摘要：

为探讨花期低温对甘蓝型油菜生长发育及生殖器官发育的影响,以甘蓝型油菜GZ恢(抗冬季寒冷强)和10B(抗冬季寒冷弱)为材料,于初花期在人工气候室进行低温(白天14 h,12 ℃;夜晚10 h,2 ℃)胁迫,设置5个处理时间:1,2,3,4,5 d,正常生长环境(白天14 h,22 ℃;夜晚10 h,18 ℃)为对照,测定了低温胁迫下植株苔茎叶和下部叶生理指标以及不同大小花蕾开放后的花粉活力和柱头可授性。结果表明:两材料在低温处理后植株叶片均表现轻微萎蔫,所有处理植株无明显受损;低温处理后叶片各生理指标变化比较复杂,以过氧化物酶(POD)敏感,多表现为显著升高,下部叶较苔茎叶升高更多,10B较GZ恢升高幅度大。渗透调节物质以可溶性糖(SS)含量变化明显,GZ恢显著增加。丙二醛(MDA)含量显著增加,10B较GZ恢升高更多,下部叶和苔茎叶两材料表现不尽一致。低温处理对两材料大于6.0 mm的花蕾花粉活力受影响均很小。小于3.0 mm的花蕾,胁迫4 d以上后期发育停止最终死亡,胁迫2~3 d花粉活力显著下降,且花蕾越小,花粉活力随处理时间增长降低越多。小于6.0 mm的各级花蕾受低温胁迫后,GZ恢花粉活力多高于10B,以3.0~6.0 mm的花蕾差异明显,因此,认为3.0~6.0 mm花蕾可作为鉴定不同品种花期耐低温指标。柱头可授性表现与花粉活力趋势一致,大于3.0 mm的花蕾低温处理3 d以内柱头可授性不受影响,处理4 d以上柱头可授性降低;小于3.0 mm的花蕾,低温处理3 d以内柱头可授性不同程度降低。这些结果表明,在植株遭受低温胁迫后,小于3.0 mm的花蕾对低温较为敏感,导致花粉活力和柱头可授性降低,甚至败育。

关键词: 甘蓝型油菜, 花期, 低温, 生理指标, 花粉活力, 柱头活力

Abstract:

In order to explore the effect of low temperature during the flowering period in Brassica napus,Brassica napus L.GZhui(strong resistance to winter cold)and 10B(weak resistance to winter cold)were used as test materials,low-temperature stress (14 h, 12 ℃ at daytime; 10 h, 2 ℃ at nighttime) to these materials for 1, 2, 3, 4, 5 d, and normal environment(14 h,22 ℃ at daytime;10 h,18 ℃ at nighttime)as control,determine the changes of physiological indexes in bolting stem leaves and lower leaves under low-temperature stress,as well as pollen viability and stigma receptivity after the opening of flower buds of different length.The research results showed that the leaves of the two materials were slightly wilted after low-temperature treatment,and there was no obvious damage to the shape of the plants in all treatments,the changes of various physiological indexes of leaves after low-temperature treatment were more complicated,and the three antioxidant enzymes were sensitive to peroxidase(POD),and most of the antioxidant was significantly increased,lower leaves more than bolting stem leaves.The content of soluble sugar(SS)in osmotic adjustment substances changed significantly,GZhui increased significantly.Malondialdehyde(MDA)content increased significantly,10B more than GZhui,and the lower leaves and bolting stem leaves showed different performances.For flower buds larger than 6.0 mm,the pollen viability of the two materials was little affected by low-temperature treatment for 4 days.For less than 3.0 mm of flower buds,the development stopped and eventually died for more than 4 days of cold stress,and the pollen viability decreased significantly after 2—3 days of stress.After the flower buds of all levels,less than 6.0 mm were under low-temperature stress,the pollen viability of GZhui was higher than that of 10B,and the difference was obvious with the flower buds of 3.0—6.0 mm,so it was considered that the 3.0—6.0 mm flower buds could be used as an indicator for identifying different varieties of low-temperature tolerance during flowering.The performance of stigma receptivity was consistent with the trend of pollen vigor.The stigma receptivity of flower buds larger than 3.0 mm was not affected within 3 days of low-temperature treatment,and the receptivity of stigma more than 4 days of treatment was reduced;the flower buds smaller than 3.0 mm,the receptivity of stigma decreased to varying degrees within 3 days of low-temperature treatment.These results indicated that flower buds(smaller than 3.0 mm)were more sensitive to low temperature,resulting in reduced pollen vitality and stigma receptivity,and even abortion.

Key words: Brassica napus L., Flowering stage, Cold stress, Physiological activity, Pollen viability, Stigma receptivity