【作者】 孙淑贞；

【导师】 林德球；

【作者基本信息】 华南师范大学 ， 植物学， 2003， 硕士

【摘要】 香蕉原产热带，喜温畏寒忌冷，当温度下降到一定程度时则受害。我国香蕉产区主要分布于华南亚热带地区，而广东省是香蕉的主要产地之一。冷害是华南香蕉产区最主要的自然灾害，因此，研究香蕉冷害问题在理论上和实践上都具有重要的意义。本文从自由基伤害学说的角度入手，研究了低温及光照、低温锻炼对香蕉幼苗生理生化方面的影响，并探讨了几种外源物质，如CaCl₂、H₂O₂、Vc、ABA对香蕉幼苗抗冷性的影响。 在研究低温及光照对香蕉幼苗膜脂过氧化作用的影响时发现，5℃低温下，香蕉幼苗冷害严重，叶片电解质渗出率明显增大，MDA含量明显提高，POD、CAT活性和叶绿素含量明显降低；10℃低温下，香蕉幼苗伤害较轻，叶片电解质渗出率和MDA含量增幅较小，POD活性明显提高，CAT活性也维持在与对照相近的水平；光照条件对上述各项生理指标有着很大的影响：5℃下的光照加剧了低温对香蕉幼苗的伤害，而10℃下的光照则减缓了低温对香蕉幼苗的伤害，可见在不同的低温条件下，光照起到了不同的作用，5℃下的光照使幼苗发生低温光抑制效应，使幼苗因低温和光照的双重伤害而受害严重。 首次对抗冷性不同的香蕉和大蕉幼苗在低温锻炼下的SOD、POD、CAT活性、电解质渗出率、丙二醛含量、可溶性蛋白质含量的动态变化进行了测定。结果显示，适宜的低温锻炼时间提高了香蕉幼苗的SOD、POD、CAT活性，缓解了膜伤害，不同抗性品种的上述生理指标变化趋势也有所差异。在低温锻炼期间，香蕉和大蕉幼苗的SOD、POD、CAT活性均呈“先上升-后下降”的动态变化趋势，而且其变化趋势与抗冷性的提高存在着明显的相关性。冷胁迫结果显示，低温锻炼提高了香蕉幼苗的抗冷性，缓解了冷胁迫对香蕉幼苗造成的生理伤害。 低温胁迫处理抑制了香蕉和大蕉幼苗的生长，降低了SOD、POD活性及可溶性蛋白质的含量，增加了电解质渗漏率和膜脂过氧化作用；采用适宜浓度的CaCl₂、H₂O₂、Vc喷洒处理，可以增强香蕉和大蕉幼苗的抗冷性，缓解SOD、POD活性的降低及电解质渗出率和膜脂过氧化作用的增加。实验表明：CaCl₂、H₂O₂的效果较好，而Vc的效果次之，抗冷性强的大蕉幼苗在低温胁迫时受到的伤害较小，保护酶系统稳定性高。 香蕉幼苗在5℃低温下胁迫24h后，SOD、POD、CAT活性明显下降，膜脂华南师范大学硕上学位论文 中文摘要过氧化作用加强，膜透性增大。常温下采用 lx 10＼ 5 x 10‘m＊·L‘ABA喷洒处理香蕉幼苗，在一定程度上提高了三种酶的活性，降低了膜脂过氧化作用和电解质渗出率，有效缓解了低温胁迫所致的酶活性的降低以及膜脂过氧化作用的加强和电解质渗出率的增加。实验结果表明 5 x 10－‘mol·L‘ABA处理效果最好，二xl旷m＊·V妞A处理有利于＊AT活性的提高，可能是因为不同的酶对外源ABA的敏感度不同所致。更多还原

【Abstract】 The banana (Musa AAA Group cv. Dazhong Gaoba) is an originally tropical fruit, and low temperature is unfavorable to its growth.If the temperature is close to chill temperature, the chilling-injury will happen.In China, the main producing area is in South China area, and Guangdong is a primary area, too.Chilling-injury is one of the important nature frosts for the banana.Therefore, the study on the chilling-injury of banana seedlings had important meanings both in theory and production. Basing on the theory of free radical, this paper studied the effects of low temperature and light, cold acculimation on some physiological and biochemical indexes in banana seedlings, and inquired into the function of some exogenous substances ,such as CaCl2, H2O2, Vc, ABA on the chilling resistance of banana seedlings.Effects of low temperature and light on the membrane-lipid peroxidation of banana seedlings were studied. At 5 C the banana seedlings had a serious damage; the permeability of cytoplasmic membranes and the malondialdehyde (MDA) contents were significantly increased; the activities of POD, CAT and the chloropyll contents were declined evidently. At 10 C, the damages of banana seedlings were light; the permeability of cytoplasmic membranes and the MDA contents were increased slightly; the activity of POD was increased; the activity of CAT was quite close to that of the control; the chloropyll content was not evidently declined. In addition, light had evident effects on the indexes that tested above,and it intensified the damages that caused by 5 C but decreased the damages that caused by 10 C.It proved that the chill-temperature photohibition intensified the damages of banana seedlings.The dynamic states of activities of enzymes (SOD, POD, CAT), the permeability of the cytoplasmic membranes, the membrane lipid peroxidations, the soluble protein contents of banana seedlings under cold acculimation were studied.The results showed that feasible time of cold acculimation not only increased the activities of enzymes, but also decreased the membrane injuries, All the indexes that above mentioned were different between varieties of banana seedlings.During the periods ofcold acculimation, the trends of the changes of three enzymes were increasing before descending, and the changes were closely related to the chilling resistance of banana seedlings.Therefore, the results of cold stress showed that cold acculimation really increased the chilling resistance of banana seedlings.Cold stress restrained the growth of banana seedlings, the activities of SOD, POD and the soluble protein contents were declined; the permeability of the cytoplasmic membranes and the membrane-lipid peroxidations were increased. Pretreatments of the banana seedlings with spraying CaCl2, H2O2, Vc at feasible concentrations before subjecting them to cold stress retarded the descent of activities of SOD, POD, and weakened the increasements of the permeability of the cytoplasmic membranes and the membrane-lipids peroxidation, but the soluble protein contents in the two varieties of banana seedlings (Musa AAA Group cv. Dazhong Gaoba and Musa ABB Group cv. Aiba Dajiao) didn’t have the same current. The results showed that CaCl2, H2O2 had perfect effects, and the effect of Vc was worse compared to the other two, The banana seedlings (Musa ABB Group cv. Aiba Dajiao) had strong chilling resistance, so the injuries and the descents of activities of enzymes were less.When banana seedlings were exposed to cold stress at 5 for 24 hours, the activities of enzymes (SOD, POD, CAT) in them were declined; the membrane-lipid peroxidations and the permeability of cell membranes were increased. Pretreatment of the banana seedlings with spraying exogenous ABA at feasible concentration before subjecting them to cold stress retarded the decline of activities of enzymes, and weakened the increasement of membrane-lipid peroxidations and the permeabilitiy of cell membranes at 5 conditions for 24 hours. The results showed that 5 + 10-4 M exogeno更多还原