Abstract

Restoration success using nursery grown plants in riparian environments of Mediterranean areas is limited by summer high mortality rate due to severe drought stress. The aim of this work is to develop a morphological / physiological modified plant which could establish itself in low water availability areas. Four morphologic formats of Salix elaeagnos Scop. were tested depending on two factors: Container volume (3 and 6 L) and pruning (pruned and not pruned). Twenty four individuals of four different formats were grown in a nursery for at least three months and outplanted in a per liter filled assay pool simulating a riverbed restoration for 12 weeks. Morpho-physiological destructive measurements of 32 plants (8 per format) were done in the beginning (T0), half, 6 weeks, (T1) and ending (T2) of the assay. It was found that in T0, there were important biomass differences, being the 6 L volume and not pruned format (6NP) the highest. During T1, water availability was high and it was advantageous for 6NP which showed absolute and relative highest growth rates. However at T2, water availability declined and relative rates of growth and new roots production were higher for the 6 L volume and pruned format (6P). Three liters formats suffered harder water stress than 6 L ones. 6 L containers better performance is explained for its high volume and depth, which leads to reaching underground water level easily. Results shown as pruning, high root /canopy ratio can be beneficial when water conditions are or will be unfavorable in river restorations now and under potential new climate change conditions.

Key words: Agronomical practices, climate change, drought stress, leaf water content, relative growth rate,relative soil.