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题名	水、盐对胡杨幼苗光合及荧光特征的影响研究
作者	李菊艳
学位类别	硕士
答辩日期	2009
授予单位	中国科学院．新疆生态与地理研究所
授予地点	北京
导师	赵成义，新疆生态与地理研究所
关键词	胡杨幼苗
其他题名	Study on the Effect of Water and Salt on Characteristics of Photosynthetic and Chlorophyll
学位专业	植物生态学
中文摘要	胡杨（Populus euphratica）具有耐盐碱、耐湿、耐旱、抗风沙等生态特性，是荒漠区自然林建群树种。在塔里木河流域干流修建防洪堤坝和生态闸后，改变了胡杨生存的水、盐条件，胡杨种子萌发和幼苗生长对水、盐的响应与适应决定了其种群的生存和发展。本文用盆栽控制试验，研究不同水分、盐分条件对胡杨幼苗株高、基径、生物量及光合、荧光特征的影响，探讨胡杨幼苗对水分和盐分的变化的响应与适应机制，为塔里木河流域的胡杨幼苗生长及种群繁殖提供依据。其主要结果如下： 1. 水分对胡杨幼苗光合及荧光特征的影响随土壤含水量减小，胡杨幼苗的株高、基径生长和生物量积累受到明显抑制；幼苗的净光合速率及对光能、CO2的利用效率显著下降，对光的生态适应能力减弱。当土壤含水量大于12.0%时，幼苗通过改变生长策略和自身的生理过程，即改变根冠比、提高水分利用效率，来适应环境的变化以提高抗旱性；当土壤含水量小于9.6%时，其自我调节能力减弱。水分对净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）和蒸腾速率（Tr）日变化规律影响不大，日变化曲线都为单峰型，当土壤含水量在21.6%～24.0%，幼苗的水分利用效率（WUE）的日变化曲线呈不明显的双峰型。荧光分析表明，土壤含水量为16.8%-19.2%，对胡杨幼苗光系统Ⅱ（PSⅡ）的损伤很小，当土壤含水量小于9.6%时，对幼苗的PSⅡ有较大损伤，当土壤含水量大于21.6%时，对幼苗的PSⅡ无较大影响，但产生过剩光能。幼苗通过增加非辐射能量耗散，避免了由于辐射能量的吸收和利用不平衡所导致的伤害。结果初步推断，胡杨幼苗生存的最适的水分范围为16.8%-19.2%，当土壤含水量小于9.6%，不利于胡杨幼苗的生存。 2. 盐分对胡杨幼苗光合及荧光特征的影响随盐浓度增大，盐分对幼苗株高、基径生长及生物量积累影响明显。当土壤含盐量小于18.32g?kg-1时，幼苗生物量减小了30%左右；当土壤含盐量达到27.95g?kg-1时，幼苗的生物量减小了80%左右，幼苗难以正常生长。随着盐浓度增大，胡杨幼苗的净光合速率下降。当土壤含盐量小于18.32g?kg-1时，幼苗通过降低蒸腾速率和提高自身的水分利用效率以提高耐盐性；当土壤含盐量大于18.32g?kg-1时，胡杨幼苗的水分利用效率降低，幼苗表现出盐害症状。不同盐浓度条件下幼苗的净光合速率的日变化曲线都为单峰型，其峰值均出现在12:00，盐分对幼苗的光合日变化规律的影响不大。荧光分析表明，当土壤含盐量小于18.32g?kg-1时，对幼苗的PSⅡ的损伤不大；但当土壤含盐量增大到27.95 g?kg-1时，幼苗的光合活性受抑，对PSⅡ造成较大的损伤；过高的盐分环境下，幼苗叶片吸收的光能超过光合作用的需要，通过启动热耗散机制保护光合机构免受光破坏。结果初步认为，维持塔里木河胡杨幼苗正常生长的土壤盐分临界值总盐为18.32g?kg-1、Cl-为2.74 g?kg-1；幼苗致死土壤盐分临界值总盐为27.95 g?kg-1、Cl-为8.38 g?kg-1。With the ecological characteristics of saline tolerance，humidity tolerance drought tolerance and anti-blown sand, Populus euphratica was the constructive species of wildwood in desert area. The water and salinity conditions of P. euphratica had changed after flood control dams and ecological sluices were built on the main stream of the Tarim River Basin. Survival and development of population of P.euphratica were influenced by the reaction and adapting to water and salinity of seed germination and seedlings growth. In this paper, the height，stem diameter, biomass, and net photosynthesis rate，fluorescence characteristics of two years old seedlings were studied by pot experiment with different treatment of water and salt. The physiochemical response and adaptive mechanisms of seedling to water and salt were investigated. The results may provide evidence for the seedlings growth and population reproduction of P.euphratica of the Tarim River Basin. The main results of this study were as follows: 1. The effect of water on the characteristics of photosynthesis and fluorescence of P.euphratica seedlings. The height，stem diameter, biomass, net photosynthesis rate(Pn), light energy efficiency(LUE)，CO2 use efficiency (CUE) and the ability of light ecological adaptation of P. euphratica seedlings were reduced significantly with the decreasing of soil water. As soil water content was higher than 12.0%, drought-resistant ability of P. euphratica seedlings was improved by the change of the root-shoot ratio and the increase of water using efficiency. As soil water content was lower than 9.6%，the self-regulation ability of seedlings was decreased. The daily variation regularity of Pn，Gs，Ci，and Tr were hardly impacted by water stress. The diurnal variation curves were all single-peak type. As soil water content was in the range of 21.6%～24.0%，the diurnal variation curve of WUE was not obvious double-peak curve. The fluorescence analysis shows that as soil water content was in the range of 16.8%～19.2%，the PSⅡof seedlings were hardly injured. Under the condition of soil water content was lower than 9.6%，the PSⅡof seedlings were severely injured. As soil water content was higher than21.6%，the PSⅡof seedlings were not injured，while the light energy of the leaves of seedlings was surplus. With the increasing of nonradioactive energy dissipation of seedlings, the injury caused by radiation energy absorption and utilization imbalance can be avoided. The preliminary results were concluded that the soil water content, from16.8% to19.2%, was the optimum water content for the survival of P.euphratica seedlings. As soil water content was lower than9.6%，the growth of the seedlings was inhibited. 2. The effects of salt on photosynthesis and fluorescence characteristics of P.euphratica seedlings. As soil salinity was less than 18.32g?kg-1，the biomass of P. euphratica seedlings was decreased by about 30% compared with those under control treatment. As the soil salinity was rise to 27.95g?kg-1，the biomass of P. euphratica seedlings was decreased by about 80% . Which indicate that the seedlings can not be survival.The photosynthetic rate was reduced with the increase of soil salinity. As soil salinity was lower than 18.32g?kg-1，the WUE and salt tolerance of P. euphratica seedlings could be mediated by the reducing of the transpiration rate. As the soil salinity was higher than 18.32g?kg-1，the WUE of seedlings was decreased. The salt injury symptoms were occurred. The diurnal variation curves of Pn were all single-peak type under different salinity conditions. The peak time was at 12:00. The daily variation regularity of Pn was hardly impacted by salinity. The fluorescence analysis showed that as the soil salinity was lower than 18.32g?kg-1，the PSⅡof seedlings was hardly injured. As the soil salinity was rise to 27.95g?kg-1, the photosynthetic activity of seedlings was inhibited，the PSⅡof seedling was severely injured. The light energy absorbed by the leaves of seedlings was more than the needs of photosynthesis of the leaves of seedlings. The photosynthetic apparatus of the leaves of seedlings was protected from photo damaged by the activating of the thermal dissipation mechanism. The preliminary results were concluded that, to maintaining the normal living of P. euphratica seedlings along Tarim River, the soil salinity threshold of the total salt and Cl- may be 18.32 g ? kg-1and 2.74 g ? kg-1, respectively. In contrary, seedlings lethal of the soil salinity threshold of the total salts and Cl- which may cause death of seedlings may be 27.95 g ? kg-1– and 8.38 g ? kg-1, respectively.
学科主题	植物生理学 ; 林学
公开日期	2010-11-12
页码	共83页
内容类型	学位论文
源URL	[http://ir.xjlas.org/handle/365004/8486]
专题	新疆生态与地理研究所_中国科学院新疆生态与地理研究所(2010年以前数据)
推荐引用方式 GB/T 7714	李菊艳. 水、盐对胡杨幼苗光合及荧光特征的影响研究[D]. 北京. 中国科学院．新疆生态与地理研究所. 2009.

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