Submitted to: Journal of Tropical Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2013
Publication Date: 12/15/2013
Publication URL: http://handle.nal.usda.gov/10113/59630
Citation: Lokhande, S., Timlin, D.J., Salokhe, V.M., Reddy, V. 2013. Simulation and assessment of planting date and climatic effects on soybean (glycine max l.) yields in Thailand using GLYCIM. Journal of Tropical Agriculture. 51:30-41. Interpretive Summary: The objective of this study was to evaluate the soybean simulation model, GLYCIM, under tropical environmental conditions for use as an on-farm decision support tool. The model was calibrated and validated using data collected at the Asian Institute of Technology, Bangkok, Thailand. Test plots consisting of various cultivars, soil types, planting dates, and environmental conditions were planted to soybean. The GLYCIM model was found to accurately calculate the crop growth, development, and yield of the plants grown on these plots. Next, a simulation study was conducted to test the model for use as an on-farm decision support tool to optimize the planting date for soybean under a range of geographical locations in Thailand. Simulations were carried out using 37 years of weather data to determine yield variations due to seven planting dates, three soil types, and three cultivars in the Sukhothai and Khonkaen areas in the northern part of Thailand. The results of the simulations indicated that delayed (middle of June to the end of June) planting showed a reduction in yield potential ranging from 7% to 35% due to a shorter growing season and increased water stress. The clay and silt loam soils showed higher yield potential compared to the sandy loam soil. These results confirmed the validity of the soybean model GLYCIM as a reliable on-farm decision support tool to optimize planting date and yields under tropical geographical locations. This information is useful for model users for on-farm decision support, scientists, and extension personnel involved in optimizing soybean yields.
Technical Abstract: The soybean model GLYCIM was used to assess soybean yield potential as a function of planting date, soil type and cultivar for growing conditions in northeastern Thailand. A study was conducted at the Asian Institute of Technology (AIT), Pathumthani, Thailand in 2005 to calibrate and validate GLYCIM for Thailand conditions. The study used three planting dates and three cultivars commonly used in Thailand, CM-2, CM-60 and SJ-5. The model validation results indicated a good agreement between simulated and observed data for phenology, growth and yield of soybean, and demonstrated the potential of the model for assessment purposes. Simulations were carried out to determine yield variations due to seven planting dates, three soil types and three cultivars using 37 years of measured weather data for two locations, Sukhothai and Khonkaen in the northern part of Thailand. Delayed (middle of June to end of June) planting showed a reduction in yield potential ranging from 7% to 35% due to a shorter growing season and increased water stress. The clay and silt loam soils showed higher yield potential compared to the sandy loam soil. There were no differences among the three cultivars and no significant interaction of cultivar with planting date or soil.