Physiological and molecular evaluation of ten Egyptian barley cultivars under salt stress conditions

Ten Egyptian barley cultivars (Giza 129, 132, 123, 127, 2000, 130, 126, 135, 128 and 133) were assessed under 0, 100 and 200 mM NaCl. The cultivars performance under salinity was measured in open field conditions using the Fv/Fm and Performance Index. Measurements of growth parameters as well as other chlorophyll fluorescence parameters (RC/CS, TFm, RC/ABS and ABS/RC) were also included. Giza 129 is considered salt-tolerant, and Giza 123 is salt sensitive cultivar. Both cultivars, along with Giza 132 (moderately salt tolerant), were used to evaluate the relative expression of the B2 and shmt genes at 0,100 and 200 mM NaCl. The expression of both genes increased in the tested cultivars upon salinity treatment. At 200 mM NaCl, B2 and shmt genes relative expression reached 1.9- and 1.5-folds in the salt-tolerant cultivar (Giza 129); while getting 1.6 and 1.2 folds in the sensitive cultivar (Giza 123). Repeating the same experiment for Giza 129, 132, and 123 under the growth chamber conditions revealed that the effect of salinity was more vigorous at the physiological and morphological levels. In addition, the gene expression was generally higher than that of the open field conditions, although exhibiting a similar trend of results. Our results under the present study indicate that Giza 129 is a candidate for further salinity-breeding studies. Furthermore, a comparison between growth chamber and open field conditions revealed a kind of adaptation of barley PSII to the continuous salt stress in the open field conditions.