Effects of Regulated Deficit Irrigation on Pear Trees cv. Conference under Temperate Zone Climate

To prevent drought stress, pear trees (Pyrus communis ‘Conference’) in Belgium and the Netherlands, under temperate conditions are equipped with a drip irrigation system. To determine the optimal soil water potential (ψsoil) threshold during shoot growth a field experiment was accomplished in a commercial orchard during three successive years (2007 2008-2009). The objective is to see the effect of a different soil moisture content during the shoot growth period. The orchard was situated on a silt loam soil, and was composed of 11 year old root pruned pear trees cultivar ‘Conference’ on Quince Adams rootstock. Each year two different irrigation regimes where accomplished and monitored by granular matrix sensors (Watermark) and gravimetric soil moisture determination. Tree water status was examined by stem water potential (ψstem). At harvest yield, fruit quality and fruit size where evaluated. Fruit size was negatively influenced when ψsoil declined to -90 kPa. However a moderate depressed ψsoil up to -60 kPa had no negative influence on production.