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International Journal of Ecology
Volume 2013 (2013), Article ID 819810, 7 pages
http://dx.doi.org/10.1155/2013/819810
Research Article

Seed Germination Characteristics of Rhus tripartitum (Ucria) Grande and Ziziphus lotus (L.): Effects of Water Stress

1Ecology and Sylvo-Pastoral Improvement Laboratory, National Research Institute of Rural Engineering, Water and Forests (INRGREF), Tunisia
2Arid and Oases Cropping Laboratory, Arid Area Institute (IRA), 4119 Medenine, Tunisia

Received 1 January 2013; Revised 8 February 2013; Accepted 12 February 2013

Academic Editor: Mousumi Chatterjee

Copyright © 2013 Zouaoui Refka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ziziphus lotus (L.) Lam. (Rhamnaceae) and Rhus tripartitum or Sumac (Anacardiaceae) are two indigenous species from arid and semiarid regions of Tunisia, characterized by a severe climate where dry seasons are very long. The combined action of anthropogenic factors and climate in arid regions caused a gradual threat of plant assets. In this context, an experimental study of the effects of water stress (0 to −1 MPa) on seeds has identified the water requirements germinal stage of both species. The results showed that both species were able to germinate at relatively low water potentials. However, beyond −0.6 MPa, germination was completely inhibited for R. tripartitum, when it reached for another 50% for Z. lotus. Increasing the concentration of PEG6000 progressively inhibited germination in both species. Only Z. lotus could be considered tolerant of water stress, because, to −1 MPa, seeds germinated with a rate of 17%. It resulted in that the species Z. lotus presented an adaptive capacity to aridity much greater than that observed for R. tripartitum.