Analysis of drought response of sunflower inbred lines by chlorophyll a fluorescence induction kinetics

The aim of the study was to screen nine inbred lines of sunflower by inducing drought for 10 d and subsequent rewatering for 5 d. Impact of drought was determined by chlorophyll fluorescence and some physiological parameters. Drought led to a decrease in the photosynthetic performance, the quantum yield, and efficiency of electron transport in sunflower lines, while it caused an increase in the absorption flux per reaction centre, dissipation of an active reaction centre, and K-band as well as L-band. Drought also decreased the total chlorophyll contents and water status of the lines, which contributed to photoinhibition. Our results suggested that drought may restrict light harvesting and electron transport in the sunflower lines at various levels. Drought did not cause irreversible membrane damage, since the lines recovered after rewatering. Considering all results, the inbred lines TT317-R and 2478-A were adversely affected by drought when compared to other lines, while 9753-2R exhibited better photosynthetic performance under drought and might be considered as the most tolerant among the lines.