【作者】 江福英；

【导师】 翁伯琦； 李延；

【作者基本信息】 福建农林大学 ， 土壤学， 2003， 硕士

【摘要】 本论文选用不同温度梯度和胁迫时间的方法，研究低温胁迫对热带豆科牧草品种圆叶决明(chamaecrista rotundifolia CPI 86134)的生长、光合作用、活性氧代谢和氮代谢等若干生理指标的影响；探讨低温胁迫对圆叶决明的伤害作用和若干机理以及牧草的抗寒措施及其机制。 1．低温胁迫对圆叶决明若干生理代谢的影响 低温胁迫对圆叶决明生长的试验结果表明，低温使圆叶决明生长受阻，低温胁迫下地上部、根长、根重、根冠比都低于常温对照。低温胁迫时圆叶决明根冠比下降，根活力也有明显的减弱。 低温胁迫下，圆叶决明叶片显微结构和亚显微结构都发生了明显变化，叶绿体和线粒体的正常结构遭到破坏，表现为叶绿体双层膜破损或消失，片层减少，排列紊乱，相互融合。线粒体膜结构丧失，脊消失，出现空泡，解体严重，难以辨认。 随低温胁迫程度的加深和低温胁迫时间的延长，圆叶决明的光合色素Chl和Car含量明显下降。15℃、10℃、5℃胁迫下的总叶绿素含量分别比对照(25℃)下降3.84％、22.40％、32.00％，5℃与对照差异达极显著水平；Car含量也分别比对照下降3.36％、14.99％、21.70％。5℃时，总叶绿素含量胁迫24h起至120h，分别比对照下降了23.34％、24.76％、26.80％、30.11％和32.00％，胁迫24h、48h、72h、96h，120h的下降量都与对照达极显著水平。Car含量分别比对照下降13.14％、14.71％、17.29％、19.28％和21.70％，与对照相比差异达显著水平。温度梯度胁迫试验结果表明，温度越低，可溶性糖含量提高越明显。15℃、10℃、5℃胁迫下的可溶性糖含量分别比对照25℃提高83.21％、224.02％、257.94％，各温度处理与对照间差异均达极显著水平。 随着低温胁迫程度的加深，圆叶决明叶片中游离氨基酸和可溶性蛋白质含量呈上升趋势，而水解氨基酸总量呈现降低趋势。15℃、10℃、5℃处理的游离氨基酸总量分别较对照25，C处理提高26.51%、128.11%和324.43%。15，C、10，C、5，C处理的水解氨基酸总量分别较对照25℃处理下降10.75%、39.57%和43.6。%。 低温胁迫下，圆叶决明叶片，伍一净产生速率和H刃:含量呈显著上升，活性氧清除系统的酶如SOD、ASA一POD活性提高，这是圆叶决明抵御活性氧伤害的一种适应性反应。当活性氧(.压一和H:压)的积累超过防御系统的清除能力时，圆叶决明叶片膜脂过氧化加剧，膜的完整性受到破坏，表现为MDA含量提高，细胞的电解质渗透率增大。 本试验所设定的极端低温(0℃)胁迫下，24h内圆叶决明叶片光合色素含量下降，·氏一净产生速率和HZ氏含量呈显著上升，SOD活性提高，细胞的电解质渗透率增大。2.圆叶决明低温胁迫的防治措施 盆栽试验结果表明，土壤浇施浓度为0.25和0.5001/L的CaCI:处理和叶面喷施浓度为100和150mg/L的ABA处理都可有效提高低温胁迫下圆叶决明光合色素的含量，降低.02一净产生速率、HZ认含量和电解质渗透率。其中以o.smmol/L CaCI:处理在效果最好，因而认为采用土壤浇施0.smmol/L CaCI:处理可有效地缓解圆叶决明受低温胁迫的危害。更多还原

【Abstract】 Pot experiments were conducted to test the effects of chilling stress on several physiological indexes such as growth, photosynthesis, active oxygen and nitrogen metabolisms of chamaecrista rotundifolia CPI86134. In this paper, we explored the harm and the mechanism of chilling stress to chamaecrista rotundifolia CPI 86134 and its protective practice to avoid the cold harm.1.Effects of chilling stress on several physiological metabolisms of chamaecrista rotundifoliaChilling stress significantly inhibited the growth of chamaecrista rotundifolia. The length and weight of shoot and root, root/shoot ratio were all decreased to compare with the contrast. The root activity decreased with the root/shoot indicated that chilling stress had great effect on inhibiting the growth of root.Chilling stress had markly effects on leaf microstructure and ultrastructure of chamaecrista rotundifolia, The chloroplast suffering from chilling stress were distinguished by a reduction in the amount of grana, grana lamellae and stroma lamellae when compared with the chloroplast of normal plant. It was also found that the membrane of the chloroplast and mitochondria ruptured, even disappeared under chilling stress. It also been found that ridge of mitochondria vanished and changed into vesiculation. The shape of the mitochondria were destroyed severely and hard to be recognized.Chilling stress severely decreased the chlorophyll (chl) and carotenoid contents in leaves of chamaecrista rotundifolia with intensifying the cold condition and lasting the time. The total content of chlorophyll (chl) under 15℃ ,10℃ ,5℃ treatments decreased 3.84%, 22.40%, 32.00% respectively to compare with the contrast of 25 . Significant difference was found between 5℃ and 25℃ . The content of carotenoid decreased 3.36%, 14.99%, 21.70% as well. At 5℃ chilling stress, the total content of chlorophyll(chl) in the treating time from 24h to 120h reduced 23.34%,24.76%,26.80%,30.11% and 32.00%. The difference between the treatments of lasting chilling stress time and the contrast were all significant. In the same condition, the content of carotenoid reduced 13.14%, 14.71%, 17.29%, 19.28% and 21.70%, they were all significantly different from the contrast. Futhermore, chilling stress significantly increased the content of soluble sugar, and the lower temperature, the more content of soluble sugar was found.Chilling stress increased the amount of total soluble protein in leaves of chamaecrista rotundifolia. The content of free amino acids and soluble protein were all greatly increased with the intensifying the cold condition. The content of free amino acids under 15℃ ,10℃ ,5℃ chilling stress increased 26.51%, 128.11% and 324.43% respectively to compare with the contrast of 25℃.Chilling stress significantly increased the leakage of electrolyte, the contents of malondialdehyde (MDA) and H2O2 as well as the net rate of (V generation in leaves of chamaecrista rotundifolia. The activities of superoxide dismutase and ascorbate peroxidase increased in chilling stress leaves as compared with normal contrast. These results indicated that chilling stress caused membrane lipid peroxidation and destroyed the completeness of plasma membrane . The change of the activities of superoxide dismutase and ascorbate peroxidase were the adaptive reactions to active oxygen stress in chilling stress on chamaecrista rotundifolia.On 0 chilling stress which designed as the ultra-low temperature in this experiment, the leakage of electrolyte and HA as well as the net rate of ·O2- generation in leaves of chamaecrista rotundifolia all significantly increased. At the same time, the activities of superoxide dismutase increased. 2. Control practices to protect chamaecrista rotundifolia from chilling stressThe cultural experiment results showed that the two treatments with the wateringconcentration of 0.25 and 0.5mmol/L CaCl2 and the spraying concentration of 100 150mg/L ABA both effectively increased the chlorophyll (chl) and carotenoid更多还原