Characterization of Paraquat-Resistant Conyza Leaves Through Delayed Fluorescence
The kinetics of chlorophyll delayed fluorescence (DF) induction was used as a tool for the detection of paraquat action in paraquat resistant (R) and susceptible (S) biotypes of Conyza canadensis. In both bio-types, a physiologically active level of paraquat rapidly inhibits the DF within 30 min after the spraying of whole plants. The inhibition of the DF in the S bio-type is irreversible, while in the R plants the DF is slowly recovered with time. This transient inhibition of photosynthesis in intact leaves is very important as concerns the explanation of the mechanism of paraquat resistance. In the present study a solid-state device for measurement of the DF is described, which is suitable for studies of photosynthesis and stress physiology under field conditions.
Key wordsdelayed fluorescence paraquat resistance Conyza canadensis
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