Interaction effects of water stress and harvest intensity and frequency on productivity of Atriplex lentiformis (Torr.) S. Wats and Nitraria schoberi L

Atriplex lentiformis and Nitraria schoberi potted seedlings were planted in green house in the college of natural recourses، Isfahan university of Tecnology by the end of summer of 2003. After 6 months establishment period the experiment began with 3 levels (20، 50، 80 percent) of cuttings in 2 forms as foliage and leaves in 5 consecutive harvest times. Two levels of irrigation; as normal and stressed were also applied. Plants production and performance were investigated and data were analyzed as a factorial design. Significant interaction effects indicated that: 1- Atriplex lentiformis is more tolerant to heavy grazing and is also more drought tolerant than Nitraria schoberi. 2- Productivity of both species declined after second harvest but water stress caused more rapid decline and Nitraria schoberi was more affected by moisture deficiency. Moderate harvesting in all cases resulted in higher production in each cutting and in total for both species. Second harvest had highest production in both species and production declined sharply after that in consecutive harvests. In normal moisture condition mean plant production was higher than stressed condition. Cutting foliage resulted in higher production than cutting leaves. Atriplex lentiformis had significantly higher production، higher digestible protein and better preference by sheep and goat. Sustainability، of vegetation is the most important factor in harsh environments therefore in spite of better performance of Atriplex lentiformis، both species should be planted in rehabilitation programs، since Nitraria schoberi is native of Iran and it can naturally be propagated.