基于DSSAT模型的广西地区甘蔗亏缺灌溉优化

Optimizing Deficit Irrigation for Sugarcane in Guangxi Province Using the DSSAT Model

【目的】优化广西地区甘蔗灌溉制度,提升甘蔗产量。【方法】分别在甘蔗苗期(T1—T4处理)、分蘖期(T5—T8处理)、伸长期(T9—T12处理)、成熟期(T13—T16处理)设定10、20、30、40 mm的亏缺灌溉处理,以每个生育期灌水量50 mm为对照(CK),共计17个处理,借助DSSAT模型研究甘蔗在不同亏缺灌溉处理下,产量、水分生产率(WUE)和灌溉水分利用效率(IWUE)的变化特征;通过确定需要优化的生育阶段,使用遗传算法对田间试验设置5个灌溉处理(40、80、120、160、200 mm)进行优化。【结果】减少甘蔗苗期、分蘖期和成熟期的灌溉量促进了WUE和IWUE的提升,且产量的提升不明显;当减少甘蔗伸长期的灌溉量时,产量表现为:T12处理>T10处理>T9处理>T11处理,亏缺灌溉对各处理产量影响明显,分别比CK产量降低了3.53、5.40、9.86、12.33 t/hm2;遗传算法对甘蔗苗期、分蘖期和成熟期的优化,提升了产量和WUE。在120 mm处理和160 mm处理下,算法优化田间亏缺灌溉的产量分别提升了2.5%、8.7%,WUE除40 mm处理外,均优于非优化的亏缺灌溉。【结论】在综合考虑甘蔗产量和WUE最优的情况下,遗传算法优化的亏缺灌溉,120 mm处理和160 mm处理具有一定的优势。

【Background】More than 85%of sugar crops in China are sugarcane and more than 90%of its sugar is made using sugarcane.The double whammy for sugarcane production in China is the dwindling water and soil resources and the increased demand for sugar.Improving water use efficiency is hence critical to sustaining sugarcane production.【Objective】This paper is to investigate experimentally the impact of the level of deficit irrigation imposed at different stages on the growth and yield of sugarcane.【Method】The experiment was conducted at a field in Guanxi province.The crop was irrigated at seedling,tillering,elongation,and mature stage with 10 mm(T1),20 mm(T2),30 mm(T3)and 40 mm(T4)of water respectively,with irrigation of 50 mm taken as the control(CK).Overall,there were 17 treatments and they randomly arranged in the field.Crop growth and development in each treatment was simulated using the DSSAT model,from which we calculated the change in water productivity,irrigation water use efficiency (IWUE) and the ultimate crop yield. These results were used to optimize the deficit irrigation using the genetic algorithm.【Result】Reducing irrigation amount at seedling, tillering or mature stage improved both WUE and IWUE, although the yield difference between the treatments was not significant. Reducing irrigation amount at the elongation stage reduced the yield significantly, with T1—T4 reducing the yield by 12.33, 9.86, 5.4 and 3.53 t/hm2, respectively. The optimized deficit irrigation calculated by the genetic algorithm had the least impact on sugarcane growth, and it improved both yield and WUE as a result. Compared with CK, the optimized deficit irrigation at 30 mm and 40 mm mm increased yield by 2.5% and 8.7% respectively. Except 40 mm, all other deficit irrigations increased WUE. 【Conclusion】Considering yield and WUE, the optimized deficit irrigation calculated by the genetic algorithm was 30 mm to 40 mm at each of the four growth stages.