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| 1 |
Assessment of changes in green space of Nanjing City using Landsat satellite data |
Xu Hao |
Open House International |
2015-3-24 |
全文 |
| 关键词： |
Green Space, Patch, Changes, Landscape Metric, Landsat, Urbanization, Nanjing, China |
| 摘要： |
Conservation of green space is crucial to the sustainablen urban development of China. Nanjing is a central city in the Yangtze River Delta cluster in eastern China. Owing to urbanization, the green spaces in this city have been affected significantly in terms of their scale and structure. Assessing such changes can provide a basis for environment protection measures and spatial layout of the green spaces using various landscapes including CA, PLAND, PD, MPS, LPI, NP, PD, TE, ED, MPI, and LSI. Coinciding with a sharp increase in urban population, the area of green spaces in Nanjing decreased by 27.06% between 1998 and 2007. The patches of green space increased by 39%, and the average area per patch decreased by about 47.52%. Green space patches were found to be unevenly distributed among the districts of Nanjing. In urban areas, significant numbers of such patches were found primarily in various types of parks, while in suburban areas, they were concentrated mainly in the hilly forestlands. Green spaces exhibited tendencies towards fragmentation, miniaturization, and discretization. |
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| 2 |
ABA improves postharvest quality of cut Lilium ‘Sorbonne’ harvested in late period |
Geng XM(耿兴敏), Li M, Lu L, Okubo H, Ozaki Y |
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2018-4-28 9:49:54 |
全文 |
| 关键词： |
abscisic acid, cut lily, flower preservation, postharvest stage, sucrose |
| 摘要： |
With the delay of harvest stage, the carbohydrate content of flower petals and the diameter of flower buds increased, but the vase life was shortened. Effects of abscisic acid (ABA) and sucrose on preservation of cut lilies were related to the harvest stage. Due to the lower level of soluble sugars and other energy
source in early harvested cut lilies, the sucrose pretreatment turned to be particularly effective for extending the vase life and increasing the flower fresh weight and bud diameter. For the cut flowers harvested at middle stage, pretreatment with sucrose or ABA separately enhanced the preservation effect, which was not observed when pretreated with the combination of sucrose and ABA. The preservation effect of the harvested flowers at the late development stage was increased by the ABA pretreatments including ABA
alone or ABA and sucrose (ABA+Suc). ABA improved sucrose uptake from the pretreatment solution and
increased soluble sugar contents in cut flower petals. Combined with sucrose pretreatment, addition of ABA alleviated leaf chlorosis symptom of cut flowers harvested in early period. |
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| 3 |
Assessing Urban Green Space distribution in a compact megacity by landscape metrics |
Liang Huilin, Chen Di, Zhang Qingping |
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2018-4-28 9:02:42 |
全文 |
| 关键词： |
urban green space (UGS), landscape and ecological quality (LEQ), landscape pattern, compact city, landscape metric;environmental sustainability |
| 摘要： |
The pattern and structure of urban green space (UGS) plays a significant role in the landscape and ecological quality (LEQ) of UGS, especially in a compact city with limited space. Based on landscape metrics, this study proposes an innovative method to quantify the effects of UGS pattern and structure on LEQ. Taking Shanghai, China as the study area, we calculated all landscape-level spatial metrics in FRAGSTATS, used correlation analysis in SPSS for data reduction, and adopted factor analysis and cluster analysis to statistically analyze the metrics and assesse the LEQ of UGS. These methods bridge the research gap of UGS distribution assessment for LEQ value by landscape metrics.
Results showed that new districts usually have higher LEQ of UGS than old towns. Of the 17 districts in Shanghai,Chongming has the highest LEQ of UGS and Hongkou has the lowest. For the UGS pattern and structure, the eight old towns are similar, in contrast to the new districts of Chongming and Pudong, which are more dissimilar than the other districts for LEQ of UGS. The findings could help compact cities having limited UGS to develop and achieve better LEQ. |
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| 4 |
Root tip chromosome karyotype analysis of hyacinth cultivars |
Hu FR(胡凤荣), Liu HH, Wang F, Bao RL, Liu GX |
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2018-4-28 9:35:46 |
全文 |
| 关键词： |
Hyacinth; Chromosome; Diploid; Triploid; Tetraploid;Karyotype analysis |
| 摘要： |
Karyotype analysis in plants helps to reveal the affinity relationships of species and their genetic evolution. The current study aimed to observe chromosome karyotypes and structures of Hyacinthus orientalis. Twenty hyacinth cultivars were introduced from Holland, and their water-cultivated root tips were used as experimental samples. A solution of colchicine (0.02%) and 8-hydroxyquinoline (0.02 M) was used as a 20-h pre-treatment. Subsequently, Carnot I was used for fixation and 45% acetic acid was used for dissociation. The squash method was selected to prepare chromosome spreads for microscopic observation. The basic chromosome number of the hyacinth cultivar was 8, and the number of chromosomes in the diploid, triploid, tetraploid, and aneuploid cultivars was 16, 23, 24, 31, and 32, respectively. The L-type chromosome was predominant in the chromosomal composition. The
hyacinth satellite was located on the short arm in numbers equivalent to the ploidy. This satellite is located on the middle-sized chromosome in the fourth group of chromosomes, demonstrating that Hyacinthus has a more primitive evolution than Lilium and Polygonatum. Among 20 hyacinth cultivars, ‘Fondant’ had the highest level of evolution and a maximum asymmetric coefficient of 61.69%. Moreover, the ratio between the shortest and longest chromosomes in this cultivar was 4.40, and its karyotype was type 2C. This study may elucidate longterm homonym and synonym phenomena. It may also provide a method of cytological identification as well as direct proof of the high outcross compatibility between hyacinth cultivars. |
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| 5 |
Effects of mulching on soil properties and growth of tea olive (Osmanthus fragrans) |
Xue N, Song WT, Zhang HC, Yang XL(杨秀莲), Wang LG(王良桂) |
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2018-4-28 9:40:06 |
全文 |
| 关键词： |
无 |
| 摘要： |
Different mulches have variable effects on soil physical properties and plant growth. This
study aimed to compare the effects of mulching with inorganic (round gravel, RG), organic
(wood chips, WC), and living (manila turf grass, MG) materials on soil properties at 0–5-cm
and 5–10-cm depths, as well as on the growth and physiological features of Osmanthus fragrans
L. ‘Rixianggui’ plants. Soil samples were collected at three different time points from
field plots of O. fragrans plants treated with the different mulching treatments. Moisture at
both soil depths was significantly higher after mulching with RG and WC than that in the
unmulched control (CK) treatment. Mulching did not affect soil bulk density, pH, or total
nitrogen content, but consistently improved soil organic matter. The available nitrogen in the
soil increased after RG and WC treatments, but decreased after MG treatment during the
experimental period. Mulching improved plant growth by increasing root activity, soluble
sugar, and chlorophyll a content, as well as by providing suitable moisture conditions and
nutrients in the root zone. Plant height and trunk diameter were remarkably increased after
mulching, especially with RG and WC. However, while MG improved plant growth at the
beginning of the treatment, the ‘Rixianggui’ plants later showed no improvement in growth.
This was probably because MG competed with the plants for water and available nitrogen in
the soil. Thus, our findings suggest that RG and WC, but not MG, improved the soil environment
and the growth of ‘Rixianggui’ plants. Considering the effect of mulching on soil properties and plant growth and physiology, round gravel and wood chips appear to be a better
choice than manila turf grass in ‘Rixianggui’ nurseries. Further studies are required to determine the effects of mulch quality and mulch-layer thickness on shoot and root growths. |
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| 6 |
Corrigendum: enhancing heat tolerance of the little dogwood Cornus Canadensis L. f. with introduction of a superoxide reductase gene from the hyperthermophilic archaeon Pyrococcus furiosus |
Geng X M(耿兴敏), Liu X, Ji M, Ji M, Hoffmann WA, Grunden A, Xiang QY. |
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2018-4-28 9:41:32 |
全文 |
| 关键词： |
antioxidant enzyme, Cornus canadensis, genetic transformation, heat tolerance, Pyrococcus furiosus,reactive oxygen species (ROS), superoxide reductase (SOR) |
| 摘要： |
Production of reactive oxygen species (ROS) can be accelerated under various biotic and abiotic stresses causing lipid peroxidation, protein degradation, enzyme inactivation, and DNA damage. Superoxide reductase (SOR) is a novel antioxidant
enzyme from Pyrococcus furiosus and is employed by this anaerobic hyperthermophilic
archaeon for efficient detoxification of ROS. In this study, SOR was introduced into a flowering plant Cornus canadensis to enhance its heat tolerance and reduce heat induced damage. A fusion construct of the SOR gene and Green Fluorescent Protein gene (GFP) was introduced into C. canadensis using Agrobacterium-mediated
transformation. Heat tolerance of the GFP-SOR expressing transgenic plants was investigated by observing morphological symptoms of heat injury and by examining changes in photosynthesis, malondialdehyde (MDA), and proline levels in the plants. Our results indicate that the expression of the P. furiosus SOR gene in the transgenic
plants alleviated lipid peroxidation of cell membranes and photoinhibition of PS II, and
decreased the accumulation of proline at 40◦C. After a series of exposures to increasing
temperatures, the SOR transgenic plants remained healthy and green whereas most of the non-transgenic plants dried up and were unable to recover. While it had previously been reported that expression of SOR in Arabidopsis enhanced heat tolerance, this is the first report of the successful demonstration of improved heat tolerance in a nonmodel plant resulting from the introduction of P. furiosus SOR. The study demonstrates the potential of SOR for crop improvement and that inherent limitations of plant heat tolerance can be ameliorated with P. furiosus SOR. |
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| 7 |
Authenticity identification and leaf blight resistance evaluation of the F1 hybrids from two Lilium cultivars ‘Sorbonne’ and ‘Francia’ |
Hu FR(胡凤荣), Liu GX, Hu YM, Guo RR, Zhu LM, Luo FX, Wang F |
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2018-4-28 9:43:47 |
全文 |
| 关键词： |
Botrytis elliptica;Disease resistance;Hybrid identification;Lilium oriental hybrids;Resistance evaluation |
| 摘要： |
This study identified the genetic transmission pattern of the leaf blight resistance of Lilium species based on resistance distribution. A total of 133 hybrids of the ‘Sorbonne’ (female parent, highly resistant to Botrytis elliptica) and ‘Francia’ (male parent, highly susceptible to B. elliptica) cultivars were selected by
inter-simple sequence repeat polymerase chain reaction. Among them, 17 were highly resistant, 42
moderately resistant, 46 moderately susceptible, and 28 susceptible. One F1 plant showed greater
resistance than Sorbonne, and 17 showed greater susceptibility than Francia. Disease resistance from Sorbonne could be inherited and was a typical quantitative trait determined by polygenes. |
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| 8 |
Pollen viability and stigma receptivity in Lilium during anthesis |
He GR, Hu FR(胡凤荣), Ming J, Yuan SX |
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2018-4-28 9:45:37 |
全文 |
| 关键词： |
Lilium;Pollen viability;Stigma receptivity Embryo sac development;Stigma;secretion |
| 摘要： |
Pollen viability and stigma receptivity are
prerequisites for successful pollination and seed set in flowering plants. In this study, the pollen viabilities and stigma receptivities of nine Lilium genotypes (six cultivars and three species native to China) were assayed by in vitro pollen germination and the benzidine-H2O2 method, respectively. Embryo sac development during anthesis was observed to further ensure the timing of controlled pollination. In addition,
the relationship between stigma secretion and
stigma receptivity was studied to estimate the pollination time based on phenotype. Anthers cracked on the day of flowering in all genotypes, but pollen germination during anthesis was not observed in Asiatic hybrids excepted for ‘Tiny pudhye’, which exhibited low pollen viability for a short period of time (from 0 to 1 day after anthesis). In the other genotypes,pollen germination rates were highest on anthesis (five
of seven genotypes), 0–1 day after anthesis (L.
sulphureum), or 0–2 days after anthesis (one Longiflorum hybrid), and then gradually decreased
with days after anthesis. While, stigma receptivity first increased and then decreased during anthesis. Formost genotypes, stigmas began to be receptive 1 day after anthesis, and all genotypes exhibited stigma receptivity at 2 days after anthesis. The durations of stigma receptivity and strongest stigma receptivity,
were genotype dependent, and were 5–8 days and
1–4 days, respectively. Moreover, on the first flowering day, 6 of 7 genotypes had mature embryo sacs, and at the time at which stigmas began to be receptive, all tested genotypes had mature embryo sacs. Some Lilium genotypes showed stigma secretion, which can be a sign of stigma receptivity. Stigmas became receptive and reached highest receptivity within 1 day of the first appearance of secretion on the surface of the
stigma and at peaking, respectively. The results of this study are valuable for the implementation of successful Lilium breedin programs. |
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| 9 |
两个桂花品种花色色素相关基因的差异表达 |
母洪娜，孙陶泽，杨秀莲，王良桂 |
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2018-4-15 19:14:49 |
全文 |
| 关键词： |
桂花;花青素;类胡萝卜素;花色基因差异表达 |
| 摘要： |
结合桂花花青素、类胡萝卜素的含量与转录组测序检测到的花色代谢相关基因的差异表达，对品种为‘橙红丹桂’和‘早银桂’的花色变化过程进行了初步研究。结果发现:苯丙氨酸裂解酶、4 － 香豆酸—CoA 连接酶、乙酰辅酶A 合酶、查耳酮合酶、Ｒ2Ｒ3 － MYB1、细胞色素P450、番茄红素ε 环化酶基因的表达与花青素和类胡萝卜素含量变化相似，这两类色素代谢路径上的其他基因均在‘早银桂’中表达量较高。此外，这种现象很可能是
多酚氧化酶(PPO)、细胞色素P450 基因在转录因子Ｒ2Ｒ3 － MYB 调控下差异表达所致，并且还发现桂花类黄酮
的代谢路径是从柚皮素开始转向二氢槲皮素进而在DFＲ、ANS 催化下形成矢车菊色素。 |
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| 10 |
珍稀树种夏蜡梅研究进展 |
芦建国，孙姿，唐桂兰 |
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2018-4-15 19:32:30 |
全文 |
| 关键词： |
夏蜡梅; 濒危植物; 群落学; 繁殖 |
| 摘要： |
夏蜡梅系我国特有濒危植物，已被列为国家二级保护植物。简要先容了夏蜡梅生物学特性、生态适应性，系统综述了夏蜡梅群落学、濒危机制、繁殖技术及育种等方面的研究进展，同时对夏蜡梅研究方向进行了展望。旨在提高人们对夏蜡梅的认识，以采取科学的保护措施，促进夏蜡梅的广泛栽植，为其推广应用提供科学参考。 |
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| 11 |
Assessing the public transport service to urban parks on the basis of spatial accessibility for citizens in the compact megacity of Shanghai, China |
Huilin Liang,Qingping Zhang |
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2018-4-28 8:58:06 |
全文 |
| 关键词： |
accessibility, geographic information systems (GIS), public transport, Shanghai, urban green space,urban park |
| 摘要： |
Urban parks and public transport are indispensable elements of a compact megacity for their environmental and social values. However, few measures of urban park accessibility have considered the public transport travel mode. Based on the framework of geographic information systems (GIS) network analysis, this study proposes an innovative method to incorporate public transport travel mode into urban park accessibility evaluations. Taking Shanghai, China, as the study area, we measured home to park and park from home travel times on multi-modal transport networks, calculated the
accessibilities by multiple equations, and compared accessibilities for different districts. These methods extend current accessibility measures by calculating accessibility at a realistic level, and provide a measure of public transport service for urban parks. The results for Shanghai show that approximately 99.95% of home to park routes might include public transport. The distribution of home to park public transport accessibility of the city was uneven. The patches with best accessibility tend to be distributed in the built-up area in the city centre. Public transport access to urban parks is inhomogeneous for different districts, because of urban park locations, road network characteristics, and uneven public transport supply. The distribution of park from home public transport accessibility has no significant correlation with district development stage. Public transport service in Shanghai takes
no account of the factors of park star rating or size. Positive actions are required to improve the
equity of public transport access to the important public health resources of urban parks. |
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| 12 |
Identification and validation of reference genes for gene expression studies in sweet osmanthus (Osmanthus fragrans) based on transcriptomic sequence data |
Mu HN, Sun TZ, Xu C, Wang LG(王良桂), Yue YZ(岳远征), Li HG, Yang XL(杨秀莲) |
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2018-4-28 9:48:27 |
全文 |
| 关键词： |
无 |
| 摘要： |
Accurate normalized data is a primary requisite for quantifying gene expression using RT-qPCR technology. Despite this importance, however, suitable reference genes in Osmanthus fragrans are not available. In this study, seven potential
candidate reference genes (OfL25-1, OfL25-10, OfRP2, OfTUA, OfTUB3, OfUBQ2 and Of18S) were evaluated to determine which one would be the most reliable reference genes. The expression levels of the candidate reference genes were analysed by RT-qPCR in flower, leaf, pedicel, blossom bud tissues, as well as in floral organs at different developmental stages.GeNormand NormFinderwere used to statistically analyse transcript variation.Results indicated
that OfRP2 and OfL25-10 were the optimal reference genes for use in RT-qPCR when analysing different stages of floral development; while OfTUB3 and OfL25-1 were optimal across tissues. The selected reference genes were used to
examineOfMYB1 expression. The results appeared to be useful for future gene expression analyses aiming to characterize developmental stages and tissues of O. fragrans. |
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| 13 |
Transcriptome sequencing and analysis of sweet osmanthus (Osmanthus fragrans, Lour.) |
Mu HN, Li HG, Wang LG(王良桂), Yang XL(杨秀莲), Sun TZ., Xu C. |
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2018-4-28 9:31:01 |
全文 |
| 关键词： |
Sweet osmanthus;Transcriptome sequencing;Bioinformatic analysis;Flower pigment |
| 摘要： |
Osmanthus fragrans is a woody, evergreen
species of shrubs and small trees that is extensively planted in sub-tropical and temperate climates as an ornamental plant in gardens and for its health benefits. The flower color ranges from ivory to orange to pink among different varieties and even color difference during the whole blossom in the sweet osmanthus. Sweet osmanthus is widely cultivated throughout China and other countries due to its prominent
fragrance, colorful flowers, and medicinal properties. However, the scanty genomic resources in the Olea family have greatly hindered further exploration of its genetic mechanism on these economically important traits. In this study, transcriptome sequencing of O. fragrans was performed using the Illumina HighSeqTM2000 sequencing platform. Next generation sequencing (NGS) of the transcriptome of O. fragrans produced 31.7G of clean bases (211,266,818 clean reads) that were assembled into 256,774 transcripts and 117,595 unigenes. Of them, 197
and 237 candidate genes involved in fragrance and pigment biosynthesis respectively were identified based on function annotation. Meanwhile, 1 unnamed protein and 468 functional unknown genes were also identified. Furthermore,mRNA sequencing expression profiling of O. fragrans were compared to previous genes’. In summary, this comprehensive transcriptome dataset allows the identification of genes associated with several major metabolic pathways and provides a useful public information platform for further functional genomic studiesin O. fragrans
Lour. |
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| 14 |
Pulsing treatment of ABA and sucrose for improving postharvest quality of cut lily flowers |
Geng XM(耿兴敏), Li M, Lu L, Okubo H, Ozaki Y |
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2018-4-28 9:51:31 |
全文 |
| 关键词： |
abscisic acid, cut lily, ethylene, physiological index, postharvest quality |
| 摘要： |
Although it is often considered as a senescence phytohormone, abscisic acid (ABA) at low concentration together with sucrose as pulsing solution displayed preservative effect on cut lily flowers. In order to further clarify the preservation mechanism of ABA, the effects of ABA pretreatment on physiological index and ethylene release were investigated. The addition of 2 mg · L–1 ABA to sucrose increased proline content
in petals. This result suggested that ABA application resulted in water stress of the cut flowers to some
extent. However the pretreatment of the cut lilies with ABA at 2 mg · L–1 delayed the degradation of soluble proteins, and promoted the activity of superoxide dismutase (SOD) enzyme, which decreased the damage to cells induced by reactive oxygen species (ROS). It was also found that the pretreatment with 2 mg · L–1 ABA inhibited ethylene release. |
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| 15 |
春兰AGL6-3基因的克隆及实时定量表达分析 |
胡月苗, 孙崇波, 向林, 胡凤荣 |
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2018-4-20 11:45:14 |
全文 |
| 关键词： |
春兰；ＡＧＬ６－３基因；蝶花；实时荧光定量表达 |
| 摘要： |
：该研究以春兰（Ｃｙｍｂｉｄｉｕｍ ｇｏｅｒｉｎｇｉｉ）正常花及其２枚侧瓣突变成唇瓣样的花瓣（简称：蝶花）为实验材料，采用ＲＴ－ＰＣＲ结合ＲＡＣＥ技术从春兰中分离出ＡＧＬ６－３基因。序列分析表明，ＡＧＬ６－３基因在春兰正常花和蝶花中序列相同，该基因含有１个７２０ｂｐ长的开放阅读框（ＯＲＦ），共编码２３９个氨基酸。系统进化树进行分析表明，该基因属于ＭＡＤＳ－ｂｏｘ基因中ＡＰ１／ＡＧＬ９组的ＡＧＬ６同源基因，命名为ＣｇＡＧＬ６－３（基因登录号为ＫＵ０５８６７９）。实时荧光定量表达分析表明，ＣｇＡＧＬ６－３在春兰正常花和蝶花各花器官中表达存在差异。在正常春兰中ＣｇＡＧＬ６－３基因在唇瓣中强烈表达，在主萼、侧萼及蕊柱中表达量较低，在侧瓣中则微乎其微；而在蝶花中ＣｇＡＧＬ６－３基因在唇瓣中强表达，侧瓣中的表达量次之，在主萼、侧萼和蕊柱中的表达量相近且均较低。研究说明，ＣｇＡＧＬ６－３基因可能在春兰蝶花侧瓣唇瓣化的过程中扮演重要角色。
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| 16 |
论城市与自然环境和谐的可能性 |
陈李波 |
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2018-3-29 8:14:37 |
全文 |
| 关键词： |
和谐,可能性 |
| 摘要： |
从城市与自然环境和谐的动因、机制及达成来论述城市与自然环境的和谐。城市与自然和谐的动因是两者在中西方都代表着2 种不同的, 但具有互补性差异的生活理想;和谐的机制是中国传统学问中的“天人合一” 与西方科学话语下的“ 生态和谐” , 而和谐的达成便是“以山水为体、以学问为魂”的城市山水园林城市建设。 |
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| 17 |
Improving Urban Water Environment in Eastern China by Blending Traditional with Modern Landscape Planning |
Cao, Jiajie (曹加杰),Yu, Junjun,Tian, Yuan,Zhao, Cai,Wang, Hao |
|
2018-5-16 13:54:32 |
全文 |
| 关键词： |
无 |
| 摘要： |
As a fundamental part of greenspace, urban water landscape contributes greatly to the ecological system and at the same time supplies a leisure area for residents. The paper did an analysis on the number of aquatic plant communities, the form of water spaces, and water quality condition by investigating 135 quadrats (90 at amphibious boundary and the land, 45 in the water) in 45transectsof15urbanandsuburbanparks.Wefoundthatwaterspaceshadmonotonousformswithlowbiodiversityandpoor waterquality.Inaddition,urbanwaterlandscapeshardlyprovidedecologicalfunctionsgivenexcessiveconstruction.Accordingly, a proposition to connect tradition with modernism in the improvement and innovation of urban water landscape planning was put forward,and further,the way to achieve it was explored.By taking Qinhu Wetland Park as a case,the principles and specific planning methods on macro- and microperspectives were discussed to guide the development of urban landscape in eastern China.
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| 18 |
Elodeid species as nursery beds for the successful seed restoration of Valksneria spirahls L |
Cao, Jiajie (曹加杰), Ruan, Honghua |
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2018-5-16 14:00:10 |
全文 |
| 关键词： |
aquatic ecosystems；eutrophication；mesocosm；seed germination；submerged aquatic vegetation |
| 摘要： |
Submerged aquatic vegetation (SAV) is often difficult to restore due to their low seedling survival rates. Therefore,we hypothesized that the elodeid macrophytes serve as effective “nursery” areas to promote success for seedlings of other SAV. However, the high density of the elodeid community may inhibit the establishment of other SAV. An experiment was conducted to explore this “nursery effect” as a restoration approach to increase the success of seed restoration. Two elodeid species were pre-planted into mesocosms to create three levels of “nursery beds”i.e., bare, sparse (approx. 100 g m–2) and dense (approx. 200 g m–2). Seeds of Vallisneria spiralis were then placed into these beds to test the seed germination and growth of V. spiralis seedlings. After three months, seed germination was lower in the bare treatment than in the sparse and dense treatments. The growth of V. spiralis seedlings was greater in the sparse treatment than in the bare and dense treatments. These results revealed that the established elodeid bed had a positive effect on the seed restoration of V. spiralis but that the restoration efficiency was significantly reduced by the high-density cover of the elodeid community. |
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| 19 |
Responses of the submerged macrophyte Vallisneria natans to elevated CO2 and temperature |
Cao, JJ (曹加杰), Ruan, HH (Ruan, Honghua) |
|
2018-5-16 14:06:55 |
全文 |
| 关键词： |
CO2 elevation；Biomass allocation； Photosynthetic performance； Submerged macrophyte；Warming |
| 摘要： |
Inorganic carbon and temperature are 2 important factors that regulate the growth of submerged macrophytes. However, experimental evidence regarding the eco-physiological changes that occur in submerged macrophytes in response to elevated CO2 and temperature is still limited. To investigate how the submerged macrophyte Vallisneria natans (Hydrocharitaceae), a common species in the waters of the middle and lower reaches of the Yangtze River, responds to these factors, we conducted a mesocosm experiment using simulated CO2 elevation (by bubbling CO2 into experimental water) and ambient temperature warming systems. During the 60 d experiment, CO2 elevation significantly increased the inorganic carbon concentration in the water column. The warming systems elevated average water temperature by approximately 3°C. The elevation of CO2 levels significantly enhanced the photosynthetic performance, growth and clonal propagation of V. natans. When combined with an increase in CO2, elevated temperatures also promoted photosynthesis and growth. The individual ramet biomass of V. natans decreased with increasing temperature, but only significantly under ambient CO2 levels. CO2 elevation increased both stolon elongation and bud number. At elevated CO2 concentration, more biomass was allocated to the stolons, roots and buds, while less biomass was allocated to the leaves. These results indicate that the eco-physiological responses of V. natans should increase its stress tolerance in aquatic plant communities under future spatial and temporal variation in CO2 levels, however, further research is required.
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Growth response of the submerged macrophyte Myriophyllum spicatum to sediment nutrient levels and water-level fluctuations |
Cao, JJ (曹加杰),Wang, Y (Wang, Ying), Zhu, ZL (Zhu, Zun-ling) |
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2018-5-16 14:09:54 |
全文 |
| 关键词： |
Auto-fragmentation · Myriophyllum spicatum · Submerged macrophyte · Sediment nutrients · Water-level fluctuations |
| 摘要： |
Sediment nutrient levels and water-level fluctuations are important factors that affect the development and growth of submerged macrophytes; however, little is known about the adaptive responses of macrophytes to these factors. We conducted an experiment using the submerged macrophyte Myriophyllum spicatum L. grown under 2 sediment nutrient levels (high: 2.7 mg g−1 total nitrogen, TN; 1.5 mg g−1 total phosphorus, TP; low: 1.45 mg g−1 TN and 0.70 mg g−1 TP) and 3 amplitudes of water-level fluctuation (static, ±50 cm, ±100 cm) in outdoor ponds. We hypothesized that increased nutrient supply would promote the growth of M. spicatum, which can acclimate to the negative effects of moderate water-level fluctuations. After 112 d of growth under high-nutrient conditions, the plants produced a greater shoot biomass (higher branch number and length), resulting in greater accumulation of total biomass. However, plant growth was inhibited by increasing the amplitude of the water-level fluctuations: at ±100 cm, the plants allocated more biomass to the roots and produced fewer and longer branches. Conversely, plant growth was promoted in the high-nutrient sediments at ±50 cm amplitude. The production of auto-fragments was increased in the high-nutrient sediment but was significantly decreased by high water-level fluctuations. Thus, sediment nutrient levels and water-level fluctuations have strong interactive effects on the growth and reproduction of M. spicatum, and increased sediment nutrients in combination with moderate water level fluctuations facilitate nutrient acquisition, plant growth, and reproduction. Our study implies that moderate water-level fluctuations benefit the restoration of submerged macrophyte communities, particularly in high-nutrient habitats.
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