低温胁迫对红果风铃木幼苗生理特性的影响

Effects of low temperature stress on physiological characteristics of Handroanthus chrysotrichus seedlings

为探究红果风铃木(Handroanthus chrysotrichus)对低温的耐受能力,以1年生红果风铃木幼苗为材料,人工模拟不同低温环境观察幼苗在低温下的受害情况,并测定SOD、MDA等生理指标和叶绿素荧光参数。结果表明:红果风铃木幼苗在遭受6℃及以上低温胁迫时,能够通过提高SOD活性、增加SS、Pro以及叶绿素含量增强植株抗寒力,进而缓解胁迫给植株带来的伤害;红果风铃木幼苗还能够提高NPQ耗散过剩的光能避免光合机构受低温破坏,但随着温度下降至2℃,PSⅡ反应中心的伤害愈发严重,光合作用能力受到显著影响。结合各项指标变化特征,推测红果风铃木幼苗能够有效通过自身调节缓解胁迫带来伤害的最低温度范围为2~5℃,具体临界点还需进一步验证。在遭受6℃及以上低温胁迫时,红果风铃木幼苗主要通过提高SOD活性和积累SS缓解低温给植株带来的损伤;随着温度下降至2℃及以下低温时,主要通过提高SOD活性和积累Pro缓解低温给植株带来的损伤。综合分析认为,红果风铃木幼苗无法抵抗0℃及以下低温产生的冻害,但对0℃以上低温有一定的耐受力,研究结果有利于红果风铃木的抗性品种选育和推广种植,对探索植物抗寒生理机制具有一定意义。

In order to explore the tolerance and reaction mechanism of Handroanthus chrysotrichus towards coldness,one year seedlings of H.chrysotrichus were put under artificially controlling low temperature treatments.Physiological indexes and chlorophyll fluorescence parameters were measured.The result shows that under low temperature stress of 6℃or above,seedlings can improve their cold tolerance and protect themselves by enhancing SOD activities,SS contents and Pro contents.In addition,seedlings can also prevent their photosynthetic system from cold damaging through improving NPQ.When the temperature reaches to 2℃,both PSⅡreaction center and photosynthetic system will be badly damaged.From these changes,we deduce that seedlings of H.chrysotrichus can resist to low temperature ranging 2-5℃and prevent the meselves from coldness through self-adjustment.However,the critical point still needs to be determined.Our paper also finds out that when facing low temperature 6℃or above,SS contents rapidly rise up.When the temperature reaches to 2℃or below,Pro contents remarkably rise up.Perhaps seedlings of H.chrysotrichus can protect themselves from low temperature 6℃or above by enhancing SOD activities and SS contents.Seedlings of H.chrysotrichus will mitigate damages of low temperature 2℃or below by enhancing SOD activities and Pro contents.It is concluded that the seedlings of H.chrysotrichus could not resist the freezing damage caused by low temperature below 0℃,but have certain tolerance to low temperature above 0℃.The results are beneficial to both selecting resistent varieties and promoting cultivation.It is also good for exploring cold tolerant ability of plants.