PLANT PHYSIOLOGY · 1987 · 61 citations · 10 references
Life SciencesPlant BiologyPlant SciencesHerbicide ResistancePhotosynthesisPlant PhysiologyChloroplast BioenergeticsChloroplast BiologyEnvironmental Responses Of PhotosynthesisHerbicide Effects On PhotosynthesisPhotosynthesis In CropsPhotosystem IiCrop Photosynthetic ResponseElectron Transport RateFluorescence Quantum YieldPhotosynthetic Photon Flux DensityPhotosynthetic PhysiologyPhotosynthetic Response To EnvironmentPhotosynthetic UptakeQuantum Yield Reduction
A triazine-resistant (R) biotype of Phalaris paradoxa L. (hood canarygrass) was superior to a triazine-susceptible (S) biotype in seed-germinability and seedling emergence. It was equal or superior to the S-biotype in growth under noncompetitive conditions. Rates of CO(2) uptake by R-plants were similar to those of S-plants, except at very low photon flux densities, where S-plants exhibited higher rates of CO(2) uptake. Fluorescence induction curves of chloroplasts isolated from R-plants indicated an alteration in photosystem II. Analysis of the light dependence of electron transport shows a reduction in quantum yield (Q(y)) in R- compared to S-chloroplasts. The same analysis, however, shows for R-chloroplasts an increase in the light-saturated electron transport rate (V(max)). The increase in V(max) compensates for the reduction of Q(y) over a wide range of photon flux densities, which may explain the similarity between R- and S-biotypes in photosynthetic potential and growth.
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