关键词: 核桃, 气温, 冻害, 预警指标

Abstract: In this paper,the daily,monthly and seasonal temperature variation features were analyzed based on observational data from stations both inside(S1,hereafter) and outside(S2,hereafter) walnut orchard and local meteorological station(S3,hereafter) in Wensu County,Aksu Prefecture,Xinjiang,China during 2012-2013. The temperature forecast equation between S1 and S3 was established by using the regression model to forecast precisely the temperature variation inside the walnut orchard and reduce the frost injury of the walnuts in winter, then four-level temperature alarm indicators were presented according to the established temperature forecast equation and phenomenon actually observed. The results show the variation of daily mean temperature and daily minimum temperature in winter both presented "three-peak-two-valley" type in both S1 and S3 stations;low temperature mainly appeared in late December to early January,with the values in S1 lower than that in S3,which also had obvious regional characteristics. Daily mean temperature and daily minimum temperature in S1 and S3 stations both showed significant positive correlations with the correlation coefficients being around 0.99;the forecast model had a good accuracy by comparing the observational temperature values with calculation values from forecast equation. The monthly mean temperature was higher than -9℃ both inside and outside the walnut orchard, and the value in S1 was lower than that in S3,so did the mean seasonal temperature and extremely minimum temperature, which was benefit for the local walnut overwintering. Through the forecast model and observation, four-level alarm indicators for monitoring the walnuts frost injury in winter were summarized,including blue warning when the daily minimum temperature would fall to -12℃ in S3 station,arrive to -15℃ in S1,and weather situation did not change obviously in next week;yellow warning when the daily minimum temperature would descend to -20℃ in S1,-16℃ in S3 station,and last for about 7 days;orange warning and red warning when the minimum temperature was kept about -19℃ and lower than -20℃ for more than seven days in S3,respectively, because under these situations,the daily minimum temperature inside the walnut orchard would be under -22℃, which can made the walnut branches,flower bud and leaf bud suffer mild or severe frost injury.With the above results, the local government at all levels could arrange agricultural activity scientifically,mitigate or prevent the impact of frost injury to walnut growth according to the warning level publicized by meteorological department.

Key words: Walnuts, air temperature, frost injury, alarm indicators