To reveal photosynthetic characteristics and biomass yield is important for evaluating introduced species adaptation to local environments. A field experiment was conducted over three consecutive years（2011–2013） t...To reveal photosynthetic characteristics and biomass yield is important for evaluating introduced species adaptation to local environments. A field experiment was conducted over three consecutive years（2011–2013） to evaluate photosynthetic characteristics, soil water content, aboveground biomass accumulation, and water use efficiency（WUE） in switchgrass（Panicum virgatum L.） populations exposed to three row spacing（20, 40 and 60 cm） treatments in two growth months（June and August） on the semiarid Loess Plateau of China. Results indicated that net photosynthetic rate（Pn）, transpiration rate（Tr）, instantaneous water use efficiency（WUEi） and plant height of switchgrass showed an increased trend, but aboveground biomass production and WUE showed an decreased trend with enlarged row spacings over the three years. The maximum daily mean Pn values（17.9, 18.4 and 19.7 μmol CO2 m^（-2） s^（-1）） were observed in 2011, and the highest aboveground biomass production（67 771.8, 6 976.8 and 6 609.2 kg ha^（-1）） were recorded in 2012 for 20, 40 and 60 cm, respectively. A close correlation between tiller numbers and aboveground biomass production（r=0.907） was observed. Pn was positively and significantly correlated with biomass per tiller, but it showed a negative correlation with aboveground biomass production. Our results confirm that wide row spacing is beneficial for single plant development, while narrow row spacing favors biomass production and water use of switchgrass in the region. It also implies that single leaf growth and performance could explain the switchgrass community density differences, while fails to account for the aboveground biomass production.展开更多
通过计算机模拟预测化合物的抗菌活性,以自制的3-芳基/烷基-6-S-2',3',4',6'-四-O-乙酰基-β-D-吡喃葡萄糖基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(3a^3j)为原料,在甲醇钠/甲醇/二氯甲烷的体系下经水解脱除糖环乙酰基,合...通过计算机模拟预测化合物的抗菌活性,以自制的3-芳基/烷基-6-S-2',3',4',6'-四-O-乙酰基-β-D-吡喃葡萄糖基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(3a^3j)为原料,在甲醇钠/甲醇/二氯甲烷的体系下经水解脱除糖环乙酰基,合成了10个化合物3-芳基/烷基-6-S-2',3',4',6'-四羟基-β-D-吡喃葡萄糖基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(4a^4j).研究表明:甲醇钠与糖苷的投料量为1∶1时,目标产物收率最高.若甲醇钠过多,糖苷键易断裂;甲醇钠过少,部分脱除的副产物增多,均会降低产率.生物活性测试表明,目标化合物对四种测试菌株(大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、白色念珠菌)均表现出较强的抗菌活性,其中化合物4f对白色念珠菌有极强的抗菌活性,MIC值为1μg·m L-1,均优于对照药物三氯生和氟康唑.此外,还利用Auto Dock 4.0程序对目标化合物(4a^4j)与大肠杆菌Fab I的相互作用和结合能的变化规律做了进一步研究.展开更多
基金financially supported by the National Natural Science Foundation of China (41371509)the Programs for New Century Excellent Talents in University, China (NCET-11-0444)
文摘To reveal photosynthetic characteristics and biomass yield is important for evaluating introduced species adaptation to local environments. A field experiment was conducted over three consecutive years（2011–2013） to evaluate photosynthetic characteristics, soil water content, aboveground biomass accumulation, and water use efficiency（WUE） in switchgrass（Panicum virgatum L.） populations exposed to three row spacing（20, 40 and 60 cm） treatments in two growth months（June and August） on the semiarid Loess Plateau of China. Results indicated that net photosynthetic rate（Pn）, transpiration rate（Tr）, instantaneous water use efficiency（WUEi） and plant height of switchgrass showed an increased trend, but aboveground biomass production and WUE showed an decreased trend with enlarged row spacings over the three years. The maximum daily mean Pn values（17.9, 18.4 and 19.7 μmol CO2 m^（-2） s^（-1）） were observed in 2011, and the highest aboveground biomass production（67 771.8, 6 976.8 and 6 609.2 kg ha^（-1）） were recorded in 2012 for 20, 40 and 60 cm, respectively. A close correlation between tiller numbers and aboveground biomass production（r=0.907） was observed. Pn was positively and significantly correlated with biomass per tiller, but it showed a negative correlation with aboveground biomass production. Our results confirm that wide row spacing is beneficial for single plant development, while narrow row spacing favors biomass production and water use of switchgrass in the region. It also implies that single leaf growth and performance could explain the switchgrass community density differences, while fails to account for the aboveground biomass production.
文摘通过计算机模拟预测化合物的抗菌活性,以自制的3-芳基/烷基-6-S-2',3',4',6'-四-O-乙酰基-β-D-吡喃葡萄糖基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(3a^3j)为原料,在甲醇钠/甲醇/二氯甲烷的体系下经水解脱除糖环乙酰基,合成了10个化合物3-芳基/烷基-6-S-2',3',4',6'-四羟基-β-D-吡喃葡萄糖基-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑(4a^4j).研究表明:甲醇钠与糖苷的投料量为1∶1时,目标产物收率最高.若甲醇钠过多,糖苷键易断裂;甲醇钠过少,部分脱除的副产物增多,均会降低产率.生物活性测试表明,目标化合物对四种测试菌株(大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、白色念珠菌)均表现出较强的抗菌活性,其中化合物4f对白色念珠菌有极强的抗菌活性,MIC值为1μg·m L-1,均优于对照药物三氯生和氟康唑.此外,还利用Auto Dock 4.0程序对目标化合物(4a^4j)与大肠杆菌Fab I的相互作用和结合能的变化规律做了进一步研究.
