Study On Occurrence Law And Influencing Factors Of Maize Drought In Heilongjiang Province

Maize is one of the major grain crops in Heilongjiang Province,and drought is the most important meteorological disaster for maize production in Heilongjiang Province.Based on the collation of meteorological data(such as precipitation and maximum temperature)and maize yield data in 1965-2014,Heilongjiang Province,the change rule of climate factor(such as precipitation and high temperature)during the growth period of maize in recently 50 years,Heilongjiang Province and the relationship between characteristics of precipitation and high temperature in typical drought years,and the relative meteorological yield are studied through many analysis methods,including precipitation anomaly percentage、Mann-Kendall methods、standardized precipitation index and correlation analysis.In order to provide a reference for agriculture to cope with climate change、crop layout structure adjustment and drought resistance and disaster mitigation.Research results show that:(1)Severe drought disasters in maize production areas in Heilongjiang Province mainly occurred from mid 1970 s to early 80 s and the beginning of twenty-first Century,especially since 2000,continuous and frequent droughts caused significant loss to maize production in Heilongjiang Province.(2)Maize growing season precipitation of Heilongjiang Province in recent 50 years mainly ranges from 400 mm to 500 mm,the average value is 434.8 mm,comparatively suitable for corn planting.Growing season average precipitation of the western region is 402.6 mm,which is the only region lower than the average value of the whole province.The values of Qiqihar,Tailai,Zhaoyuan,Lindian and some other places in this region are even lower than 375 mm,which cannot meet maize’s basic need of water.They are especially arid regions,irrigation must be relied on to maintain normal growth and development of corn.The results of precipitation anomaly percentage show that the interannual variation of precipitation during the growing season of maize in the western region and Sanjiang Plain region is relatively large,indicating that the precipitation distribution in these areas is very unstable and prone to floods and droughts.According to the results of the Mann-Kendall mutation test and the standardized precipitation index,two mutations of precipitation in Heilongjiang Province mainly occurred in the past 50 years,respectively,in the early 1980 s and late 1990 s.From 1970 s to early 80 s and the beginning of this century,there was relatively little rain,which coincided with the severe drought period.The analysis of trends of monthly average precipitation in four regions of Heilongjiang Province compared with maize’s water requirement shows that the growing season precipitation distribution of maize and spring maize’s water requirement trend are roughly the same.In addition,the period of maize water shortage in the central and southern regions of Heilongjiang,the northern region and the Sanjiang Plain area mainly occurred in June and July,but in the western region,corn are in a state of water shortage during the entire growing season.(3)During the growth period,maize in the western region of Heilongjiang Province is facing severe heat stress.AT(accumulated temperature above 30℃)average values of maize growth period in Heilongjiang Province in 1965-2014 range from 7.4 to 58.6℃·d.AT in the western region of Heilongjiang Province is generally high,the AT average annual value of Tailai County is 58.6℃·d.In addition to Qiqihar,Longjiang,Lindian and Anda,AT years average values in the growth period of maize are more than 40℃·d.The distribution of AD(accumulated days with the maximum temperature above 30℃)in Heilongjiang Province is similar to that of AT distribution,and the highest value in the province also appears in Tailai county(26.5 days).In addition,the AD values of Qiqihar,Lindian and some other places in this region are also higher.(4)The results of climatic factors analysis in typical arid years show that not only the low precipitation and high temperature will lead to severe drought,but even in the year of abundant precipitation,the uneven distribution of precipitation will lead to drought.When a variety of adverse factors work together,the loss caused by drought will be more serious.The western region of Heilongjiang Province has high temperature,low rainfall,irregular precipitation and some other meteorological condition which leads to drought,therefore,it is the highest drought risk area in the province.Corn drought in Heilongjiang Province are mainly drought in spring and summer,mainly occurred in the early stage of corn growth,high temperature stress in this period is generally mild,precipitation effect on the drought is the most direct and significant.