| Biological sciences & biotechnology |
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| Effects of simulated waterlogging on growth, physiological and biochemical characteristics of Metasequoia glyptostroboides seedlings |
| Bai Linli, Han Wenjiao, Li Changxiao |
| (Key Laboratory for the Eco-Environment of the Three Gorges Reservoir Region of the Ministry of Education, College of Life Sciences, Southwest University, Chongqing 400715, China) |
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Abstract The disruption of natural flow regimes in river systems poses many challenges to riparian ecosystems and their native species. The construction of the Three Gorges Dam has altered the flow regimes of the upper Yangtze River and created a riparian zone with a vertical gap of 30 m. Because of the anti-seasonal change of the water level caused by annual water regulation, plants grown on the riparian zone of the Three Gorges Reservoir Area (TGRA) may suffer from submergence, and often display dynamic change characteristics. Such water level change is likely to disturb the normal ecophysiological rhythm of the native tree species of the riparian zone. These hydrological changes highlight the importance of screening suitable tree species for reforestation in the TGRA and similar environments. Thus, the native tree species Metasequoia glyptostroboides, will most likely to experience continuous submergence or inundation. Current research on M. glyptostroboides seedlings is more focused on genetic structure, membrane composition, chemical property, growth and photosynthesis, and the like. However, the eco-physiological implications of submersion on M. glyptostroboides seedlings are not well known, especially under the condition of full-submersion.
The aim of this study was to investigate the responding characteristics of the M. glyptostroboides seedlings to the water level change in the TGRA, and provide theoretical basis for species selection for revegetation in the riparian zone of the TGRA.
Measured indexes included protective enzymes such as superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (ASP) and catalase (CAT), osmotic adjustment substances such as soluble protein and free proline, and membrane lipid peroxidation such as malondialdehyde (MDA), as well as photosynthetic characteristics and biomass accumulation of the two-year old M. glyptostroboides seedlings to submergence, upon mimicking the water level change in the riparian zone of the TGRA. Based on soil moisture change pattern in the TGRA, water treatments including control (CK), half-submersion (HS), and full-submersion (FS) were applied.
The activities of SOD, POD, ASP, CAT and content of free proline of M. glyptostroboides seedlings in HS and FS group were higher than that in CK after submersion. Under submersion, MDA content in HS and FS group increased as compared with that in CK. The net photosynthetic rate of M. glyptostroboides seedlings in HS was significantly higher than that in CK. Root-shoot ratio in FS was significantly higher than that in CK, but no significant difference was detected between FS and HS. Leaves of M. glyptostroboides seedlings in FS were leaf bud, and survival rates were 100%.
The results indicated that antioxidant enzymes, osmotic adjustment substances and photosystem Ⅱ have a positive response during submersion, M. glyptostroboides seedlings show strong adaptability to the submersion. Thus, M. glyptostroboides should be considered as one of the potential species for revegetation in the TGRA.
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Published: 20 September 2015
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模拟水淹对水杉苗木生长与生理生化特性的影响
通过对在不同土壤水分处理下水杉(Metasequoia glyptostroboides)保护酶系［超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)、抗坏血酸过氧化物酶(ascorbate peroxidase,ASP)、过氧化氢酶(catalase,CAT)］活性及渗透调节物质(可溶性蛋白、游离脯氨酸)和细胞膜脂过氧化产物［丙二醛(malondialdehyde,MDA)］含量以及光合特性、生物量的测定,探讨水杉对三峡库区水位变化的响应特性和耐水淹适应能力。模拟三峡库区消落带土壤水分变化格局,以二年生水杉苗木为试验材料,设置对照组(control,CK)、半淹组(half-submersion,HS)和全淹组(full-submersion,FS)3个处理。结果表明:在水淹胁迫下,SOD、POD、ASP、CAT活性以及游离脯氨酸含量均升高。在水淹胁迫下,水杉叶片MDA含量与CK相比差异不显著,无统计学意义。HS净光合速率(net photosynthetic rate,Pn)显著高于CK；FS的根冠比显著高于CK,但与HS相比差异不显著,无统计学意义。全淹植株呈叶芽形式,水淹植株存活率均达100％。在淹水期间,由于抗氧化酶、渗透调节物质、光系统Ⅱ的积极响应,水杉表现出极强的水分适应能力。因此,可以考虑将水杉列为三峡库区消落带植被构建的候选树种之一。
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