جستجوی مقالات مرتبط با کلیدواژه "آب لب شور" در نشریات گروه "آب و خاک"

With the development of localized irrigation in arid and semi-arid areas, the soil is more susceptible to salinization. The salt accumulation in the soil can reduce crop yields, destruction of plants and even resulting the soil uncultivable. In this research, flood leaching and trickle leaching methods (tape) were investigated in a pistachio orchard. Comparing with the flood method, the results showed that, the amount of leaching water used in the trickle method was reduced by 62.7% for the first leaching leading to a total reduction of 26.7%. In the flood leaching method, the entire surface of the farm is leached, while in the 6-row method water to be directly use in saline accumulation areas, which saves leaching water. Also, in the trickle and flood methods the uniformity coefficient of salinity distribution increased by 7% and 3% respectively. In the trickle method, the salt mass balance added due to irrigation can be removed with only one washing step, while in the flood method, the mass of leached salt is less than the mass of added salt. For orchards leaching with localized irrigation, it is recommended to apply more leaching water to salts accumulation areas and for improving the salts management effectiveness low-leaching rates applied alternately is recommended.

To assess the role of non-conventional water in arid regions, an Operational toolbox was designed comprising an integrated allocation model and a decision support module. The Water Evaluation And Planning System (WEAP) was used to define and calibrate the existing conditions. Possible scenarios for water supply (including conventional and non-conventional water) and consumptions (including drinking, agriculture and industry) where examined under current and potential future scenarios. A multiple attribute decision-making tool was utilised to rank various scenarios. The toolbox was used in an arid catchment of Iran, where indiscriminate use of conventional water resources, has posed a dominating water shortage.The results of the various scenarios showed that there is no scope to increase in agriculture allocation while the industrial allocation may be increased provided the non-conventional water is utilised to a certain extent. The results obtained from the toolbox has indicated that water transfer from other catchments is not an attractive option compared to the use of non-conventional water The results imply the effective role of recycling for the industrial water allocation, and desalination for the drinking water supply management.

Production and growth of plants in many parts of the world due to degradation and water scarcity have been limited and particularly, in recent decades, agriculture is faced with stress. In the most parts of Iran, especially in the Khorasan Razavi province, drought is a fact and water is very important. Due to melon cultivation in this province, and the conditions of quality and quantity of water resources and water used to produce the melon product in this province, any research done on the use of saline and brackish waters is statistically significant. To study the effects of different water salinity and water management on some of the agronomic traits of late summer melon with drip irrigation, an experiment with 7 treatments and 3 repetitions was conducted in a randomized complete block design, in Torogh station, Mashhad. The irrigation treatments were: 1- fresh water from planting to harvesting, 2- water (3 dS/m) from planting to harvesting, 3- water (6 dS/m) from planting to harvesting, 4- water (6 dS/m) from 20 days after plantation to harvesting, 5-water (6 dS/m) from 40 days after plantation to harvesting, 6-water (3 dS/m) from 20 days after plantation to harvesting, 7-water (6 dS/m) from 40 days after plantation to harvesting. Row spacing and plant spacing were 3 m and 60 cm, respectively and the pipe type had 6 liters per hour per unit of meters in the drip irrigation system. Finally, the amount of salinity water, number of male and female flowers, number of seed germination, dry leave's weight, leaf area, chlorophyll (with SPAD) etc. were measured and all data were analyzed by using MSTAT-C software and all averages of data, were compared by using the Duncan test. Results and Discussion The results of analysis of data showed the following: Number of seeds germination: Salinity in water irrigation had no significant effects on the number of seed germination. However, there was the most number of seed germinations in the fresh water treatments. However, with increased water salinity, the time of seed germination reduced. The maximum delay in germination of seeds was in the treatment that was irrigated with fresh water from the beginning of cultivation. Number of flowers: First, the male flowers appeared and after 5 to 7 days, the appearance of female flowers began. The effect of irrigation treatments on female flower appearance was significant. With increased water salinity, the number of male flowers decreased. There was the lowest male flower in the treatment that was irrigated with saline water from the beginning, but there was no significant difference among the other treatments. Root, steam and leaves: The effect of saline irrigation water on dried leaves’ weight and dry root weight was significant at 1% and 5% levels, respectively. Fresh treatment and salinity treatment have the least and the most root dries weight, respectively (irrigated from the beginning with fresh or saline water). Two treatments that were irrigated with fresh and brackish water from thebeginning of cultivation have the highest leaf growth. The same trend was true for steams. In general, in all treatments, after applying different quality water to the end of the growing season, the trend of plant growth was similar to the others. Chlorophyll: One of the most common measurements made by plant scientists is the determination of Chlorophyll concentration. The SPAD index was used for comparison of chlorophylls. With an increase of the salt in irrigation water, the SPAD index was also increased. The maximum and minimum SPAD was in the treatments that were irrigated with saline water (treatment A) and fresh water (treatment C) from the beginning of cultivation, respectively. Yield: With increasing the salinity of water, the total yield decreased. Salinity in irrigation water had a significant effect (at the 5% level) on total yield. The mean yield of brackish and salinity irrigation water treatments were 17.5% and 26% less than the fresh water irrigation treatment, respectively.These differences were significant. However, there was no significant difference between the yield of cases using brackish or salt water. The results showed the following: Salinity in irrigation water had no significant effect on the number of seed germinations. However, there was the most number of seed germinations in the fresh water treatments, but by raising the salinity of water, the time of seed germination was reduced. With increasing the salinity of water, the number of male flowers decreased. There was the lowest male flower in the treatment that were irrigated with salt water from the beginning, but there was no significant difference between the other treatments. The effect of salinity water on leaf dry weight and dry root was significant at 1% and 5% levels, respectively. Fresh and salinity treatments have the least and the most root dry weight, respectively (irrigated from the beginning with fresh or salt water). Two treatments that were irrigated with fresh and brackish water from the beginning of cultivation have the highest leaf growth. The same trend was true for steams. Two treatments that were irrigated with fresh and brackish water from the beginning of cultivation have the highest leaves areas. And they had significant difference with other irrigation treatments. With an increase in the salt in irrigation water, the SPAD index also increased. The mean yield of brackish and salinity water irrigation treatments were 17.5% and 26% less than that of fresh water irrigation treatment, respectively.These differences were significant. But there was no significant difference between the yield of brackish and salt water.

Great sturgeon is one of the most economically important species. However, in recent years overfishing, illegal fishing, etc., have resulted in severe declines in the stocks of this species. For conservation, stock of this species, determination of gonadal situation and its gonadal growth exchanges is very important. This paper is a histological approach to gonadal staging in 74 Huso huso in the 4 – and - 5 - year old classes. The fishes were reared in brackish water concert tanks under controlled conditions. A small section of the gonads of each fish was removed by biopsy. The gonadal tissue was fixed in buoin solution. They were dehydrated in different diluted solutions of alcohol and chloroform until they were clear. Then they were embedded in paraffin and sectioned at 7 µm and stained by hematoxylin and eosin method. Of the four-year old fish, %56 and %44 were males and females, respectively. %6 of males were at stage I %11 stage I-II %61 stage II %13 stage II-III %11 stage III-IV and %8 were at stage IV-V. %3 of the females were at unknown stage %3 stage I %11 stage I-II %60 stage II %14 stage II-III and 9% stage III. Of the 5 year old fish, %12.5 of males were at stage II % 25 stages II-III %50 stages III and %12.5 were at stage IV. %62.5 of females were at stage II and %37.5 were at stage II-III. Results of this study Compared with those obtained from fishes of the same age class studied in natural habitats as well as the results obtained for the farmed sturgeons from freshwater medium indicate that there is no similarly in the stage of gonadal development in different conditions. Longest stage in tow sexes was stage II that is longer in females, and passing of stage II in males is faster. Males showed more sexual maturity than females. Gonadic growth in culture medium is faster than wild condition, and it is faster in brackish water than fresh water. So, we can state that brackish water is a suitable medium for gonadic growth of Great sturgeon.