Fluorescence decline ratio comparison with quantum yield ratio for plant physiological status and herbicide treatment responses

Abstract

Plant fluorescence is normally measured using the ratio Fv/Fm (quantum yield) An alternative measurement fluorescence decline ratio (R_fd) can be used instead of Fv/Fm The usefulness of the R_fd ratio in comparison to Fv/Fm was tested with three plant species of differing leaf character Diurnal trends were measured after treatment with two herbicides diuron a lipophilic photosynthesis inhibiting herbicide and dalapon a lesslipophilic nonphotosynthesis inhibiting herbicide In wheat both herbicides were tested with three nonionic surfactants of differing hydrophile lipophile balance (HLB) The R_fd ratio was a more sensitive numerical indicator of plant responses and provides an alternative approach to monitoring and measuring the effect of stress factors in plants