| Popis: |
In this article, the relationship between the fluorescence characteristics of the leaves of different grape varieties (electron transport intensity between photosystems – ETR – and variable fluorescence – Fv) and the relative water content (RWC) in the leaves was studied. It was found that the more drought-resistant the grape variety is, the slower the decrease of ETR value with RWC reduction. According to the value of Fv, we can estimate the degree of damage to the photosynthetic apparatus as a result of water deficiency, i.e., how irreversible is the damage caused by drought? According to the obtained results, when the RWC in the leaves decreases from 65% to 50–53%, the value of Fv practically does not change and ranges from 0.7 to 0.8, which indicates a stable reaction center of PS2 on work. But with a further reduction of the water content, damage to the reaction center PS2 is observed, which is indicated by the decrease of the Fv to 0.5–0.6. The value of Fv is especially reduced under red light (FVʹ). If the water stress is not removed in time, the reaction center PS2 will be irreversibly damaged. In relation to the reduction of RWC in vine leaves, the dynamics of ETR was studied. It was found that when the water content reduced by 15–20%, in drought-resistant grape varieties the ETR value decreased by 6–12%, while in less drought-resistant varieties it decreased by 30–50%. The obtained results can be used to determine the relative drought resistance of different grape varieties. |
