Journal of Water Research in Agriculture
Year:2011 | Volume:24 | Issue:2|Papers Count:7

In order to examine the possibilities for sustainable land and water management in Iran, this research was carried out with two types of research and their combinations, i.e. theoretical and empirical research during 2005- 2009. In the theoretical part, which is the scope of this paper, the co-evolution of agricultural technologies, social institutions, and ethical and religious mentalities throughout history were studied. The results showed that three periods could be distinguished: pre-modernity, industrial modernity, and reflexive modernity. The pre-modern era can be characterized by its key technical system (the Qanat system of underground water conveyance channels), its main governance institution (the Buneh cooperative organization of agricultural production) and its ethico-religious belief system (Zoroastrianism and Islam). The epoch of industrial modernity can be identified by the partial replacement of Qanats by deep wells and large dams, the substitution of the Buneh by a system of smallholding, and the emergence of a mechanistic worldview. Currently, Iran seems to be in stage of transition from industrial modernity to what has come to be known as reflexive or second modernity. Reflexive modernity can be characterized by the revitalization of traditional structures and their integration with the structures of industrial modernity, in such a way that the benefits and advantages of both will be preserved as much as possible.

In this research, the effects of four furrow irrigation treatments on some qualitative traits of soybean (Glycine max L. Merrill) were studied. Irrigation treatments consisted of full irrigation (100% soil moisture deficit compensation), conventional deficit irrigation limited to 50 and 75 percent compensation, and partial root drying for 50 percent of soil moisture deficit compensation. Soybean qualitative traits studied included seed oil and protein content and some morphological characteristics of shoot and root. The experiment was set up as a randomized complete blocks design with three replications at Research Field of Tehran University, Karaj. The amounts of irrigation water used exactly compensated soil moisture deficit (negligible loss). Results indicated that, with increased water stress, seed oil percentage decreased, while seed protein percentage increased. Under deficit irrigation, shoot growth decreased, but root growth increased. In various treatments of this study, not only seed oil percentage and, often, morphological characteristics did not have a significant difference, but water used in PRD50% treatment was half of that in DI50%.

Mineral accumulation and salinity increase osmotic pressure of soil solution and decrease the free energy of water, while plants alleviate this phenomenon by osmotic adjustment. In this situation, plants try to adjust their osmotic potential by accumulating N- compounds such as proline and OH-compounds in cell cytoplasm A such, part of photosynthetic products and ion accumulation needed for osmotic adjustment is consumed, thereby decreasing ion concentration needed for growth and yield of plants. Nowadays, biological methods are used to enable plants against salinity condition. In order to evaluate the role of mycorrhizal symbiosis in this respect, a completely randomized experimental design was set up in greenhouse condition with three levels of salinity i.e.4, 8, 12 dS/m using NaCl and CaCl2 in equal molar ratio, 5 inoculation treatments of mycorrhizal fungi including Glomus mosseae, Glomus intraradices, Glomus etunicatum, and a mixture of the mentioned species and check plants without inoculation, and two wheat cultivars, namely, Chamran and the promising Line 9 (Bank"S"/vee" S") as salininty semi tolerant and tolerant cultivars, respectively. Results showed that by increasing the salinity level, proline accumulation increased in wheat flag leaves. In Chamran cultivar, this concentration was higher than that in Line 9. On the other hand, water use efficiency, K, N, P, and Ca uptake in line 9 were higher than in Chamran cultivar. The difference between inoculated and un-inoculated treatments in Chamran cultivar and line 9 were significant for all the measured indicators. Mixed fungal treatment was more effective than the other fungal treatments in decreasing proline accumulation as well as increasing water use efficiency and mineral uptake in Chamran cultivar and Line9.

Drought stress is an important growth limiting factor for crop plants e.g. wheat. Large arable areas of Iran, where wheat is the main staple food, undergo drought stress. Therefore, it is necessary to investigate practical methods for increasing the yield of wheat in these conditions. Many plant growth promoting rhizobacteria (PGPR) contain 1-aminocyclopropane 1-carboxylate (ACC) deaminase enzyme that can convert the ACC, the immediate precursore of ethylene in plants, to ammonia and a-ketobutyrate and cause decrease in stress ethylene. In this greenhouse research, the effects of two strains of Sinorhizobium meliloti KYA40 and KYA71 that contain ACC deaminase enzyme and KYA95 (without ACC deaminase enzyme activity, used as a negative control) were investigated on growth and nutrients uptake of wheat under different levels of water stress. in a factorial randomized complete block design (RCBD). The water treatments consisted of d0=40-60% available water (AW), d1=20-30%AW, and d2=5-15 % AW. The results showed that inoculation with KYA40 strain increased the shoot length, shoot weight, root length, leaf area, and potassium uptake of wheat. The KYA40 strain increased the shoot weight in treatment d2. Strain KYA71 increased Cu and Mn uptake in treatment d0.

This study was conducted in order to determine the effect of deficit irrigation on yield and water use efficiency of new clones of potato. The study was conducted in Agriculture and Natural Resources Research Center of Hamedan Province in split plot design based on Randomized Complete Block with three replications. The main factor consisted of 6 irrigation treatments: 50, 60, 70, 80, 90 and 100 percent of crop water requirements. The sub-plots consisted of four potato clones and the control cultivar Sante. Water was applied by drip irrigation (tape). Measurements included water use efficiency in different irrigation treatments, total yield, tubers size, deformed tubers, decayed tubers, marketable yield and dry matter of the tubers. Results of multiple analysis variances of two years of experiment demonstrated that the effect of water treatment and clone was significantly different at 1% level in total traits, including the number and average yield of large tubers, seed tubers, and small tubers as well as total yield and water use efficiency. Maximum yield belonged to clone 397008-2 (72.7 Ton/ha). though it was not significantly different in 80, 90 and 100% irrigation regimes. In most water treatment, clone 397008-2 had the highest yield, although a significant difference between this clone and clones 397007-9 and 3970015-13 was not observed. Also, this clone had the highest WUE in irrigation treatment supplying 80% of potato water requirement. The highest percentage of tuber dry matter was achieved in the 60% irrigation treatment (22.87 %), which was significantly different (at 1% level) than the 50, 70 and 80% irrigation treatments. Overall, the maximum WUE belonged to the 80% irrigation treatment, being significantly different (at 5 percent level) than the other treatments. The results showed that provision of 80 percent of water requirement, in addition to saving water compared with the 90 and 100 % treatments, increased the water use efficiency significantly. Clone 397008-2 was better adapted to deficit irrigation than the other clones. Therefore, planting of this clone is recommended in areas faced with water shortages.

To Study the effect of irrigation water quality on yield of cantaloupe (Cucumismelo L. ' garmak') under trickle irrigation, a field experiment was conducted using three different irrigation water salinities of 2, 5, and 8.3 dS.m-1 (Q1, Q2 and Q3, respectively) with three replications. The study was carried out for two years in Rudasht Experimental Station in Isfahan. Treatments were applied as randomized complete block design. The results showed that the increase in irrigation water salinity from 2 dS.m-1 to 5 and 8 dS.m-1 caused significant reduction in fruit yield, number of fruits and fruit average weight. The average fresh fruit yield in the three water quality treatments was 45.2, 40.2, and 33.9 tons.ha-1, respectively. In comparison with the 2 dS.m-1 treatment, fresh fruit yield reductions in the treatments 5 dS.m-1 and 8.3 dS.m-1 were about 11.1 and 25 percent, respectively. The threshold soil salinity value (ECe) of cantaloupe under drip irrigation was found to be 2.3dS.m-1, while its yield reduction per unit increase in ECe was 11.7 percent.

In order to study the effects of omitting irrigation at some growth stages of apricot on the yield, fruit quality, and water use efficiency, an experiment was carried out in 2009 and 2010 seasons with randomised compelet block design and four irrigation treatments in four replications. The treatments were: E1) irrigation at all growth stages, E2) omitting irrigation water until pit hardening (lag phase) stage and irrigating in other growth stages), E3) irrigation from early season and omitting irrigation at pit hardening (lag phase) stage, then, irrigating till the end of the growing season, E4) irrigation from early season and omitting irrigation 15 days before harvesting, followed by irrigation to the end of the growing season. The apricot trees (prunus armenica, cv Askarabad) were 10 years old and irrigation system was bubbler. Fruits were harvested after maturity, but irrigation water measurement continued untill the end of the growing season. After determining the yield, fruit quality, and water use efficiency, statistical analyses of the experimental data was carried out on. According to the results, effects of omitting irrigation on yield and water use efficiency were significant at 1%, with the E3 giving the highest yield of 14767.88 kg/ha and water use efficiency of 2.69 kg/m3. The effect of omitting irrigation on leaf relative water content and the ratio of flesh to kernel were significant at 5% level. The E3 treatment (irrigation omitting at pit hardening) had the highest leaf relative water content and the flesh to kernel ratio, which were, respectively, 0.73 and 18.19.