated plants, during phenological development, there were decreases in photochemical efficiency of photosystem II (ΦPSII), and from SRS. A similar influence of the extending phenological stages on ΦPSII was observed for electron transport rate (ETR). In SRS to SFS, the decrease of Chl. (a+b) and Car was paralleled with the decrease of Fv/Fm, which indicated that pigments breakdown was accompanied by the decreasing of the maximum photochemical efficiency. The results of this study suggest that extending phenological stages along with increasing water deficiency stress resulted in significant alterations in chlorophyll fluorescence parameters and pigment contents in SRS and SFS.