Cell growth in suspension-culture of Populus nigra var. italica and the efficiency of micro-callus formation according to cell plating method

acido naftilacetico auxinas auxine auxins cal callo callus cells cellule citoquininas crecimiento croissance cultivo in vitro culture in vitro culture media cytokinine cytokinins growth in vitro culture medio de cultivo milieu de culture naa nitrogen content populus nigra teneur en azote