IRANIAN JOURNAL OF RANGE AND DESERT RESEARCH
Year:2003 | Volume:10 | Issue:1|Papers Count:8

Replacement of annual crops such as rainfed wheat with enduring species like alfalfa on unsuitable lands is of core objectives of Forest, Range and Watershed organization of Iran. This is responsibility of research sectors to seek for the ways through which more forage production could be achieved. This research was conducted using spilt plot design in time and completely randomized blocks with four replicates. Mixture of Medicago sativa-Bromus inermis and Medicago sative-Agropyron elongatum were tested in this experiment. Percentages of the mixtures were the treatments set as 100% Medicago, 75% M. and 25% B., 50% M. and 50% B., 25% M. and 75% B. and finally 100% B. The same method was used for the second mixture. Results shows that the difference between Uni., i.e. 100% Medicago and mixture of the species in time is significant. Production of mixtures starts growing form year second. Maximum yield in the first mixture belongs to Pure Medic with 658.04 kg of D.M./ha. In the second however mixture of 25% M. and 75% A. has the highest production i.e.1436.6 kg of D.M./ha.

Located 72 km. South-East of Tehran,Abardeg Sand Stabilization Station have dry hot summer and moderately cold winter. Average annual precipitation is 174 mm. (nine year average) and temp. around 16.5C. so far more than 2000,000 hectares of sand covered lands, have been rehabilitated. Haloxylon ammodendron (C.A.Mey) Bge. is one of the main species successfully used in sand dune stabilization programmes throughout the country. The objective of this study was to examine the composition and structure of the pests at different phenological phases of saxaul plants. Eight phenological stages have been recognized over the entire growing season which begins with emerging out from winter dormancy followed by flower buds appearance; full flowering; flowering end; fruit setting; seed ripening; duration of seeds on the plants; defoliation period and winter dormancy initation. Each phases have carefully investigated and the emerging time as well as the abundance of different pest species associated with saxaul plants monitored and the data recorded in specially-designed tables. In the begining phase which occur as mid-Feb. to early April, saxaul plants are subject to attack by a gall-producing flies of Cecidomyiidae family as well as two species of gall mites of Eriophyidae and Tenuipalpidae families and also saxaul thrips (Haplothrips kermanensis Zur. Str.). Following stages which include emergence of buds and flowers as well as full flowering to fruit setting which constitute the critical periods of plant life and occur as early April to late September, compries activity of such pests as aphid (Xerophilaphis saxaulica Nev.), Haplothrips kermanensis Zur. Str. Caillardia inedita Log., Julodis beetle (Julodis iris var. euphratica Cast.et.Gorg.); saxaul weevil (Chromosomus fischeri Fah.) saxaul grasshopper (Dericorys albidula Serv.) ; white scale (Acanthoccua abaii Danzig.) and three of mouse species (Meriones libycus Lich., M.persicus Blanford. And Allactaga elater Lich.). And finally, fruit setting and seed ripening periods occur as late September through mid-Nowember, during which Haloxylon plants is subject to damage by Proceratia casariella Rosler., which is a serious pest feeding on seeds. In general, based on gathered data, haloxylon plants are now subject to attack and damage by twenty-five distinct pest species of twelve orders and nineteen families Through conducting biological studies on the key pests as well as observations phenological host plant, we will be able to prevent pests outbreak or take appropriate steps towards pest control.

Salt tolerance of several alfalfa populations and cultivars (Bami,Yazdi, Rehnani, Hamadani, Gharayonjeh , Renger and Krisari) were carried out in this study. The selected alfalfa were grown in Johnson solution culture supplemented with NaCl concentration of –0.07, -0.17,-0.37 and –0.57 Mpa in greenhouse. Plants were harvested at 0.10 flowering time. Salt stress decreased the plants height, dry weight of root and shoot, dry weight of leaves, leaf area and root length, while percent of leaves increased with salt. Population of Yazdi, Rehnani and Bami had higher yield compare to others. Among the cultivars Kerisary had the most leaf percentage. Hamedani and Gharayonjeh population scored the lowest for all parameters measured except for the shoot height. Chemical analysis of plants under sodium chloride treatments showed that Na and Cl increased in both shoot and roots with increasing salt.

Short-term effects (one grazing season) of rotation and continuous grazing systems and heavy, medium and light grazing intensities animal weight in Bromus tomentellus pasture was studied in Homand Absard Station. Each system was analyzed by a completely random block design. 4 Lambs were applied as grazer animals in each treatment from which 3 lambs were weighted periodically ( 12-14 days).The results showed that there was not any significant differences in weights of systems but there were reduction when the grazing intensities increased.

Comparisons on growth characteristics of Panicum antidotale Retz. have been carried out in solis of different texture (light, medium, heavy) and different irrigation regimes (4, 8, 12 day intervals) using a hydrophilic polymer. The results showed that the use of polymer increased the rate of seed germination in soil with light texture, but had no effect on phenology of the plants. Polymer treatment, irrigation interval and soil texture positively affected the establishment and survival of plants by 10, 30 and 49% respectively. The interaction effects between irrigation and soil texture on survival of plants were 90%. There was no significant interaction between polymer and other treatments. Application of polymer increased the number of panicles in each plant by 85.5%. The use of polymer decreased the variation of the number of panicles in irrigation and soil texture treatments. Effects of soil texture and irrigation alone, incresed the number of panicles by about 12 and 2.7 fold, respectively. However, the rates of survival and number of panicles were affected mainly by soil texture and then irrigation and polymer, respectively. Application of polymer improved some growth characteristics, but had limited effect on conditions with low irrigation and heavy soil texture.