花期冷积温对油菜结荚结子的影响

Effect of cold accumulation temperature at flowering stage on seed setting of rapeseed

基于怀化农业气象试验站于2011—2020年的油菜(Brassica napus L.)开花挂牌观测试验,获得不同类型天气开花的油菜有效荚角数、单荚子粒数等资料,采用冷积温指标综合表达低温强度和低温持续时间;通过相关分析、逐步回归统计等方法,建立油菜有效荚果率、单荚子粒数与冷积温的关系模型,研究油菜开花时受害冷积温指标。结果表明,持续3~5 d的低温阴雨或单纯性短期低温(包括个发性霜冻日、日最低气温约为-0.5℃时),对油菜结荚结子影响较轻,有效荚果率为正常天气的80%~99%,单荚子粒数(20.1±1.6)粒,相当于正常天气的91%;持续7 d以上的低温阴雨或3 d以上霜冻、霜冻累计时间达40 h以上时,有效荚果率为正常天气的20%~77%(平均61%),单荚子粒数为正常天气的27%~56%(平均47%)。当以持续4 d为开花时段单元时,开花前2 d至后3 d为冷积温影响关键期,有效荚果率或单荚子粒数分别达到正常天气70%时,单纯低温天气冷积温指标分别为≥36.0℃和≥29.7℃,无日照低温阴雨天气冷积温指标分别为≥21.2℃和≥14.3℃。

Based on the flowering observation experiment of rapeseed(Brassica napus L.)in Huaihua agricultural meteorological ex⁃periment station from 2011 to 2020,the effective pod number and single pod grain number of rapeseed flowering in different types of weather were obtained,and the cold accumulation temperature index was used to comprehensively express the low temperature intensi⁃ty and low temperature duration.Through correlation analysis,stepwise regression statistics and other methods,the relationship model between effective pod rate,single pod grain number and cold accumulated temperature of rape was established,and the index of dam⁃aged cold accumulated temperature during flowering was studied.The results showed that low temperature and rain lasting for 3~5 days or simple short-term low temperature(including individual frost days and daily minimum temperature of about-0.5℃)had little ef⁃fect on seed setting of rape.The effective pod rate was 80%~99%of that in normal weather,and the number of single pod seeds was(20.1±1.6),which was equivalent to 91%of that in normal weather.The effective pod rate was 20%~77%(average 61%)and the number of single pod seeds was 27%~56%(average 47%)of that in normal weather when low temperature and rain lasted for more than 7 days or frost accumulated for more than 3 days or frost accumulated for more than 40 hours.When the flowering period lasted for 4 days,the key period of cold accumulation temperature was from 2 days before flowering to 3 days after flowering.When the effective pod rate or single pod grain number reached 70%of that in normal weather,the cold accumulation temperature indexes in low tempera⁃ture weather were≥36.0℃and≥29.7℃,respectively,and the cold accumulation temperature indexes in low temperature and rainy weather without sunshine were≥21.2℃and≥14.3℃,respectively.