The effect of application of copper fungicides on photosynthesis parameters and level of elementary copper in hops
K. Krofta | J. Pokorný | T. Kudrna | J. Ježek | J. Pulkrábek | J. Křivánek | D. Bečka
Photosynthesis and transpiration rates in the interval of 30 min before and 30 min after copper fungicide application show an increase from the level of 5.0 to 7.0 µmol CO2/m2/s and 0.75 to 1.00 mmol H20/m2/s. Long-term measurements show that the increase of photosynthesis rate after copper application is temporal and fades away after 10-14 days. No stress response was induced after the application of copper fungicides. Contents of copper in hop cones are up to 500 mg/kg if total amount of applied copper does not exceed 15 kg/ha. Contents of copper on leaves are 2-5 times higher at the same application dose. Application of 5 kg copper per one hectare of vigorous growth of Agnus variety increases content of copper on hop leaves by 1000 mg/kg at least. The same amount of copper increases its content in hop cones by 300 mg/kg at the ripening period. Tight correlation between the amount of copper applied and its content in hops does not exist. Elementary copper from leaves is brought into harvested hops in the form of biological admixtures. Copper content in hop cones shows a decreasing trend, which is given by gradual increase of cones size at the ripening period. Similar trend on hop leaves shows that washing off and dissolving of copper compounds by atmospheric water can participate in this process as well. Common content of copper in untreated hop cones and leaves is up to 20-25 mg/kg.
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