Abstract:

Huang-Huai-Hai Plain is located in the south of Yanshan Mountains and north of Huaihe River,including the alluvial plains of the Yellow River (Huanghe),Huaihe River and Haihe River and some hilly and mountainous areas.It belongs to semi-arid and semi-humid area with annual precipitation of 500-900 mm.It is also the main winter wheat planting area in China.Based on the daily meteorological data of 49 agriculture-meteorological stations in Huang-Huai-Hai Plain from 1961 to 2017 and the daily SPEI index calculated by Penman-Monteith model,the changes of drought duration and drought intensity in the main growth stages of winter wheat in the region in recent 56 years were analyzed from the perspective of meteorological drought,and the future trend of drought was predicted by R/S method.The results show as follows: (1) The drought duration in the north is short,the drought intensity is weak,and the drought duration in the south is long and the drought intensity is strong in the vegetative stage and the vegetative and reproductive stage of winter wheat,but in the reproductive growth period of winter wheat the drought distribution is contrary to that in the first two growth periods.(2) Analyzing the change trend of each station,we can see the duration of drought is opposite to the intensity of drought during the whole growth period of winter wheat.(3) Analyzing the change trend of each year,the drought had a significant slowdown trend from 1961 to 2017.Except for what’s indicated by a few stations,the duration and intensity of drought had a gradual slowdown trend from 2003 to 2017 in the vegetative growth period and the progressive period of winter wheat,while in the reproductive growth period,drought had a gradual slowdown trend from 2007.(4) From the perspective of future trends,the duration of drought in vegetative growth period will become shorter and the intensity of drought will become weaker.The duration and intensity of drought in advanced period will be basically consistent with those in the past 56 years.The duration of drought in reproductive growth period will become longer and the intensity of drought will become stronger.This study analyzed the drought characteristics of winter wheat in various growth stages in the Huang-Huai-Hai Plain,aiming at understanding and grasping the evolution characteristics of drought and the occurrence law of drought during the growth stages of winter wheat,providing a scientific basis for ensuring food security and drought prevention and disaster reduction.

Key words: daily SPEI index')">

daily SPEI index, Huang-Huai-Hai Plain, winter wheat, growth stage, drought