A Comparative Study of Seed Germination And Seedling Emergence of Two Wild Edible Allium Species Endemic to Zagros Areas

Abstract

Allium L. is one of the largest and most diversified monocotyledonous genera worldwide. These taxa have wide geographical distribution range mainly occurred in the northern hemisphere with an important center of diversity in the Mediterranean and Irano-Anatolian regions. They include an important number of taxa of high economic values (wild edible, cultivated, medicinal, ornamentals, etc.). These geophytes species exhibit diversified adaptation strategies that permit them to persist under harsh environmental conditions. The present experimental study was designed to understanding better the environmental factors that control the natural regeneration of the two wild edible Allium (A. calocephalum and A. notabile) species endemic to Zagros areas via evaluating the effect of different (i) pre-sowing treatments on seed germination rate and (ii) soil depth on seedling emergence timing. The results of the present study confirmed relatively high seed and bulbs viabilities under the different pre-sowing treatments. In general, both Allium species have a relatively similar germination trend (around 80% without treatments) and seedling emergence (from bulbs at 5 cm) patterns. The high rate of seed germination for A. calocephalum was found under cold stratification for 1 month and soak in water for 3 days and GA3 1500 ppm with 83%, 86%, and 85%, respectively. The different germination pattern was found for A. notabile with 83%, 85%, 84% for soaking water for 2 and 3 days and GA3 1000 ppm, respectively. Whoever, these two threatened species from different taxonomical groups and habitats have different adaptation strategy. A. notabile is Mediterranean species exhibiting an optimum seedling emergence in autumn-early winter with summer underground organ dormancy to avoid the hot-dry conditions; While, A. calocephalum is IranoAnatolian species exhibiting an optimum seedling in late winter-early spring permitting it to persist thanks to its avoidance strategy of the harsh winter climatic conditions. The results of this research support the idea that Allium species from different habitats exhibit different seed germination and seedling emergency strategies allowing it to persist. The evidence of this experimental study enriches our understanding of the diversified adaptation strategy of the plants. In this context, further experimental investigations are needed to evaluate the crucial rule of the seed germination ecology and bulbs dormancy strategies on the population dynamic and persistence.