Document Type : Research Paper - Agroecology

Authors

• Hassan Shahbazi ¹
• khosro Azizi ²
• Sajjad Rahimi-Moghaddam ³
• Solieman Mohamadi ⁴
• Naser Akbari ³

¹ Ph.D Student of Agrotechnology, Department of Production Engineering and Plant Genetic, Faculty of Agricalture, Lorestan University, Khorramabad, Iran

² Professor, Department of Production Engineering and Plant Genetic, Faculty of Agriculture, Lorestan University, Khorramabad, Iran

³ Assistant Professor, Department of Production Engineering and Plant Genetic, Faculty of Agriculture, Lorestan University, Khorramabad, Iran

⁴ Associate Professor, Seed and Plant Improvement Research Department, West Azerbaijan Agricultural and Natural Research Center, AREEO, Ormia, Iran

Abstract

Introduction
 Background: Crop simulation models provide the possibility to study the effect of agronomic management practices on agricultural production activities in a given location. The models are mechanistic and process-oriented that are able to simulate different agricultural systems (including arid and semi-arid areas such as Iran) through different sub-models (biological, environmental, managerial, and economic sub-models) connected with the main engine of the models. The APSIM-Barley model can be used to evaluate the management practices on barley crop. The current research was carried out to evaluate the APSIM-Barley model in relation to simulating the growth, development, and yield of three barley cultivars (Azaran, Jolgeh, and Bahman) under different conditions of nitrogen and irrigation supplies.
 Materials and methods
 In order to evaluate the APSIM-Barley model regarding simulating and quantifying the phenological stages, biomass, and grain yield of different barley cultivars, some independent experiment datasets were used. For crop model calibration, an experiment was conducted in a factorial split plot design at the Agricultural Research Center of Hamedan in 2019. The main factor consisted of three irrigation levels (30-40, 60-70, and 90-100% of the field capacity) and sub-factors included cultivar levels (Azran, Jolgeh, and Bahman as early, mid, and late cultivars, respectively) and three nitrogen levels (zero, medium, and optimum). For model validation, another series of independent datasets in different years consisting of published articles and research projects were used. For assessing the efficiency of the crop model and comparing the simulated and measured values, R2, nRMSE, d-index, and MBE indices were used and OriginPro software was considerd for all statistical analysis and drawing of figures.
Results and Discussion
 The simulation results of APSIM-Barley model in the calibration step showed that nRMSE for days to flowering and maturity was 2.43 and 2.4%, respectively.  Also, under full water and nitrogen conditions, nRMSE for the leaf area index of Azaran, Jolgeh and Bahman cultivars was 13.5, 14.1, and 10.7%, respectively, and under severe water and nitrogen stresses, it was 16.5, 18.6, and 26.5% respectively. At this step, and nRMSE and d-index for biomass and grain yield were 24.9% and 0.98 and 15.2% and 0.96, respectively.  In model validation step, nRMSE, d-index, R², MBE were 15.02%, 0.96, 0.82 and 0.34 t ha^-1, respectively, for grain yield.
 Conclusion
In general, the results showed that the APSIM-Barley model was able to simulate the growth, development, and grain yield of different barley cultivars with acceptable accuracy under different water and nitrogen management conditions in different years and regions. Therefore, the APSIM-Barley model can be used as a reliable tool in future studies such as climate change assessment, yield gap analysis, agricultural zoning, and etc. by other researchers.
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Keywords

• Biomass
• Days to flowering
• Leaf area index
• Modeling

Main Subjects

• A: Agroecology