نشریه مدیریت آب در کشاورزی
سال سوم شماره 1 (پیاپی 5، بهار و تابستان 1395)

A clear understanding of the relation between irrigation water and soil salinity is necessary for precise analysis of data obtained from salinity experiments or from field observations. Soil salinity is expressed in terms of salinity of saturation extract (EC e) and soil solution) ECss with the use of EC e being more common. Often it is assumed that soil salinity (EC e) is always greater than irrigation water salinity (ECiw). However¡ EC e can be less or greater than ECiw. The determining factor in setting this relation is the amount of leaching fraction. In the layer within the root zone where leaching fraction is high¡ EC e is less than ECiw. Field data show that EC e within the root zone can even become less than half of ECiw. It is also shown here that EC e in the interval between two irrigation episodes does not change and remain constant¡ while ECss increases with time because of the crop water uptake.

Irrigation canals leading to increased resistance against scour the walls and water losses. They can be reduced influence that water in the soil. So the irrigation canals are essential for increased efficiency of water. Primer irrigation canals need for operating and maintaining that is costly and should be paid by government and public sector. Therefore, the participation of farmers in the operating and maintaining is essential. This study surveys has been conducted fieldwork in the third grade irrigation canals city of Rasht. The specific objective of the study is to investigate the factors affecting farmer's social-economic and professional farmers in the participation of, operating and maintaining of irrigation canals. The questionnaire was the main toll for collecting data. The validity of the questionnaire was approved by 15 subject specialists and reliability assessed with Cronbach's alpha 0.75 Obtained. The population of this research was 203 paddy farmers. By Gorgesi-Morgan formula 133 samples were selected with random sampling. The results showed the individual characteristics age, education, land holding, total income, social and economic condition of paddy farmers with participation of operating and maintaining of irrigation canals have significant positive relationship.

An experiment was conducted as a split plot design (with three replications) to evaluate effect of water deficit on seed germination of safflower cultivars. The main plots comprised six cultivars viz. Dizaj Hossein Beig¡ Koshaksara¡ Aghkand¡ N05¡ 917405 and 51063 and the sub main plots comprised three levels of osmotic potentials of 0¡ -0.6¡ and -1.7 bar. Results showed that stress levels affected germination percentage¡ plumule and seedling length. In addition¡ safflower cultivars had different germination percentages. Applying stress at -1.7 bar decreased plumule and seedling and ridicule lengths. Base on ability in germination under water deficit condition Dizaj Hossein Beig¡ Koshaksara¡ Aghkand are the suitable cultivar to cultivate in the water deficit conditions.

Water¡ as a natural resource is essential to form regional landscapes and very crucial for optimal functioning of ecosystems and human life. Now¡ this vital resource is under increasing pressure. Changes in the hydrological regime due to climate¡ demographic and economic factors have brought serious consequences for people and the environment. The importance of water governance in determining the ability of a country to meet the challenges of future climate has been emphasized in Water recent international congresses and published sources. In fact¡ many of them in this time properly announced that the global water crisis¡ is the crisis of governance not a crisis of scarcity. By examining resources and studies on water resource management in Iran could be confirmed that the concept of governance in general and specifically water governance¡ is as a discussion topic that many aspects of it still has not been explained properly¡ and missing a lot of discussions in world literature studies in the field of water in Iran is felt. Enjoying the water world literature¡ this article attempts to review concepts¡ challenges¡ tools and institutional arrangements related to this topic.

Based on proper conditions in terms of climate variability¡ Iran has a great potential in the production of ornamental and medicinal plants. The cultivation of these plants because of numerous features such as the possibility of refining environmental parameters¡ the higher productivity of production inputs¡ exchange intensity low (low needs to Dollar)¡ the possibility of the production out of season¡ value added and job creation and importing of the currency has increased since the late 70’s solar decade. That''s why the government has been done enormous investments to create the necessary infrastructure (construction of greenhouse complex and specialized export terminal and the construction of four flowers and plant terminal in the cities of Tehran¡ Mahalat¡ Dezful and Tonekabon) in order to modify the structure of the system supply and sale of the product¡ recently. Despite the vast diversity of climate and cultivation of medicinal species and the climatic conditions of various decorative and fits in any area in the country¡ a considerable part of it located in arid and semi-arid regions and in terms of the provision of allocation of water resources have limitations. Therefore¡ the need for proper planning in order to optimum use of limited resources of water in the country feel. In this regard¡ one of the most important goals in the domestic cultivation of medicinal plants and decorative is the planning of irrigation for the production of these products. Due to having multiple applications and values such as decorative¡ medicinal and health¡ Rose is one of the plants which has a special place for international trade. Iranian species of this plant is unique in the world. This plant is very resistant to environmental conditions and is well tolerated different weather conditions and water stress. Also¡ compared to the drought-resistant and depending on the area of culture¡ between 7 to 15 days once in the time of flowering and 20 to 30 days once in other periods of growth is irrigated. Increasing development of this plant in agricultural sector particularly in provinces with an arid and semi-arid climate due to the resistance of it to the water deficit conditions can be used as a strategic product in the field of supporting rural economy¡ job creation for youth and villager’s small industries¡ create specific position for Iran. The purpose of this article while reviewing the capabilities of rose as a native plant of the country for compatibility with the rising terms of dryness and drought¡ irrigation management¡ outlining this flower.

A lot of water is wasting through the canals and ponds. The use of geosynthetic materials such as geomembrane liners¡ have been welcomed by farmers due to their low cost¡ rapid installation and low water seepage. In this research¡ seepage water lost in 7 ponds with HDPE geomembrane lined in Semnan province was studied. To determine water lost¡ ponding method was used. The results showed that in the pools that were lined with HDPE geomembrane¡ the amount of water seepage lost was 4.5 to 46 (meanly 25) mm/m2/day. Water seepage losses in the stone and cement of pools was 74.5 to 84 (meanly 80) mm/m2/day. So¡ water seepage in geomembrane lined pools in about 30% of ston-lined pools. Water seepage losses in Geomembrane lining¡ was 20 times less than ston-lined. High-speed¡ short implementation time¡ lower cost¡ greater durability and very good seal¡ are the most important reasons for accepting the Geomembrane covers. The biggest weakness of the Iranian Geomembranes plates was width low. Low width sheets¡ increased cost of the projects.

Usage of drip tape irrigation systems for cereal crops is one of the problems that is increasing in many parts of Iran.Too much Focus on the water shortage leads to some solutions like drip tape irrigation for ceral crops which may reduce the problem temporarily but by the time causes the adverse effects on the environment. In this reasearch the innate problems related to drip tape irrigation as well as the environmental impact of plastic wastes which is incorporated in the environment by this irrigation method were investigated by calculating the amount of plastic wastes. The results showed that if the current trend continue¡ the share of agriculture in plastic wastes production will be very high. Environmental impacts of polyethylene are transfer of polyethylene pieces by wind or other factors which turns the point-source to nonpoint-source pollution that results in a progressive spread of undesirable effects such as the death of marine animals or being trapped in plastic wastes¡ hormonal disorders¡ and finally incorporation in human food chain¡ effects on livestock¡ pollution of water and soil resources due to its resistance to degradation¡ reduction in soil porosity¡ visual pollution and negative impact on tourism¡ production of harmful toxins such as carbon dioxide and hazardous dioxins due to burning the drip tapes and finally air pollution and global warming. If policymakers and water managers don’t consider these concerns¡ despite the waste of national capital by this irrigation method it will destroy national resources and will cause unstable operation of this irrigation system.