Journal of Water Research in Agriculture
Year:2011 | Volume:25 | Issue:1|Papers Count:8

In order to get a better grasp of the opportunities and constraints of transition to sustainable land and water management in Iran, four large-scale qualitative–quantitative surveys were designed to find out the attitudes, interests, and values of land and water stakeholders including farmers, village informants, soil and water experts, and policymakers. To collect data needed for answering research questions, different instruments including questionnaires, semi-structured interviews and open-ended interviews were used. These empirical investigations were carried out in 2007-2008 in Iran. Finally, with the integration of the theoretical and empirical researches the main contours of a more reflexive and sustainable land and water resource management in Iran were sketched. Accordingly, this reflexive framework includes four key elements. First, reflexive land and water technological innovation with its strategy of contextualization strives for restoration and integration of traditional and modern technology that focuses on the whole socio-technical system. To achieve this technological strategy, and as a second element, reflexive land and water governance should facilitate the inclusion of stakeholders in the process of transition. The third element is the Islamic land and water ethics with the core concepts of Islamic stewardship and environmental virtue ethics that can help people to understand how to live a good life in relationship to nature and the environment. The fourth element covers the reflexive soil and water sciences revitalized by an Islaminspired mode of inquiry that encourages achievement of stewardship management. This post-normal science and Mode 2 science facilitates the democratization of science to cope with the issue of interdisciplinarity and the exclusion of stakeholders (improving the relation between science and society) in the scientific atmosphere and research area. Finally, the land and water professional of tomorrow was portrayed as a “transdisciplinary engineer” and a “public leader”.

The objective of this study was to compare water and nitrate losses and water use efficiency in two alternate furrow irrigation regimes (fixed and variable) with conventional every-furrow irrigation under fertigation. Field experiments were carried out at the Experimental Station of the College of Agriculture and Natural Resources, University of Tehran, Karaj, in 2010. Three fertigations were applied for maize during the growing season. The results indicated that water losses in runoff were smaller in the alternate furrows method compared to the conventional every-furrow irrigation. Nitrate losses in runoff for the first, the second, and third fertigations were, respectively, 32.4%, 44.3%, and 80.3% in the conventional furrow irrigation, 31.2%, 35.1% and 40.2% in the fixed alternate furrow irrigation, and 25.7%, 32.7% and 36.9% in the variable alternate furrow irrigation, respectively. There was no significant difference between the conventional and the variable alternate furrow irrigation in terms of biomass and dry matter yields. Water use efficiency for the conventional, fixed alternate and variable alternate furrow irrigations were 1.61, 1.31 and 2.82 kg/m3, respectively. Variable alternate furrow irrigation not only decreased water and nitrate losses in fertigation but also significantly increased water use efficiency.

In order to evaluate drought stress effects induced by polyethylene glycol on seedling characteristics and growth of 8 bread wheat genotypes (Sardari 101, Homa, Rasad, Azar 2, Zarrin, Gascogen, Marten and Sayson), a 4×8 factorial experiment was carried out using completely randomized design with three replications. Results showed significant differences between bread wheat genotypes in all studied characteristics, except in radicle length (RL) plumule length (PL) ratio, root fresh weight (RFW), and root fresh weight (RFW) to plumule fresh weight (PFW) ratio. Interaction effects of genotype × drought stress levels were significantly different in all seedling traits except radicle length (RL), seedling fresh weight (SFW) and plumule fresh weight (PFW). With decrease of water potential, germination percentage, RL, PL, coleoptile length (CL), SFW, and PFW were decreased. According to cluster analysis, the 8 genotypes were placed in 3 different groups. Orthogonal polynomial analysis showed that dryland and irrigated cultivars were in two different groups. Under drought stress condition, Homa had the highest RL and PL as well as higher proportion of SFW and plumule fresh weight compared to the other cultivars. Homa showed more tolerance to drought stress than the other studied cultivars.

Plant growth promoting (PGR) Rhizobacteria enhances, directly or indirectly, growth and yield of plant. In this research, the efficiency of four strains of Fluorescent pseudomonads on growth index of rice is determined under saline condition. A pot experiment based on factorial completely randomized design was carried out with four replications. Five levels of saline irrigation water (700, 1400, 2800, 4200 and 5600 mS/cm from sea water source) and four inoculants (P. putida 11, P. putida 4, P.putida 108 and P.fluorescens 169) and a control (no inoculation) pot were used. Rice plant roots were inoculated with desired strains and transplanted in pots. During the growing period, the pots were irrigated with the abovementioned saline waters to the saturation point. Before harvest stage, growth indices such as plant height, number of tillers and number of spikelet were measured and, after harvest, dry weight of shoots, 1000 grain weight, and grain yield were determined. Results indicated that, with increasing salinity level, the amount of grain yield, 1000 grain weight, number of tillers, plant height, and dry weight of shoots decreased significantly (P<0.01). Meanwhile, inoculation with the bacteria strains increased the mentioned indices significantly at all salinity levels. Among the strains, P. fluorescent 169 exerted the greatest effect on yield, number of tillers, plant height, and dry weight of rice shoots in saline and non-saline conditions. Therefore, in saline condition, strains of Fluorescent pseudomonas can be used for promoting growth and yield of rice.

Due to the limitation of suitable water resources in arid and semi-arid areas, saline and brackish water is an important source for irrigation. Use of brackish waters is limited to salt tolerant crops or is used alternately with scarce freshwater resources in surface irrigation methods. Therefore, in this study, surface and sub-irrigation methods were investigated for production of tomato that is one of the world's major food crops. To achieve the proposed objective, a randomized complete block design experiment was performed in three replicates. Three levels of saline water (S1=0.7, S2=2 and S3=4 dS/m) were applied by two irrigation methods (M1=surface irrigation and M2=sub-irrigation). Water table level in sub-irrigation method was kept at 80 cm below the soil surface. The soil texture was clay loam. The results of this study showed that the salinity (p<0.01) and the interaction of irrigation method and salinity (p<0.05) had significant effect on tomato yield. But, irrigation method did not have any significant effect on tomato yield. The maximum yield (50.6 ton/ha) corresponded to M1S1 treatment and the minimum yield (37.4 ton/ha) was obtained in M1S3 treatment. The tomato yield in sub-irrigation system was higher (17.1 percent) than that in surface irrigation system when 4 dS/m water was applied. Irrigation method had significant effect (p<0.05) on fruit weight and number of fruit. Also salinity had significant effect (p<0.01) on fruit diameter, plant height, and wet weight. Salinity had significant effect (p<0.05) on the number of fruit. Among the irrigation treatments, M2S1 and M1S3 with, respectively, 9.4 and 4.9 kg /m3 had, the highest and the lowest water use efficiency.

This experiment was conducted to study drought tolerance in different genotypes of flax (Linum usitatissimum L.), including 10 breeding lines and five landraces. The genotypes were separately evaluated under two irrigation regimes based on 70 and 140 mm evaporation from class A Pan. The experiments were carried out in a randomized complete block design with three replications at the research farm of Isfahan University of Technology, in 2009. The results of analysis of variance showed that there were significant differences (P<0.01) among the genotypes for water stress indices and seed yield. According to the assessment of different water stress indices (SSI, STI, TOL, GMP and MP) STI seems to be the most suitable index for recognizing the more drought tolerant genotypes. Based on STI index, Chaharmahal landrace was the most tolerant genotype and the breeding line of KO10 was the most sensitive one. Seed yield for Chaharmahal landrace was 1468 and 1335 kg/ha while genotype KO10 produced 527and 111 kg/ha in the first and second irrigation treatments, respectively.

Different types of equations have been proposed to predict the sodium adsorption ratio (SAR), in drainage water. These empirical equations are tested here against the data of a lysimetric study to verify their validity. To obtain the basic relationships, a set of 116 water chemical analysis throughout Iran including river water, groundwater, and drainage water was used. Also, a set of 30 drainage water analyses was used for which precise measurements of irrigation and drainage water quality and quantities were available through a lysimetric experiment. Cylindrical lysimeters with internal diameter of 40 cm and height of 180 cm were filled with a sandy loam soil and irrigated weekly with natural water. Alfalfa was grown in the columns for a period of 3 years. Simple correlations between irrigation water SAR (SARiw) and SARdw yielded very poor regression coefficient (R2= 0.108). While steady state assumption i.e. concentrations being in direct proportion to 1/LF, could reasonably predict SARdw (R2=0.802), despite some variations in LF during the season. This correlation is comparable with more complex methods recently proposed.

Pan evaporation is one of the principal components of water resources management plans in arid and semi arid climates. One of the methods used in pan evaporation and evapotranspiration estimation studies is time series analysis. For such analyses, several models have been proposed, among which ARIMA, AR, MA are widely used. The aim of this study was to evaluate the performance of this type of models in estimation of pan evaporation in a five-year period (2006-2010) in Shiraz station. The results showed that the ARIMA (1, 1, 1) model yielded better estimates of temporal variations of time series compared to the other models, with a correlation coefficient and RMSE of 0.92 and 1.64 mm.day-1, respectively. Taking into account the lack of long record of pan evaporation data and the reasonable results of this study, application of these models in other climates is highly recommendable.