Application Of WOFOST Crop Model For Winter Wheat Yield Simulation In Anhui

The main planting areas of Winter Wheat in the Huaihe River and its north area were the main planting areas of Winter Wheat in our province.The cultivation and management of wheat was not enough only by traditional cultivation methods,so computer simulation with the aid of crop model was an effective auxiliary tool.It was of great significance for the development of agricultural production in China to develop agricultural scientific research with the combination of computer technology as well as the rational and effective use of the model to simulate crop growth.Based on the WOFOST crop model,in this paper took Anhui winter wheat as the research object,collected the database of crop,soil and meteorological data.Based on the sensitivity analysis of the input parameters of the model,the model parameters were determined and the data base suitable for the winter wheat growth simulation in this area was constructed.After this,the model localization and calibration were completed,so the WOFOST can be used in this area.The model was used to simulate the growth of Winter Wheat in one day interval,and the results of the model output were screened and processed.The simulated value of growth days,the simulated value of leaf area index of 2011-2013 years,which were compared and analyzed by the measured value.At the same time,the yield of Winter Wheat of 2004-2013 years was simulated and measured by the measured value.The results were compared and analyzed to explore the application of WOFOST model in winter wheat planting area in China.The conclusions are as follows:(1)Whether it was based on TAGP and TWSO output indicators,or under the two productivity levels of potential and water constraints,the sensitivity of parameter of the WOFOST model were TSMU1,FRTB,CVO,CVS,DVSI,SPAN,SLATB.And the relative sensitivity was greater than 0.5,which indicating that the relative sensitivity of parameters of the WOFOST model was basically the same in different production indexes and different production conditions.(2)Based on the TAGP production index,under the two productivity levels the sensitivity of parameters of WOFOST to were quite different from those of RMR,RMS,CVO,SPAN and TSUM2.Under the conditions of potential productivity level,they were 0.9928,0.8394,0.4809,0.3289 and 0.1986 respectively,meanwhile their corresponding values were 0.0418,0.1937,0.8527,0.6134 and 0.3488 under the water limited productivity level.Based on the TWSO production index,under the two productivity levels the sensitivity of parameters of WOFOST to were quite different from those of CVO,CVS and SPAN.Under the conditions of potential productivity level,they were 0.4812,0.7315 and 0.3290,meanchile their corresponding values were 0.8525,0.4977 and 0.6234 under the water limited productivity level.This indicated that there were some differences in sensitivity of parameters of WOFOST model under two productivity levels.(3)Generally speaking,the simulated days of total growth period of winter wheat in 2011-2013 years were 218,213 and 222 respectively,with an average value of 217.67.While the measured values of the total growth period in these three years were 229,224 and 221 respectively,with an average of 224.67.So we can calculate the error of average was 7 days.The average error of the number of days the simulated and measured days was 0.67 days from seedlings to flowering stage of winter wheat.Meanwhile the average error of the number of days from emergence to flowering period was 8 days and which was 2.67 days from flowering to maturity.It can be seen that the longer the growth period was,the greater the simulation error was.The simulation of the number of days in the whole growth period of Winter Wheat with the WOFOST model basically coincides with the actual situation,indicating that the model had a good simulation effect and provided a reference for the application of the model.(4)The leaf area index of winter wheat can effectively reflect its growth and development.The measured value of LAI was compared with the simulated value,we got the overall trend was consistent,while the maximum value of simulation was 6.5 and the maximum value of measurement was 6.37.It can be found that the WOFOST model has a better simulation effect on the leaf area index of winter wheat after being corrected and the situation was basically consistent with actuality.In addition,LAI in simulation value increased from 0 to peak need 161 days,while from the peak to the lowest point of the late growth period was 60 days.This indicated that the early stage of winter wheat growth was a long process.On the other hand,it had been proved that the TSUM was the most sensitive parameter for WOFOST model,and which was the key factor for the growth of winter wheat.(5)Based on the statistical analysis of the measured yield and simulated yield of winter wheat from 2004 to 2013,the average of 10 year measured yield was 6887kg/ha.But the average of simulated yield was 7842.4kg/ha,and the deviation was 955.4kg/ha.In general,the overall trend was that the simulated and measured values fluctuate upward,but more obviously,the simulated yield was higher than the measured,which was because the model was realistic and simplified.The WOFOST model automatically ignored many uncertainties in the reality of winter wheat growing.The simulation conditions were ideal,and the effects of pests and natural disasters were not considered.This was also the point which all the models were to be improved.The linear fitting of simulated yield and measured yield shows that R2 was 0.7483,and the simulated yield was close to the measured one.The results of paired sample t test showed t=-11.649,bilateral significant probability(bilateral Sig)P=0.000<0.05,showing a significant difference between the measured value and simulated one,and the difference between the two groups of data was significant statistically.As a whole,the WOFOST model was applied to simulate and validate growth period,leaf area index of three years and yield of ten years of winter wheat in Anhui province.It was concluded that this model had good application value in cultivation and management of winter wheat in Anhui area.After calibration,the applicability and predictability of the model can provide a theoretical reference for winter wheat production in Anhui and other places.It had important guiding significance for improving the modern agricultural management level and the protection of winter wheat production in our province.