Abstract:

Drought and limited rainfall seriously affect high and stable yield of maize in the growing season in Jilin Province. To alleviate serious impact caused by drought, it is necessary to figure out the meteorological index and occurrence frequency of drought in maize growing season, and clarify the risk of drought in various parts of the province. Based on the index of rainfall deficit rate and the daily precipitation data of 47 meteorological stations in Jilin Province from 1961 to 2019, the occurrence frequency of light, medium, heavy and extreme drought in different maize growing periods, and the occurrence frequency of successive drought were analyzed. The results showed that the drought of maize growing season in Jilin Province was divided into three stages: the early stage (April 21 to June 10), the middle stage (June 11 to July 31) and the late stage (August 1 to September 20). Compared with water demand, when the effective rainfall deficit was about 28%, 40%, 55% and more than 62% in the early stage of maize growth, and the effective rainfall deficit was about 32%, 46%, 60% and more than 67% in the middle and late stages, there were light, medium, heavy and extreme drought, and the loss of maize yield per unit area was more than 10% and 15% respectively under heavy drought and extreme drought. The occurrence of drought in maize growing season was frequent, and had a geographical difference. It was more frequent and serious in the western part of the province, while it was less frequent and much lighter in the southeastern part. The drought frequency was the maximum in the early growing stage and lower in the late stage. The frequency was the lowest in the middle stage. The frequency of drought was about 80%, 50% and 65% in the early, middle and late stages in western part of the province, and about 25% of the drought was for successive stages. The frequency of drought was about 50%, 25% and 35% in the early, middle and late stages in the central and northeastern parts, mainly medium drought, and about 10% of the drought was for successive stages. The average frequency of drought was about 25%, 10% and 15% in the early, middle and late stages in southeastern part, mainly light drought, and less than 5% of the drought was for successive stages. The occurrence of drought was related to the water deficit in farmland, and mainly depended on the effective rainfall and water demand in maize growing season.

Key words: water deficit rate, drought period, classified drought, occurrence frequency, regional change, Jilin Province