| Summary: | In cotyledons and roots of Cucumis sativus seedlings, the presence of phosphatases was proved at two optimal pH values: 6.4 and 5.0. The phosphatases are characterized by low substrate specificity. Among the analysed substrates the following were hydrolyzed particularly preferentialy while fissuring: pnitrophenylophosphate (pNPP), adenosinotriphosphate (ATP), pyrophosphate, β-naphthylophosphate and in case of the cotyledon extracts also calcium phytinate. Mo, Zn, Cu and Co present in an incubation mixture inhibited this activity. Analysis of the phosphatase activity in cotyledons and roots of cucumber seedlings showed that in early phases of cucumber growth (germination and the first week of growth in ligth), the activity remained at a relatively high level and had a few peaks connected with the vegetable growth phase whereas the frequency of their accurance was connected with the analysed organ. It was stated that changes of the phosphatase activity were visibly correlated to changes of the phosphorus content in the period under study. In roots similar correlations were not observed.
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