Screening for Genetic Variation in the Circadian Clock in Barley Landraces from Palestine

The plant circadian system controls a large number of processes such as photosynthesis, stomatal opening, photoperiodic development and gene expression. We used the prompt chlorophyll fluorescence technique to measure circadian rhythms in 14 barley landraces from diverse eco-geographic environments from within Palestine. Non‐photochemical quenching and optimal PSII quantum yield (Fv/Fm) chlorophyll fluorescence parameters were measured. The different barley accessions varied in several circadian parameters including period, amplitude and relative amplitude error of the circadian rhythm of fluorescence. Correlations between circadian traits, for example, circadian period length, and the conditions at the site of origin of the accessions (elevation) were observed, suggesting that variation in the circadian clock is important for adaptation to different growth conditions including elevation, temperature and rainfall. These results suggest the presence of genetic variation in the circadian core oscillator in landrace barley genotypes originating from different environments.