engleski

Evaluating photosynthetic performance of different barley cultivars under stress using chlorophyll a fluorescence

The current cereal production is challenged by the abiotic stress induced by climate changes. Selection and breeding processes aim to select barley cultivars with better adaptation to stress. Drought stress presents one of the environmental stresses with significant impact on agricultural production worldwide. The main objective of this study was to screen and evaluate twenty winter barley cultivars for their photosynthetic performance by using fast chlorophyll a fluorescence parameter during growth season in the experimental fields where plants were exposed to stressful conditions due to drought treatments. Measurements were taken at three growth stages: booting, flowering and grain filling. Total performance index (PITOTAL), which describes potential of energy conservation within photosynthetic apparatus from exciton to the reduction of end acceptors of photosystem I, showed that barely cultivars differed in their response to drought stress. PITOTAL increased from booting to grain filling stage in most of the cultivars except for nine cultivars were decline was observed. In order to estimate the contribution of the different components (density of reaction centers, trapping to dissipation ratio and efficiency of excitation energy conversion to electron transport and performance index) to PITOTAL value, we transformed data to logarithmic values to obtain the parameter of partial driving forces. Stress conditions during growth season induced decrease of total driving force (DFTOT) in six cultivars at flowering stage. Dissipation and density of reaction centers mainly contributed to the lower value while efficiency of excitation energy conversion to electron transport and performance index mainly contributed to higher PITOTAL value in all other cultivars. At grain filling stage all cultivars, except one, revealed positive total driving forces. In conclusion, obtained results suggested that at flowering stage of growing, barley cultivars were more sensitive to stressful conditions comparing to grain filling stage during which plants exhibited more stability in processes within photosynthetic apparatus indicating an adaptation to stress conditions.

barley, performance index, photosynthesis, development, drought stress

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