| In recent years,climate change characterized by global warming is gradually affecting the agricultural planting system,species distribution and growth of plants.Phenological period,the most sensitive sensor of plants,is also changing along with climate change.Present studies suggest that climate warming will continue to advance the spring phenology but postpone the autumn phenology of plants,besides,this effect for some natural plants is nonlinear.As not only the sensitivity of crop phenology toward climatic factors is different from natural plants,but also affected by varietal replacement,farming measures and other human factors,so it's non-linear response characteristics might be special.Therefore,by referring to the data provided by CMA agricultural meteorological station,this paper studies the spatial and seasonal variation of different phenological period of winter and spring wheat in China as well as its relationship with temperatures.In the following,thermal unit method is adopted to fit the influence of temperature change and variety change on winter wheat,after progressively removal,it analyzes the impact of winter and spring wheat varieties and precipitation on phenological period.Researches show that the zonal arrangement in space of China winter and spring wheat in regards of phenological period occurrence time and duration has a lot to do with latitude.Various phenological period occurrence time before the seedling establishment period of winter wheat is delayed gradually from north to south,while the various phenological period occurrence time after the seedling establishment period of winter wheat is advanced gradually from north to south,after comparing phenological periods in different partitions,it found out that southern winter wheat partition is the most advanced,with the heading period of 5.37d/10a,(P<0.1)while northern winter wheat partition is the most postponed,with seedling establishment period of 6.22 d/10a(P<0.01).Various phenological period occurrence time of spring wheat is gradually advancing along with the decreasing of latitude,and the overall trend is late in northeast and northwest,early in the middle,and the northeast is later than the northwest.Comparison among different partitions found that the earliest partition is northern Xinjiang,with the mature period of 4.91d/10a,while the most delayed partition is Qinghai-Tibet,with the milk ripe stage of 9.54d/10a(P<0.01).The relationship between various phenological period duration of China winter-spring wheat and the antecedent temperature is not always in linear trend,in individual partitions,it is nonlinear relationship.From the linear relationship point of view,no matter the national overall trend or individual partitions trend,the phenological period before stop growing stage is delaying along with the increasing of temperature,but after the period of seedling establishment,it is advancing along with the increasing of temperature.In regards of linear postpone,northern winter wheat partition has the most delayed time,with the stop growing stage of 4.1 days/?(N=825,P<0.01),while southern winter wheat partition has the least delayed time,with the tillering stage of 1.3 days/?(N=654,P<0.01);northern winter wheat partition has the most advanced time,with the elongation stage of 5.5 days/?(N=782,P<0.01),while Xinjiang winter wheat partition has the least advanced time,with the milk ripe stage of 3.8 days/?(N=269,P<0.01).No matter the national overall trend or individual partitions trend,various phenological period of spring wheat shows the trend of advancing,the most advanced and the least advanced partitions of spring wheat phenological period along the temperature is the milk ripe stage and seeding stage in Qinghai-Tibet spring-winter wheat region and north xinjiang winter wheat region,respectively,is 5.4day/?(N=115,P<0.01)and 3.3days/?,respectively.But the specific performance of each partition is different.The relationship between China winter wheat phenological period duration and antecedent temperature,winter wheat seedling emergence-tillering and seedling emergence-stop growing period in each partition as well as the seedling duration in southern winter wheat partition and Xinjiang winter wheat partition is not significantly related to antecedent temperature;in other regions,the phenological period duration of sowing seeds-seedling emergence and seedling emergencereturning green gets shortened along with the increase of antecedent temperature.In terms of linear trend,the maximum shortened days in main area of winter wheat phenological period duration along with the increase of antecedent temperature is the southern winter wheat region,with seedling emergence-jointing stage of 12.8 days/?(N=577,P<0.01),while minimum shortened days is Xinjiang winter wheat region,with seedling emergence-milk ripe stage of 5.5 days/?.The relationship between spring wheat phenological period duration and antecedent temperature,from the national trend,the phenological period duration and antecedent temperature before seedling emergence-jointing stage are not significantly related,but after the seedling emergence-milk ripe stage,the duration is decreasing along with the increasing of antecedent temperature.In regards of linear relations,along with the increase of antecedent temperature,the main area is Qinghai-Tibet region,with the seedling emergence-tillering stage of 1.6 days/?.However,the specific performance of each partition varies.Variety changes make the thermal unit of China winter and spring wheat increase linearly,winter wheat seedling emergence-mature thermal unit increases 4.1?/year,spring wheat seedling emergence-mature thermal unit increases 3.5?/year.Fluctuations also exist in winter-spring wheat linear increase of thermal unit in different developmental stages.The influence and correlation of precipitation toward winter-spring wheat phenological period is not as significant as temperature,but it also has a certain effect.The thermal unit and precipitation changes of winter wheat phenological period in Southern winter wheat and Xinjiang winter wheat partitions have low correlation.Only the stop growing-reviving period thermal unit in Northern winter wheat and Xinjiang winter wheat partitions increases along with the decrease of antecedent precipitation,with an increase of 0.8?/mm and 0.5?/mm,respectively.In addition,the heading-mature period in Northern winter wheat partition also increase along with the increase of antecedent precipitation,and the increase is about 0.07?/mm.The relationship between spring wheat phenological period and antecedent precipitation is as follows:the thermal unit in sowing seeds-seedling emergence period decreases along with the increase of antecedent precipitation,the maximum reducing partition is in northern Xinjiang spring wheat,with the sowing seeds-seedling emergence period of 0.35?/mm.After seedling emergence-heading stage,thermal unit accumulation in phenological period increases along with the increase of antecedent precipitation,and the maximum increasing partition is in northern Xinjiang spring wheat,with the seedling emergence-milk ripe stage of 0.18?/mm. |
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