Titre : | ON THE OPTIMIZATION OF LOW DOSAGE APPLICATION SYSTEMS : IMPROVEMENT OF DOSE ADVICE AND EARLY DETECTION OF HERBICIDAL EFFECTS |
Auteurs : | INGRID RIETHMULLER-HAAGE ; WAGENINGEN UNIVERSITEIT |
Type de document : | Thèse-Mémoire |
Editeur : | WAGENINGEN : WAGENINGEN UNIVERSITEIT, 2006 |
Format : | 134 P. |
Langues: | Anglais |
Concepts : |
MAUVAISE HERBE
TEMPS HERBICIDE PHOTOSYNTHESE FLUORESCENCE DOSAGE |
Résumé : | Application of herbicides at rates below the recommended label dose has received considerable attention in recent years as it is a means of reducing overall herbicide use. To minimize the risk of inadequate weed control in these situations, the Minimum Lethal Herbicide Dose (MLHD) technology, which was specifically developed for the use of low rates of photosynthesis inhibiting herbicides, relies on an appropriate calculation of the optimum herbicide dose and on an early detection method of herbicidal effects to evaluate the efficacy of the treatment shortly after application. The study described in this thesis was undertaken to further improve the prediction of the optimum dose of photosynthesisinhibiting herbicides and to explore the opportunities of expanding the MLHD-technology to acetolactate synthase (ALS) inhibiting herbicides. The first part of the study examined the influence of pre-spraying weather factors on the efficacy of photosynthesis-inhibiting herbicides. The results put forward that pre-spraying weather conditions have a considerable effect on herbicide efficacy and that this effect is mainly through an effect on herbicide uptake. Herbicide-specifie correlations between uptake and individual weather parameters were found. These correlations were non-species specifie and indicate that inclusion of pre-spraying weather conditions in advisory systems that recommend on the use of reduced herbicide dose rates is recommendable. In the second part of the study the extension of the MLHD technology to acetolactate synthase (ALS) inhibiting herbicides, particularly the development of an early detection method of herbicidal efficacy, was explored. Application of the ALS inhibiting herbicides metsulfuron-methyl on Solanum nigrum and Polygonum persicaria plants resulted in a progressive reduction in CO2 fixation and the relative quantum efficiency of photosystem 1 (lDpsl) and photosystem II (lDpslI) electron transport, emerging a couple of days after herbicide application. < 1 > PSII tumed up to be one of the most promising and practical parameters to use when designing an early detection method for sensing the toxicity of metsulfuron-methyl. The loss of < 1 > PSII was light-dependent and could be earliest detected at the base of the youngest leaf of treated plants. |
Exemplaires (2)
Cote | Support | Section | Disponibilité |
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632.9 RIE | Texte imprimé | AG - Agrosciences | Disponible |
RES 11327 | Texte imprimé | Réserve | Disponible |