Gas exchange and chlorophyll fluorescence of four sorghum genotypes under drought stress and rehydratation

Abstract

Water deficit (drought) is an important environmental factor affecting physiological processes in plants. The present work focuses on the study of changes in physiological responses of juvenile plants (plants in the vegetative phase of growth BBCH 14-16) of selected sorghum genotypes Dokok, 30485, Barnard Red and Ruzrok to water deficit and after rehydration. Water deficit affected the observed physiological parameters - gas exchange and chlorophyll fluorescence. Genotypic differences were also confirmed, with Dokok appearing to be the more sensitive genotype and Ruzrok and Barnard Red appearing to be tolerant. Following rehydration, these parameters increased but did not reach the levels of the control plants. A significant decrease in photosynthetic rate (Pn), transpiration (E) and fluorescence compared to the control was found in the water-deficient variant twice for 10 days and 6 days between rehydration periods. Only in the variant where water deficit (14 days) was followed by irrigation (10 days) transpiration increased in genotype 30485. Chlorophyll fluorescence (Fv/Fm) also decreased significantly in this cultivar. The results suggest that a rehydration period of 14 days is insufficient to restore the photosynthetic functions of stressed sorghum plants.

Keywords

• photosynthesis
• transpiration
• genotype
• sorghum bicolor (l.) moench
• water deficit