【作者】 易小林；

【导师】 李名扬；

【作者基本信息】 西南大学 ， 园艺学， 2011， 博士

【摘要】 紫御谷(Pennisetum glaucum’Purple Majesty’)是有世界育种产业“奥斯卡”美誉的全美园艺新品种大赛(All America Selections, AAS)评选的2003年金奖获奖品种,具有很高的科研和观赏价值。自紫御谷引种国内以来,凭借其优良的观赏性状,正被迅速推广于各地城市园林绿化中,逐渐成为重要的城市绿化地被植物。实验模拟干旱、高温和干旱高温双重胁迫三种逆境条件,研究了紫御谷在此三种条件下的生理生化响应,以及水杨酸(Salicylic acid, SA)缓解其逆境伤害的效应,为紫御谷在重庆的育苗种植提供参考。研究结果如下：1.早期的干旱胁迫会促进紫御谷幼苗根系的生长,使根系的总根长、根表面积和根体积增加,同时也增加了根系活力。随着胁迫时间的延长,幼苗总根长、根表面积、根体积和根冠比下降,根系活力也减弱。高温以及高温干旱双重胁迫抑制紫御谷幼苗根系的生长,使紫御谷幼苗根系的鲜物质含量、总根长、根表面积、根体积和根尖数减少。SA处理能增加干旱、高温及其双重胁迫下的紫御谷幼苗根系的鲜物质含量、总根长、根表面积、根体积、根系活力和根冠比。说明SA处理能减缓干旱、高温以及双重胁迫对根系的伤害,促进根系的生长。2.干旱、高温及双重胁迫处理后,紫御谷叶绿体基粒数量明显减少,基粒垛叠不明显,且基粒片层排列松散,说明干旱、高温和双重胁迫使叶绿体的膜结构遭到不同程度的破坏。而0.5 mmol·L-1的SA预处理紫御谷叶片,在干旱、高温及其双重胁迫条件下,叶绿体膜结构相对完整,基粒片层较紧密,表明SA能有效保护叶绿体的膜结构。干旱、高温及其双重胁迫处理降低了紫御谷幼苗叶片叶绿素a、叶绿素b、叶绿素总含量和Car含量,SA处理能增加干旱、高温及其双重胁迫处理的紫御谷幼苗叶片在各个胁迫处理时期的叶绿素a、叶绿素b、叶绿素总含量和Car含量。3.干旱、高温及其双重胁迫处理降低了紫御谷幼苗叶片的光合能力,使紫御谷幼苗叶片的净光合速率、气孔导度、蒸腾速率下降；SA处理能增加干旱、高温及其干旱高温双重胁迫处理的紫御谷幼苗叶片的光合能力,使紫御谷幼苗叶片的净光合速率、气孔导度、蒸腾速率得到了不同程度的增加。干旱、高温及其双重胁迫显著降低紫御谷叶片的初始荧光(Minimal fluorescence, Fo)和光下实际光化学效率(Photochemical efficiency of PSII,ΦPSII), SA处理可有效增加干旱、高温以及双重胁迫处理的紫御谷幼苗叶片的Fo和ΦPSⅡ。干旱、高温以及双重胁迫处理也降低了紫御谷叶片的最大光能转化效率(Photochemical quantum efficiency, Fv/Fm),除了双重胁迫处理的差异显著外,其它处理差异不显著。SA处理可有效增加干旱、高温以及双重胁迫处理下的紫御谷叶片的Fv/Fm。4.高温胁迫的3-7天,紫御谷幼苗产生羟自由基的能力和对照相比,差异不显著,但在第9天时,迅速升高,且显著高于对照；干旱以及双重胁迫的紫御谷幼苗产生羟自由基的能力随时间快速升高,在胁迫处理的各个时期内,产生羟自由基的能力都显著高于对照；SA处理能降低干旱、高温及其双重胁迫的紫御谷幼苗产生羟自由基的能力。在干旱、高温及其双重胁迫下,紫御谷叶片抗超氧阴离子自由基活力单位都比对照有所降低,在进行胁迫同时施用SA处理后,部分时期的抗超氧阴离子自由基活力单位比相应的胁迫处理有所升高。干旱、高温及其双重胁迫下,紫御谷幼苗过氧化氢含量都比对照有所升高,而在进行胁迫同时施用SA处理后,过氧化氢含量比相应的胁迫处理有所降低,表明SA对干旱、高温及其双重胁迫有一定的缓解作用。5.干旱、高温及其双重胁迫显著或极显著增加了紫御谷幼苗叶片的相对电导率和丙二醛(Malondialdehyde, MDA)含量,随着胁迫处理时间的延长,相对电导率和MDA含量呈递增的趋势,且干旱以及干旱高温双重胁迫下的紫御谷幼苗叶片的相对电导率增加的幅度大于高温胁迫处理的。而SA处理能减轻干旱、高温及其双重胁迫对紫御谷幼苗叶片的相对电导率和MDA含量,对膜结构起一定的保护作用。干旱以及干旱高温双重胁迫处理的紫御谷幼苗叶片的可溶性蛋白含量都呈先增加后下降的趋势。干旱高温双重胁迫处理的第5天,可溶性蛋白含量达到最大值,而干旱胁迫处理则在第7天达到最大值。高温胁迫处理的紫御谷幼苗叶片的可溶性蛋白含量是先升后降再上升。干旱、高温及其双重胁迫处理的紫御谷幼苗叶片的可溶性蛋白含量,除了在高温胁迫处理的第5天含量高于同期对照外,其它时期都显著低于同期对照(P<0.05)。SA预处理能增加干旱、高温及其双重胁迫紫御谷幼苗叶片的可溶性蛋白含量。在胁迫处理的各个时期,SA预处理紫御谷幼苗叶片的可溶性蛋白含量都高于同期胁迫处理的,但又低于同期对照的。高温胁迫下紫御谷幼苗叶片的可溶性糖含量与对照组差异不明显；干旱胁迫紫御谷幼苗叶片的可溶性糖含量先升后降,在干旱胁迫的第3天、第5天和第7天,可溶性糖含量高于同期对照。在双重胁迫处理的4个时期,可溶性糖含量显著或极显著高于同期对照。水杨酸预处理能增加干旱、高温及其双重胁迫紫御谷幼苗叶片的可溶性糖含量。对照、干旱、高温以及干旱高温双重胁迫处理下的紫御谷幼苗叶片脯氨酸(Praline, Pro)含量随时间出现先增后降的趋势,在第7天时达到最大值。高温胁迫处理的前期,Pro含量明显高于对照且差异显著,高温胁迫处理的后期,Pro含量略高于对照,但差异不显著。SA处理则降低了高温胁迫处理各个时期的Pro含量。干旱以及干旱高温双重胁迫处理下的紫御谷幼苗叶片Pro含量都显著或极显著的高于同期对照,SA处理降低了干旱以及干旱高温双重胁迫处理下的紫御谷幼苗叶片Pro含量。6.干旱胁迫的3-5天,紫御谷幼苗叶片的过氧化物酶(Peroxidase, POD)和抗坏血酸过氧化物酶(Ascorbate peroxidase, APX)活性迅速升高,显著高于对照,干旱胁迫的7-9天,POD和APX酶活性迅速降低,显著低于对照。SA预处理能增加干旱胁迫下紫御谷幼苗叶片的POD和APX酶活性。高温以及高温干旱双重胁迫显著降低紫御谷幼苗叶片的POD和APX酶活性,但POD活性在高温以及高温干旱双重胁迫处理过程中变化不大。SA预处理能显著增加高温和高温干旱双重胁迫下紫御谷幼苗叶片的POD和APX酶活性。干旱、高温、高温干旱双重胁迫使紫御谷幼苗叶片的超氧化物歧化酶(Superoxide dismutase, SOD)和过氧化氢酶(Catalase, CAT)活性降低,SA预处理能提高干早、高温及其双重胁迫紫御谷幼苗叶片的SOD和CAT酶活性。7.在干旱和高温胁迫的早期(3天、5天),IAA含量高于对照,但随胁迫时间延长,IAA含量呈下降趋势,后期(7天、9天)IAA含量低于对照。干旱高温双重胁迫后,IAA含量在所有处理和对照中,一直处于最高水平,在所有时期均高于同期对照的。SA处理能增加干早胁迫下紫御谷幼苗叶片的IAA含量,同时也增加了高温胁迫处理5天、7天和9天的紫御谷幼苗叶片的IAA含量。干旱、高温以及干旱高温双重胁迫能明显增加ABA的含量,SA处理能降低干旱、高温及其双重胁迫紫御谷叶片ABA含量。干旱胁迫处理第3天和第5天,紫御谷幼苗叶片的茉莉酸(Jasmonic acid, JA)含量与对照相当；之后JA含量快速升高,显著高于对照。高温胁迫处理后,紫御谷幼苗叶片的JA含量与对照差异不明显。双重胁迫处理第3天JA稍低于对照；之后JA含量快速升高,均高于同时期对照的JA含量。SA处理能降低干旱、高温及其双重胁迫下紫御谷幼苗叶片的JA含量。更多还原

【Abstract】 Purple Majesty is the gold medal winner chosen in 2003 by All America Selections (AAS) who has the good reputation of "Oscar" of world breeding industry, which is highly valuable in scientific researches and ornamental. In recent years, Purple Majesty has been promoted to the garden construction in various cities because of its excellent ornamental, and Purple Majesty will most likely be an important green plant in the city. Drought stress, high temperature stress and the double stress were simulated in the experiment to research the correlative physiological and biochemical indexes of Purple Majesty,at the same time, salicylic acid’s mitigating the negative effects of temperature stress on Purple Majesty was also studied. By this study, we hope to elucidate a series of response mechanisms of Purple Majesty on drought stress, high temperature stress and the double stress and achieve the goal of further increasing the resources of the landscape ground cover plants in Chongqing. The flowing is the results:1.Root vigor and root ratio will increase when the area and root volume increase,as the stress time extend, drought stress on the Purple Majesty at the early time of seeding can promote seedling root growth, so that the material content of fresh roots, total root length, root surface total root length, root surface area, root volume and root-shoot ratio decreased root activity is also reduced. Drought stress,high temperature stress and the double stress can inhibit the root growth of Purple Majesty seedlings, while reduce the fresh root material content of seedlings, total root length, root surface area and root volume, the number of root tips. SA treatment can increase Purple Majesty seedings roots fresh matter content, total root length, root surface area, root volume, root activity and root-shoot ratio caused by the drought stress, high temperatures stress and drought, high temperature double stress. This proved that SA treatment can slow down the root injury because of drought, high temperatures and the double stress, and then promote the root growth of seedings.2.Drought stress,high temperature stress and the double stress treatment significantly reduced the number of chloroplast grana, grana of stacking was not obvious, and the grana lamellae arranged in a loose, indicating that drought stress, high temperatures stress and drought, high temperature double stress treatment can make varying degrees of damage on membrane structure of chloroplasts.At the condition of drought stress, high temperatures stress and drought, high temperature double stress,0.5mmol·L-1 of SA treatment on the Purple Majesty seedlings can make Chloroplast membrane structure relatively complete, grana lamellae more closely, indicating that SA can effectively protect the chloroplast membrane structure. Drought stress, high temperature stress and the double stress treatment reduced the chlorophyll a, chlorophyll b, total chlorophyll content and Car content of Purple Majesty seedlings, while SA treatment can increase the chlorophyll a, chlorophyll b, total chlorophyll content and Car content of Purple Majesty seedlings under drought stress, high temperature stress and the double stress treatment at each treatment period.3.Drought stress, high temperature stress and the double stress treatment reduced the photosynthetic capacity of the leaves of Purple Majesty seedlings, making the net photosynthetic rate, stomatal conductance, transpiration rate decreased, while SA treatment can increase the photosynthetic capacity of the leaves of Purple Majesty seedlings,in this way, making the net photosynthetic rate, stomatal conductance, transpiration rate increased in varying degrees.In the drought stress,high temperature stress and the double stress treatment, Fo andΦPSⅡof Purple Majesty seedlings leaves was significantly lower than the control, SA treatment can effectively increase the Fo andΦPS II of Purple Majesty seedlings under drought stress,high temperature stress and the double stress treatment; In the drought stress and high temperature double stress, Fv/Fm of Purple Majesty seedlings leaves was significantly lower than the control, SA treatment can effectively increase Fv/Fm of Purple Majesty leaves under drought stress,high temperature stress and the double stress treatment, indicating that drought and high temperature stress on PSII damage was less than the double stress of drought, heat damage to PSII.4.The ability difference to generate hydroxyl radicals was not significant between heat stress and control in 3-7 days,but in the 9th day, the content increased rapidly and significantly higher than the control;The ability to generate hydroxyl radicals of Purple Majesty seedlings increased rapidly as time goes by under drought stress and double stress,and the ability to generate hydroxyl radicals in stress treatment was higher than the control in all the time; SA treatment can reduce the ability to generate hydroxyl radicals under drought stress,high temperature stress and the double stress treatment. Compared to the control, the anti-superoxide anion radical activity unit under the drought stress, high temperature stress and the double stress treatment reduced a little, while after the SA treatmen, anti-superoxide anion radical activity unit were higher than the coressponding stress treatment.Hydrogen peroxide levels were all somewhat higher than control under drought stress, high temperature stress and the double stress treatment, while after SA treatmen,it will be somewhat lower than the corresponding stress theatment, indicating that SA treatmen had some role in mitigation under the drought stress,high temperature stress and the double stress treatment.5.The relative conductivity and MDA content of Purple Majesty seedling leaves increased if drought stress, high temperature stress and the double stress treatment was significant or very significant, With the stress treatment time, the relative conductivity and MDA content had a increasing trend,and relative conductivity rate of increase in drought stress and drought,heat double stress is greater than the single heat stress treatment. The SA treatment can reduce the relative conductivity and MDA content of Purple Majesty seedling leaves because of drought stress, high temperature stress and the double stress treatment, playing a protective role on the membrane structure.The soluble protein in the Purple Majesty seedling leaves firstly increased and then decreased under drought stress and the drought,high temperature double stress.In the 5th day of the drought,high temperature double stress, the soluble protein content reached the maximum,while in drought stress treatment,it did not reach the maximum until the 7th day.But in the high temperature stress, the soluble protein content in the Purple Majesty seedling leaves was first increased and then decreased,but in the last it increased again. In the drought stress,high temperature stress and the double stress treatment, the soluble protein content in the Purple Majesty seedling leaves were significantly lower than control (P<0.05),except in the 5th day under the the high temperature stress. SA treatment can increase the soluble protein content in the Purple Majesty seedling leaves under the drought stress, high temperature stress and the double stress treatment, In various periods of stress treatment, the soluble protein content in the Purple Majesty seedling leaves were higher than the same stress and lower than the same control.The soluble sugar content in the Purple Majesty seedling leaves was not significantly different between the high temperture and the control;Under the drought stress, the soluble sugar content in the Purple Majesty seedling leaves firstly increased and then decreased,in the third day、5th day and 7th day three periods of drought stress, the soluble sugar content was higher than the control of the same period.In 4 hours under double stress, the soluble sugar content was significantly or very significantly higher than the same period control. Salicylic acid pre-treatment can step to increase the soluble sugar content in the Purple Majesty seedling leaves under the drought stress, high temperature stress and the double stress treatment.The Pro content in the Purple Majesty seedling leaves under the control, drought stress, high temperature stress and the double stress treatment increased first and then decreased,in the 7th day reached to the maximum. In pre-heat stress treatments,the Pro content was significantly higher than room temperature and the difference was significant, post-heat stress treatments, the Pro content was a little higher than the control.,but the difference was not signicant, SAtreatment reduced the Pro content of all periods under high temperture stress. The Pro content in the Purple Majesty seedling leaves under drought stress and double stress wereboth signicantly or very signicantly higher than that in the control, SA Treatment reduced the Pro content in the Purple Majesty seedling leaves under drought stress and drought, heat double stress.6.The POD and APX activity of Purple Majesty seedling leaves increased rapidly, significantly higher than the control at 3-5 days under drought stress, but in 7-9 days of drought stress, POD and APX activity decreased rapidly and significantly lower than the control. SA pre-treatment can increase the POD and APX activity of Purple Majesty seedling leaves under drought stress. High temperature and high temperature, drought double stress significantly reduced the POD and APX activity of Purple Majesty seedling leaves, but POD activity changed little in high-temperature and high temperature, drought double stress treatment. SA pre-treatment can significantly increase the POD and APX activity of Purple Majesty seedling leaves under high temperature and high temperature, drought double stress. Drought stress, high temperature stress and the double stress treatment decreased the SOD and CAT activity of Purple Majesty seedling s, SA pretreatment can improve SOD and CAT activity of Purple Majesty seedling leaves under drought stress, high temperature stress and the double stress treatment.7.In the early period (3、5d) of drought and high temperature stress,IAA content was higher than the control,but as the time went on,it would have an decreased trend,in the late time (7、9d),IAA content was lower than the control.After the drought,heat double stress,IAA content were always the highest levels in all treatments. SA treatment can increase the IAA content in the Purple Majesty seedling leaves under drought stress,while the IAA content in the 5d、7d、9d of Purple Majesty seedling leaves under high temperature stress also increased.The ABA content in the control was always at a low level, drought stress, high temperature stress and the double stress treatment can significantly increase the ABA content, SA Treatment reduced the ABA content under the drought stress,high temperature stress and the double stress treatment.The JA content in the 3d and 5d of the Purple Majesty seedling leaves was about the same as the control; After that, the JA content increased rapidly,and significantly higher than the control.But after the high temperature stress,the difference was not significant from the control.In the 3d of drought,heat double stress treatment,the JA content was a little lower than the control,and then increased rapidly,which were higher than the Corresponding control. SA treatment can decrease the JA content of the Purple Majesty seedling leaves under the drought stress, high temperature stress and the double stress treatment.更多还原