Change picker font size for android

I want to change the size and the font size of a picker for android, i've tried a lot and nothing works. Here's my code:

var selectProducto = Ti.UI.createPicker({
        width:'auto',
        height:'auto',
        font:{fontSize:PixelsToDPUnits(18)}
    });
 
    var data = [];
    data[0]=Ti.UI.createPickerRow({title:'Selecciona'});
    data[1]=Ti.UI.createPickerRow({title:'Strawberries'});
    data[2]=Ti.UI.createPickerRow({title:'Mangos'});
    data[3]=Ti.UI.createPickerRow({title:'Grapes'});
    selectProducto.add(data);
 
    selectProducto.selectionIndicator = true;
 
    self.add(selectProducto);