Atmospheric CO_(2)concentration is elevated globally,which has“CO_(2)fertilization effects”and potentially improves plant photosynthesis,yield,and productivity.Despite the beneficial effect of CO_(2)fertilization be...Atmospheric CO_(2)concentration is elevated globally,which has“CO_(2)fertilization effects”and potentially improves plant photosynthesis,yield,and productivity.Despite the beneficial effect of CO_(2)fertilization being modulated by vapor pressure deficit(VPD),the underlying mechanism is highly uncertain.In the present study,the potential roles of hormones in determining CO_(2)fertilization effects under contrasting high and low VPD conditions were investigated by integrated physiological and transcriptomic analyses.Beneficial CO_(2)fertilization effects were offset under high VPD conditions and were constrained by plant water stress and photosynthetic CO_(2)utilization.High VPD induced a large passive water driving force,which disrupted the water balance and consequently caused plant water deficit.Leaf water potential,turgor pressure,and hydraulic conductance declined under high VPD stress.The physiological evidence combined with transcriptomic analyses demonstrated that abscisic acid(ABA)and jasmonic acid(JA)potentially acted as drought-signaling molecules in response to high VPD stress.Increased foliar ABA and JA content triggered stomatal closure to prevent excessive water loss under high VPD stress,which simultaneously increased the diffusion resistance for CO_(2)uptake from atmosphere to leaf intercellular space.High VPD also significantly increased mesophyll resistance for CO_(2)transport from stomatal cavity to fixation site inside chloroplast.The chloroplast“sink”CO_(2)availability was constrained by stomatal and mesophyll resistance under high VPD stress,despite the atmospheric“source”CO_(2)concentration being elevated.Thus,ABA-and JA-mediated drought-resistant mechanisms potentially modified the beneficial effect of CO_(2)fertilization on photosynthesis,plant growth,and yield productivity.This study provides valuable information for improving the utilization efficiency of CO_(2)fertilization and a better understanding of the physiological processes.展开更多
Industrial-scale experiments were conducted to study the effects of tertiary air declination angle(TDA)on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler i...Industrial-scale experiments were conducted to study the effects of tertiary air declination angle(TDA)on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler in China with the multiple-injection and multiple-staging combustion(MIMSC)technology at medium and high loads.The experimental results indicated that as the TDA increased from 0°to 15°,the overall gas temperature in the lower furnace rose and the symmetry of temperature field was enhanced.The ignition distance of the fuel-rich coal/air flow decreased.In near-burner region,the concentration of O2 decreased while the concentrations of CO and NO increased.The concentration of NO decreased in near-tertiary-air region.The carbon in fly ash decreased significantly from 8.40%to 6.45%at a load of 260 MW.At a TDA of 15°,the ignition distances were the shortest(2.07 m and 1.73 m)at a load of 210 MW and 260 MW,respectively.The main and reheat steam temperatures were the highest(557.2℃ and 559.4℃ at a load of 210 MW,558.4℃ and 560.3℃ at a load of 260 MW).The carbon in fly ash was the lowest(4.83%)at a load of 210 MW.On changing the TDA from 15°to 25°,the flame kernel was found to move downward and the main and reheat steam temperatures dropped obviously.The change of TDA has little effect on NO_(x) emissions(660–681 mg/m^(3) at 6%O_(2)).In comprehensive consideration of the pulverized coal combustion characteristics and the unit economic performance,an optimal TDA of 15°is recommended.展开更多
基金y the National Natural Science Foundation of China(Grant No.32102466)the Major Scientific Innovation Project of Shandong Province(Grant No.2022CXGC020708).
文摘Atmospheric CO_(2)concentration is elevated globally,which has“CO_(2)fertilization effects”and potentially improves plant photosynthesis,yield,and productivity.Despite the beneficial effect of CO_(2)fertilization being modulated by vapor pressure deficit(VPD),the underlying mechanism is highly uncertain.In the present study,the potential roles of hormones in determining CO_(2)fertilization effects under contrasting high and low VPD conditions were investigated by integrated physiological and transcriptomic analyses.Beneficial CO_(2)fertilization effects were offset under high VPD conditions and were constrained by plant water stress and photosynthetic CO_(2)utilization.High VPD induced a large passive water driving force,which disrupted the water balance and consequently caused plant water deficit.Leaf water potential,turgor pressure,and hydraulic conductance declined under high VPD stress.The physiological evidence combined with transcriptomic analyses demonstrated that abscisic acid(ABA)and jasmonic acid(JA)potentially acted as drought-signaling molecules in response to high VPD stress.Increased foliar ABA and JA content triggered stomatal closure to prevent excessive water loss under high VPD stress,which simultaneously increased the diffusion resistance for CO_(2)uptake from atmosphere to leaf intercellular space.High VPD also significantly increased mesophyll resistance for CO_(2)transport from stomatal cavity to fixation site inside chloroplast.The chloroplast“sink”CO_(2)availability was constrained by stomatal and mesophyll resistance under high VPD stress,despite the atmospheric“source”CO_(2)concentration being elevated.Thus,ABA-and JA-mediated drought-resistant mechanisms potentially modified the beneficial effect of CO_(2)fertilization on photosynthesis,plant growth,and yield productivity.This study provides valuable information for improving the utilization efficiency of CO_(2)fertilization and a better understanding of the physiological processes.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51706054)the China Postdoctoral Science Foundation(Grant No.2019M660633).
文摘Industrial-scale experiments were conducted to study the effects of tertiary air declination angle(TDA)on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler in China with the multiple-injection and multiple-staging combustion(MIMSC)technology at medium and high loads.The experimental results indicated that as the TDA increased from 0°to 15°,the overall gas temperature in the lower furnace rose and the symmetry of temperature field was enhanced.The ignition distance of the fuel-rich coal/air flow decreased.In near-burner region,the concentration of O2 decreased while the concentrations of CO and NO increased.The concentration of NO decreased in near-tertiary-air region.The carbon in fly ash decreased significantly from 8.40%to 6.45%at a load of 260 MW.At a TDA of 15°,the ignition distances were the shortest(2.07 m and 1.73 m)at a load of 210 MW and 260 MW,respectively.The main and reheat steam temperatures were the highest(557.2℃ and 559.4℃ at a load of 210 MW,558.4℃ and 560.3℃ at a load of 260 MW).The carbon in fly ash was the lowest(4.83%)at a load of 210 MW.On changing the TDA from 15°to 25°,the flame kernel was found to move downward and the main and reheat steam temperatures dropped obviously.The change of TDA has little effect on NO_(x) emissions(660–681 mg/m^(3) at 6%O_(2)).In comprehensive consideration of the pulverized coal combustion characteristics and the unit economic performance,an optimal TDA of 15°is recommended.
