Water and Nitrogen Interaction in Peaches for Processing: 2007 vs. 2008

Peach is an important fruit crop in Spain, which has progressively increased in recent years. Last trends in the peach orchards in the horticultural zone of Lleida have been towards high density plantations, new cultivars and drip irrigation systems. Under semiarid conditions, water and nitrogen monitoring is needed to achieve good results with respect to fruit yield and quality. A field experiment was set up in 2006 on clingstone peach 'Andross' in a commercial orchard under mechanical harvesting for the processing industry. Trees were unthinned and trained on a free palmette. The soil type was loam textured, well drained, with a high content of coarse elements and a petrocalcic horizon at 45 cm depth (Xeric Petrocalcids). Three irrigation strategies were evaluated according to fruit growth stages: full irrigation (FI) throughout the season, Iirrigation restriction at Stage II (IR2) receiving 30% of FI, and irrigation restriction at Stage III (IR3) receiving 70% of FI. These were combined with three nitrogen fertilization treatments: 0, 60 and 120 kg N/ha. Trees were fertigated on a daily basis. Trees were individually harvested with a continuum trunk shaker. Daily patterns of soil moisture were monitored with capacitance probes. Results showed that irrigation restriction and nitrogen dosing affected yield and fruit quality at commercial harvest. The individual effects of irrigation strategies and N doses and interactions of both factors were analysed. In 2007, there was a positive yield effect for N applied to fully irrigated trees, while the opposite was observed when the irrigation restriction was applied during stage-III. No interaction was observed in 2008.