【作者】 苏常红；

【导师】 王道龙；

【作者基本信息】 中国农业科学院 ， 生态学， 2007， 硕士

【摘要】 我国设施园艺业发展迅速，面积居世界第一，但绝大多数为简易型，对环境可控程度低，保温、增温能力差，寒冷季节寒害频发；温室与塑料大棚的平均透光率只能达到50％左右，北方春秋多风沙，使透光率进一步降低，低温弱光并发灾害时有发生，给设施园艺蔬菜生产造成了严重影响；苗期易发生萎蔫、黄化、结冰、死苗、沤根等；开花结果期易发生落花、落果、化瓜等。针对温室内低温弱光采取的措施包括：选用新型滴流膜，适时揭盖草帘，安装镀铝反光膜，人工照明补光，选育温室生产专用品种等，这些措施有的操作麻烦，有的耗资较大；相比之下，施用化学物质防治低温弱光具有操作简便、省时省力的优点。研究表明，向植物施加一些外源物质如Ca²⁺、ABA、GB（甜菜碱）、氯化胆碱等能提高植物的抗冷力，其作用机理大致如下：一是增强细胞膜在低温下的稳定性；二是参与低温信号转导，诱导抗冷基因的表达；三是作为渗透调节物质，维持低温下细胞内外水分平衡，保持细胞的稳定性。ALA（5-氨基乙酰丙酸）作为一种新开发的植物生长活性物质，是所有卟啉化合物的前体，影响叶绿素的合成，提高光合效率，增强植物抗冷性和耐弱光性的能力。本研究以四叶期番茄为试材，喷施不同浓度的CaCl₂、GB、ALA，经低温弱光处理后，通过测量番茄幼苗的净光合速率、气孔导度等生理指标和计算冷害指数，筛选出了1.0mmol／L的CaCl₂、2.5mmol／L的GB（甜菜碱）、30mg／L的ALA三种有效浓度；进一步试验表明三种物质增强番茄耐低温弱光能力的贡献各有不同，CaCl₂主要对增强番茄耐低温方面起作用，ALA主要对耐弱光方面贡献大。将上述三种物质按不同比例进行组合，在四叶期番茄上进行试验，筛选出了效果较好的组合Ⅳ。低温弱光对植物细胞的伤害是多方面的，首先低温使细胞膜系统受损，破坏植物体内抗氧化酶系统，膜脂过氧化加剧，活性氧积累；SOD作为植物体内主要的抗氧化酶之一，低温易使SOD活性降低，MDA含量积累；本研究表明喷施合适浓度的ALA、GB、CaCl₂能使番茄幼苗在低温弱光下保持SOD酶的活性，同时降低MDA含量，SOD活性与MDA含量呈显著的负相关，此外能降低电解质外渗率，保持膜系统的稳定性。脯氨酸和可溶性糖作为植物细胞内主要的渗调物质，对植物耐冷力具有重要作用；本研究中，喷施ALA、GB和CaCl₂使番茄植株在低温弱光逆境下叶片脯氨酸和可溶性糖含量保持较高水平。光强不足易导致植物叶绿素含量降低，叶绿素a／b降低；研究表明喷施上述三种物质有助于番茄叶片在低温弱光下保持较高的叶绿素含量水平，降低叶绿素a／b值，而叶绿素a／b降低对于提高LHCP1的捕光能力，增强电子传递链电子转移效率，提高逆境下植物光合作用。更多还原

【Abstract】 Even though China now boast the largest area of fertility horticulture in the world, most of them are simple type with very low level of environmental controlling; the capability of increasing and keeping the temperature in the greenhouse is very weak, so much that chilling are very frequent in the cold season. The photo permeability rate of the greenhouse and plastic shed can only get to 50%. To make things worse, the frequent sandy weather in northern China further lowers the photo permeability. Chilling and low light always happen together, which cause very serious consequences such as wilting, etiolation, freezing, dieing, root-rotting in the seedling period and flower dropping, fruit dropping, fruit withering in the flowering and fruit-bearing period. The measure against chilling and weak light include adopting new-type plastic film, clearing the film timely, opening and cover the grass curtain at regular time, installing light-reflecting aluminizing film or illuminating equipments to increase light intensity etc.. These measures are either troublesome or costly. By contrast, application of chemicals against chilling and low light, if possible, can be much convenient and time and labor-saving.Research shows that applying some exogenous chemical substances such as Ca²⁺、ABA（abscisicacid）、GB （Glycine Betaine）, CC （Choline Chloride） etc. can enhance the resistance ability of plants against chilling, which function through three mechanics as follows: first, increase the stability of the cellular membrane under chilling, second, function in the signal transduction of chilling and induce expression of cold-resist genes, third, as a osmotic substance, keep the water balance inside and outside the cell and maintain natural condition of the cell. ALA （5-Aminolevulinic Acid）, a newly-developed plant active substance, as a necessary precursor for all porphyrin compound, play a significant role in the synthesis of chlorophyll and can increase the net photosynthesis rate, furthermore it can enhance plant against chilling and low light.In this study, four-leaved tomato seedlings, as the testing material, were sprayed with solutions of CaCl₂、GB、ALA of different concentrations then treated with chilling and low light simultaneously. By measuring the net photosynthetic rate, conductivity of stomata and calculating the chilling-induce-wilting index, 1mmol/L of CaCl₂, 2.5mmol/L of GB, 30mg/L of ALA were selected as effective concentration. Further experiment shows the function of the 3 chemicals towards single chilling and single low light are different. CaCl₂ mainly functions against the single chilling while ALA mainly contributes to photosynthesis under low light. Combining these 3 chemicals with different proportion into 8 formulas, formula IV was selected as the most effective through testing on four-leaved tomato seedlings.Chilling and low light damage plant in many ways, first, it damages the cellular membrane system and increases the leakage rate of electrolyte; second, it destroys antioxidant enzymes system, which cause the lipid peroxidation and accumulation of activate oxygen, third, it affect the level of osmotic regulator; last, low light can cause decrease of chlorophyll content in plant and the ratio of chlorophyll a/b. This study demonstrate that ALA, GB, CaCl₂ of appropriate concentration can alleviate the electrolyte leakage of the tomato seedlings under chilling and low light, and keep the stability of the membrane system. Chilling can lower the activity of SOD and accumulate MDA, This study shows that application of ALA, GB, CaC12 of appropriate concentration can keep the activity of SOD high of tomato seedlings under chilling and low light and keep low level of MDA simultaneously; activity of SOD and MDA content are of significantly negative correlation. Proline and soluable sugar, two major osmotic regulators, play very important roles in the anti-chilling of plant. This study shows that application of ALA, GB, CaCl₂ can help keep high level of praline and soluable sugar in the leaf. Besides, application of the above substances can help keep the level of total chlorophyll high and decrease the ratio of chlorophyll a/b, which exert a very critical function in improving the light-harvesting capability of LHP1 and enhancing the electron-transmitting efficiency of electron-transmitting chain, further increase the photosynthesis of plants under adverse conditions.更多还原