桔梗种子萌发与成苗对干旱胁迫的响应及其调控技术研究

发布时间：2018-04-13 07:01

本文选题：桔梗 + 干旱胁迫　；参考：《西安理工大学》2017年博士论文

【摘要】：桔梗是一种在我国山丘区广泛分布的食同源型植物资源,人工栽培有很高经济效益。人工栽培和自然资源抚育都需要以种子繁育后代群体,但桔梗种子细小(千粒重1g),通常被播在表土层,在种子萌发和成苗阶段易受干旱胁迫影响,造成缺苗断垄,制约了桔梗栽培产量提升和野生资源的保护。研究干旱胁迫下,桔梗种子萌发和种子苗生长特征;幼苗生理生化变化及光合特征;克隆抗旱关键基因,并分析干旱胁迫和外源NO(一氧化氮)对相关基因表达的影响;探索提高干旱下桔梗种子田间成苗率的方法措施等,对山丘区生态保护和农民脱贫具有重要意义。通过本文研究取得以下主要结果。1.采用聚乙二醇(PEG-6000)模拟不同程度的干旱胁迫,测定在干旱胁迫下桔梗种子发芽率、发芽势、发芽指数、活力指数及其幼苗叶片游离脯氨酸含量、可溶性糖含量、抗氧化酶活性和丙二醛含量等指标,研究了干旱胁迫对桔梗种子萌发和幼苗生长的影响,结果表明:(1)在干旱胁迫下桔梗种子初始萌发时间延后,发芽率、发芽势、发芽指数、活力指数、胚芽长、胚根长、根长/芽长和苗鲜重等指标均比对照明显降低,且随干旱胁迫程度的增加,上述各指标均呈显著下降趋势;干旱胁迫对桔梗幼苗胚根生长的抑制作用比对胚芽更为明显。(2)10%PEG-6000处理的幼苗游离脯氨酸含量略高于对照,其余各处理游离脯氨酸含量均低于对照;低浓度PEG-6000(≤5%)处理桔梗幼苗可溶性糖含量略低于对照,而高于一定浓度PEG-6000(≥10%)处理后其含量显著高于对照。(3)与对照相比,不同浓度PEG-6000处理后桔梗幼苗叶片超氧化物歧化酶(Superoxide dismutase,SOD)活性均显著升高,而过氧化物酶(Peroxidase,POD)活性均显著下降,低浓度PEG-6000(5%)处理后叶片过氧化氢酶(Catalase,CAT)活性与比对照相比略有升高,但差异未达显著水平,较高浓度PEG-6000(≥10%)处理叶片CAT活性比对照显著降低;PEG-6000处理后的幼苗叶片丙二醛(Malondialdehyde,MDA)含量均明显高于对照。研究发现,干旱胁迫对桔梗种子萌发和幼苗生长具有明显的抑制作用,轻度干旱下桔梗胚根伸长即被显著抑制,可能是桔梗种子田间出苗率低的主要原因。施50μM SNP(NO供体)后桔梗种子苗PgNia1/Nia2基因和PgABI4基因表达量均显著升高,表明桔梗PgNia1/Nia2基因和PgABI4基因在应答干旱胁迫及应答NO中发挥重要作用。6.桔梗种子丸粒化适宜配方为55%草甸土、43%耕层土、0.5%羧甲基纤维素、1%磷酸氢二胺、0.5%保水剂、500μmol/LSNP;丸粒化种子裂解时间为70.3s,丸粒中含籽率87.0%、单籽率为68.3%、单丸含籽数2.61粒。正常供水条件下,丸粒化种子发芽率明显下降,发芽势略有下降,但与对照CK1(正常供水下种子未丸粒化处理)间差异不显著;在15%PEG胁迫下,丸粒种子发芽率、发芽势分别为84.7%、68.7%,均显著高于对照CK2(未丸粒化种子15%PEG胁迫处理)。桔梗种子丸粒化后适宜适当深播,播种深度为5cm时其田间成苗率可达72.7%,显著高于其它各处理,是解决桔梗栽培中成苗困难的有效措施。
[Abstract]:Platycodon grandiflorum is a widely distributed in China's hilly areas and edible plant resources, artificial cultivation has a very high economic benefit. The artificial cultivation of natural resources and tending are needed to seed breeding populations, but the seed (1g 1000), usually small seeded in the topsoil, on Seed Germination and seedling stage affected by drought stress, causing sprout deficiency, restricted the promotion and cultivation of Platycodon grandiflorum yield protection of wild resources. Under drought stress, seed germination and seedling growth characteristics; physiological and biochemical changes and photosynthetic characteristics; cloning of key genes and analysis of drought, drought stress and exogenous NO (nitric oxide) effect on the expression of related genes; to explore methods and measures of improving drought seed seedling rate of field, has important significance for ecological protection in hilly areas and farmers out of poverty. The following results obtained through this study.1. The use of polyethylene glycol (PEG-6000) to simulate different degrees of drought stress, drought stress determination in Platycodon grandiflorum seed germination rate, germination potential, germination index, vigor index and seedling leaf free proline content, soluble sugar content, index of antioxidant enzyme activity and MDA content, studied the effects of drought stress on seed germination, and seedling growth the results showed that: (1) in the initial germination time delayed under drought stress, grandiflorum seed germination rate, germination potential, germination index, vigor index, plumule length, radicle length, root / shoot length and fresh weight of seedling index decreased obviously, and increased with the degree of drought stress, the above indicators are decreased significantly; drought stress on seedling radicle growth inhibitory effect of Platycodon grandiflorum on germ is more obvious. (2) the seedling proline content of 10%PEG-6000 treatment was slightly higher than the control and other treatments free The proline content was lower than that of the control; low concentration PEG-6000 (less than 5%) seedling root soluble sugar content was lower than the control, and the higher concentration of PEG-6000 (10%) after treatment the content was significantly higher than that of control. (3) compared with the control group, after treatment with different concentrations of PEG-6000 grandiflorum superoxide dismutase (Superoxide dismutase. SOD) activity increased significantly, and the peroxidase (Peroxidase, POD) activity decreased significantly, low concentration of PEG-6000 (5%) after the treatment of leaf catalase (Catalase, CAT) activity and ratio of photographic slightly increased, but the difference was not significant, the higher concentration of PEG-6000 (10%) CAT activity of leaves decreased significantly compared with the control seedlings; MDA after treatment with PEG-6000 (Malondialdehyde, MDA) was significantly higher than that of control. The study found that has obvious inhibition on the germination of seeds and growth of Platycodon grandiflorum seedlings under drought stress Under mild drought, which was significantly inhibited the radicle elongation of Platycodon grandiflorum seed, may be the main reason of low germination rate in the field. The 50 M SNP (NO donor) after the seed seedling PgNia1/Nia2 gene and PgABI4 gene expression were significantly increased, showed that jiegeng PgNia1/Nia2 gene and PgABI4 gene in response to drought stress and response in NO play an important role in.6. seed pelleting suitable formula for 55% meadow soil, 43% topsoil, 0.5% carboxymethyl cellulose, 1% amine hydrogen phosphate two, 0.5% water, 500 mol/LSNP; pelleted seed cracking time is 70.3s. The rate of seed containing 87% pellets, single seed rate was 68.3%, single pill the number of seeds contained 2.61 grains. Under the condition of normal water supply, pelleted seed germination rate decreased, germination potential decreased slightly, but compared with CK1 (normal water supply without seed pelleting) no significant difference; under 15%PEG stress, the germination rate of seed germination is divided into pellets. For 84.7%, 68.7%, CK2 were significantly higher than the control (without pelleted seeds 15%PEG stress). The seed pelleting after suitable for deep sowing, sowing depth is 5cm when the field survival rate was 72.7%, significantly higher than that of the other treatment, is an effective measure to solve the difficulties of the seedling planting.

【学位授予单位】：西安理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S567.239

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