10个桉树无性系抗寒锻炼特性的研究

Studies on the cold-hardening characteristics of 10 eucalyptus clones

采用人工低温处理结合电导法,测定了10个桉树无性系在未锻炼、锻炼与脱锻炼等不同处理下冻害胁迫抗性的半致死温度。研究结果表明,大部分的无性系在6℃10d+3℃10d的锻炼处理后,比对照株的冻害胁迫抗性增强,剔除实验期间苗龄变化的影响后半致死温度平均降低6℃。脱锻炼后,抗寒锻炼获得的抗冻性消失,大部分降到比对照株更低的抗冻性水平。桉树无性系的抗冻性受抗寒锻炼的影响,抗寒锻炼能提高桉树无性系的抗冻性。根据锻炼后的maxΔLT50与锻炼前的CK0对桉树不同无性系的抗冻性,将10个无性系划分为4种类型即冷抗可锻炼型(RA)、冷抗不可锻炼型(RUA)、冷敏可锻炼型(SA)、冷敏不可锻炼型(SUA),其中XL2和XL6为冷抗可锻炼无性系,XL4属冷抗不可锻炼无性系,XL7属冷敏不可锻炼的无性系;其它6个无性系为冷敏可锻炼无性系。

By Electrolyte Conductivity Method and laboratory cold treatments, the LT50 （or TK50, the temperature at which 50 percent of the population were killed） of 10 eucalyptus clones after non-hardening, cold-hardening and de-hardening treatments were all measured. Results showed that after the treatment of 10 days＇ 6℃ and 10 days＇ 3℃ cold-hardening, there was a decrease of 6℃ in LT50 indicating an increase in cold-resistance compared to CK plants. But after cold-dehardening treatment, this gained increase in cold-resistance vanished, mostly drop back to a level lower than CK plants. So, the cold-hardening treatment influenced, and in most clones, enhanced the cold-resistance of eucalyptus clones. According to the LT50 before cold-hardening and the max ΔLT50 after cold-hardening, cold-resisting mechanisms of eucalyptus clones are grouped into 4 types： freezing resistant and able to acclimate type （RA）; freezing resistant but unable to acclimate （RUA）; freezing sensitive but able to acclimate （SA）; freezing sensitive and unable to acclimate （SUA）. And by this sorting method, XL2 and XL6 were categorized into type RA, XL4 into type RUA, XL7 into type SUA, and the other clones tested into type SA.