10个香橼半同胞家系子代苗抗寒性研究

对10个3年生香橼半同胞家系子代进行了抗寒性研究。结果表明,各家系子代苗之间的抗寒性有显著差异。春江7号和新世纪2号的抗寒性差,在田间-11℃自然低温下受冻级别均达Ⅲ级,耐寒指数为3.25～3.40,半致死温度分别为-7.91℃和-7.05℃。春江5号抗寒性较强,耐寒指数为2.17,半致死温度为-13.28℃。其余家系抗寒性中等,-11℃田间自然低温下受冻级别均为Ⅱ级,耐寒指数为2.33～2.86,半致死温度为-11.69℃～-9.91℃。在-3℃～-15℃低温胁迫下,家系子代苗叶片内SOD活性、可溶性蛋白质含量、脯氨酸含量及丙二醛(MDA)含量均有极显著差异,并随处理温度降低总体呈先上升后下降的趋势。SOD活性、可溶性蛋白质含量及脯氨酸含量与耐寒指数、半致死温度均呈负相关,MDA含量与耐寒指数、半致死温度呈正相关。一般SOD活性、可溶性蛋白质含量及脯氨酸含量高,MDA含量低的家系,耐寒指数、半致死温度低,抗寒性强;反之,SOD活性、可溶性蛋白质含量及脯氨酸含量低,MDA含量高的家系,耐寒指数、半致死温度高,抗寒性差。香橼各家系通过上述生理指标的综合变化来调节自身对逆境的适应性,增强抗寒性,减少逆境的伤害,为耐寒品种选育提供生理基础。

Cold resistance of 10 half-sib families of Citrus medica

The cold resistance of ten 3 years old half-sib families of Citrus medica was studied.The results showed that the cold resistance of different families had significant difference.Chunjiang No.7 and Xinshiji No.2 had poor cold resistance with the lethal temperature 50(LT50) of-7.91℃ and-7.05℃ respectively.The average freezing grade of both Chunjiang No.7 and Xinshiji No.2 were grade three,their cold resistant index was between 3.25 and 3.40 at natural temperature of-11℃ in field.The other families had the medium cold resistance,their average freezing grade were grade two,and their cold resistant indexes were between 2.17 and 3.0 at natural temperature of-11℃ in field.Their lethal temperature 50(LT50) were between-13.28℃ and-8.23℃.Under low temperature,the activities of SOD,the contents of soluble protein,proline and MDA in leaves of different families had significant difference and increased at first and then decreased as the temperature decreased.The indexes of cold resistance and the lethal temperature 50(LT50) were positively related to activities of SOD,the contents of soluble protein and proline,and negatively related to contents of MDA.The half-sib families of Citrus medica adjusted themselves by those indexes to adapt the adversity and reduce the injury.