关键词: 西安, 西安, 土壤养分, 变化动态

Abstract: The paper aims to clarify the quantitative relationship between frost intensity and frost damage degree of crops, taking spring frost damages to corn in central Gansu Province as research objects, and from the research points of hazard-formation factors and vulnerability of hazard-affected bodies, the level indexes of spring frost disasters to corn were established. The authors used negative anomaly of surface minimum temperature as the leading index, which could reflect the dynamic change of cold tolerance of crops in key growth stages, and could combine frost intensity and growth stage of crop; selected supplementary indexes as hourly negative accumulated surface temperature and surface minimum temperature, which could reflect that the frost intensity was the cumulative effect of intensity and duration of low temperature; at last, the authors referred to crop freezing rate, and constructed a complete index system. The indexes could be calculated easily and had obvious physics and phenology significance. Upon examination, the real agreement and the basic agreement rate of the indexes could reach 80%, indicating that the indexes could be applied to practice.