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

Abstract

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