Knowledge Resource Center for Ecological Environment in Arid Area
| 珍稀濒危植物沙冬青种子生理生态学研究 | |
| 其他题名 | Studies on seed ecophysioiogy of the rare and endangered plant species - Ammopiptanthus spp |
| 杨期和 | |
| 出版年 | 2004 |
| 学位类型 | 博士 |
| 导师 | 叶万辉 |
| 学位授予单位 | 中国科学院华南植物园 |
| 中文摘要 | 豆科（Leguminosae）沙冬青属（Ammopiptanthus）是我国西北荒漠地区唯一的常绿阔叶植物，是该区植物区系中的特有属。它是第三纪亚热带常绿阔叶林的孑遗成份，仅包括两种，即新疆沙冬青（A.nanus（M．Pop．）Chengf．）和蒙古沙冬青（A．mongolicus（Maxim）Chengf．）。两种植物分布地区狭窄，新疆沙冬青仅生长在我国西北与吉尔吉斯斯坦交界处（74°-77°E，38°-41°N，1800-2800mASL）的狭长地带，蒙古沙冬青生长在97a-1O8°E、37042°N之间戈壁的南侧，多数种群集中于阿拉善荒漠（105°-107°E，39°-41°N，1000一2200 m ASL），它们均被列为国家濒危保护植物。迄今为止，关于沙冬青种子生物学特性的研究尚少，本文重点对沙冬青属的种子生理生态学特性进行研究，主要结果如下：1结实特性及果实和种子形态特性植株结实有明显的大小年；水分是影响结实的重要环境因子；野生植株结英率低（通常低于10％），且果实在成熟过程中虫害严重（虫害率通常在30％以上）；种子千粒重大（分别为27～3 9g和39～45g），种皮光滑无附属物。这些研究表明，有效种子量少和种子不易传播是种群扩散的限制因子。\n2种子硬实性硬实种子贮藏寿命长，种子易形成硬实是沙冬青对旱生环境的适应；但硬实种子吸胀困难，不易萌发，这是引起种群不能顺利自然更新的原因之一。3种子萌发特性及萌发影响因素种子萌发时不需光。萌发的温度范围广（5－4O℃），从一个侧面反映了沙冬青起源于古亚热带，但对温带气候也有较强的适应性。种子大小对新疆沙冬青种子萌发无显著影响，但对蒙古沙冬青影响显著：颜色对种子最终发芽率无显著影响，但对发芽指数影响显著。土壤盐份和湿度是限制种子萌发的主要因素，但低浓度的盐胁迫（0.3％-0.6％）和水分胁迫（2-5Bar）对种子萌发无显著抑制甚至还有促进作用。研究表明沙冬青种子萌发时耐盐耐早，对荒漠环境有强的适应性。相比之下，蒙古沙冬青种子萌发时的耐盐性较强，而新疆沙冬青耐早性较强。4土壤环境因子对种子出苗的影响土壤深度、类型、湿度和盐份含量均显著影响种子出苗，出苗率和出苗速度随深度、盐份含量和紧实度的升高而降低。幼苗死亡率高，并随湿度、盐度和土壤紧实度升高而增加。种子的出苗和幼苗存活情况表明，蒙古沙冬青耐盐性较强，新疆沙冬青的耐早性较高。5脱水生理特性轻度脱水能提高低成熟度沙冬青种子的发芽力，但继续脱水，含水量降低至一定值以下，发芽力下降。种子黄熟以后，成熟度继续提高，脱水耐性反而变弱。在脱水过程中，电导率逐渐上升，脱氢酶活性逐渐下降，而CAT、POD和SOD活性在脱水初期上升，而后又降低。两种沙冬青种子属于正常型种子，但新疆沙冬青种子脱水耐性较强。6贮藏生理特性含水量约为8～2O％的种子在-10℃、5℃密封贮藏7个月，发芽力无显著变化，但在室温（18～32℃）和35℃下显著降低，温度越高，下降越快。在贮藏过程中，种子酶活性与发芽力均呈显著正相关，电导率与之呈负相关。虫害会引起种子在贮藏过程中大量损耗，新疆沙冬青种子更严重。以上结果说明生态环境的恶化造成沙冬青种子产量少和落地种子不易获得适宜的萌发和出苗条件，严重的病虫害又损害了大量种子和幼苗，再加上人类活动导致种群数目减少和生境进一步恶化，是沙冬青濒危的重要原因。对沙冬青属种子生理生态特性差异进一步分析可知，蒙古沙冬青种子耐盐性较强和虫害较轻是其分布更广泛的重要原因，新疆沙冬青耐早性较强是其长期适应更干早生境的结果。因此沙冬青既是自然稀有种，又是人为稀有种。要立即采取有效措施进行保护，可采取原位保护和迁地保护相结合的方法，由于两个种在生理生态特性有所不同，可结合它们的自身特性采取具体保护措施。 |
| 英文摘要 | Ammopiptanthus Cheng f., belonging to Leguminosae, is the only genus that is evergreen broad-leaf plant in northwestern desert of China, and has been considered as one of the most unique and keystone plants of local flora in the region. Ammopiptanthus is a relict survivor of the evergreen broadleaf forest of ancient subtropics from the Tertiary period and comprises only two related taxonomical species, A. nanus (M. Pop.) Cheng f. and A. mongolicus (Maxim.) Cheng f. Both species are narrowly distributed, A. nanus is restricted to the borders between China and Kyrgyzstan, growing between 74°-77°E and 38°-41°N at altitudes of 1800-2800m; while A. mongolicus is endemic to the south Gobi desert ranging between 97°-108°E and 37°-42°N, with most populations in Ala-shan Plateau (105°-107°E, 39°-41°N, and 1000-2200m altitude). These two species have been categorized as 'endangered' and subjected to protection'in China. Few researches on seed biology had been carried out up to now, so the eco-physiological characteristics of Ammopiptanthus seeds were investigated in the present study and the main results are highlighted as follows: 1 Fruiting traits of maternal trees and morphological characteristics of fruits and seeds There existed yearly fluctuation in fruit yield of Ammopiptanthus. Water supply was a key factor influencing fruiting. Fruit-bearing percentage of wild maternal trees was low (fruit-bearing percentage generally was below 10%), and the fruits were seriously damaged by insects during development (insect-boring percentage generally was above 30%). The seeds were very lubricous and had high 1000-grain weight (the 1000-grain weight was 27-39 g and 39~45 g respectively). The results revealed that lack of viable seeds and unability of seeds to be dispersed were the important factors restricting population to spread. 2 Hardseededness in seeds The seeds tended to become hard at maturity with long storability, which showed that Ammopiptanthus had strong adaptation to arid environments. But it was difficulty for hard seeds to imbibe and germinate, which was one of the key reasons why the population could not generate successfully. 3 Characteristics of seed germination and factors influencing germination The germination required no illumination, and that the seeds could germinate at a wind temperature (5～40 ℃) reflected from one side that the Ammopiptanthus originate in ancient subtropics and high adaptation to temperate zone. Seed size had hardly effect on germination of A. nanus, but had significant effect on that of A. mongolicus. Seed color had hardly any effect on final germination percentage, but had significant effect on germination index. The salt concentration and soil moisture were the key factors restricting seed germination, but slight salt or water stress had no significant inhibition, and even had acceleration on germination. The results showed that Ammopiptanthus had high tolerance to salt and drought during the period of seed germination, and the salt-tolerance of A. mongolicus was more than that of A. nanus, but the drought-tolerance was reverse between the two species. 4 Effect of environmental factors in soil on seedling emergence The depth, type, moisture and salt of soil had significant effect on seedling emergence, and the percentage and velocity of seedling decreased with increase of moisture content, salt concentration, and compaction of soil. The salt-tolerance of A. mongolicus during the period of seedling emergence in soil was more than that of A. nanus, but the drought-tolerance was reverse between the two species. 5 Seed physiology of desiccation Slight desiccation could promote germination of seeds with less mature levels, but when seed moisture content dropped to below a certain degree through further desiccation, the germination was reduced. The desiccation tolerance of seeds harvested after stage of yellow ripeness weakened as the mature level rose. The relative electrical conductivity built up gradually during the process of desiccation, butthe dehydrogenase activity declined. The activity of CAT, POD and SOD rose at early stages of desiccation, but then all decreased gradually decreased at late stages. Ammopiptanthus seeds had high desiccation-tolerance, but the tolerance of A. nanus was more than that of A. mongolicus. 6 Seed physiology of storage The germinability of Ammopiptanthus seeds with moisture content of 8-20% had no significant reduction after storage at -10 ℃ and 5 ℃ for 7 months, but decreased significantly after storage at ambient temperature (18~32X:) and 35*C, and decreased faster at 35 ℃ than at ambient temperature. There was significant positive correlation between enzyeme activity and germinability, but negative between electrical conductivity and germinability. Most of Ammopiptanthus seeds were damaged by insects during storage, and the seeds of A. nanus were damaged more seriously than those of A. mongolicus. The above results made clear that the awful ecological environment could not provide the suitable conditions for seed production and germination, serious disease and insect pest damaged most seeds and seedlings, and man-made destruction reduced maternal population, which were the most important reasons why Ammopiptanthus had been declining. Further analysis of the difference between A. nanus and A. mongolicus revealed that more salt-tolerance and less insect pest of seeds were the reason why A, mongolicus distribute more widely than A. nanus, and more drough-tolerance of A. nanus seeds than that of A. mongolicus would be contributed to long adaptation to more arid envioroment. So this species became endangered owing to both natural and artificial causes, and some effective measurements should be taken immediately to protect this endangered species according to their respective characteristics of ecophysiology, such as in situ conservation and ex-situ conservation. |
| 中文关键词 | 沙冬青 ; 结实 ; 种子 ; 硬实 ; 萌发 ; 脱水 ; 贮藏 |
| 英文关键词 | Ammopiptanthus fruiting seed hardseed germination desiccation storage |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院华南植物园 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286371 |
| 推荐引用方式 GB/T 7714 | 杨期和. 珍稀濒危植物沙冬青种子生理生态学研究[D]. 中国科学院华南植物园,2004. |
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