engleski

THE PHOTOSYNTHETIC EFFICIENCY IN SUNFLOWER PLANTS AT STRESSFUL GROWTH CONDITIONS

Lately, we are witnessing climate crisis that are disrupting the cultivation and production of agricultural crops. Consequently, the conducted study’s objective is to clarify the influence of climate changes on the photosynthetic efficiency of sunflower plants (Helianthus annuus L). The investigation focuses on the influence of heat and light stress during the flowering of two selected sunflowers genotypes. The analysis of variance shows statistically significant differences between genotypes for all tested parameters of photosynthesis, as well as between treatments except for parameter variable fluorescence at step J. Based on the results, genotype 1 was less sensitive to the changes in the photosynthetic apparatus caused by stressors than genotype 2. The heat and light stress caused the difference between treatments in genotype 2 for the parameter initial intensity of the fluorescence to be larger. The inhibition of the oxygen-evolving centre was stronger in genotype 2 as well, and this resulted in lower values of the maximum fluorescence intensity. The genotype 2 had a larger increase in the re-oxidation of the plastoquinone than genotype 1, i.e. the values of the variable fluorescence at step J were higher for genotype 2. The plants adapted to stressful conditions by lowering the values of the maximum quantum yield of photosystem II, but its values in the genotype 2 decreased below 0.75 relative units indicating damage to the photosynthetic apparatus’ functioning. At the same time, performance index on absorption basis, which gives insight into the plant’s vitality, as well as the parameters from which the index was calculated, confirmed a larger impact of stress on genotype 2.

Helianthus annuus, heat stress, light stress, PIABS, FV/FM

nije evidentirano