Assessment of phytosanitary treatments on different wheat species by a global method, the so-called thesigraphy
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Centre de Biophysique 6, rue Blatin, 63000 Clermont-Ferrand, France
Int. Agrophys. 1995, 9(2): 157–163
An assessment test of phytosanitary treatments on 7 wheat species was carried out in Auvergne (France) through a global method - the thesigraphy. This analysis consists of making and decoding images of dendritic crystallization called biothesigrams. The images result from the rapid and controlled evaporation of an aqueous solution of CuCl and a leaf extract. It is interpreted on the basis of three image parameters: texture, central figures and signs that inform about the level of de-naturation and pollution of the substance under study. Those three parameters were evaluated according to eight leaf samples at the end of the vegetative cycle in wheat cultures. The count of thesigraphical spots is considered as an indicator of the intracellular occurrence of xenobiotic products. The morphology of the texture and central figures allows for the calculation of a semi-global thesigraphical index, indicating the plant vitality. The exponential increase of the spots within the 29 days after spreading pesticides expresses the gradual accumulation in the wheat leaves. Those products slowly disappear within the 21 days before harvesting. The semi-global thesigraphical index shows the parallelism between the vegetative cycle of the control wheat species and that of the treated ones.