E. Amiri; M. Rezaei; M. Bannayan Awal
Abstract
Abstract
To evaluated ORYZA2000 model in Iran, this study was carried out during 2004 till 2007 at Rice Research Institute of Iran, Rasht. The experiment was conducted as split plot in complete randomized block design and three replicates. Three irrigation levels were the main plots and four levels ...
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Abstract
To evaluated ORYZA2000 model in Iran, this study was carried out during 2004 till 2007 at Rice Research Institute of Iran, Rasht. The experiment was conducted as split plot in complete randomized block design and three replicates. Three irrigation levels were the main plots and four levels of N application were allocated sup-plots model. Simulated and measured values leaf area index (LAI) and biomass of leaves, panicles, total aboveground biomass and crop N dynamics, was evaluated by adjusted coefficient of correlation; t-test of means; and absolute and normalized root mean square errors (RMSE). Results show that, with normalized root mean square errors (RMSEn) of 5–51%, ORYZA2000 satisfactorily simulated crop biomass and N uptake that strongly varied between irrigation and nitrogen fertilizer. Yield was simulated with an RMSE of 155–464 kg ha-1 and a normalized RMSE of 3–11%. Simulated LAI generally exceeded measured at low rates of nitrogen application. Results show that, ORYZA2000 could be used successfully to support N and irrigation management under the limited conditions.
Keywords: Rice, Model, Evaluation, Nitrogen, Irrigation
M. Navabian; M. Aghajani; M. Vazifehdost; M. Rezaei
Abstract
Abstract
Rice is most important agricultural crop of Guilan province sensibility to salinity and alkalinity of water and soil. In recent years, using of toxicants and fertilizers in farmlands, constructing several dams upstream, entering agricultural, homemade and industrial sewage in to a river, and ...
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Abstract
Rice is most important agricultural crop of Guilan province sensibility to salinity and alkalinity of water and soil. In recent years, using of toxicants and fertilizers in farmlands, constructing several dams upstream, entering agricultural, homemade and industrial sewage in to a river, and drought have decreased gradually discharge of river and increased salinity of Sefidrud River as an irrigation source of Sefidrud irrigation network of Guilan province. This research tries to determine the optimal intermittent and depth of irrigating of rice in proportion to salinity of Sefidrud River using of optimization- simulation mechanisms as is the decrease in crop efficacy become minimum. To achieve this, an agro hydrological SWAP was used to simulate different stages of rice growing and an optimization model was used in a reasonable range of the intermittent rice irrigation period and depth with regard to different growth stages. Because some types of rice are affected by salinity, field experiments of Hashemi variety in Rasht in 1386 were used to calibrate the model. Optimal values of the intermittent irrigation regime in current salinity of the Sefidrud River (1.747 ds/m) included 8 days intermittent irrigation period and the depth of water for irrigating was 1, 3, 4 and 5 for vegetative, tiller, maturity and harvest stages respectively. The comparison of results of optimization- simulation model with field data in 1389 showed good efficiency of this model in irrigation optimization. In the field experiment 8 days intermittent period with irrigation 5 cm in depth was highest crop performance in 2 ds/m salinity.
Keywords: Rice, Intermittent irrigation management optimization, Sefidrud, Salinity, SWAP model
M. Rezaei; N. Davatgar; K. Tajdari; B. Abolpour
Abstract
Abstract
Guilan is a famous province in growing rice in Iran. Recently, due to shortage of water, farmers' desire to use groundwater in order to grow rice in northern part of Iran has been increasing rapidly. The fact that rice is sensitive to water quality, caused concern about rice cultivation sustainability ...
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Abstract
Guilan is a famous province in growing rice in Iran. Recently, due to shortage of water, farmers' desire to use groundwater in order to grow rice in northern part of Iran has been increasing rapidly. The fact that rice is sensitive to water quality, caused concern about rice cultivation sustainability in the area, especially in drought years. This study was done to investigate the spatial variability of some important ground water quality factors including EC, SAR and Na of samples taken from 135 wells over the region during the summer of 2007. First, the accuracy of Kriging (Ok) and Inverse Distance Weighting (IDW) with 3 different powers (1, 2 and 3) in mapping the studied parameters were evaluated. Then the final map was presented. The result showed that spherical model gave the best result to simulate the Vriograms. Although negligible difference was observed between the methods, Ok and IDW1 performed better in comparison to the IDW2 and IDW3. The final map showed that Ec in central part of the region, where the Sepidrod River meets the Caspian Sea is dramatically high which will threaten the sustainability of rice cultivation in the area. The other factors were in suitable level.
Keywords: Groundwater, quality, spatial variability, Iran
M. Rezaei; M. K. Motamed; A. Yousefi; E. Amiri
Abstract
Abstract
In order to study the effects of different irrigation management on water productivity of local, improved and hybrid rice varieties an experiment was carried out on a split plot design with 3 replications. The varieties were splited on 5 irrigation methods (i.e. full irrigation, AWD, 5, 8 and ...
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Abstract
In order to study the effects of different irrigation management on water productivity of local, improved and hybrid rice varieties an experiment was carried out on a split plot design with 3 replications. The varieties were splited on 5 irrigation methods (i.e. full irrigation, AWD, 5, 8 and 11 day irrigation interval) at Rice Research Institute of Iran, Rasht during cropping season of 2006. The results showed that interval irrigation reduced water use. Full irrigation with 593 mm had the highest water use and 11 day interval with 406 mm the lowest. Yield in hybrid, improved and local varieties were 6147, 5147 and 3987 kg/ha respectively. Results showed that yield loss in the varieties due to water stress (full irrigation, 5, 8 and 11 day interval irrigation) in hybrid were 9,19,23 and 44 percent, in improved were 14, 19, 23 and 29 percent and in local variety were 5,4,10 and 17 percent respectively. Local variety was the most resistant and hybrid was the most susceptible variety.
Keywords: Intermittent Irrigation, yield, water productivity, rice
K. Majdsalimi; S.B. Salvatian; M. Rezaei
Abstract
Abstract
Shortage and improper distribution of rainfall in tea growing period are important growth limiting factors in tea fields in Northern part of Iran. If there is not any other limited factors, supplemental irrigation by sprinkler can increase tea yield. This study was carried out in order to investigate ...
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Abstract
Shortage and improper distribution of rainfall in tea growing period are important growth limiting factors in tea fields in Northern part of Iran. If there is not any other limited factors, supplemental irrigation by sprinkler can increase tea yield. This study was carried out in order to investigate the optimum sprinkler irrigation interval on yield and water use efficiency of tea. The experiment was conducted on a CRBD with three replications during tea planting period of 2002-04 in Fouman tea research station. The irrigation treatments were 4, 8, 12 and 16 day irrigation intervals along with rainfed treatment as control. Results showed that control and 4 day interval treatment with 1483 and 3443 kg/ha had the lowest and highest yield respectively, and 8, 12 and 16 day irrigation intervals were in next grade, respectively. In term of water use efficiency, control and 4 day treatment in dry period with 0.34 & 0.67 kg (made tea)/m3 of used water had the maximum and the minimum water use efficiency. Irrigation water use efficiency in growing period for 4, 8 ,12 and 16 day treatments were 0.66, 0.55, 0.48 and 0.36 kg/m3, respectively. Since very short period of dry season in the last year of the experience(2004), no significant difference was observed in yield.
Keywords: Tea, Sprinkler irrigation, Irrigation interval, Water use efficiency