Abstract: Climate change has changed the breeding environment of crops.More specifically,the increase of accumulative temperature in winter has changed the suitable sowing period of winter wheat (SSPWW).The spring frost and dry-hot wind have damaged the physiological function of wheat.To guide agricultural production better,it is important to determine the optimum sowing period of winter wheat in the context of climate change.Based on the daily meteorological data of 3 meteorological stations in Rizhao area from 1951 to 2016,using the methods of trend analysis and correlation test,the spring frosts duringthe SSPWW the effective accumulative temperature ≥ 0℃ is 400-750℃·d before winter,during the wheat's jointing stage and the temporal and spatial variation of high temperature dry-hot wind weather during the wheat's milk-ripe stage were investigated.The results show that the effective accumulative temperature ≥ 0℃ before winter i.e.the period during October 2 to December 20 increases with a ratio of 1.572℃·a^-1 at Donggang district in recent 62 years,of 1.339℃·a^-1 at Wulian County in recent 58 years and of 1.513℃·a^-1 at Ju County in recent 66 years.In addition,the SSPWW in Rizhao area does not occur an abrupt change.As a result,the SSPWWs at Donggang District,Wulian County and Ju County are confirmed as the periods during October 20-25,October 17-20 and October 11-15,which are 5-10 days later than traditional sowing periods and theoretically avoid frost damage in the winter wheat's jointing stage as well as decrease high temperature dry-hot wind damage for 69%,85% and 75% in the wheat's milk-ripe stage,respectively.In short,this study plays a positive role in guiding local winter wheat production.

Key words: Winter wheat, Climate change, Suitable sowing period, Effective accumulative temperature, Spring frost, Dry-hot wind