Major nutritional issues in deciduous fruit orchards of Northern Italy

Abstract

Most deciduous fruit crops in Italy are grown in the north and especially in the eastern part of the Po River Valley (mainly in the Emilia Romagna and Veneto regions) and in the Adige River Valley (South Tyrol and Trento provinces). Soils in the wide Po River Valley, where pear (Pyrus communis), peach and nectarine (Prunus persica), kiwifruit (Actinidia deliciosa), plum (Prunus domestica and P. insititia), apricot (Prunus armeniaca), cherry (Prunus avium), and apple (Malus domestica) are grown, are alluvial, generally fertile, fine textured, alkaline, often calcareous and well enriched with Ca. Apple plantings are concentrated in the Adige Valley and located on a variety of soil types, including sandy loam, loamy sand soils or sandy clay, sometimes calcareous. Integrated fruit production is gaining importance and represents more than 80% of apple production in South Tyrol and about 60% of peach and nectarine production in Emilia Romagna. Under these conditions, the main objectives of mineral nutrition are to reconcile production and environmental concerns (minimize nutrient leaching, soil pollution, volatile emissions). In particular, fertilization aims to improve external and internal fruit quality and storage ability, reduce production costs, maintain soil fertility, avoid nutrient deficiency and excess and control tree vigor. Nitrogen applications have strongly decreased in recent years and there is a need to improve the efficiency of N fertilizers while avoiding deficiencies. Research is focussing on application technology, timing of N uptake, internal cycling of N and methods for assessing the need for N application (e.g., using estimates of native soil N availability). Early diagnosis of bitter pit is recommended for guiding applications of Ca sprays. Iron deficiency and chlorosis is a major problem in pear, peach and kiwifruit grown in alkaline and calcareous soils and Fe chelates are usually applied annually to the soil or to the canopy. Current research is focused on agronomic means for controlling the problem and on developing rootstocks tolerant to Fe deficiency.