低温胁迫对秋石斛‘三亚阳光’成苗生理特性的影响

Effects of Low Temperature Stress on the Physiological Characteris-tics of Dendrobium Sonia Hiasakul Mature Plant

秋石斛(Dendrobium spp.)是一类原产于热带地区的观赏植物,适合在高温高湿的环境栽培,易受到低温胁迫。为探究秋石斛成苗对低温胁迫的生理响应及耐寒性,本研究以秋石斛‘三亚阳光’成苗为试验材料,观察及测定在15、10、5℃低温胁迫处理1、2、4、8 h和1、2、4、8、16 d后的外部形态变化和生理指标,统计各处理材料恢复生长后的落叶率,分析各处理材料的可溶性蛋白、可溶性糖、游离脯氨酸、丙二醛和叶绿素含量,以及电导率等抗寒生理指标变化规律,并根据不同温度处理的相对电导率,拟合Logistic方程计算半致死温度(LT50),进行低温半致死温度(LT50)和抗寒生理指标相关性分析,探究不同低温环境下秋石斛成苗形态及生理响应特性,了解其生长发育的规律。结果表明,低温胁迫导致秋石斛‘三亚阳光’成苗的相对电导率、游离脯氨酸含量、丙二醛含量及落叶率均随着胁迫时间的延长明显增长,且处于较高水平;可溶性蛋白含量和可溶性糖含量不断波动,处于先上升后下降,再上升的状态;而叶绿素含量则逐渐减少,经5℃处理16 d后的叶绿素含量降到最低,含量为0.2534 mg/g。通过相关性分析发现游离脯氨酸含量、丙二醛含量、落叶率均与半致死温度有极显著的相关性,叶绿素含量与半致死温度呈显著相关性,推测这些生理指标含量可作为‘三亚阳光’成苗耐寒性鉴定的主要指标。本研究结果为确定秋石斛‘三亚阳光’成苗耐寒鉴定指标和处理秋石斛冷害问题提供了理论依据,并为进一步研究秋石斛对低温损伤的抗性奠定了基础。

Dendrobium is a class of ornamental plants native to tropical regions,suitable for cultivation in high tem-perature and high humidity environment,and susceptible to low temperature stress.To investigate the physiological response and cold tolerance of Dendrobium to low temperature stress,Dendrobium‘Sonia Hiasakul’mature(SH)were treated in temperature 15℃,10℃and 5℃for 1 h,2 h,4 h,8 h,and the physiological indexes and morphological changes of SH were surveyed 1 d,2 d,4 d,8 d and 16 d after.The changes of physiological indexes included soluble protein,soluble sugar,free proline,malondialdehyde(MDA),chlorophyll content,electrical conductivity and the defo-liation rate of the treated plants.Based on the relative conductivity of different temperature treatments,a Logistic equa-tion was fitted to calculate the half-lethal temperature(LT50)of SH,and a correlation analysis between the half-lethal temperature at low temperature(LT50)and the physiological indexes of cold resistance was conducted,with the aim to investigate the morphological and physiological response characteristics of SH under different low temperature envi-ronment and to understand the pattern of its growth and development.The electrical conductivity,free proline,malondialdehyde(MDA)content and the defoliation rate of SH increased significantly with the extension of the stress time and the soluble protein and soluble sugar content fluctuated continuously,in a state of rising,falling,then rising again.The chlorophyll content decreased gradually,reaching the lowest 0.2534 mg/g treated at 5℃for 16 d.Correla-tion analysis revealed that the free proline,malondialdehyde(MDA),defoliation rate and semi-lethal temperature were all highly significantly correlated and chlorophyll content and semi-lethal temperature were significantly correlated,and it was speculated that the content of the physiological indicators was related to the cold resistance characteristics of SH.The study would provide a theoretical basis for determining the cold tolerance identification index and dealing with cold damage in SH,and lay a foundation for further research on the resistance of Dendrobium hybrids to low temperature damage.