Introduction: Wild almond (Amygdalus scoparia Spach) is a very important forest species with a wide distribution range in arid and semi-arid areas of Iran. Considering that the study on the geographical variation of morphological traits of this species in the limits of its natural distribution is considered an important step in the genetic studies and the protection of these forest resources, the present research was planned and implemented.
Material and methods: In this research, in order to investigate the geographical changes of the morphological characteristics of this species, 10 representative populations of wild almond were selected from the province with different distribution and ecological conditions, and in each population, the number of 21 to 25 of parent trees of wild almond were determined and the seeds of each of parent trees were collected from the four sides of the tree crowns. To determine the weight of 100 seeds, 400 seeds were randomly selected from each tree and the wet, dry weight and dimensions of the seeds were measured. In order to investigate the characteristics of the leaves, 20 healthy and expanded leaves were selected and the external characteristics of each of them including length, width, area and width of the leaf were measured. Ten parent trees were randomly selected from each population and after preparing the seeds for germination, the seeds were planted in Shahid Jabal Amilian Nursery using a randomized complete block design with 3 replications. In this experimental design, 100 parent trees as 100 genotypes were randomly placed in each block, and for each parent tree, 10 seeds were planted in a row of 10 in polyethylene pots. At the end of the growth period, the number of leaves, stems, branches of the seedlings, the length and diameter of the stem, the length of the main root of each seedling, as well as the height of the seedling and the collar diameterwere measured.
Results: Based on the results, significant differences between the studied populations were observed in all the studied attributes. Weight of 100 seeds, leaf area and number of stems showed significant changes among the studied traits. In drier areas they had smaller weight, seed size and leaf dimensions compared to wetter areas. This study showed that seed width had a higher correlation with seed weight among the examined traits. Also, the results showed that the height of the seedlings decreased with the increase in longitude and decrease in rainfall, as well as the increase in temperature from west to east of Isfahan. In addition, the findings of the present research showed that the height of the seedling trees of wild almond increased from the east to the west of Isfahan province, and the dimensions of their leaves decreased from the north to the south and this means that in the seedling stage, the plant shows bidirectional geographical diversity with latitude and longitude, but the influence of latitude on the observed diversity was much higher than that of longitude.
Conclusion: Generally, the findings of this study indicate the existence of significant differences in a wide range of morphological traits of seeds, mother shrubs, leaves and seedlings from natural populations of wild almond in Isfahan province. According to the results, while emphasizing on paying attention to the origin of the seed in forest planting operations with this species, it can be stated that the wild almond has a high ability to adapt to the environmental conditions of its habitats in Isfahan province.