Pollination of flowers initiates postpollination development in orchid (Doritaenopsis hybrida Hort.) flowers, including perianth senescence, stigma closure, and ovary development. Because ethylene is thought to play ...Pollination of flowers initiates postpollination development in orchid (Doritaenopsis hybrida Hort.) flowers, including perianth senescence, stigma closure, and ovary development. Because ethylene is thought to play a key role in coordinating these developmental changes, the authors studied the temporal and spatial patterns of expression of genes encoding 1 aminocyclopropane 1 carboxylic acid (ACC) synthase and ACC oxidase following pollination associated factor treatments in orchid flowers. Both ACC synthase and ACC oxidase mRNA accumulation in the various parts of the flowers is induced by auxin, and ethylene, but not by emasculation. The patterns of both ACC synthase and ACC oxidase mRNA accumulation are similar in all floral organs following auxin and ethylene treatments. Further, in situ hybridization analysis indicates that the ACC oxidase mRNA is localized in epidermal and parenchyma cells of the stigma after auxin and ethylene treatments. The putative roles of auxin, ethylene and emasculation are discussed in terms of the regulation of ACC synthase and ACC oxidase gene expression in flowers.展开更多
Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the hab...Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the habitat fragmentation and unduly commercial collections. Previous observation showed that this species has very low and even no fruit set, and the pollinators are not observed before this report. The present observation was conducted at the Shennongjia, Hubei Province during the spring of 2002. The results showed that Bombus (Diversobombus) trifasciatus Smith, B. imitator Pittion and one species of Apis visited the flowers of the orchid, but only B. tritasciatus could carry pollinaria on its body and was the legitimate pollinators of C amoena. During 113 h of observation, only nine visitations were recorded. The bumblebees mainly appeared during 12:00-15:00 during the day. Bumblebees stayed in a flower only a few seconds and never more than ten seconds. The flowers would persist in fresh for about three weeks when they were not pollinated, but 3 or 4 d after pollinated, the pollinated flowers underwent a series of color and morphological changes including stalk elongation and ovary swelling. Therefore, stalk elongation can be considered an index of fruits set. Artificial pollination indicated that C amoena is a highly self-compatible and outcrossing species, but dependent on pollinators for fruit set. Based on the field observations, we concluded that pollination system of C amoena is deceptive. The fruit set in nature is not very low (26.98% on average) compared to other deceptive orchids, which may be related to small population sizes. The number of pollinia removal is much higher than that of fruit set, indicating that there are some degrees of pollinia wasting in C amoena.展开更多
[Objective] The aim was to study on temporal-spatial distribution model of cold chain logistics for vegetables. [Method] Broccoli was taken as an example. Detailedly, time-space distribution model of cold chain logist...[Objective] The aim was to study on temporal-spatial distribution model of cold chain logistics for vegetables. [Method] Broccoli was taken as an example. Detailedly, time-space distribution model of cold chain logistics for broccoli was proposed from standpoints of costs and benefits based on changes of time and space, and a comprehensive evaluation was made on timeliness, efficiency, risks, added- value of products and satisfaction of information in cold-chain logistics. [Result] The efficiency of cold chain logistics for vegetable can be greatly improved by temporal- spatial distribution model of cold chain logistics. [Conclusion] Costs and benefits of vegetables in temporal-apstial distribution could be evaluated by the model.展开更多
For different texts, different translation strategies should be adopted. This paper makes a case study on lines from Disney animation picture Mulan in the light of functional concept of translation. And it draws a con...For different texts, different translation strategies should be adopted. This paper makes a case study on lines from Disney animation picture Mulan in the light of functional concept of translation. And it draws a conclusion that in the process of film translation, the translator is allowed to make some adaptations to make the translated version more appropriate in the original context, and that the translator is supposed to have both "semantic awareness" and "functional awareness", to achieve the equivalence between the SL text and TL text functionally.展开更多
The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col e...The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col ection methods on pol en vitality of Zygocactus truncates and the results showed that the culture medium containing 200 g/L saccharose, 20 mg/L boric acid, and 20 mg/L calcium chloride is suitable for pol en germination of Zygocactus truncates; when the temperature kept below 20 ℃, pol en germination period last short, and germination rate kept higher;pol en germination performed better with filaments, and pol en tube grew wel .展开更多
[Objective] The aim was to explore the relationship of pollen types and blooming plants,pollen fertility and meteorological factors during the falling process of pollen in the atmosphere.[Method] The falling record of...[Objective] The aim was to explore the relationship of pollen types and blooming plants,pollen fertility and meteorological factors during the falling process of pollen in the atmosphere.[Method] The falling record of pollen in Lanzhou University in spring in 2009 was obtained by 10 m platform natural falling method.The pollen falling number,duration,relationship among falling types and surrounding plants,as well as weather were discussed.[Result] Main pollen types included Populus L.,Salix,Paulownia and Platanaceae.Its pollen falling number,duration was consistent with the flowering period of corresponding plants in the garden;the classification and richness of falling of pollen was influenced by wind.The larger the wind was,the richer the variety become.There was basically no pollen from outside.The authors failed to observe the distinct changes of palynological assemblage in sandy storm weather.[Conclusion] The study could lay basis for the study of the modern progress of natural plants pollen.展开更多
Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μ...Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m?2·s?1). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m?2·s?1 to 569.00 μmol·m?2·s?1 (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m?2·s?1 or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m?2·s?1 (8–961 lx), or 10 μmol·m?2·s?1 for above 6 h. Keywords Muehlewbeckia complera - Shade tolerance - Cultivation - Photosynthesis CLC number S602.1 Document code A Foundation item: This study was supported by the Research Foundation of Northeast Forestry University.Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong展开更多
Aim Isolation and structural elucidation of the constituents from the dried flower buds of Magnolia biondii Pamp. Methods Column chromatography and TLC were used to isolate chemical constituents. Spectroscopic methods...Aim Isolation and structural elucidation of the constituents from the dried flower buds of Magnolia biondii Pamp. Methods Column chromatography and TLC were used to isolate chemical constituents. Spectroscopic methods were employed for structural elucidation. Results One benzo furanoid neolignan (licarin B) and two bisepoxy lignans (magnolin, fargesin) were isolated and identified. Conclusion Licarin B is the first reported benzofuranoid lignan from the family Magnoliaceae.展开更多
Tissue culture has been widely used for mass propagation of Phalaenopsis. However, somaclonal variation occurred during micropropagation process posed a severe problem by affecting product quality. In this study, wild...Tissue culture has been widely used for mass propagation of Phalaenopsis. However, somaclonal variation occurred during micropropagation process posed a severe problem by affecting product quality. In this study, wild type and peloric flower buds of Phalaenopsis hybrids derived from flower stalk nodal culture were used for cDNA-RAPD and cDNA suppression subtractive hybridization analyses in order to study their genetic difference in terms of expressed sequence tags. A total of 209 ESTs from normal flower buds and 230 from mutants were sequenced. These ESTs sequences can be grouped into several functional categories involved in different cellular processes including metabolism, signal transduction, transcription, cell growth and division, protein synthesis, and protein localization, and into a subcat- egory of proteins with unknown function. Cymbidium mosaic virus transcript was surprisingly found expressed fre- quently in the peloric mutant of P. Little Mary. Real-time RT-PCR analysis on selected ESTs showed that in mutant flower buds, a bZIP transcription factor (TGA1a-like protein) was down-regulated, while up-regulated genes include auxin-regulated protein kinase, cyclophilin, and TCP-like genes. A retroelement clone was also preferentially expressed in the peloric mutant flowers. On the other hand, ESTs involved in DNA methylation, chromatin remodeling and post- transcriptional regulation, such as DNA methyltransferase, histone acetyltransferase, ERECTA, and DEAD/DEAH RNA helicase, were enriched in normal flower buds than the mutants. The enriched transcripts in the wild type indicate the down regulation of these transcripts in the mutants, and vice versa. The potential roles of the analyzed transcripts in the development of Phalaenopsis flowers are discussed.展开更多
[Objective] This study aimed to reveal responses of Magnolia multiflora to soil drought stress. [Method] Pot experiment was employed to simulate drought stress, and photosynthetic and physiological indices of M. multi...[Objective] This study aimed to reveal responses of Magnolia multiflora to soil drought stress. [Method] Pot experiment was employed to simulate drought stress, and photosynthetic and physiological indices of M. multiflora were determined. [Result] The net photosynthetic rate (Pn) of M. multiflora did not change significantly under mild drought stress, and reduced significantly under moderate and severe drought stress. Drought stress reduced stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci), and compared with those in the control group, the Pn, Gs, Tr and Ci under severe drought stress declined by 61.04%, 86.27%, 87.77% and 42.63%, respectively. The malondialdehyde (MDA) content in M. multiflora leaves did not increase significantly under mild drought stress, and increased significantly under moderate and severe drought stress. The MDA content in M. multiflora leaves under severe drought stress was 1.63 times as high as that in the control group. The proline (Pro) and soluble sugar contents of M. multiflora increased significantly with the aggravation of drought stress, and those under severe drought stress were 8.06 times and 3.16 times respectively higher than those in the control group. [Conclusion] M. multiflora has a strong drought tolerance, and is suitable for growing in relatively arid environment. It can be used as candidate for vegetation restoration in hydropower engineering slope.展开更多
The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions: (1) Wha...The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions: (1) What is the ecological niche of the different epiphytic orchid species? (2) What are the ecological factors that threaten epiphytic orchid's population under anthropogenic disturbances? Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis (PCA). The correlations between the different site factors were statistically significant. Spearman's rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height (dbh) of host had the highest significant positive correlation coefficient (0.67 and 0.64 respectively). On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient (-0.80 and -0.61, respectively). Different epiphytic orchid species interact differently with the given set of environmental factors: for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees (species and size) and increasing air pollution, resulting in increasing host bark pH.展开更多
[Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the ...[Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the least square method, fre- quency distribution, aggregation index, m*-m regression analysis and Taylor's pow- er law model. [Result] The field distribution of broccoli plants with clubroot disease tended to be aggregated distribution, m'-m regression analysis showed that the el- ementary composition of the spatial distribution of diseased or infected plants was individual colony, the individuals attracted each other; the disease had obvious dis- ease focus in the field, and the individual colony showed uniform distribution pattern in the field. Taylor's power law showed that the spatial pattern of individual dis- eased or infected plant with clubroot disease tended to be uniform distribution with the increase of the density. On the basis of this, Iwao optimal theoretical sampling model and sequential sampling model were established, namely N =273.954 1/m- 59.698 5, To (N)=0.368 4N±1.926 8√N, respectively, it meant that when surveying N plants, if the accumulative incidence rate exceeded upper bound, the field can be set as control object; if the accumulative incidence rate didn't reach lower bound, it can be set as uncontrol field; if the accumulative incidence rate was between upper bound and lower bound, it should be surveyed continuously until the maximum sample size (mo=0.368 4) appeared, that was, the disease incidence was 15%, so the sampling number should be 684 plants. [Conclusion] The research results had very important instructive meaning for disease control.展开更多
We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, ...We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be planted in areas where orchids still exist to provide more trees for orchid population enlargement (e.g. along riparian system). Native species should be favoured; the pool of such native host species is wide.展开更多
文摘Pollination of flowers initiates postpollination development in orchid (Doritaenopsis hybrida Hort.) flowers, including perianth senescence, stigma closure, and ovary development. Because ethylene is thought to play a key role in coordinating these developmental changes, the authors studied the temporal and spatial patterns of expression of genes encoding 1 aminocyclopropane 1 carboxylic acid (ACC) synthase and ACC oxidase following pollination associated factor treatments in orchid flowers. Both ACC synthase and ACC oxidase mRNA accumulation in the various parts of the flowers is induced by auxin, and ethylene, but not by emasculation. The patterns of both ACC synthase and ACC oxidase mRNA accumulation are similar in all floral organs following auxin and ethylene treatments. Further, in situ hybridization analysis indicates that the ACC oxidase mRNA is localized in epidermal and parenchyma cells of the stigma after auxin and ethylene treatments. The putative roles of auxin, ethylene and emasculation are discussed in terms of the regulation of ACC synthase and ACC oxidase gene expression in flowers.
文摘Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the habitat fragmentation and unduly commercial collections. Previous observation showed that this species has very low and even no fruit set, and the pollinators are not observed before this report. The present observation was conducted at the Shennongjia, Hubei Province during the spring of 2002. The results showed that Bombus (Diversobombus) trifasciatus Smith, B. imitator Pittion and one species of Apis visited the flowers of the orchid, but only B. tritasciatus could carry pollinaria on its body and was the legitimate pollinators of C amoena. During 113 h of observation, only nine visitations were recorded. The bumblebees mainly appeared during 12:00-15:00 during the day. Bumblebees stayed in a flower only a few seconds and never more than ten seconds. The flowers would persist in fresh for about three weeks when they were not pollinated, but 3 or 4 d after pollinated, the pollinated flowers underwent a series of color and morphological changes including stalk elongation and ovary swelling. Therefore, stalk elongation can be considered an index of fruits set. Artificial pollination indicated that C amoena is a highly self-compatible and outcrossing species, but dependent on pollinators for fruit set. Based on the field observations, we concluded that pollination system of C amoena is deceptive. The fruit set in nature is not very low (26.98% on average) compared to other deceptive orchids, which may be related to small population sizes. The number of pollinia removal is much higher than that of fruit set, indicating that there are some degrees of pollinia wasting in C amoena.
基金Supported by Tianjin Science and Technology Development Project (060YFGNC1900)National Key Technology R&D Program in the 11th Five-year Plan of China(2012BAD38B01)~~
文摘[Objective] The aim was to study on temporal-spatial distribution model of cold chain logistics for vegetables. [Method] Broccoli was taken as an example. Detailedly, time-space distribution model of cold chain logistics for broccoli was proposed from standpoints of costs and benefits based on changes of time and space, and a comprehensive evaluation was made on timeliness, efficiency, risks, added- value of products and satisfaction of information in cold-chain logistics. [Result] The efficiency of cold chain logistics for vegetable can be greatly improved by temporal- spatial distribution model of cold chain logistics. [Conclusion] Costs and benefits of vegetables in temporal-apstial distribution could be evaluated by the model.
文摘For different texts, different translation strategies should be adopted. This paper makes a case study on lines from Disney animation picture Mulan in the light of functional concept of translation. And it draws a conclusion that in the process of film translation, the translator is allowed to make some adaptations to make the translated version more appropriate in the original context, and that the translator is supposed to have both "semantic awareness" and "functional awareness", to achieve the equivalence between the SL text and TL text functionally.
文摘The research, based on pol ens of Zygocactus truncates during ful-bloom period, selected suitable culture medium and temperature for pol en germination and explored the effects of storage temperatures and pol en col ection methods on pol en vitality of Zygocactus truncates and the results showed that the culture medium containing 200 g/L saccharose, 20 mg/L boric acid, and 20 mg/L calcium chloride is suitable for pol en germination of Zygocactus truncates; when the temperature kept below 20 ℃, pol en germination period last short, and germination rate kept higher;pol en germination performed better with filaments, and pol en tube grew wel .
基金Supported by Foundation for Excellent Youth Scholars of CAREERI,CAS(51Y184991)~~
文摘[Objective] The aim was to explore the relationship of pollen types and blooming plants,pollen fertility and meteorological factors during the falling process of pollen in the atmosphere.[Method] The falling record of pollen in Lanzhou University in spring in 2009 was obtained by 10 m platform natural falling method.The pollen falling number,duration,relationship among falling types and surrounding plants,as well as weather were discussed.[Result] Main pollen types included Populus L.,Salix,Paulownia and Platanaceae.Its pollen falling number,duration was consistent with the flowering period of corresponding plants in the garden;the classification and richness of falling of pollen was influenced by wind.The larger the wind was,the richer the variety become.There was basically no pollen from outside.The authors failed to observe the distinct changes of palynological assemblage in sandy storm weather.[Conclusion] The study could lay basis for the study of the modern progress of natural plants pollen.
基金Supported by the Research Foundation of Northeast Forestry University.
文摘Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m?2·s?1). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m?2·s?1 to 569.00 μmol·m?2·s?1 (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m?2·s?1 or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m?2·s?1 (8–961 lx), or 10 μmol·m?2·s?1 for above 6 h. Keywords Muehlewbeckia complera - Shade tolerance - Cultivation - Photosynthesis CLC number S602.1 Document code A Foundation item: This study was supported by the Research Foundation of Northeast Forestry University.Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong
文摘Aim Isolation and structural elucidation of the constituents from the dried flower buds of Magnolia biondii Pamp. Methods Column chromatography and TLC were used to isolate chemical constituents. Spectroscopic methods were employed for structural elucidation. Results One benzo furanoid neolignan (licarin B) and two bisepoxy lignans (magnolin, fargesin) were isolated and identified. Conclusion Licarin B is the first reported benzofuranoid lignan from the family Magnoliaceae.
文摘Tissue culture has been widely used for mass propagation of Phalaenopsis. However, somaclonal variation occurred during micropropagation process posed a severe problem by affecting product quality. In this study, wild type and peloric flower buds of Phalaenopsis hybrids derived from flower stalk nodal culture were used for cDNA-RAPD and cDNA suppression subtractive hybridization analyses in order to study their genetic difference in terms of expressed sequence tags. A total of 209 ESTs from normal flower buds and 230 from mutants were sequenced. These ESTs sequences can be grouped into several functional categories involved in different cellular processes including metabolism, signal transduction, transcription, cell growth and division, protein synthesis, and protein localization, and into a subcat- egory of proteins with unknown function. Cymbidium mosaic virus transcript was surprisingly found expressed fre- quently in the peloric mutant of P. Little Mary. Real-time RT-PCR analysis on selected ESTs showed that in mutant flower buds, a bZIP transcription factor (TGA1a-like protein) was down-regulated, while up-regulated genes include auxin-regulated protein kinase, cyclophilin, and TCP-like genes. A retroelement clone was also preferentially expressed in the peloric mutant flowers. On the other hand, ESTs involved in DNA methylation, chromatin remodeling and post- transcriptional regulation, such as DNA methyltransferase, histone acetyltransferase, ERECTA, and DEAD/DEAH RNA helicase, were enriched in normal flower buds than the mutants. The enriched transcripts in the wild type indicate the down regulation of these transcripts in the mutants, and vice versa. The potential roles of the analyzed transcripts in the development of Phalaenopsis flowers are discussed.
基金Supported by National Natural Science Foundation of China(No.51179094)~~
文摘[Objective] This study aimed to reveal responses of Magnolia multiflora to soil drought stress. [Method] Pot experiment was employed to simulate drought stress, and photosynthetic and physiological indices of M. multiflora were determined. [Result] The net photosynthetic rate (Pn) of M. multiflora did not change significantly under mild drought stress, and reduced significantly under moderate and severe drought stress. Drought stress reduced stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci), and compared with those in the control group, the Pn, Gs, Tr and Ci under severe drought stress declined by 61.04%, 86.27%, 87.77% and 42.63%, respectively. The malondialdehyde (MDA) content in M. multiflora leaves did not increase significantly under mild drought stress, and increased significantly under moderate and severe drought stress. The MDA content in M. multiflora leaves under severe drought stress was 1.63 times as high as that in the control group. The proline (Pro) and soluble sugar contents of M. multiflora increased significantly with the aggravation of drought stress, and those under severe drought stress were 8.06 times and 3.16 times respectively higher than those in the control group. [Conclusion] M. multiflora has a strong drought tolerance, and is suitable for growing in relatively arid environment. It can be used as candidate for vegetation restoration in hydropower engineering slope.
文摘The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions: (1) What is the ecological niche of the different epiphytic orchid species? (2) What are the ecological factors that threaten epiphytic orchid's population under anthropogenic disturbances? Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis (PCA). The correlations between the different site factors were statistically significant. Spearman's rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height (dbh) of host had the highest significant positive correlation coefficient (0.67 and 0.64 respectively). On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient (-0.80 and -0.61, respectively). Different epiphytic orchid species interact differently with the given set of environmental factors: for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees (species and size) and increasing air pollution, resulting in increasing host bark pH.
基金Supported by Agricultural Key Projects of Science and Technology Program of Taizhou City in Zhejiang Province(121KY17)~~
文摘[Objective] To further improve the prediction and forecast and continuous control ability of broccoli clubroot disease. [Methods] The spatial distribution pattern of diseased or infected plants was analyzed using the least square method, fre- quency distribution, aggregation index, m*-m regression analysis and Taylor's pow- er law model. [Result] The field distribution of broccoli plants with clubroot disease tended to be aggregated distribution, m'-m regression analysis showed that the el- ementary composition of the spatial distribution of diseased or infected plants was individual colony, the individuals attracted each other; the disease had obvious dis- ease focus in the field, and the individual colony showed uniform distribution pattern in the field. Taylor's power law showed that the spatial pattern of individual dis- eased or infected plant with clubroot disease tended to be uniform distribution with the increase of the density. On the basis of this, Iwao optimal theoretical sampling model and sequential sampling model were established, namely N =273.954 1/m- 59.698 5, To (N)=0.368 4N±1.926 8√N, respectively, it meant that when surveying N plants, if the accumulative incidence rate exceeded upper bound, the field can be set as control object; if the accumulative incidence rate didn't reach lower bound, it can be set as uncontrol field; if the accumulative incidence rate was between upper bound and lower bound, it should be surveyed continuously until the maximum sample size (mo=0.368 4) appeared, that was, the disease incidence was 15%, so the sampling number should be 684 plants. [Conclusion] The research results had very important instructive meaning for disease control.
文摘We studied distribution and site conditions of epiphytic orchids in a gradient of human interference in Kathmandu valley, central Nepal. The aim was to understand the recent distribution pattern of epiphytic orchids, with respect to (i) the micro-site conditions and (ii) the type and intensity of land use. The occurrence of epiphytic orchids was recorded for a grid with 1.5 km cell size. The cells represent different types and intensities of human impact. Site factors such as bark rugosity, bark pH, diameter at breast height (dbh; 1.3 m) of host trees, exposure to wind and sunlight intensity were recorded. With regard to the species richness and abundance of epiphytic orchids, we compared different human impact categories from very strong human impact (settlement area) to very low human impact (national park). Remote sensing was used for a supervised classification of land cover. Ficus religiosa turned out to be the most important host species for orchids in urban areas, while Schima wallichii and Alnus nepalensis significantly host orchids in the other categories. Both species richness and abundance of epiphytic orchids were significantly higher under very low human impact (forest in national park) and also some remaining patches of primary forest than the other regions. Micro-climate is crucial for orchid populations. Host bark pH, bark rugosity, sunlight intensity and host exposure were significantly different for all human impact categories in order to harbour epiphytic orchid species. Habitats with a mixture of mature trees are suitable and essential for the conservation of viable populations of epiphytic orchids in settled areas. The study reveals that to improve the population size of orchids it is essential for future urban forestry to: (i) Protect old trees as carriers of existing epiphytic orchid diversity, (ii) protect medium old trees to ensure that they may become old trees, (iii) plant new host trees for the future, (iv) plant in groups instead of single isolate trees. Trees should especially be planted in areas where orchids still exist to provide more trees for orchid population enlargement (e.g. along riparian system). Native species should be favoured; the pool of such native host species is wide.