Nohut’ta (Cicer arietinum L.) metribuzinin metabolizasyonu ve transferi

Metabolization and transfer of metribuzin in chickpea (Cicer arietinum L.)

Abstract

Weed control continues to be one of the most important constraints in chickpea (Cicer arietinum L.) production. In Türkiye, there are very few fully selective herbicides to control weeds in chickpea cultivation areas, and many of these herbicides are imported and expensive. Moreover, phytotoxicity damage is frequently encountered in chickpeas and serious yield losses occur due to errors made by producers in application times and doses.

Since 2020, metribuzin, a triazinon herbicide, has been registered for preemergence applications at a dose of 140 ml/da for the control of various monocot and dicot weeds appearing in chickpea cultivation areas in Türkiye.
The aim of this study was to determine the basis of chickpea tolerance to metribuzin and to measure different reactions to metribuzin in the plant. As a result of pre-emergence applications, the metribuzin adsorption capacity of chickpea, the transfer rate to the above-ground parts of the plants, the metribuzin concentrations and metabolites in the leaves, which are the target areas of metribuzin, and other plant parts were determined and evaluated. The metabolism rates in different organs and the resulting metabolites were determined in more detail. This study utilized various radiometric methods (different extraction methods, Radio-HPLC (radiochromatography), autoradiography, oxidizer, etc.) using 14C-metribuzin (radioactive metribuzin labeled with 14C). In the studies on metribuzin tolerance, absorption by roots and metabolism, the TWIST variety, a Kabuli variety of French origin, was examined in simplified systems in heat and humidity controlled plant growth cabinets. The absorption capacity of metribuzin by roots and cotyledons, the transfer rate to the above-ground parts, the metribuzin concentrations in the stem and the leaves, which are the target areas, were determined by separating the plant into different organs and determining the metribuzin concentration for each organ. In the second stage, metabolism stages in different organs were examined. These analyses were performed using 14C-metribuzin and various radiometric methods (R-HPLC (radiochromatography, oxidizer, phosporimager, etc.).
The analyses performed show that metribuzin is intensively taken into the plant body via roots and metribuzin is transported to the leaves. As a result of R-HPLC analyses, many different metribuzin metabolites were detected in the roots, stems and leaves 21 days after application. The concentrations of metribuzin and its metabolites in the leaves are quite different. There is more radioactivity accumulation in young leaves than in old leaves.
The basis of chickpea metribuzin tolerance can be associated with the low capacity of the transport rate to chloroplasts and the high detoxification capacity through different pathways, thus greatly reducing the transfer of the active substance to chloroplasts and preventing the metribuzin concentration in the target region from reaching the critical value.
Keywords: Metribuzin, Chickpea, Cicer arietinum, selectivity, tolerance, metabolization, detoxification.