Study on freezing index and weather conditions causing Shaanxi apple florescence freezing injury in 2013

【Objective】For exploiting climate resources and promoting the long-term disaster prevention system of Shaanxi apple industry.【Method】The article includes the statistical study of the climatic background causing the injury in 2013 in Shaanxi,and the analyses on the weather factors,disaster information in Xunyi county in the recent 14 years. It reviews the weather factor value as well as the damage by fluorescence freezing injury in 30 apple bases in Shaanxi in 2013. In conclusion,the article draws risk zones on climate for growing apple in Shaanxi.【Result】The results show that by using the minimum temperatures(TD,TD≤-5 ℃,-3 ℃≥TD>-5 ℃,0 ℃≥TD>-3 ℃) or the“cumulative harmful cold values”(X,X≥3.0 ℃·d-1,3.0 ℃·d-1>X≥0.3 ℃·d-1,0.3 ℃·d-1>X≥0.0 ℃·d-1) of cold weather process in apple blossom time to divide Shaanxi apple florescence freezing damage into 3 levels as severe,moderate,light are more consistent with the practical damage; and by using apple inflorescence cold rates [80%,100%),[30%,80%),[10%,30%) to categorize the disaster reduction rates as [30%,50%),[10%,30%) and under 10% are more consistent with the situation. The climate risks of apple growing in Shaanxi province is gradually reduced from northwest to southeast.【Conclusion】In spring,apple inflorescence cold rates can be used to predict yield reduction rate;Shaanxi apple florescence freezing injury risk decreases from northwest to southeast gradually.