北方寒旱区白菜型冬油菜安全越冬的临界指标分析

利用2011-2014年北方13个省、市、区48个不同生态点试验的数据，分析不同品种在不同生态点的越冬率、产量变化，越冬率与产量的相关性，旨在研究白菜型冬油菜在北方不同生态区的越冬安全性，确定北方冬油菜通用的安全越冬的越冬率临界值，明确影响北方冬油菜越冬率的主要因子。结果表明，不同白菜型冬油菜品种在北方不同生态地区越冬率差异较大，产量也差异较大，越冬率变幅为10%~99%，强抗寒品种越冬率>70%。回归分析表明，越冬率与产量存在明显的线性正相关，回归方程符合y=ax+b, 当越冬率<70%时，产量随越冬率的增加而增加，当越冬率为70%时单位面积产量基本趋于稳定, 越冬率大于70%时，越冬率对产量的影响不明显。协方差分析表明，与冬油菜越冬率相关性最为密切的因子是品种，其次是极端最低气温、冬季气温、年均气温、≤0℃的冬季负积温、纬度、经度等。因此，70%的越冬率可作为北方地区冬油菜通用安全越冬的越冬率临界值，采用强抗寒品种，极端最低气温–31.79℃、冬季气温–7.20℃、年均气温6.38℃、负积温–997.57℃，纬度低于44.83°，经度高于80.34°是保证冬油菜安全越冬的必要条件。

Critical Index Analysisof Safe Over-wintering Rate ofWinter Rapeseed (Brassica rapa) in Cold and Arid Region in North China

To research the safe over-wintering rate of winter rapeseed (Brassica rapa) in different ecological areas in North China, to confirm the critical value of over-wintering rate, and to clarify the main factors affecting over-wintering rate, we collected the data of long term multi-location field experiments at 48 ecological sitesin 13 provinces and cities and areas in 2011–2014 with winter rapeseed varietyLongyou 7, Longyou 6, Longyou 8, Longyou 9, Tianyou 4, Tianyou 2 toanalyzethe over-wintering rate and yield and the correlations between them. The results indicated that there were significant differencesof over-wintering rate in different ecological areas, which ranged from 10% to 99% and the yield also had significant difference in different locations.Theover-wintering ratesof varieties with strong cold resistance were over 70%.Regression analysis showed a significant linearcorrelation between over-wintering rate and yield,with the regression equation ofy=ax+b.The yield increased with the increase of over-wintering rate when the over-wintering rate <70%, and tended to stable when the over-wintering rate was 70%, butdidn’t had significant influence on yield when >70%.In conclusion, variety is one of the key factors affecting the over-wintering rate of winter rapeseed.The critical value of safe over-wintering rate in north Chinais 70%, and the corresponding planting conditionsare the strong cold resistant varieties,the extreme lowest temperature–31.79°C, the temperature of winter–7.20°C,annual average temperature 6.38°C, negative cumulative temperatures in winter–997.57°Cin planting areas, latitudebelow 44.83°and longitude over 80.34°.