Assessment of chlorophyll fluorescence as a screening tool for salt tolerance in barley genotypes

Abstract

Can chlorophyll fluorescence reliably identify salt-tolerant barley lines? This research evaluated twenty-four spring barley genotypes exposed to 150 mM NaCl in a controlled facility at the University of Reading during 2023. Seedlings grew in half-strength Hoagland solution, and fluorescence parameters Fv/Fm, ΦPSII, qP, and NPQ were recorded at 0, 3, 6, 9, 12, and 15 days after salt imposition. Salt stress reduced Fv/Fm by 8.3-27.6% across genotypes, with a mean decline of 14.9%. Genotypes retaining Fv/Fm above 0.72 after 15 days were classified as tolerant. A strong positive correlation (r = 0.83, p<0.01) existed between Fv/Fm at day 15 and shoot dry weight under saline conditions. Leaf Na⁺/K⁺ ratio also correlated negatively with Fv/Fm (r = −0.71, p<0.01). These findings suggest that Fv/Fm and ΦPSII measured after two weeks of salt exposure can effectively screen large barley populations for salt tolerance at an early growth stage.