【作者】 罗芳丽；

【导师】 曾波；

【作者基本信息】 西南大学 ， 生态学， 2007， 硕士

【摘要】 三峡水库建成后这些地段由于有近半年时间都处于完全水淹情况下，很少有植物能够生存，从而给库区内消落带造成水土流失、环境污染等一系列问题，这成为三峡水利工程建设带来的最严重的生态问题之一，采用在消落带内人工构建植被是保护三峡库区消落带生态环境的重要措施之一。在人工植被构建中，选择适应水淹环境的植物物种并明确其水淹耐受机理十分重要，是解决三峡库区消落带问题迫切所需的。水淹会改变土壤的生理、生化和生物特性，从而显著改变植物生长的环境条件，对于植物来讲，水淹主要影响植物的生理特性、形态学特征和解剖学特征。水淹的主要危害之一是导致土壤缺氧，缺氧会引起植物的光合生产降低、地上和地下部分的生长减慢、总生物量积累降低、死亡率增加。本文针对水淹对植株的危害，分别从植株的光合作用、叶绿素荧光、水下光合和生长四个方面探讨，水淹是否会极大地影响几种常见岸生植物的生理和生长特征。本实验在三峡库区生态环境教育部重点实验室研究基地中进行，所用材料为三峡库区几种常见岸生植物，分别于2005年5月中旬和2006年5月中旬取自嘉陵江沿岸。实验材料每盆3株。盆中央内径为25cm，高15cm，盆内土层厚度12cm。保证所有实验植株具有相同的土壤基质、光照条件和水分条件，并给予相同的除草等实验管理，栽培2-3月后进行水淹实验，测定了在不同的水淹条件下，植株的光合作用、叶绿素荧光、水下光合和生长。通过研究三峡库区岸生植物野古草（Arundinella anomala Steud．）和秋华柳（Salix variegata Franch．）对水淹的光合响应，研究结果发现：在水淹前期，水淹对野古草和秋华柳的光合特性影响较小，直到水淹60 d后，才对野古草和秋华柳的光合特性有显著影响，且影响程度随水淹深度的不同而不同，其中水淹20 d后，半淹处理的野古草叶片净光合速率比对照高出16.1％。水淹60 d后，水下0.5m和水下2m的野古草植株净光合速率显著低于对照和半淹，其净光合速率分别为7.51μmol·m^-2·s^-1和9.15μmol·m^-2·s^-1。水淹40 d后，相同水淹深度处理下秋华柳植株的净光合速率显著高于耐水湿环境的垂柳（Salix babylonica L．）（p＜0.05）。水淹90 d后，全淹处理植株的光合能力较对照有显著的下降（p＜0.05），对照、水下0.5 m和水下2 m植株的净光合速率分别为13.2μmol·m^-2·s^-1、10.1μmol·m^-2·s^-1和8.05μmol·m^-2·s^-1，同时全淹植株PSⅡ的最大光化学效率也有一定程度的下降，显著低于对照和水淹根部处理的植株（p＜0.05）。结果表明水淹处理对野古草和秋华柳净光合速率的影响显著小于对其他一些耐淹或不耐淹的植物物种的影响。水淹处理60天后，野古草和秋华柳叶片仍具有较为正常的电子传递速率、表观量子效率、叶绿素利用效率和羧化效率，其光合速率下降的原因主要表现在光合机构PSⅡ有功能的反应中心含量降低，同时也有可能与叶绿素合成和叶片中Rubisco的催化活性和数量多少有关。通过研究水淹对构建三峡库区消落带的几种备选植物光合特性的影响，结果表明：水淹30d后，菖蒲、甜根子草和香根草的净光合速率与对照无显著差异，地瓜藤由于水淹而死亡。水淹60d后，菖蒲、甜根子草、芦苇和牛鞭草的净光合速率分别下降到对照的75.1％、80.5％、40.7％和55.7％，同时香根草的净光合速率比对照增加了16.9％。水淹90d后，由于长期水淹芦苇全部植株均无绿色叶片，并有2／3植株死亡，菖蒲、甜根子草、香根草和牛鞭草的净光合速率分别为对照的51.7％、57.8％、67.8％和33.4％。水淹60d后，牛鞭草、芦苇、菖蒲和甜根子草的胞间CO₂浓度显著高于对照植株，同时其气孔限制值显著低于对照植株。水淹90d后，所有水淹植株的胞间CO₂浓度都显著高于对照植株，气孔限制值显著低于对照植株。所以水淹后植株的净光合速率下降主要由非气孔限制因素引起的。通过研究水淹对三峡库区两种岸生植物秋华柳（Salix variegata Franch．）和野古草（Arundinella anomala Steud．）水下光合的影响，结果表明：（1）秋华柳和野古草在水下的光合速率（放氧速率）显著高于典型的陆生植物香樟（Cinnamomum camphora（L．）Presl．）和马唐（Digitaria sanguinalis（L．）Scop．），也显著高于不耐淹物种燕麦草（Arrhenatherum elatius），同时与耐淹物种虉草（Phalaris arundinacea）和皱叶酸模（Rumex crispus）的水下光合相当。水淹5d和15d后，在低CO₂浓度和低光强的测定条件下秋华柳和野古草植株的水下放氧速率显著高于相同水淹处理和测定条件下的陆生植物香樟和马唐的水下放氧速率，且显著高于不耐淹物种燕麦草在低CO₂浓度和高光强下全淹处理一周后的水下放氧速率，但略低于耐淹物种虉草和皱叶酸模在低CO₂浓度和高光强下全淹处理一周后的水下放氧速率。同时，水淹20d和40d后，在高CO₂浓度和高光强的测定条件下秋华柳和野古草的水下放氧速率与相同处理和测定条件下耐淹物种虉草和皱叶酸模的水下放氧速率相当，同时显著高于不耐淹植物燕麦草的水下放氧速率。（2）在长期水淹的条件下，秋华柳和野古草仍具有水下光合的能力。在水淹60d后，水淹2m的秋华柳和野古草植株的水下放氧速率显著低于对照植株的水下放氧速率，但仍具有水下光合的能力。同时，研究也表明在水淹60d后，秋华柳表现出比野古草强的水下光合能力。通过研究三峡库区岸生植物秋华柳（Salix variegata Franch．）对水淹的生长响应，结果表明：随着水淹时间的增加，水淹根部植株不定根数量不断增加，而全淹植株只有极少量的不定根产生。水淹根部植株的主茎长的增加、分枝数的增加、主茎新生叶片数、根生物量的积累和总生物量的积累都高于全淹植株，全淹植株在水淹过程中，其主茎长、分枝数、主茎新叶数、根生物量和总生物量都有增加，同时其凋落叶片较多。水淹90 d后，秋华柳植株的存活率为100％。综上，本论文：（1）通过水淹对所选的几种物种的光合作用的影响的研究，明确了水淹对其中野古草、秋华柳、牛鞭草、甜根子草、芦苇、菖蒲和香根草的光合能力影响较小，而对地瓜藤的影响相对较大；（2）通过水淹对秋华柳和野古草的叶绿素荧光的影响的研究，明确了水淹对秋华柳的最大光化学效率较小，而对野古草的最大光化学效率相对较大。（3）通过水淹对秋华柳和野古草水下光合的影响的研究，明确了这两种植物的水下能力显著高于典型的陆生植物，且在长期水淹的条件下仍具有水下光合的能力。（4）通过水淹对秋华柳生长特性的研究，明确了在不同的水淹深度下，秋华柳采取不同的生长方式，在水淹根部的条件下，植株受水淹的影响较小，水淹植株的生长与对照植株的差异不显著，而在全淹的条件下，植株会降低植株的生长速率，减少植株地上和地下部分的生物量积累；更多还原

【Abstract】 Flooding changes a series of physical, chemical and biological factors in the soil, altering dramatically the environmental conditions for species growth. In plants, flooding affects different aspects of the physiology, morphology and anaomy depending on the species. Flooding reduces the photosynthetic rate of many plant species, particularly of flood-intolerant species. The main adverse effects of flooding are reduction in shoot and root growth, reduction in whole plant biomass, change in biomass partitioning and promotion of overall plant senescence and mortality. Complete submergence imposes considerable stress on plant functioning, predominantly by way of oxgen deprivation. Some of the species generally inhabit poorly drained habitats, where floodwater may remain stagnant for a substantial period of the growing season, and shoot elongation is at these sites an efficient solution to avoid oxygen deficiency. Many species, on the other hand, experience submerged conditions that too deep for the shoot to reach the surface. A straightforward way to reduce shortage of both oxygen and carbohydrates under such conditions would be the continuation of photosynthesis under water. As photosynthesis produces both oxygen and carbohydrates, it may alleviate stress considerably in completely submerged plants.To reveal the effects of flooding on the photosynthesis and growth of several riparian plant species in Three Gorges reservoir region, a flooding simulation experiment was conducted, the photosynthesis, chlorophyll fluorescence, growth and underwater photosynthesis of those plant species were analyzed. The results of the experiments showed that:Photosynthetic responses of riparian plant species Arundinella anomala Steud. and Salix variegata Franch. in Three Gorges Reservoir Region as affected by simulated flooding The results indicated that all photosynthetic characteristics were influenced by both the water depth and the duration of inundation, flooding didn’t have significant effects on photosynthetic characteristics of A.anomala and S. variegata exposed to inundation less than 60 days and the treatment effects varied with different flooding depths. After 20d of inundation, the aboveground half-submerged A. anomala had 16.1% higher Pn than control plants. After 60d inundation, Pn of A. anomala submerged with 0.5m water depth and plants submerged with 2m water depth were significantly lower than the Pn of control and aboveground half-submerged plants, the net photosynthetic rates of plants fully submerged decreased to 7.51μmol·m^-2·s^-1 and 9.15μmol·m^-2·s^-1. After 40 days inundation, the net photosynthetic rate of S. variegata was significantly higher than flood-intolerant species Salix babylonica L.. After 60 d and 90 d inundation, the photosynthetic capacity and Fv/Fm of wholly submerged plants decreased significantly as compared with the photosynthetic capacity and Fv/Fm of control and belowground-submerged plants, but the plants could still maintain high photosynthetic capacity. These results indicated that the net photosynthetic rate of A. anomala and S. variegata were much less affected by flooding than other flood-tolerant species and flood-intolerant species. The decrease of the net photosynthetic rate was mainly due to the damage of PSⅡ, and probably was also caused by the synthesis of photosynthetic pigment and the degradation of Rubisco, but for S. variegate, the decrease of Pn was probably caused by the degradation of Rubisco and the light utilization capacity. The results indicate that A. anomala and S. variegata can maintain high photosynthetic capacity after being inundated for 60 days and are promising species that can be applied in construction of riparian vegetations in the Three Gorge Reservoir Area.Photosynthesis of six kinds of terraneous plants in Three Gorges reservoir region as affected by simulated floodingPThe results showed that flooding did not have significant effects on net photosynthetic rate （Pn） of Acorus calamus L. Saccharum spontaneum L. Vetiveria zizanioides L. subjected to 30 days inundation, but after 30 days flooding Ficus tikoua Bur. died of inundation. After 60d inundation, Pn of Acorus calamus L., Saccharum spontaneum L., Phragmites communis（L.）Trin. and Hemarthris compressa （L. f.） R.Br. submerged with 2m water depth decreased to 75.1%, 80.5%, 40.7% and 55.7% of plants controlled, Pn of Vetiveria zizanioides L. submerged with 2m water depth contrarily had 16.9% higher Pn than controlled plants. After 90d inundation, All Phragmites communis （ L.） Trin. plants had no green leaves, 2/3 of total plants died of inundation, Pn of Acorus calamus L., Saccharum spontaneum L., Vetiveria zizanioides L. and Hemarthris compressa （L. f.） R.Br. submerged with 2m water depth decreased to 51.7%, 57.8%, 67.8% and 33.4% of controlled plants. After 60d inundation, Intercellular CO2 concentration（Ci） of Hemarthris compressa （L. f.） R.Br., Phragmites communis（L.）Trin., Acorus calamus L. and Saccharum spontaneum L. was significantly higher than plants controlled, stomatal limitation（Cs） of Hemarthris compressa （L.f.） R.Br., Phragmites communis （L.） Trin., Acorus calamus L., Saccharum spontaneum L. was significantly lower than plants controlled. After 90d inundation, Ci of all kinds of plants submerged with 2m water depth was significantly higher than plants controlled, Cs of these plants was significantly lower than plants controlled, so the dominant reason for inhibition of photosynthesis is non-stomatal inhibiting factor.Underwater photosynthesis of the riparian plant Salix variegata. Franch and Arundinella anomala Steud. in Three Gorges reservoir region as affected by simulated floodingIt was shown that before 40d inundation the underwater photosynthesis of S . variegata and A . anomala submerged with 2m water depth did not have significance lower than the underwater photosynthesis of control. After 5d and 15d inundation, the underwater photosynthesis of S . variegata and A . anomala submerged with 2m water depth was significantly higher than Cinnamomum camphora L. and Digitaia sanguinalis, respectively. After 60d inundation, the underwater photosynthesis of S. variegata and A . anomala controlled was significantly higher than plants submerged with 2m water depth, but they still had underwater photosynthesis and the underwater photosynthesis of S . variegate was higher than A . anomala. Our work shows that as regards underwater photosynthesis, S. variegata and A . anomala have high tolerance to inundation, they are promising species for revegetation of riparian area in Three Gorge reservoir region.Gowth of the riparian plant Salix variegata Franch. in Three Gorges Reservoir Region responding to simulated floodingThe results showed that during the 32 days flooding period, the number of adventitious roots of belowground-submerged plants was increasing with the duration of flooding, while the wholly submerged plants only had few adventitious roots. The belowground-submerged plants had higher increase in stem length, number of shoots, and newly generated leaves on stem, root biomass and total plant biomass than wholly submerged plants. During the flooding period, the stem length, number of shoots, and newly generated leaves on stem, root biomass and total plant biomass of wholly submerged plants increased, and the number of shed leaves of wholly submerged plants was higher than control and belowground-submerged plants. After 90d inundation, all belowground-submerged and wholly submerged S. variegata is 100 % survived. The results indicate that S. variegata shows high growth adaptability after an inundation of 90 days and is a promising species that can be applied in revegetation of riparian zone in Three Gorge reservoir region.In general, this paper: （1） studied the photosynthesis of several kinds of terraneous plants after different flooding treatments. It was found that the photosynthesis of these species（Salix variegata Franch., Arundinella anomala Steud., Acorus calamus L., Saccharum spontaneum L., Vetiveria zizanioides L., Phragmites communis （L.） Trin. ） was mildly affected by long-term inundation, but the photosynthesis of Ficus tikoua Bur .was obviously affected by long-term inundation. （2） Studied the chlorophyll fluorescence of S. variegata and A. anomala after different flooding treatments. The result showed that the chlorophyll fluorescence of S. variegata was not obviously affected by long-term inundation, but the chlorophyll fluorescence of A. anomala was greatly affected by long-term inundation. （3） Determined the underwater photosynthesis of S. variegata and A. anomala after different flooding treatments. It was found that the underwater photosynthesis （release of oxygen） of S . variegata and A . anomala was significantly higher than two kinds of typical terraneous, and after long-term inundation, S . variegata and A . anomala could maintain photosynthetic capacity. （4） Discussed the growth of S. variegata after different flooding treatments. It was found that plant would take different growth strategy under different inundation condition, plant belowground submerged was mildly affected, the growth indexes of the plant belowground submerged did not significantly decrease compared to the plants controlled. When whole plant was submerged, the growth rate would be slowed down, the shoot biomass and the root biomass would be reduced.更多还原