Sustainable strategies for irrigation in salt-prone Mediterranean: SALTMED

Abstract

This paper presents an overview of SALTMED, a project whose goal was to increase productivity and sustainability of irrigated cropping of tomato on salt-prone land. The tomato variety Floradade, identified as having good salt tolerance, was grown in Egypt and Syria over 3 years with either drip or furrow irrigation using either blended saline and fresh water or the cyclical application of fresh and then saline water. In Egypt, fruit yield and fruit number were highest with the combination of drip irrigation and blended water. In Syria, tomato yield under drip irrigation was also higher than that under furrow irrigation and tomato yield decreased with increasing salinity of the irrigation water. SALTMED, a mathematical model that incorporated evapotranspiration, plant water uptake and solute transport, crop yield and biomass production was developed. There was good agreement between simulated and observed yield in Syria and Egypt over 3 years, confirming the value of SALTMED as a tool for use by experts in the management of salt-prone irrigation systems. The effects of salinity on growth and yield of tomato varieties growing in a greenhouse in Spain were also investigated. Salinity reduced the commercial yield, mainly due to a decrease in fruit weight and to a lesser extent by a reduction in fruit number and by increasing blossom end rot in fruits. Evaluation of pre-treatment of seedlings with drought or salinity in the laboratory demonstrated that tomato plants ‘haloconditioned’ at the 3–5-day-old stage produced more shoot and root biomass than non-conditioned control plants. The physiological traits, ‘root Na selectivity’, ‘leaf tissue tolerance’, ‘leaf-to-leaf tolerance’ and the ‘K/Na ratio’ were evaluated as tools for breeding varieties with enhanced tolerance to salt. Selectivity and K/Na appeared to be the most promising characters for breeding purposes. Heritability of physiological traits was estimated in a set of 135 F 8 recombinant inbred lines from a cross between Lycopersicon pimpinellifolium and L. esculentum. Heritabilities of water use efficiency (WUE) were particularly high, in both control and saline conditions.