Correlation Between the Carbon Isotope Composition (\delta^{13}C) of Puccinellia ciliata and Balansa Clover in Duel Stresses of Waterlogging and Salinity (NaCl)

Theoretically, plants growing under stress conditions, such as in saline or waterlogged conditions, should behave with ^{13}CO_2 discrimination and have different \delta^{13}C values. Therefore, this experiment was conducted to evaluate the effect of factors such as salinity and hypoxia in affecting delta values of Puccinellia ciliata and Balansa clover (Trifolium michelianum Savi. Var balansae boiss). This study reveals that these two species (C_3 plants) behave differently and B. clover has more positive \delta^{13}C values (7.6\%) compared to P. ciliata. The overall average of \delta^{13}C were -28.85 and -26.66 ^0/_{00}, respectively, for P. ciliata and B. clover. The \delta^{13}C values for the shoots and roots of the two species also have different values (more positive values in roots compared to shoots). Waterlogging and salinity have a significant affect on {13}CO_2 discrimination and, statistically, these effects on \delta^{13}C values are significant (p<0.001). This means that environmental factors, such as salinity and waterlogging, create a situation for plants in which the discriminate rate against \delta^{13}C would be changed (less discrimination for hypoxia and more for salinity conditions). The combined effects on species and plant parts of waterlogging and salinity are not statistically insignificant on \delta^{13}C values, however, each factor separately has a significant effect on \delta^{13}C values. P. ciliata was grown in different seasons (summer and winter) and showed significant differences in \delta^{13}C values (by almost 4\%). The carbon content (\%) of the two species was different, but, were not related to \delta^{13}C, respectively.