نشریه حفاظت و بهره برداری از منابع طبیعی
سال یکم شماره 2 (پاییز 1378)

In recent decades, big share of executive capabilities, capital and activities of the government have been allocating to develop the pressurized irrigation systems. Concluding these programs and specifying the development status of these systems in different locations of country can be regarded as a guideline to assign future strategies. Present research, survey the pressurized irrigation projects performed from 1990 to the end of September 2007 in different townships of Golestan province. In addition, development trend and status of pressurized irrigation systems were also evaluated. Based on the results, totally 1020 pressurized irrigation projects with 22990.86 hectares area have been performed in Golestan province, which have covered only 6.64 percent of irrigated lands area or 3.2 percent of total agricultural lands area. The most numerous pressurized irrigation have been performed in the second economical- social- cultural development program of country with a significant difference to other development programs. It seems that general policiy on the country scale is the most important factor in the lack of pressurized irrigation development in Golestan province. Continuous changes in policies and instability of adopted policies are the main reasons of fluctuation in developing of these systems while, technical, social, cultural and executive factors have little effects. Current paper present comprehensive conclusion of sprinkler and trickle irrigation projects from various aspects in Golestan province and its dependant townships.

The histopathological effect of acute toxicity of ammonia was investigated on rainbow trout (Oncorhynchus mykiss) for 15 days using static water method. Present investigastion was performed during 24 hours in five groups with 13 specimens (with an average weight of 15g) in each group. Each group were exposed to different consentrations (including 0, 10, 15, 20, 25mg/l) of ammonia. Mortality percenentage and toxicity signs were recorded during experiment. Based on current results, lethal concentration of ammonia during 24 hours was 25mg/l. The highest mortality rate (70-80%) at lethal concentration was observed early in the experiment. High ammonia levels (higher than 15mg/l) caused convulsion, ataxia, bending of body muscle and opened operculum. In microscopic tissue studies of kidney, liver and gills, hyperemia, hemorrhagi cell necrosis and influx of inflammatory cells were observed.

Multiple shoot induction has been suggested to be a suitable method for regeneration of hybrid plants in wide crosses as well as for regeneration of transgenic plants. Shoot and root induction response were studied in four species of cotton consisting of G.herbaceum G.arboreum, G.hirsutum, and G.barbadense. Two media were employed and explants were prepared from plantlets originated from mature and immature cotton embryo cultures. According to obtained results, seeds planted on MS1 and MS2 medium germinated after 48 hours and produced roots and cotyledons after 3-4 days. G.hirsutum and G.arboretum showed the highest and the lowest germination percent among four species. In complete embryo cultures of tetraploid species, emergence and development of shoots occurred in the second week whereas, in the case of diploid species it occurred in the third week. In general, the results showed that MS2 and SH were the best media for shoot and root induction, respectively. Tetraploid species showed to be superior to diploid cotton species for shoot number and G.barbadense and G.arboreum were superior for root production. Based on present study, multiple shoot induction would be appropriate for micro-propagation and regeneration of recalcitrant species and new genetically modified cottons (GM cottons) derived from biotechnological methods, as well as, preparation of sterile tissues, organ and seedling by in vitro culture.

A lot of surveys observed that destruction of Hyrcanian forest has been increased and their natural characteristics will be lost in a short period of time. The attention is not paid to select the forest area for continuing studies as permanent plot. There are contact parcels in forestry plans with natural site conditions that make opportunity for conducting permanent plot. Thus, the permanent plots on parcel 32 in Shast-Kolate forest was selected and were done several succeed educational and research projects such as: the relation of soil properties with spatial tree patterns and tree groups in mixed beech forest, changes of horizontal and vertical structure in natural Beech forest, effect of light competition on crown expansion of trees in a mixed multi storied forests and the heterogeneity of structure in mixed beech forest. Some results of these researches were introduced in this paper. Making permanent sample plot in other areas of Hyrcanian forests is led to comprehensive studies based on scientific fundamentals.

Present research was conducted to compare the effect of using triticale and corn silage in feed ration on performance of feedlot male Zel lambs. Four levels of triticale silage including 0, 33.3, 66.6 and 100 percent replaced with corn silage were applied in a completely randomize design with 4 treatments on 40 male Zel lambs. Weight gain, feed intake and feed conversion ratio were measured during 84d of experimental period and carcass characteristics were evaluated at the end of experiment. Results showed that except dry matter intake that decreased on treatment with 100 percent replacement (P<0.05) there were no significant differences for weight gain, feed conversion ratio and carcass characteristics among treatments (P>0.05). The results of current study showed that complete replacement of triticale silage with corn silage has no considerable effect on performance of Zel lambs and using of mentioned silage until 30 percent of diet can be recommended.

Two experiments were conducted to determine the chemical composition and apparent digestibility of dried malt sprouts and its substitution in the ration of fattening lambs. In first experiment, chemical composition (in AOAC method) and in vivo digestibility coefficient was determined using four mature male Atabay lambs. In second experiment, thirty male lambs with initial weight of 33.01±2.74 kg, were used in a completely randomized designed for a three- month experiment. Concentrate (barley and beet pulp) was replaced by malt sprout at levels of 0, 15 and 30 percents. Weight gain, dry matter intake and feed conversion ratio were measured in three treatments. The results showed that dry matter, crude protein, ether extract, organic matter, crude fiber and NFE of malt sprout were 83.7, 14.8, 2.5, 75.5, 19 and 61.3 percent respectively. Digestibility coefficient of dry matter, crude protein, ether extract, organic matter, crude fiber and NFE were 67.90, 69.50, 37.2, 71.1, 57.2 and 87.3 percent respectively. The highest daily weight gain (223g/day) was achieved by lambs fed 0% malt sprout and the lowest daily weight gain (200g/day) was achieved by lambs fed 30% malt sprout but no significant differences were found among treatments. Dry matter intake (approximately 1.46 kg/day) was similar in three rations. Feed conversion ratio was better in control group (6.56) than groups with 15 and 30 percent malt sprout. The results showed that malt sprout can be used until 30% of total ration in fattening Zel lambs.

This experiment was conducted in order to study the effect of different levels of raw and treated rice bran with acetic acid on the performance and carcass composition of broiler chickens. 500, unsexed Ross 308 broiler chicks were reared on the floor pens for 42 day. A corn-soy dietary treatment and four extra dietary treatment containing 10 and 15 percent of rice bran with and without acetic acid was formulated according to NRC, 1994 recommendations for starter (0-21d) and finisher (22-42d) periods. Each of 5 dietary treatments was fed to 4 replicate groups of 28 chicks. Result showed no significant difference between birds fed control diet those were fed rice bran for body weight gain and feed conversion ratio. Increasing level of rice bran from 10-15% of the diet resulted significant increase of feed intake. Based on results of this experiment, there was no significant difference between carcass compositions of all broilers. Treatment of rice bran with acetic acid had no improvement on the performance of broiler chickens.