(Controlling the nutrition of glasshouse cucumbers in a soilless culture system by nitrate and amino-N content of petiole sap)

amino compounds analyse de tissus anbausystem azote besoin nutritionnel cucumis sativus cultivo sin tierra culture sans sol fertilisation fertilizer application feuille gewebeanalyse gurke hojas leaves necesidades de nutrientes nitrat nitrate nitrates nitratos nitrogen nutritional requirements soilless culture stickstoff tissue analysis