五种金花茶组植物的耐寒性比较研究

金花茶组植物是世界珍稀、濒危的观赏植物,具有极高的观赏价值和药用价值.为了比较金花茶组植物的耐寒性,以五种金花茶组植物为材料,采用人工模拟低温环境的方法对其2年生叶片进行低温胁迫处理,应用电导法研究五种金花茶种质在20℃(常温对照)、8℃、-2℃、-7℃、-12℃、-17℃、-22℃和-27℃低温下相对电导率的变化,配合Logistic方程,测定其低温半致死温度(LT50),以及叶片中游离脯氨酸、可溶性糖和丙二醛的含量.结果表明:五种金花茶的低温半致死温度(LT50)范围为-14.58~-12.74℃,其中金花茶为-14.58℃、龙州金花茶为-14.27℃、柠檬黄金花茶为-13.44℃、直脉金花茶为-13.09℃、东兴金花茶-12.74℃.低温半致死温度能反映金花茶种质的耐寒性,金花茶和龙州金花茶耐寒性强,其次为柠檬黄金花茶和直脉金花茶,东兴金花茶耐寒性较弱.在降温过程中,五种金花茶叶片相对电导率随温度降低呈S型上升,与温度呈负相关;脯氨酸、可溶性糖和丙二醛含量均呈现先上升后下降的趋势.同一低温条件下,半致死温度低的金花茶脯氨酸和可溶性糖的含量更高,而丙二醛含量更低.该研究结果为金花茶组植物耐寒种质选育提供了科学依据,为人工种植金花茶提供了技术支持.

Cold tolerance of five species of Camellia sect. Chrysantha

Camellia sect. Chrysantha are world-famous economic and ornamental plants with high ornamental and medicinal values. In order to determine the cold tolerance, to lay a theoretical foundation for cold tolerance breeding and to provide a technical support for artificial cultivation of Camellia sect. Chrysantha, two-year old leaves of five species were employed as materials and treated under artificially simulated low temperature environment, including C. nitidissima, C. longzhouensis, C. limonia, C. multipetala and C. tunghinensis. We obtained the changes of electrolyte leakage rates (REC) at 20℃ (nor-mal temperature control), 8℃,-2℃,-7℃,-12℃,-17℃,-22℃ and-27℃ by using conductance method,calcu-lated the semi-lethal low temperatures ( LT50 ) based on the changes in electrolyte leakage rates ( REC) under different low temperature stresses with the Logistic equation, and also analyzed the contents of free proline, soluble sugar and malondial-dehyde ( MDA) in leaves. The results showed that the semi-lethal temperature ( LT50 ) of five species was:C. nitidissima-14.58℃, C. longzhouensis -14. 27 ℃, C. limonia -13. 44 ℃, C. multipetala -13. 09 ℃, and C. tunghinensis -12. 74 ℃. The cold tolerance of five species Camellia sect. Chrysantha could be reliably reflected by the semi-lethal temperature. C. nitidissima and C. longzhouensis had high cold tolerance. C. limonia and C. multipetala had medium cold tolerance. C. tunghinensis had poor cold tolerance. The REC of the five species increased following an S-curve with the tem-perature drop, and temperature showed highly significant negative correlation to cold tolerance. The contents of free proline, soluble protein and MDA increased first and then decreased. Under the same temperature treatment, C. nitidissima with low-er LT50 temperature had higher contents of free proline, soluble protein and lower contents of MDA. The results provide the information for selection of cold-tolerant germplasm of Camellia sect. Chrysantha.