【作者】 张超；

【导师】 李彦慧；

【作者基本信息】 河北农业大学 ， 园林植物与观赏园艺， 2012， 硕士

【摘要】 本文以4年生白玉兰(Magnolia denudata)、紫玉兰(Magnolia liliflora)和二乔玉兰(Magnolia soulangeana)花瓣为试材,研究其在保定地区的抗寒性及花色变化机理。测定了花瓣的过冷却点,以及低温处理后的相对电导率、褐变率,并以盛花期为例测定了花瓣的渗透调节物质的含量、抗过氧化物质含量、保护酶活性、花瓣色度值、色素含量以及在自然花期过程中花色变化的相关指标,探讨其在保定地区早春抗寒适应性以及花色变化机理,主要研究结果如下:(1)3种玉兰花瓣不同花期的过冷却点温度差异显著,同一树种蕾期的过冷却点温度最低,初花期其次,盛花期最高。蕾期,紫玉兰过冷却点温度最低,二乔玉兰其次,白玉兰最高;初花期和盛花期二乔玉兰的过冷却点温度最低,紫玉兰次之,白玉兰最高。(2)不同低温处理后花瓣的相对电导率和褐变率均与温度的变化呈负相关关系,且均与Logistic方程有较高的拟合度,通过回归方程求得3种玉兰半致死温度以花瓣蕾期最低,初花期次之,盛花期最高。(3)随着处理温度的下降,3种玉兰的MDA含量和活性氧产生速率不断增加,与相对电导率的变化趋势一致,且以白玉兰上升的幅度最大,二乔玉兰变化幅度最小。(4)随着低温胁迫的加重,3种玉兰的渗透调节物质变化趋势不一致,可溶性蛋白是白玉兰和紫玉兰低温胁迫后的主要渗透调节物质,而可溶性糖在二乔玉兰和紫玉兰的抗寒过程中起到主要渗透调节物质。(5)3种玉兰抗坏血酸(ASA)和谷胱甘肽(GSH)的含量随着温度的降低呈现先上升后下降的趋势,但变化的幅度不尽相同,其中以二乔玉兰两种物质的含量在各个处理温度均要高于其它两种玉兰,表明其抗寒性要强于另外两种玉兰。(6)3种玉兰花瓣的SOD、POD、APX、GR抗氧化酶活性均随着温度的降低呈现先升高后下降的趋势,在降温初期,保护酶活性升高,表明保护酶清除细胞内氧自由基的能力加强,当低温胁迫继续加大,植物细胞膜脂过氧化程度加大,保护酶活性降低。(7)采用模糊数学隶属度对3种玉兰花瓣盛花期在不同低温下的各项生理指标进行综合评定,得出3种玉兰的抗寒能力为:二乔玉兰>紫玉兰>白玉兰。(8)低温影响3种玉兰的花色,对于二乔玉兰和紫玉兰,随着温度的降低,花瓣明亮度降低,红色度减弱,彩色度变淡,同时低温导致花色苷和类黄酮含量合成受阻,相关酶活性紊乱,严重影响了两种玉兰花色的正常表达。(9)自然状态下,3种玉兰随着花期的推移,花瓣明亮度增强,红色度以及彩色度减弱,PAL和CHI活性逐渐减弱,pH值不断增大、可溶性糖、花色苷、类黄酮含量不断降低,且3种玉兰花色苷和类黄酮含量在不同花期均差异达极显著。更多还原

【Abstract】 Four-years-old petals of Magnolia denudata, M.liliflora and M.soulangeana as materials were used to research their cold resistance and chromogenic mechanism of flowers in Baoding area. Super-cooling points, relative electrolyte leakage, browning rate in all blossom and osmotic adjustment substance, anti-oxidant defense substance content, protect enzymes, floral color index, pigment content in full blossom after lower temperature treatment were determined as well as the relative indexes about the floral variation in flowering stage in order to discuss the cold resistance and chromogenic mechanism of flowers, some main conclusions were summarized as follows:(1)The super-cooling points in different flowering stage of 3 Magnolia petals have significant difference. For the same species the super-cooling point of the bud stage was the lowest, first stage second and full stage the highest. In the buds, Magnolia liliflora had the lowest super-cooling point, Magnolia soulangeana second, Magnolia denudate the highest. Both the first and full blossom, Magnolia soulangeana had the lowest, super-cooling point, Magnolia liliflora second and Magnolia denudate the highest.(2)Relative electrolyte leakage and browning rate had a negative correlation with the temperature variation after the low temperature treatment. Moreover it had a high goodness of fit with the Logistic equation. After calculating the low semi-lethal temperature according to the Logistic equation, we found that buds were lowest, first blossom second and full blossom the highest.(3) As the temperature dropped, the MAD contents and O2- generation rates increased gradually, having the same changing trend with the variation of relative conductivity and a significantly negative correlation with the treatment temperature. Among this M. denudata has the largest rising while Magnolia liliflora the smallest.(4) With the increase of the low temperature stress, the osmotis adjusment substances of the 3 kinds of Magnolia have different trends. Soluble protein may be the main osmotic regulation substance after low temperature stress. Soluble sugar contents were the main osmotic regulation substance in the process against low temperature.(5) The contents of ASA and GSH were in increasing trends and then decreasing of the 3 Magnolia kinds, while having the different extent. Of which the contents of the two substance of M.soulangeana were significant higher than the others, which indicated that its hardness against cold were stronger than the other two.(6) SOD、POD、APX and GR activity all had a first up then down trend of the 3 Magnolia, at the beginning of the low temperature, the protect enzyme decreased, which indicated that the ability of eradicating the O2- strengthened. When the low temperature strengthened, the plant cells over oxidation deepen, and the protect activity decreased.(7) The cold-resistant ability of this 3 Magnolia in full blossom was evaluated comprehensively using subordinate function method and the main results was Magnolia soulangeana had stronger cold-resistant ability, followed Magnolia liliflora, and Magnolia denudata had poorer cold-resistant ability.(8) Low temperature impact the floral color of the 3 Magnolia species, for M.soulangeana and M.liliflora, as the temperature lowered, the lightness L*-value, chromatic component a*-value and C*-value decreased. Meanwhile low temperature stress was a hinder to the synthesis of anthocyanin and flavonoid, disordered the activity of relative enzymes and seriously affected the normal color expression of the 3 Magnoliaa species.(9)Under natural state, with the passage of the blooming, the lightness strengthened, red and colorful index wreaked, PAL and CHI activity abated, pH index increased continually and soluble sugar, anthocyanin, and flavonoid content decreased rapitidly, and the anthocyanin and flavonoid contents have a significant difference during different flowering stage of the 3Magnolia.更多还原