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Faranak Baradaran-Hazaveh; Hossein Babazadeh; Ebrahim Amiri; Hossain ebrahimi
Abstract
Pulses have a special position, after wheat and rice, in the Iranian people diet. The growth of these plants is very fast and water stress has an important effect on their yield. The objective of this study was to evaluate the DSSAT Model in simulating the growth and yield of cowpea under different levels ...
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Pulses have a special position, after wheat and rice, in the Iranian people diet. The growth of these plants is very fast and water stress has an important effect on their yield. The objective of this study was to evaluate the DSSAT Model in simulating the growth and yield of cowpea under different levels of irrigation water. An experiment was conducted as a randomized complete block design (RCBD) with three replications in Kiashahr City, Iran, in the crop seasons of 2017 and 2018. The main treatments included irrigation with management of 40%, 60%, 80%, 100%, and 120% of plant water requirement and the three sub-treatments included irrigation at vegetative or reproductive stages, and full irrigation. In this experiment, the DSSAT simulation model was used to evaluate water efficiency and water balance components. Evaluation of simulated and measured values of grain yield was performed using the parameters of coefficient of determination, t-test, root mean square error (RMSE) and root mean square normalized error (nRMSE). The results showed that the difference between the predicted grain yield and the observed values was acceptable (RMSE=92 and nRMSE = 12.62%). Total biomass was also well simulated (RMSE=130 and nRMSE = 5.91%). Using the measured grain yield and water balance components simulated from the DSSAT model, the water productivity based on evapotranspiration (WPET) was about 33% lower than that based on transpiration (WPT). According to the results, irrigation with 100% water requirement at both vegetative and reproductive stages resulted in the highest transpiration (383mm), and was selected as the optimum irrigation management during the growing season.
h a; h b; Hossain ebrahimi
Abstract
Salinity is considered as one of the main problems affecting the growth and yield of many plants. Salinity tolerance varies with the amount of nitrogen uptake. The aim of the study was modeling the response of tomato (Solanum lycopersicum) under simultaneous salinity and nitrogen deficiency stresses. ...
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Salinity is considered as one of the main problems affecting the growth and yield of many plants. Salinity tolerance varies with the amount of nitrogen uptake. The aim of the study was modeling the response of tomato (Solanum lycopersicum) under simultaneous salinity and nitrogen deficiency stresses. The indoor pot experiment was conducted in Damavand region, Iran, in 2015. The experiment was carried out on tomato plant in a factorial randomized complete block design with 3 replications. The treatments consisted of six levels of salinity (1, 2, 4, 6, 8 and 10 dS/m) and three levels of nitrogen including zero, 50 and 100 percent of the N-fertilizer needs. The maximum dry matter yield (25.8 gr) was obtained in the treatment with salinity of 1 dS/m and fertilizer consumption of 100%, while the minimum dry matter yield (5.8 gr) belonged to the treatment with salinity of 10 dS/m and no fertilizer application. Modified Liebig-Sprengel (LS) and Mitscherlich-Baule (MB) models were used to evaluate tomato response to nutrients. Comparison of statistics showed that for modeling tomato plants response to simultaneous salinity and nitrogen stresses, modified MB model (d=0.95) fitted better to the measured data compared to modified LS model (d=0.88). Therefore, modified MB model was recommended to estimate relative yield of tomato. Also, results showed that, at a fixed salinity level, by increasing amount of nitrogen application, the yield of dry matter was increased, while yield of dry matter decreased with increasing salinity. Threshold of yield decline in saline conditions is not fixed and depends on the amount of nitrogen in the soil. Decline of relative yield with increase in salinity wasn’t significant in zero-nitrogen treatment, which showed the influence of nitrogen deficiency relative to salinity. Therefore, threshold of tomato yield decline could be increased by nitrogen fertilizer management.