reza saeidi; Hadi Ramezani Etedali; Abbas Sotoodehnia; abbas kaviani; Bijan Nazari
Abstract
In this study, yield and evapotranspiration of maize (cv. SC 704) were investigated under salinity stress and nitrogen deficiency. The experiment was carried out in a randomized complete block design. Electrical conductivities of saline water treatments were 0.5( 15S0"> ), 2.1( 15S1)"> , 3.5( 15S2) ...
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In this study, yield and evapotranspiration of maize (cv. SC 704) were investigated under salinity stress and nitrogen deficiency. The experiment was carried out in a randomized complete block design. Electrical conductivities of saline water treatments were 0.5( 15S0"> ), 2.1( 15S1)"> , 3.5( 15S2) "> , and 5.7( 15S3) "> dS. 15m-1"> . Nitrogen deficiency treatments were 100% ( 15F0"> ), 75% ( 15F1"> ), 50% ( 15F2"> ), and 25% ( 15F3"> ) of nitrogen fertilizer requirement based on soil testing. The treatments were carried out in three replications and in plots with area of 9 m2. In different treatments, evapotranspiration of maize was between 220 to 349 mm and dry matter yield between 9.4 to 15.2 ton.ha-1. With increase in the salinity levels in , , , and treatments, the slopes of yield function were estimated as 0.2, 0.207, 0.218, and 0.231, respectively. Also, with reduction of nitrogen at salinity levels of , , and , the slopes were estimated as 0.175, 0.182, 0.194 and 0.221, respectively. The results showed that, with increasing stresses, yield of maize decreased more than evapotranspiration. The coefficient of was calculated using the Doorenbos-Kassam relationship. With reduction of nitrogen at salinity levels of , , and , values of coefficient were estimated as 1.01, 1.048, 1.119, and 1.272, respectively. Also, with increase in the salinity at nitrogen levels of , , and , Ky values were estimated as 1.15, 1.19, 1.258, and 1.328, respectively. On the average, Ky was calculated as 1.27. Under the highest stress 15 S3F3"> , water and nitrogen use efficiency decreased by: 38% and 34.5%, respectively, compared to the control treatment (S0F0). The results showed that the water requirement and yield of maize under the mentioned stresses were less than the region’s potential. Under these conditions, by supplying soil nitrogen and reducing water use, water resources will be used optimally and yield will increase.
Mahnoosh Jenab; Bijan Nazari
Abstract
Improvement of water productivity is very essential for achieving water and food security. One of the basic strategies in this field is determination of crop yield gap and water productivity gap, which is the difference between the present actual situation and the potential situation. This research was ...
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Improvement of water productivity is very essential for achieving water and food security. One of the basic strategies in this field is determination of crop yield gap and water productivity gap, which is the difference between the present actual situation and the potential situation. This research was carried out for wheat in Qazvin province according to GYGA protocols, which is an international methodology. At first, the map of climatic zones of the province was prepared based on Emberger method by using GIS. Then potential yield gap of wheat was estimated according to calibration and simulation of version 5 of Aqua crop model. Results showed that yield gap in various climate zones of the province was between 4502-6271 kg/ha, evapotranspiration water productivity gap was between 0.56-0.66 kg/m3 and water (irrigation and effective rain) productivity gap was between 0.57-0.71 kg/m3. Results showed that actual wheat yield in Qazvin province is 37 percent of the potential yield. Also, relative evapotranspiration water productivity index was 0.47 and relative water productivity index was 0.31. These indices show the ratio of the actual to potential productivities. Based on this research results, the extent of gap between optimum and current condition of yield and water productivity is very wide. Yield gap is 63% of potential yield and water productivity gap is 69% of potential water productivity. This issue represents the considerable weakness existing in management of agricultural production and irrigation and reflects the potential opportunities for strengthening these operation, improving water productivity, decreasing the pressure on water resources, and increasing food security.