Effect of partial root zone drying on growth, yield and fruit quality in greenhouse tomato cultivation

Partial rootzone drying (PRD) is a new irrigation system which allows a reduction of seasonal irrigation volume, near the 50% of a well watered crop, and improves fruit quality parameters, without significant yield reduction. In the PRD technique only half of the root system is irrigated, the other half is maintained in drying soil. After 10-15 days, the wet and the dry root zone are inverted. This system of watering would allow separating some positive effects of water deficit (better fruit quality, restriction of side-shoot growth and reduction of the transpiration losses) from the negative effects such as fruit yield reduction. Given the extension of tomato greenhouse cultivation in Sardinia and considering that water deficit is often applied to limit excessive vigour and increase extra-quality of berry production, two year trial in greenhouse (2004-2005), to verify the effects of PRD on the growth, yield and fruit quality in tomato, were carried out. In both years, PRD technique was compared with the following treatments: 100% MET (maximum evapotranspiration) as well watered control thesis and 50% MET, irrigated on both sides of the root system; in the second trial a further thesis, a PRD treatment with a shorter switch cycle was evaluated. No significant difference in vegetative growth, yield and fruit quality parameters was found between PRD and 50% MET thesis. The seasonal volume reduction with both irrigation systems has always caused a significant yield reduction compared with the well watered check.