Abstract： Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteris...Abstract： Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 195os to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between chances in nlant communities and water nollution. InDianehi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 195os and 196os, were reduced to four types covering 2.4% by the late 2ooos. Alien plant communities started to appear in the lake in the late 197os, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 197os, declined to lo community types, covering 9.3% of the surface, by the late 2ooos. Alien plant communities appeared in the middle 198os, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively andpositively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.展开更多
There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant develop...There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant development and temporally with photoperiod, understanding the relations between these factors and nitrate contents in the consumed herbs are vital for the development of agrotechnical strategies for nitrate avoidance. Therefore, the distribution profiles of nitrate content and nitrate reductase （NR） activity were analyzed in 14 accessions of Andrographis paniculata （Burm.f.） Wall. ex Nees., a medicinal plant widely used as a component of many herbal teas and medicinal infusions. Significant variation in nitrate accumulation in the plant was observed between the accessions, and most contained nitrate levels beyond the safety limit recommended according to the European Commission＇s Scientific Committee on Food. Nitrate content increased with plant development and leaf age, and that in leaf segment was higher in the middle of the leaf than at its tip or base; the nitrate concentration in plant organ followed the order of petiole 〉 leaf 〉 stem, and it was lower at mid-day than in the early morning or evening. Gradients of NR activity were negatively correlated with nitrate content in all studied temporal and spatial profiles. Identification of the characteristic spatial and developmental profiles of nitrate accumulation and NR activity in A. paniculata can guide the development of harvest strategies, aiming at minimizing nitrate contents in the consumed herbal tissue.展开更多
基金funded by the National Natural Science Foundation of China(Grant No.31560092,U0933601)National Scientific and Technological Basic Work of China(No.2012FY110300)+1 种基金Science Fund of China’s Yunnan Government(Grant No.2015BB018,2009CC024)the State Key Laboratory of Phytochemistry and Plant Resources in West China(Grant No.P2015-KF11)
文摘Abstract： Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 195os to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between chances in nlant communities and water nollution. InDianehi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 195os and 196os, were reduced to four types covering 2.4% by the late 2ooos. Alien plant communities started to appear in the lake in the late 197os, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 197os, declined to lo community types, covering 9.3% of the surface, by the late 2ooos. Alien plant communities appeared in the middle 198os, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively andpositively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.
文摘There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location in plant and plant development and temporally with photoperiod, understanding the relations between these factors and nitrate contents in the consumed herbs are vital for the development of agrotechnical strategies for nitrate avoidance. Therefore, the distribution profiles of nitrate content and nitrate reductase （NR） activity were analyzed in 14 accessions of Andrographis paniculata （Burm.f.） Wall. ex Nees., a medicinal plant widely used as a component of many herbal teas and medicinal infusions. Significant variation in nitrate accumulation in the plant was observed between the accessions, and most contained nitrate levels beyond the safety limit recommended according to the European Commission＇s Scientific Committee on Food. Nitrate content increased with plant development and leaf age, and that in leaf segment was higher in the middle of the leaf than at its tip or base; the nitrate concentration in plant organ followed the order of petiole 〉 leaf 〉 stem, and it was lower at mid-day than in the early morning or evening. Gradients of NR activity were negatively correlated with nitrate content in all studied temporal and spatial profiles. Identification of the characteristic spatial and developmental profiles of nitrate accumulation and NR activity in A. paniculata can guide the development of harvest strategies, aiming at minimizing nitrate contents in the consumed herbal tissue.
