零上低温对咖啡幼苗的影响

EFFECTS OF LOW TEMPERATURE ABOVE 0℃ ON COFFEE SEEDLINGS

用2℃、5℃和8℃分别对中、小粒种咖啡幼苗处理4～5天,结果表明,随着低温强度的增强与处理时间的延续,叶片含水量、Vc含量和超氧物歧化酶(SOD)活性不断下降,而丙二醛(MDA)含量、电导率和钾离子外渗量却逐渐增加,与此同时,呈现幼苗叶片受害面积不断扩大,受害程度相应加重。以上述生理生化指标为依据,比较不同品种对零上低温的反应,反映了中粒种咖啡幼苗对低温比小粒种咖啡幼苗更为敏感。当不同低温处理后回到室温下半个月,观察其生长情况,发现5℃连续处理4天,中粒种咖啡幼苗整株干枯直至死亡,2℃连续处理3天,小粒种咖啡幼苗致死。

Seedlings of Coffea robusta and Coffea arablca were treated at 2℃, 5℃ and 8℃ for 4-5 days. Results showed that, with the lower temperature and the continuation of the treatment, the foliar contents of water and vitamin C (Vc)decreased and the activity of superoxide dismutase (SOD) declined continuously; on the orther hand, the content of malonaldehyde (MDA), electron conductivity and leakage K^+ increased gradually. At the same time the damaged area of seedling leaves expanded increasingly and the injury was aggravated correspondinly. On the basis of the above findings, a comparison of responses of Coffea species to low temperature above 0℃ was made to disclose that the seedlings of Coffea robusta were more sensitive to low temperature than those of Coffea arabica.After treatment at different low temperatures, the coffee seedlings were placed under room temperature for 15 days for observation. It was found that robusta coffee seedlings teated at 5℃ for 4 days on end dried up and eventually died, and arabic coffee seedlings treated at 2℃ for 3 days on end also died.