The effects of cold atmospheric-pressure plasma jet (CAPPJ) were investigated on germination and early seedling growth of fenugreek (Trigonella foenum-graecum L) seeds. A two-electrode argon CAPPJ system with and with...The effects of cold atmospheric-pressure plasma jet (CAPPJ) were investigated on germination and early seedling growth of fenugreek (Trigonella foenum-graecum L) seeds. A two-electrode argon CAPPJ system with and without an additional grounded electrode [accelerating grounded (AG) electrode] was used at different exposure times. After 16 h of observation, the germination rates increased by 4 and 7 times, without and with using an AG electrode, respectively, for 1 min of plasma exposure. An increase in shoot fresh weight was observed, especially at 10 min exposure time. A high dry weight of root and shoot at 1 min-AG exposure time was observed. The root:shoot ratio was lower in plasma-treated seedlings, compared with the control plants. The study found that the O-radical emission line (777.4 nm) enhanced 5 times, due to the presence of an AG electrode, which increased the axial electric field and led to the formation of more streamers. The three stated effects (O-radicals, enhancement of the electric field and streamers) could be the cause for the stimulation of seed germination and seedling growth parameters when using the CAPPJ. The scanning electron microscope images showed the etching of the seed surface layers, which was more pronounced when an AG electrode was applied. The results of the current study indicate that the germination rates increased due to the increase of O-radical concentration and the etching of the seed surfaces.展开更多
Ohud mountain is one of the main important historic sites in the Arab Peninsula,and it is distinguishable over the rest of the mountains in the region.No extensive floristic survey has been carried out on Ohud mountai...Ohud mountain is one of the main important historic sites in the Arab Peninsula,and it is distinguishable over the rest of the mountains in the region.No extensive floristic survey has been carried out on Ohud mountain because of the rugged topography of this mountain.The current study investigates the floristic diversity and the correspondence of environmental factors of the phytogeographical distribution of plants,based on the floristic analysis of the present region.The research question is about the relationships between the species diversity and the human impacts of populated area at lowlands around Ohud mountain.A total of 59 species belonging to 56 genera and 28 families were recorded.Asteraceae had the highest contribution,about 12%of the total plant species.The analysis of the life forms demonstrated the prevalence of therophytes(68%)followed by chamaephytes(24%),indicating the adaptation of these life forms to hyperarid conditions.The chorological analysis indicated the predominance of the bi-regional taxa over the other phytochoria.Most of the recorded plant species belong to Saharo-Arabian and Sudano-Zambezian(24%)phytochoria.TWINSPAN analysis was performed to detect the indicator species of different vegetation groups and confirmed by detrended correspondence analysis(DCA or DECORANA).It is concluded that species richness and diversity revealed clear variation along the mountain and among the studied sites.Plant species diversity and richness were more pronounced in the intermediate portion of the elevation gradients across the mountain,with a decrease in the high altitudinal belts.The decrease was also recorded at the lower altitudes,where human impacts clearly affected vegetation;leading to a decrease in alpha diversity.In addition,the beta diversity among moderately highlands and lowlands was considerably high indicating the heterogeneous species composition among the studied sites along mountain elevations.The general pattern of vegetation groups distribution is controlled by a number of environmental factors;such as latitude,longitude,elevation,organic matter and some anions and cations.A Canonical Correspondence Analysis(CCA)ordination revealed that the vegetation structure has a strong association with the latitude of the mountain followed by organic matter and Magnesium.It is recommended that the populated area should be subjected to restoration of mountain ecosystem that might be degraded by human activities.展开更多
文摘The effects of cold atmospheric-pressure plasma jet (CAPPJ) were investigated on germination and early seedling growth of fenugreek (Trigonella foenum-graecum L) seeds. A two-electrode argon CAPPJ system with and without an additional grounded electrode [accelerating grounded (AG) electrode] was used at different exposure times. After 16 h of observation, the germination rates increased by 4 and 7 times, without and with using an AG electrode, respectively, for 1 min of plasma exposure. An increase in shoot fresh weight was observed, especially at 10 min exposure time. A high dry weight of root and shoot at 1 min-AG exposure time was observed. The root:shoot ratio was lower in plasma-treated seedlings, compared with the control plants. The study found that the O-radical emission line (777.4 nm) enhanced 5 times, due to the presence of an AG electrode, which increased the axial electric field and led to the formation of more streamers. The three stated effects (O-radicals, enhancement of the electric field and streamers) could be the cause for the stimulation of seed germination and seedling growth parameters when using the CAPPJ. The scanning electron microscope images showed the etching of the seed surface layers, which was more pronounced when an AG electrode was applied. The results of the current study indicate that the germination rates increased due to the increase of O-radical concentration and the etching of the seed surfaces.
文摘Ohud mountain is one of the main important historic sites in the Arab Peninsula,and it is distinguishable over the rest of the mountains in the region.No extensive floristic survey has been carried out on Ohud mountain because of the rugged topography of this mountain.The current study investigates the floristic diversity and the correspondence of environmental factors of the phytogeographical distribution of plants,based on the floristic analysis of the present region.The research question is about the relationships between the species diversity and the human impacts of populated area at lowlands around Ohud mountain.A total of 59 species belonging to 56 genera and 28 families were recorded.Asteraceae had the highest contribution,about 12%of the total plant species.The analysis of the life forms demonstrated the prevalence of therophytes(68%)followed by chamaephytes(24%),indicating the adaptation of these life forms to hyperarid conditions.The chorological analysis indicated the predominance of the bi-regional taxa over the other phytochoria.Most of the recorded plant species belong to Saharo-Arabian and Sudano-Zambezian(24%)phytochoria.TWINSPAN analysis was performed to detect the indicator species of different vegetation groups and confirmed by detrended correspondence analysis(DCA or DECORANA).It is concluded that species richness and diversity revealed clear variation along the mountain and among the studied sites.Plant species diversity and richness were more pronounced in the intermediate portion of the elevation gradients across the mountain,with a decrease in the high altitudinal belts.The decrease was also recorded at the lower altitudes,where human impacts clearly affected vegetation;leading to a decrease in alpha diversity.In addition,the beta diversity among moderately highlands and lowlands was considerably high indicating the heterogeneous species composition among the studied sites along mountain elevations.The general pattern of vegetation groups distribution is controlled by a number of environmental factors;such as latitude,longitude,elevation,organic matter and some anions and cations.A Canonical Correspondence Analysis(CCA)ordination revealed that the vegetation structure has a strong association with the latitude of the mountain followed by organic matter and Magnesium.It is recommended that the populated area should be subjected to restoration of mountain ecosystem that might be degraded by human activities.
