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atefeh roudbari; ali bagheri
Abstract
Unfortunately, at some meteorological stations, there are no facilities for measurement of some weather parameters, so, they should be estimated. Therefore, determining the correctness of the reference evapotranspiration (ETo) method by using the estimated data is very important. Based on this, the objective ...
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Unfortunately, at some meteorological stations, there are no facilities for measurement of some weather parameters, so, they should be estimated. Therefore, determining the correctness of the reference evapotranspiration (ETo) method by using the estimated data is very important. Based on this, the objective of the present study was to evaluate the performance of the Penman-Monteith method for estimating ETo in Mazandaran Province, Iran, when solar radiation (Rs), vapor pressure (ed) and relative humidity (RH) data are not available. Data of Sari, Qarakheil, and Amol synoptic stations were used to compare the estimated ETo by the Penman-Monteith method for the complete and limited data sets. The results showed that when RH and ed data were missing, the Penman-Monteith method was still a very good option for estimating ETo in Sari, Ghaemshahr and Amol station, with RMSE values smaller than 0.3 mm day-1. However, when Rs was missing, the Penman-Monteith method was not good enough for estimating ETo, and RMSE increased to more than 1 mm day-1. The results also showed that solar radiation was the most effective parameter on ETo estimation and both vapor pressure and relative humidity had the same effect on ETo estimation.
moazam khaleghi; Ali Shahnazari; farzad hasanpour; F K
Abstract
The scarcity of freshwater and increasing water demand for irrigation has led to the application of new irrigation methods and also use of saline water resources. For this purpose, a field study was conducted in two crop seasons (2014 and 2015) for evaluating the effect of quantity and quality ...
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The scarcity of freshwater and increasing water demand for irrigation has led to the application of new irrigation methods and also use of saline water resources. For this purpose, a field study was conducted in two crop seasons (2014 and 2015) for evaluating the effect of quantity and quality of irrigation water on morphological attributes and quality of sunflower in the experimental farm of Sari Agricultural Sciences and Natural Resources University. Treatments were arranged as factorial based on randomized complete block design with three replications. treatments included full irrigation with fresh water (FI), full irrigation with saline water (SI), full irrigation with alternative use of saline water and fresh water (FSI), partial root zone drying irrigation with fresh water (PRD1), partial root zone drying irrigation with saline water (PRD2) and partial root zone drying irrigation with alternative use of saline and fresh water (PRD3). Saline water with an electrical conductivity of 5.4 dS/m was obtained from 20 percent mixing of Caspian seawater with fresh water. The results showed that, in most morphological characteristics, significant difference was not found between the treatments of PRD1, PRD3 and FSI compared with FI. The highest oil content (56%) was obtained from PRD2 and PRD3. SI treatment had the lowest oil content. The maximum oil yield was found in treatments FI and PRD1 with amounts of 1831 and 1783.5 kg per ha, respectively. The lowest level of oil and protein yield was found in PRD2 and SI treatments in both years. It could be concluded that in the water crisis condition and the need to use less water or saline water instead of fresh water, PRD3 and FSI methods are recommendable as the optimal management.