A fast and reliable method to measure the activity
of photosynthetic herbicides in intact plants

Table of Contents

Introduction

  • Introduction

    The delayed fluorescence emission, natural to all green plants, has been known to scientists for over fifty decades ...

  • The Problem

    Modern agriculture relies essentially on herbicides for managing weeds and the use of herbicides is not foreseen to diminish in near future. Understanding the mechanism ...

Theory

  • The Photosynthetic Apparatus

    Photosynthesis of green plants occurs in special organelles inside the plant cells called chloroplasts. The chloroplasts have double outer envelope ...

  • Photosystem 2

    Photosystem 2 is the largest protein complex found in nature and due to its unique function is also one the most studied. The holocomplex of PS2 is consisted of some 25 ...

  • Chlorophyll Fluorescence

    Fluorescence is the light emitted by an excited pigment molecule upon its return to the ground state ...

  • Fluorescence Induction

    If a photosynthetic sample is kept for some time in the dark and then illuminated, its fluorescence will first rise quickly with time ...

  • Delayed Fluorescence

    Delayed fluorescence, which is also called delayed luminescence, delayed light emission, or afterglow, is the extremely weak light emitted by preilluminated photosynthetic samples ...

  • Induction Curves of Delayed Fluorescence

    Like the variable fluorescence, DF undergoes a series of transient changes during the dark-to-light adaptation of the photosynthetic sample, which are called DF induction ...

  • Photosynthetic Herbicides

    Over 60% of the herbicides introduced in the last 40 years act on the chloroplast functions. More than half of all commercially available herbicides ...

The Method

  • Treatment with herbicides

    There are several approaches for the application of herbicides to the target plants - spraying with pulverizer, vacuum infiltration of leaves, soaking the leaves in herbicide solution ...

  • Principles of DF measurement

    A classical apparatus for registration of DF is the phosphoroscope. It is a rotating disc with perforations (holes) placed between the light source and the measured sample ...

  • Analysis: DFIC of untreated plants

    The induction curve of the millisecond delayed fluorescence of dark-adapted untreated healthy pea leaves, measured at room temperature under high-intensity actinic light ...

  • Analysis: Effects of herbicides on the DFIC

    By inhibiting the electron transport at the acceptor side of PS2, the herbicides drastically alter the DF properties. In the presence of herbicides the intensity of DF is suppressed ...

  • Analysis: Dose-response curves

    The dose-response relationship can be obtained by measuring the effect of the given herbicide (response) at a set of different concentrations (doses) ...

Reference

Sidebars

  • Fluorescence yield

    The term fluoresecence yield, or quantum yield of fluorescence, φf , references the number of photons emitted as fluorescence relative to the total number of absorbed photons ...

  • DF kinetic components

    At each moment the DF intensity is determined by the number (concentration) of reaction centres in a state capable of producing charge recombination ...

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