Effect of climate change on maize(Zea mays) growth and yield based on stage sowing

The experiment of sowing by stages can develop different conditions of climate change for maize(Zea mays) growth in natural fields.Using method of statistic analyses,effect of climate change on maize growth and yield was researched according to 6 years' data of the experiment of sowing by stages in the middle of the maize belt of the Northeast China.Here climate change indicated mainly changes of temperature and humidity.The seedling emergence rate,growth rate,filling process,and accumulation of dry matter were indications of the situation of maize growth.Changes of air temperature and humidity can influence obviously vegetative and reproductive growth and production of maize.Under the conditions of normal moisture,if air temperature rises 1℃,there will be 3 days ahead of time in sprouting stage of maize;about 6 days and 4 days will be reduced during the period of seedling emergence to tasseling stage and tasseling to mature stage respectively;the seedling emergence rate and growth rate after sprouting stage will increase by 17%.If relatively cumulative temperature increases by 10%,relative dry weight of 100 grains of maize will increase by 13%.However,filling time will shorten obviously and grain weight will lighten if air humidity is low during filling period.If cumulative temperature of main growing season increases by 100 ℃·d,per unit area yield of maize will increase by about 6.3%;and if mean temperature rises 1 ℃ during the period of tasseling to mature stage,per hectare yield of maize will increase by about 550 kg;but if aridity index increases 0.1 during the same time,per hectare yield will decrease about 860 kg.When temperature is above 22 ℃ during the period of tasseling to mature stage,if aridity index is between 0.75 and 0.9,maize yield will reach to the maximum,that means that cooperation between higher temperature and larger humidity is favorable to maize filling and mature and yield increase.Under the conditions of suitable moisture,climate warming speeds up maize development and filling and makes biomass increase,so that per unit area yield of maize increases;however,climate drying limits use of heat resources,shortens maize filling time and rate,and decreases weight of 1000 grains of maize in growth season of the Northeast China,so that maize yield decreases.In the future,under the conditions of climate warming and suitable moisture,planting area of late maize should be expanded and the maize belt should extend to the north and the east of the Northeast China,per unit area yield and ultimate production of maize will increase.But trend of climate warming and drying would result in more serious and frequent drought of main planting area of maize in the middle and the west of the Northeast China,which will bring about maize yield decrease and uncertainty and threaten seriously future development of maize production.So,to enhance comprehensive defense of agricultural drought is prerequisite for to suit future climate warming and drying and spread middle-late and late variety of maize.