Journal of Arid Environments (1995) 29:305-315 A comparative study of seed germination of two Allium species from different habitats in the Negev Desert highlands Y. Gutterman*, R. Kamenetsky* & M. Van Rooyent * The Jacob Blaustein Institute for Desert Research & Department of Life Sciences, Ben-Gurion University of the Negev, Sede Boker Campus 84990, Israel and -t Department of Botany, Faculty of Natural Sciences, University of Pretoria, South Africa (Received 16 August 1993, accepted 11 September 1993) Seed germination ofAllium truncatum and Allium rothii from natural populations in the Negev were compared over a range of NaC1 concentrations, naturally fluctuating or constant temperatures, light and dark. No germination occurred after the first 7 days ofimbibition. The fastest germination was at 10 and 15°C but there was none at 25°C. The higher the NaC1 concentration, the lower the germination. Allium truncatum plants inhabit wadis with crowded vegetation and the seeds germinate in the dark better than in the light, in natural and constant temperatures. Allium rothii plants inhabit open areas. There is no difference between germination in light and dark, in constant 5 to 15°C. Germination at 20°C in light is higher than in dark and in naturally fluctuating temperatures the germination in dark is higher. Keywords: adaptation; geophytes; germination; light or dark; natural and constant temperatures; NaCI concentrations Introduction Species of genus Allium are widely distributed in semi-desert and desert zones of the Northern Hemisphere. Twenty-nine Allium species have been found in Israel (Kollman, 1986). With the spread of species of genus Allium from moderate climatic zones to arid regions they have acquired many morphological and ecological adaptations. Their life cycles have become characterized by a long intra-bulb development period as well as ephemeroidization of above-ground organs and root systems (Kamenetsky, 1992). Because many bulbous species develop under extreme and unpredictable desert conditions, the adaptation strategy and population dynamics are very important for species survival. Propagation by seed may play a principal role in this process and successful seed germination could provide stable development of populations of species (Went, 1953). The aim of this set of experiments is to compare the seed germination of two Allium species from the Negev Desert highlands, in light or dark, in a range of constant or in naturally fluctuating temperatures, as well as in different salt concentrations, during the germination season. Allium truncatum (Feinbr.) Kollman & D. Zohary, and AUium rothii 0140-1963/95/030305 + 11 $08"00/0 O 1995 AcademicPress Limited