ARTIFICIAL SUBSTRATES, LIQUID FERTILIZATION AND APPLE CULTURE. RESULTS ON MODEL AND AMOUNT OF GROWTH.

One year old apple plants (cv. "Golden Delicious") on M26 and M27 were grown for 5 months, in 3.5 l containers with peat/sand substrate (50/50 v/v), using 2 fertilizing treatments and a irrigation with deionized water (as control).

The interation between nutritive supply and rootstock on the cultivar's growth and nutritional status was evaluated.

The results show that, in a system limiting root development, the vigour class of the rootstock emerges only with fertilizing treatments. Furthermore specific interactions rootstock/nutritive supply emerge and, in this connection, the more dwarfing rootstock seems to show a closer relationship with the fertilizing treatments.

As regard to nutritional status a positive correlation between nitrogen supply and foliar content was detected for M26 rootstock, while in M27 the relative proportions of inorganic nitrogen seem to have a more relevant effect respect to total nitrogen supply.