Investigating the Effects of Number and Frequency of Incisions on Production and Survival of Astragalus keyserlingii

Tragacanth Gum is one of the most important medicinal and industrial products of rangelands and is obtained from the incision of gum tragacanth-producing Astragalus including Astragalus keyserlingii. The conservation of Astragalus species in rangelands has a special place in terms of economic profit and soil conservation. The increase in price of gum tragacanth in recent years and more attention of beneficiaries to the extraction of this material from the existing Astragalus in the rangelands could cause the destruction of Astragalus species producing gum tragacanth. This research was aimed to provide a scientific method for the exploitation of gum tragacanth as well as the conservation this species. The study was conducted in Tiran, Isfahan province, Iran using a split plot design in the layout of a completely randomized blocks design with three replications. Each replication included 30 shrubs that were exploited for the first time. Treatments included the number of incisions and harvests. The traits were gum tragacanths production, the plant mortality percent and canopy cover percent. According to the obtained results, the number of harvests had a negative effect on canopy cover. This result clearly shows that this plant is resistant against the incision since it has maximum canopy cover percent even under three-time incision in the sixth year. The highest mortality equivalent to 53% was recorded in six-time harvest and the highest production was obtained for six-time harvest a year with an average value of 156.9 g per 30 shrubs, having no significant difference with the four time one a year. Overall, two scars and four-time harvest could be recommended for the exploitation of A. keyserlingii.