Alireza Tavakoli; Abdolmajid Liaghat; Amin Alizadeh
Abstract
Crops growth and production in rainfed systems is a function of changes in climatic parameters. Identification of the effective parameters and planning for their management and/or adapting agronomic practices to those changes will result in improving production baseline and yield prediction. In order ...
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Crops growth and production in rainfed systems is a function of changes in climatic parameters. Identification of the effective parameters and planning for their management and/or adapting agronomic practices to those changes will result in improving production baseline and yield prediction. In order to estimate climate-yield production functions, we analyzed eight crop seasons data (1998-2006) of 25 climate parameters and rainfed wheat grain yields of four cold and semi-cold regions of Lorestan province including Aleshtar, Khoram-Abad, Aligodarz, and Boroujerd. Correlation coefficients of linear and non-linear regressions were established between each weather parameter, as the independent variable, and wheat grain yield. By path analysis method, correlation coefficients were separated into direct and indirect effects. Results showed that, in local models of production functions, the role of vapor pressure deficit during crop growth was very important. Rain water productivity of all regions determined for eight crop seasons, and the amounts of maximum, minimum, and average rain water productivity were 0.341, 0.132, and 0.234 kg per cubic meter precipitation, with the average being 20 percent lower than the national average (0.292 kg.m-3). The maximum temperature of Oct-Nov, sunshine hours,, autumn precipitation, and maximum seasonal temperature were the most sensitive parameters with respect to grain yield prediction. Determination of the effective climatic factors and the degree of their effects will help farmers in adopting improved agronomic practices (such as proper planting dates, suitable cultivars, and improving soil water holding capacity), thereby controlling the negative factors affecting criop growth and yield and improving the effectiveness of the positive factors.
Masoud Mohammadi; Hossin Molavi; Abdolmajid Liaghat; Masoud Parsinejad
Abstract
Salinity and water stress are the main problems of agricultural production in many parts of the world, especially in arid and semi-arid areas. Therefore, this study was conducted to investigate the effects of Zeolite application under salinity and ...
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Salinity and water stress are the main problems of agricultural production in many parts of the world, especially in arid and semi-arid areas. Therefore, this study was conducted to investigate the effects of Zeolite application under salinity and water stress conditions on yield and yield components of Corn in Karaj, Iran. A factorial design with randomized complete block arrangement was used with three replications including three factors: salinity, irrigation water, and Zeolite application. Irrigation water, salinity and Zeolite application factors consisted of two levels each:W1=100% and W2=50% of crop water requirement; S1=0.7, S2=5 dS/m, and Z1=0 and Z2=10 t/ha, respectively. The soil texture was clay loam. Results showed that salinity and water stresses reduced yield and yield components, while Zeolite application increased them. Simultaneous impact of salinity, deficit irrigation, and Zeolite application had significant effect on corn yield, the 1000 kernels weight, number of grains per ear, and plant height. The maximum corn yield, 1000 seeds weight, number of grains per ear, and plant height were, respectively, 7233.3 kg/ha, 309 g, 504, and 220.7 cm and corresponded to W1S1Z2 treatment, while the minimum corn yield, 1000 seeds weight, number of grains per ear and plant height were 2296 kg/ha, 101.7 g, 159, and 146.3 cm, respectively, and belonged to W2S2Z1 treatment. The maximum water use efficiency (1.41 kg/m3) and its minimum (0.68 kg/m3) were observed in W2S1Z2 and W1S2Z1 treatments, respectively.
Mina Shakiba; Abdolmajid Liaghat; Farhad Mirzaei
Abstract
Effluent disposal and its harmful impacts on environment are an important challenge in drainage projects and environmental problems in Iran. Therefore, by analyzing the flow net and determining the flow paths, efforts must be made to reduce the amount of effluent and improve its quality. This study aimed ...
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Effluent disposal and its harmful impacts on environment are an important challenge in drainage projects and environmental problems in Iran. Therefore, by analyzing the flow net and determining the flow paths, efforts must be made to reduce the amount of effluent and improve its quality. This study aimed to observe the mixing depth as an effective parameter affecting the salinity of effluent. In this experiment, a plaxiglass model was used to investigate the effect of water table head on mixing depth. Mixing depth is the farthermost flow line below the drainage pipe installation depth. At first, KMnO4 and NaCl were added to groundwater supply to increase the salinity of groundwater to 20 dS/m. Then, by using different input discharge and water table head, the variety of mixing depths was determined with photography. Results showed that with increase in the amount of irrigation water, the water table head and mixing depth increased and caused high salinity of the effluent. For instance, by increasing water table head from 8 cm to 23 cm, salinity of the drainage water raised about 80 percent. Finally, the mixing depth was determined as a function of outflow discharge, hydraulic conductivity, depth of impervious layer, and head in the middle of the drainage water. In the next step, the model was validated using observed experimental field data collected from sugar beet development projects in Amirkabir unit located in Khuzestan, Iran. The comparison was done between the salinity that was simulated by the model and the measured value. The results showed the effect of mixing depth on salinity of effluent.