This paper evaluates the potential of nine multipurpose tree species for afforestation of degraded land in the Khorezm region, Central Asia, particularly their suitability for biodrainage i.e., lowering the elevated groundwater table through the transpirative capacity of plantations. For this purpose water use (WU), water use efficiency (WUE) and tree physiological factors influencing transpiration were assessed during two consecutive years. Mean daily leaf transpiration differed significantly among the species and ranged during the seasons from 4.5-5.2 mmol m-2 s-1 for Prunus armeniaca L. to 4.5-10 mmol -2 s-1 for Elaeagnus angustifolia L. WU differences were triggered by species physiological features such as capability of water uptake by roots. Transpiration rates and the length of fine roots correlated highly (r = 0.7). Correlations of leaf transpiration rates with leaf area were weaker (r = 0.6). No correlations were found between salt content in plants and water uptake under conditions of slight-to-moderate rootzone soil salinity. Values of WUE per root and shoot DM were similar averaging, respectively, 0.2 and 0.3 g DM g-1 water for two-year-old trees, and decreased with age. In addition to WU characteristics, also salinity tolerance, growth rate and the ability to produce fodder and fuelwood must be considered during species selection. Regarding these features, the N-fixing E. angustifolia ranked the highest, combining high WU, fast growth and production of nutritious feed. Examined Populus spp. and Ulmus pumila L. ranked lower but still represented potential candidates for biodrainage purposes. Typical fruit species in the region such as P. armeniaca and Morus alba, showed low biodrainage potential.
Bibliographical noteFunding Information:
Acknowledgements The research was conducted within the framework of German/Uzbek project ‘‘Economic and ecological restructuring of land-and water use in the Region Khorezm (Uzbekistan): A pilot project in development research’’. The German Ministry for Education and Research (BMBF; project number 0339970A), the Ministry for Schools, Science and Research of the State of Northrhine-Westfalia financially supported this study. Additional funds from German Academic Exchange Service (DAAD) are gratefully acknowledged. We are thankful for the valuable comments from two anonymous reviewers on the earlier version of this manuscript. This paper is a revised, extended version of a presentation at the 21st European Regional Meeting of the International Commission on Irrigation and Drainage held in May 15– 19, 2005 in Frankfurt/Oder, Germany.
- Root growth
- Transpiration per unit leaf area
- Water use efficiency
ASJC Scopus subject areas
- Agronomy and Crop Science