【作者】 田治国；

【导师】 王飞；

【作者基本信息】 西北农林科技大学 ， 园林植物与观赏园艺， 2012， 博士

【摘要】 万寿菊属（Tagetes）植物为菊科（Compositae）一年生草本，具有重要的观赏和经济以及生态价值。目前在我国广泛种植并在城市园林绿化中普遍应用。但在生产培育和园林应用中，高温和干旱胁迫会导致植株叶片萎蔫、叶色枯黄和花期缩短等，影响其观赏效果和植株的正常生长。本文以万寿菊属常见的9个观赏品种为试验材料，采用室内模拟高温胁迫（昼夜温度38/21℃）和自然持续干旱胁迫的方法，分别研究了9个品种耐热性和抗旱性的差异，采用数学多元统计分析方法结合形态指标进行了品种的抗性综合评价。并从中选择了抗性差异较大的2个品种即：抗性强的‘金门’（Tagetes patula L. cv. Gate Gold）和抗性差的‘迪阿哥’（Tagetes patula L. cv. Durango）为试材，进行其抗性生长和生理特性的研究。系统研究了两个品种在不同生长阶段（苗期和初花期）分别对高温和干旱胁迫的生长（叶面积、叶厚、根冠比和生物量等）和叶片形态显微结构以及生理响应（渗透调节系统、水分状况、抗氧化系统、光合系统、花粉活力和柱头活性等）；并通过相关性分析筛选出与高温和干旱关系密切的主要生理指标对‘金门’和‘迪阿哥’进行了苗期高温干旱交互胁迫下的生理研究。通过以上试验内容揭示万寿菊对逆境胁迫的形态和生理适应机制，为今后万寿菊抗逆育种与生产应用提供理论依据和参考。获得的主要研究结果如下：1.9个品种在38/21℃高温胁迫下生长和生理表现不同。通过数学多元统计分析方法结合高温半致死温度和热害指数对9个品种耐热性进行综合评价结果为：‘巨人’、‘金门’和‘拳王’耐热性强；‘发现’和‘珍妮’次之；‘鸿运’、‘小英雄’、‘大英雄’和‘迪阿哥’4个品种耐热性差。2.自然持续干旱胁迫下，供试品种生长和生理均受到不同程度的影响。通过数学多元统计分析方法结合旱害指数综合评定9个品种抗旱性强弱为：‘珍妮’、‘金门’、‘鸿运’和‘拳王’抗旱性强；‘巨人’抗旱性次之；‘大英雄’、‘发现’、‘小英雄’和‘迪阿哥’抗旱性差。3.抗性强的‘金门’与抗性差的‘迪阿哥’叶片形态和解剖结构相比，具有叶面积小；气孔小；下表皮气孔密度高；上表皮、下表皮和角质层厚；栅栏组织排列紧密的叶片抗性结构。38/21℃高温胁迫下，‘金门’和‘迪阿哥’苗期和初花期生长均受到不同程度的影响和抑制。耐热性强的‘金门’变化较小；而耐热差的‘迪阿哥’相对增长量、叶色和生物量等均受到高温的明显影响，尤其苗期生长受到显著抑制。另外，高温胁迫4d对‘迪阿哥’叶片组织结构影响显著，主要表现为叶片紧密度、栅栏组织和角质层均显著降低；而‘金门’变化差异不显著。4.38/21℃高温条件下，两个抗性不同的品种苗期和初花期生理发生不同变化。高温胁迫4d明显提高了两个品种渗透调节物质含量。其中，Pro在抗性差的‘迪阿哥’中积累较多，Pro在万寿菊中的累积是一种伤害性反应；而SPC和SSC在‘金门’叶片和花中增加幅度均高于‘迪阿哥’。同时，高温胁迫对‘迪阿哥’叶片RWC的抑制显著高于‘金门’。苗期叶片与初花期叶片和花中的H₂O₂、O₂.-、MDA和RC均明显提高，尤其‘迪阿哥’增加更显著。保护酶（SOD、POD、CAT、APX）活性和抗氧化物质（ASA、GSH）含量在高温影响下均被激活，整体表现为先增加后降低的变化趋势，个别指标在‘迪阿哥’中表现为持续性连续下降的变化。高温胁迫明显提高了‘金门’酶的活性和抗氧化物质含量，但胁迫4d后‘迪阿哥’部分酶活性明显低于处理前水平。另外，高温胁迫下‘迪阿哥’光合色素、净光合速率、气孔导度和水分利用效率均显著下降；而‘金门’光合色素、净光合速率和气孔导度变化较小，水分利用效率明显提高，蒸腾速率较对照显著降低。而且38/21℃高温处理下，‘迪阿哥’花粉活力和柱头活性明显降低，影响高于‘金门’。5.干旱胁迫6d后，抗旱性差的‘迪阿哥’苗期和初花期地上和地下生物量均显著下降；而‘金门’变化不显著。干旱胁迫提高了2个品种的气孔密度，其中‘迪阿哥’上表皮气孔密度增加幅度明显高于‘金门’。另外，干旱胁迫导致万寿菊叶片上表皮、下表皮和栅栏组织厚度降低，叶片紧密度下降，抗性差的‘迪阿哥’品种下降幅度较大，而‘金门’变化差异不显著。6.干旱胁迫下，两个抗性不同品种苗期和初花期生理变化不同。干旱胁迫下生理指标整体变化趋势与高温胁迫表现相似。‘金门’苗期和初花期不同生长阶段，叶片和花的保护酶活性在干旱胁迫下持续的时间和增加的幅度均显著高于抗旱性差的品种。同时‘金门’保持了较高的RWC、SPC、SSC和抗氧化物质（ASA、GSH、Car）含量以及较低水平的H₂O₂、O₂.-、MDA和RC。另外，干旱胁迫前期（2d）两个品种净光合速率、气孔导度、胞间CO₂浓度均降低；而后期净光合速率、气孔导度持续下降，而胞间CO₂浓度表现为增加。试验证明万寿菊干旱胁迫前期光合作用降低由气孔因素引起的，后期光合下降由非气孔因素引起的。7.万寿菊叶片和花应对高温和干旱胁迫的响应机理不同。4种保护酶活性在两个抗性不同品种叶中均明显高于同期花；而抗氧化物质含量（ASA、GSH）在花中显著高于叶片。高温胁迫和干旱胁迫下，花中积累的H₂O₂含量、O₂.-、MDA含量和RC均高于叶片。8.相关分析表明，万寿菊苗期和初花期的RWC、SOD、POD、CAT、APX和Car与热害指数和旱害指数均呈显著或极显著负相关，且相关系数较高；Pro、H₂O₂、O₂.-、MDA和RC与热害指数和旱害指数呈显著或极显著正相关。另外，万寿菊初花期的光合参数与胁迫后植株的形态表现关系也较为密切。相关系数较高的指标可以作为今后鉴定万寿菊属其他品种耐热性和抗旱性的重要生理指标。9.高温干旱交互胁迫下，‘迪阿哥’的H₂O₂、O₂.-、MDA和RC均持续性显著增加，而保护酶活性明显降低，胁迫4d后4种酶活性均显著低于对照，其表现与高温或干旱单一胁迫表现不同；而‘金门’胁迫4d后4种酶活性均显著高于0d。可见，‘金门’在短期（4d）的高温干旱交互胁迫下仍然具有较强的活性氧清除能力，抗高温干旱能力较好,综合抗性较好。10.综合分析认为：‘拳王’和‘金门’耐热性和抗旱性均较强；而‘大英雄’、‘小英雄’和‘迪阿哥’耐热性和抗旱性均较差。‘金门’和‘拳王’可作为今后万寿菊生产和育种尤其是园林应用的首选。更多还原

【Abstract】 Marigold （Tagetes） which belongs to the Compositae family is usually used as a beddingplant and cut flower. It has important ornamental, economic and ecological value. Thoughmarigold plants have good adaptability, their planting regions have along dry and heat periodwhich certainly depress plant growth and cause a limitation to the production of the plants.The effects of heat stress （day/night38/21℃）or continuous soil drought stress on thedifference of tolerance were studied in9marigold cultivars. The tolerances of the9cultivarswere evaluated through multiple statistics analysis. On the basis of the results, Tagetes patulaL. cv. Gate Gold （strong resistance） and Tagetes patula L. cv. Durango （weak resistance）were selected as experimental materials to study their mechanism of growth and physiologicalresponse differences under heat and drought stress at different growth stage （seeding and earlyflowering stage）. We try to explore the changes of growth and the mechanism ofphysiological characters （osmotic adjustment, water status, defensive enzymes andphotosynthesis） as well as anatomical structures in different tolerance of two marigoldcultivars after they suffered stress. In addition, the main indexes were selected by correlativeanalysis to evaluate the differcence of the two cultivars under heat and drought stress. It willprovide value reference to instruct marigold breeding of marigold tolerance in regions aridand semi-arid areas.The main results were as follows:1. The growth and physiological responses of9cultivars were differently responded toheat stress （38/21℃）. Heat tolerance of9cultivars was comprehensively evaluated with themethod of multiple statistics analysis, LT50and heat index. According to the results,‘Giant’,‘Gate Gold’ and ‘Chokdee’ were higher tolerance to38/21℃heat stress,‘Discovery’ and‘Janie’ were moderate resistant intensity to heat stress, while ‘Bonanza’,‘Little Hero’,‘GreatHero’ and ‘Durango’were sensitive to heat stress.2. Water stress has different influence on the growth and physiological indexes in9marigold cultivars. The drought resistance of9cultivars was evaluated by multiple statisticsanalysis and drought index. The results of the resistance to drought stress as follow:‘Janie’, ‘Gate Gold’,‘Bonanza’ and ‘Chokdee’ were high-tolerant cultivars,‘Giant’ was next,‘GreatHero’,‘Discovery’,‘Little Hero’ and ‘Durango’ were weaker in drought tolerance.3. From the leaf anatomic stucture, the ability of tolerance in ‘Gate Gold’ with smallleaves and stomata, stomatal density of lower epidermis, leaf thickness and cutin layerthickness, as well as stockade tissue thickness were stronger than in ‘Durango’. After4days38/21℃heat treatment, growth of two cultivars were inhibited to various degrees at seedingand early flowering stage, especially the relative growth rate and plant biomass of ‘Durango’at seeding stage was obviously declined comparing with control, while the changes weremuch slighter in ‘Gate Gold’. In addition, the tightness of leaf tissue structure, cutin layerthickness and stockade tissue thickness were decreased highly in ‘Durango’ after4days heatstress, but were not influenced significantly in ‘Gate Gold’.4. There were differences in physiological responses of two cultivars under38/21℃stress. The contentes of osmotic adjustment in marigold were stimulated. Pro contentaccumulation was higher in‘Durango’ than in ‘Gate Gold’. However, SPC and SSC contentesin leaves and petals increased more rapidly in ‘Gate Gold’ than that in ‘Durango’. Meanwhile,leaves of ‘Gate Gold’ maintained more relative water content than ‘Durango’ during heattreatment. Additionally, heat stress caused MDA, RC, O₂.-and H₂O₂increased in the twocultivars, especially in heat-sensitive cultivar ‘Durango’. SOD, POD, CAT, APX, ASA andGSH were increased initially, and then decreased. However, some of index of ‘Durango’were reduced during the heat treatment. On day4, the protective enzymes and non-enzymaticantioxidants （GSH and ASA） of the leaves and petals in ‘Gate Gold’ were higher than in‘Durango’. In addition to that, photosynihetic pigment, net photosynthesis rate, stomatalconductance and water use efficiency declined in ‘Durango’ with heat stress, while therewere little changes in photosynihetic pigment, net photosynthesis rate and stomatalconductance, water use efficiency increased as well as transpiration rate decreasedsignificantly in ‘Gate Gold’.5. The results showed that plant biomass of ‘Durango’ were lesser than control after6days water stress. Furthermore, stomatal density of two cultivars increased under droughtstress, especially in upper epidermis of ‘Durango’. Additionally, the tightness of leaf tissue,the upper epidermis and lower epidermis thickness and stockade tissue thickness weredecreased highly in ‘Durango’ after4days water stress, but not significantly in ‘Gate Gold’.6. Under drought stress, the change tendencies of physiological index were similar toheat stress. There were also striking differences in two cultivars. The raise rate, prolongedtime and activity peaks of SOD, POD, CAT and APX as well as ASA and GSH contents inleaves and petals of ‘Gate Gold’ were higher than those of ‘Durango’, while MDA, RC, O₂.- and H₂O₂of ‘Gate Gold’ were lower than those of ‘Durango’. Additionally, netphotosynthesis rate, stomatal conductance and intercellular CO₂concentration decreased from0d to2d stress. However, net photosynthesis rate, stomatal conductance continoued to declinewith stress time, while intercellular CO₂concentration showed increase at later stages of waterstress （4-6d）. Therefore, the decrease of photosynthesis in marigold may be linked to stomatallimitation under light water stress, while that may be attributed to nonstomatal limitationunder heavy stress.7. The leaves and petals of marigold responded differently when suffering stress. Theantioxidant enzymes in leaves were higher than in petals, but conversely, the AsA and GSHwere lower in leaves than in petals. Further, MDA, RC, O₂.-and H₂O₂in petals were muchhigher than those of leaves.8. The path coefficient analysis showed a significant negatively correlation betweenRWC, SOD, POD, CAT, APX, Car and heat index. However, there was significant positivecorrelation between Pro, H₂O₂, O₂.-, MDA, RC and heat index of the two cultivars understress. These indexes which higher coefficient may be applied as identification of toleranceindexes in Tagetes other cultivars.9. The contents of H₂O₂, O₂.-, MDA and RC showed increased remarkably in ‘Durango’in all process of high temperature and drought stress, while the enzyme activities in ‘Durango’decreased notably on day4and were lower than that of control. It was different in single heatstress or drought stress. On the contrary, antioxidant enzyme activities in ‘Gate Gold’ wereraised at first and then reduced but still higher than those of control.‘Gate Gold’ maydecompose the active oxygen effectively under heat and drought stress, and perform strongerstress resistant adaptability.10. The high-tolerant marigold cultivars included ‘Chokdee’ and ‘Gate Gold’, while‘Great Hero’,‘Little Hero’ and ‘Durango’ were weaker in tolerance.‘Chokdee’ and ‘GateGold’ are recommended for ornamental landscapes that receive high temperature in growthseason.更多还原