Photosynthetic products are mainly produced by leaf and green silique of oil-seed rape （Brassica napus L.） at reproductive growth stage. This study aimed to compare photosynthetic features of leaf and green silique ...Photosynthetic products are mainly produced by leaf and green silique of oil-seed rape （Brassica napus L.） at reproductive growth stage. This study aimed to compare photosynthetic features of leaf and green silique of ‘Qinyou 7’ hybrid oilseed rape variety. Results showed that, during photosynthetic day time, net photosynthetic rate （PN） and sto-matal conductance （gs） of leaf were markedly higher than that of silique. Compared with silique, leaf had signifcant higher PN, gs, light saturated net photosynthetic rate （PNmax）, light saturation point （LSP）, and apparent quantum yield （AQY）, but lower light compensa-tion point （LCP）, CO2 compensation point （Γ） and carboxylation effciency （CE） under var-ious light densities and CO2 concentrations. Carboxylation activities of ribulose-1, 5-bis-phosphate carboxylase/oxygenase （Rubisco）, phosphoenolpyruvate carboxylase （PEPC） and chlorophyll a, b （Chl a, b） of leaf were signifcantly higher than that of silique shell. Our study demonstrated that leaf of oilseed rape at reproductive growth stage had higher photosynthetic capacity than green silique due to its higher carboxylation activity of pho-tosynthetic enzymes as well as higher gs and Chl contents. This study might have good implication in selecting a biological control strategy to enhance seed yield and oil produc-tion of oilseed rape.展开更多
Eddy covariance technique was used to measure carbon flux during two growing seasons in 2003 and 2004 over typical steppe in the Inner Mongolia Plateau, China. The results showed that there were two different CO2 flux...Eddy covariance technique was used to measure carbon flux during two growing seasons in 2003 and 2004 over typical steppe in the Inner Mongolia Plateau, China. The results showed that there were two different CO2 flux diurnal patterns at the grassland ecosystem. One had a dual peak in diurnal course of CO2 fluxes with a depression of CO2 flux after noon, and the other had a single peak. In 2003, the maximum diurnal uptake and emitting value of CO2 were -7.4 and 5.4 g·m-2·d-1 respectively and both occurred in July. While in 2004, the maximum diurnal uptake and release of CO2 were -12.8 and 5.8 g·m-2·d-1 and occurred both in August. The grassland fixed 294.66 and 467.46 g CO2·m-2 in 2003 and 2004, and released 333.14 and 437.17 g CO2·m-2 in 2003 and 2004, respectively from May to September. Water availability and photosynthetic active radiation (PAR) are two important factors of controlling CO2 flux. Consecutive precipitation can cause reduction in the ability of ecosystem carbon exchange. Under favorable soil water conditions, daytime CO2 flux is dependent on PAR. CO2 flux, under soil water stress conditions, is obviously less than those under favorable soil water conditions, and there is a light saturation phenomena at PAR=1200μmol·m-2·s-1. Soil respiration was temperature dependent when there was no soil water stress; otherwise, this response became accumulatively decoupled from soil temperature.展开更多
基金supported by the Key R&D Program Project of Shaanxi Province,China(2018NY-025)the Key R&D Program Project of Shaanxi Province,China(2017ZDXM-NY-007)
文摘Photosynthetic products are mainly produced by leaf and green silique of oil-seed rape （Brassica napus L.） at reproductive growth stage. This study aimed to compare photosynthetic features of leaf and green silique of ‘Qinyou 7’ hybrid oilseed rape variety. Results showed that, during photosynthetic day time, net photosynthetic rate （PN） and sto-matal conductance （gs） of leaf were markedly higher than that of silique. Compared with silique, leaf had signifcant higher PN, gs, light saturated net photosynthetic rate （PNmax）, light saturation point （LSP）, and apparent quantum yield （AQY）, but lower light compensa-tion point （LCP）, CO2 compensation point （Γ） and carboxylation effciency （CE） under var-ious light densities and CO2 concentrations. Carboxylation activities of ribulose-1, 5-bis-phosphate carboxylase/oxygenase （Rubisco）, phosphoenolpyruvate carboxylase （PEPC） and chlorophyll a, b （Chl a, b） of leaf were signifcantly higher than that of silique shell. Our study demonstrated that leaf of oilseed rape at reproductive growth stage had higher photosynthetic capacity than green silique due to its higher carboxylation activity of pho-tosynthetic enzymes as well as higher gs and Chl contents. This study might have good implication in selecting a biological control strategy to enhance seed yield and oil produc-tion of oilseed rape.
文摘Eddy covariance technique was used to measure carbon flux during two growing seasons in 2003 and 2004 over typical steppe in the Inner Mongolia Plateau, China. The results showed that there were two different CO2 flux diurnal patterns at the grassland ecosystem. One had a dual peak in diurnal course of CO2 fluxes with a depression of CO2 flux after noon, and the other had a single peak. In 2003, the maximum diurnal uptake and emitting value of CO2 were -7.4 and 5.4 g·m-2·d-1 respectively and both occurred in July. While in 2004, the maximum diurnal uptake and release of CO2 were -12.8 and 5.8 g·m-2·d-1 and occurred both in August. The grassland fixed 294.66 and 467.46 g CO2·m-2 in 2003 and 2004, and released 333.14 and 437.17 g CO2·m-2 in 2003 and 2004, respectively from May to September. Water availability and photosynthetic active radiation (PAR) are two important factors of controlling CO2 flux. Consecutive precipitation can cause reduction in the ability of ecosystem carbon exchange. Under favorable soil water conditions, daytime CO2 flux is dependent on PAR. CO2 flux, under soil water stress conditions, is obviously less than those under favorable soil water conditions, and there is a light saturation phenomena at PAR=1200μmol·m-2·s-1. Soil respiration was temperature dependent when there was no soil water stress; otherwise, this response became accumulatively decoupled from soil temperature.
