| Over the past century,the global climate is undergoing a change of warming which is as the main characteristics and global average temperature has risen by 0.78 ℃.Climate change will cause the change of temperature which can directly affect the crop growth period length and start(end)time,then the balance between supply and demand of the agricultural water will be broken.The study of crop phenological period is the hotspot and leading edge in the field of agricultural production and irrigation management.Therefore,it is of great significance for agricultural management to carry out the study of the change of crop water requirement based on crop phenological period,especially it can provide direct technical support for the research of agricultural water supply and demand.In this paper,by means of the WheatGrowth model and the lowest accumulated temperature of the requirement of growth,the beginning and the end time of the different crops are calculated to analyze the crop growth period and the trends of different phenophase.The results are as follows:The optimal seeding time,the seedling stage and tillering stage of winter wheat showed the tendency of significant delay,however,from the over-wintering stage to the mature of winter wheat,the beginning of the growth period were characterized by significant trend in advance.From seeding time to the mature period,the summer maize showed an advanced trend.The change trend of the optimal sowing time and the seedling stage were not significant,while the spinning and mature period characterized by significant trend in advance.The overall trend of sowing and seedling stage of spring maize were in advance,but the change trend was not significant.The spinning and the mature period characterized by significant delay.Overall,the growth period of winter wheat,summer corn and spring corn days showed a decreasing trend and the whole stages shorten obviously in Haihe river basin.In addition,combined with phenological period and crop growth change under climate change,the evolution of crop demand water is studied based on crop phenological period.The results are as follows:From the interannual variation characteristics of sowing time to maturity of winter wheat water requirement,in addition to the green-jointing stage and grouting-mature present a trend of increasing water demand,the water demand variation during the rest of the growth period showed varying degrees of decline.The water demand of summer maize growth period showed different degrees of decline.The average annual crop water demand during emergence-spinning period declined significantly and climate tendency rate was 5.9 mm/10 a.The water demand of spring maize growth period showed different degrees of decline.The average annual crop water demand during spinning-maturity period declined significantly and climate tendency rate was 5.2 mm/10 a.From the overall trend,water requirement of winter wheat,summer maize and spring maize in growth period showed different degrees of decline.Under the background of global warming,the crop growth period shorten,and the water demand decreased in Haihe river basin,however,rain was not focused in haihe river basin which was easy to occur drought and flood events.So it was important to strengthen the optimization allocation of water resources and carry out agricultural efficient water saving irrigation mode in the haihe river basin. |
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