Risk Assessment and Classification of Drought Injury to Maize in Songliao Plain, China.

Abstract

The frequency of drought injury occurrence is high in Songliao Plain which is the most major maize-growing region of China and is also one of the major contributors to the well-known Maize Belt of the Temperate Zone in the world. Moreover, the danger of drought injury to maize increases recently with global warming. In this paper, the relationships between the fluctuation of maize yield and drought injury were analyzed using the crop yield-climate analysis method. On the basis of above study, the parameters and model of risk assessment of drought injury to maize were presented according to a method of risk assessment to human environment. Then, risk assessment and classification of drought injury to maize in Songliao Plain were carried out using fuzzy cluster analysis.(1) From 1949 to 1990, the minus values years of fluctuation of maize yield due to meteorological disasters accounted for 55%, which 60% was caused by drought injury.(2) Spectrum analysis on time series of deviation percentage of maize yield indicated in past 42 years occurrence of bad harvest or very bad harvest years caused by drought injury shows approximately the 4-year period.(3) The regression equation for the relationship between fluctuation of maize yield and the extent of drought injury was expressed in the form of curvilinear expression (r=0.99, α<0.01). Therefore fluctuation of maize yield can be estimated according to change of extent of drought injury.(4) The regression equation for the relationship between the risk extent of drought injury to maize calculated by model of risk assessment and reduction of maize yield caused by drought injury was better described by a linear relationship (r=0.97, α<0.01).(5) The risk extent of drought injury to maize in Songliao Plain was classified into 4 types, that is, Heavy danger, Middle danger, Light danger and Slight danger.