| Northeast China(NEC) is one of the most important production regions of spring maize in China. And it is the region where is experiencing a significant climate warming in China. Thus, it is necessary to evaluate the up limit and historical trend of yield, impact of climate change on spring maize and adaptation mechanism which are important to achieve high yield.In the study, data for climate, crop, and soil of tipical agricultural experiment stations in NEC were used for the evaluation of DSSAT and APSIM models. These two models were then used for maize growth and yield sensitivity tests to temperature, precipitation and CO2 at 10 tipical sites in NEC. And then, long-term historical trends of potential, attainable, and average farm yields were studied using APSIM model in Lishu, Jilin, which is a tipical maize production region. The impacts of climate change, improvements in agricultural practices and cultivars on potential, attainable yields in Lishu, Jilin were quantified through designing different scenarios with the simulation of APSIM model. Based on a 2 two-year experiences of spring maize in Lishu, Jilin, mechanism of high-yielding for newer maize cultivars and adaptation to climate change were also studied, the main conclusions are as follows:(1) APSIM and DSSAT-maize model had a similar response to temperature, precipitation and CO2: yield of spring maize in NEC is more sensitive to temperature than other climate, then is the precipitation; effect of CO2 on spring maize is not significant. However, the growth period of spring maize was only affected by the temperature, and shortened with the increase of temperature. There also were some differences between APSIM and DSSAT model in spring maize simulation under different environments in NEC. APISM model is more sensitive to temperature than the DSSAT model; under high nitrogen level, APISM had a better simulation in yield. However, DSSAT model responsed better under low nitrogen level than APSIM model, and had a good result in yield and LAI simulations.(2) From 1961 to 2009, the potential, attainable and average farm yields of spring maize in Lishu, Jilin were approximately 15100 kg hm-2, 10900 kg hm-2, and 5400 kg hm-2, respectively, with significant increasing trends of 1800—1980 kg hm-2·(10 a)-1, when the agricultural practices and cultivars were improved. However, the potential and attainable When the cultivar and agricultural practices were fixed, the potential and attainable yields were 9635—19904 kg hm-2 for different maize cultivars bred in different years, and statistically decreased, during the past five decades, no matter whichever cultivar was selected from the 10 cultivars. From 1961 to 2009, the potential and attainable yields of spring maize in Lishu, Jilin, reduced by 2.1% and 8% due to the climate change. Climate change mainly shorten the length of reproductive season, and decreased biomass and grain weight of spring maize in NEC.(3) For the period of 1961—2009, the potential and attainable yields increased by 62.2% and 80.5%, respectively, due to the improvements in agricultural practices and cultivars. The combined effects of climate change and improvements in agricultural practices and cultivars led to an increment of 53.6% and 70.3% for potential and attainable yields, respectively. For newer cultivars, the accumulated biomass during the reproductive season increased which would lead to a higher grain weight per ear(grain yield per plant). In addition, the grain weight per plant was the main reason leading to the increase of maize yield per hectar for newer maize cultivars. Ratio of length of reproductive season to the length of the whole growing season lengthened for newer maize cultivars, which was benefit to the accumulation of dry matter and grain filling, leading to the increase of yield. |
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