Vpliv bakrovih spojin na aktivnost polifenol oksidaz v listih, vršičkih in grozdju vinske trte sorte 'Merlot' (Vitis vinifera L.)
The influence of spraying of copper compounds on polyphenol oxidase activityin leaves, shoot tips and grape of vine cv. 'Merlot' (Vitis vinifera L.)