干旱区生态环境知识资源中心

The implementation of a polluter-pays principle is increasingly generating additional water resources which are used for irrigation mainly in arid and semi-arid Mediterranean areas. In the south-east semi-arid region of Spain (Campotejar-Murcia), a field experiment was carried out during four years to assess the performance of adult mandarin trees irrigated with saline reclaimed water and subjected to regulated deficit irrigation (RDI) during the second stage of fruit growth. Plant and soil water status, electrical conductivity of the saturated paste extracts and leaf gas exchange was periodically monitored and the final yield was characterized. The concentration of salts within the plant root zone increased up to critical levels at the end of each deficit irrigation period. The plant significantly reduced its stem water potential in the RDI period without significant effect on its photosynthetic performance. The total number of fruits, slightly affected by RDI, was significantly reduced under the combined effect of RDI and irrigation water quality. Under arid and semi-arid climatic conditions, the combination of RDI strategies and saline reclaimed water should be managed carefully to avoid long term irreversible effects on the soil-plant production system.