مطالعه تغييرات ذخاير كربوهيدرات مالي محلول در گونه هاي مهم مرتعي منطقه استپي نيراستان يزد

An Investigation of the Soluble Carbohydrate Reserve Changes in Dominant Species of Steppe Regions in Yazd Province

A knowledge of the Process of change in available carbohydrate reserves in dominant plant species is indispensable in a sound model of range management. Three species of Salsola rigida, Artemisia sieberi and Stipa barbata are the dominant species in the steppe regions in Yazd province. An investigation involving these species was conducted in the range and animal research station of Nir during 2001. Root and shoot in these species were sampled in eight stages from late May to late December. Soluble carbohydrate was determined using Phenol_ Sulphuric Acid method. Treatments were distributed in a split plot (in time) design. The three species were randomly employed in main plots. Results demonstrated that Stipa barbata shoot had the maximum percentage of soluble carbohydrate as compared to the other two species. This difference was significant between Stipa barbata and Salsola rigida, while Artemisia sieberi stood between these two species. The three species were significantly different for the percentage of root soluble carbohydrate. The percentage of root soluble carbohydrate in Salsola rigida, Artemisia sieberi and Stipa barbata were 1.371, 0.760 and 0.384, respectively. In general, Artemisia sieberi and Salsola rigida contained the maximum soluble carbohydrate during seeding stage, while in Stipa barbata this hapened in flowering stage. According to the results, the minimum damage to growth in these species occurs during the mentioned phonological stages. In addition, it was revealed that grazing Stipa barbata is more sensitive to late grazing as compared to the other studied species due to soluble carbohydrate changes during its phenological stages. This It may be one of the main reasons for Stipa barbata extinction in Steppe regions.