Cultivar differences in the operation of the photosystem II of barley leaves

Differences between nine spring barley cultivars on structural and functional parameters of PSII operation are shown. Variability of the parameters used changed from 2.2…2.5 (oxidized quinones pool and maximum photochemical efficiency) to 24.6% (performance index PI ABS_total ). Parameters characterizing the values of excitation energy fluxes (ABS/RC; TRo/RC; ETo/RC) varied to a small extent - 3.1...6.5%, while the lost energy (DIo/RC) much stronger - 14.6%. The efficiency of electron transport from quinine Q B and the entire PSII until the PSI’s primary acceptors varied even more - 18.1 and 17.4%, respectively. The PI ABS integral performance index combined cultivars into two groups only; PI ABS_total index showed more clear differences in cultivars. Cv. Novichok and Fermer were significantly inferior to cv. Forward, Belgorodsky 100, Boyarin and Bionic in most of the studied parameters. However, according to the results of a cluster analysis, cv. Novichok and Forward turned out to be similar to each other, as well as cv. Fermer, Boyarin and Bionic, which separated into the same cluster. Probably, the action of PSII in cultivars of the same cluster differs only quantitative but not qualitative. Therefore, for breeding work on pyramidizing the genes controlling operation of this photosystem, it is advisable to crossing cultivars belonging to different clusters.