Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus L.) based on the e...Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus L.) based on the ecophysiological processes and using a three-layer radiation balance scheme for calculating the radiation interception and absorption by the layers of flowers, pods, and leaves within the canopy. Gaussian integration method was used to calculate photosynthesis of the pod and leaf layers, and the daily total canopy photosynthesis was determined by the sum of photosynthesis from the two layers of green organs. The effects of physiological age, temperature, nitrogen, and water deficit on maximum photosynthetic rate were quantified. Maintenance and growth respiration were estimated to determine net photosynthetic production. Partition index of the shoot in relation to physiological development time was used to calculate shoot dry matter from plant biomass and shoot biomass loss because of freezing was quantified by temperature effectiveness. Testing of the model for dynamic dry matter accumulation through field experiments of different genotypes, sowing dates, and nitrogen levels showed good fit between the observed and simulated data, with an average root mean square error of 10.9% for shoot dry matter. Thus, the present model appears to be reliable for the prediction of photosynthetic production in oilseed rape.展开更多
Aims Black spruce(Picea mariana[Mill.]B.S.P.)and white spruce(Picea glauca[Moench]Voss.)are congeneric species.Both are moderately shade tolerant and widely distributed across North American boreal forests.Methods To ...Aims Black spruce(Picea mariana[Mill.]B.S.P.)and white spruce(Picea glauca[Moench]Voss.)are congeneric species.Both are moderately shade tolerant and widely distributed across North American boreal forests.Methods To understand light effects on their ecophysiological responses to elevated CO_(2),1-year-old seedlings were exposed to 360µmol mol−1 and 720µmol mol−1 CO_(2)at three light conditions(100%,50%and 30%of full light in the greenhouse).Foliar gas exchanges were measured in the mid-and late-growing season.Important Findings Elevated CO_(2)increased net photosynthesis(Pn)and photosynthetic water use efficiency,but it reduced stomatal conductance and transpiration.The stimulation of photosynthesis by elevated CO_(2)was greatest at 50%light and smallest at 100%.Photosynthesis,maximum carboxylation rate(Vcmax)and light-saturated rate of electron transport(Jmax)all decreased with decreasing light.Elevated CO_(2)significantly reduced Vcmax across all light treatments and both species in mid-growing season.However,the effect of elevated CO_(2)became insignificant at 30%light later in the growing season,with the response being greater in black spruce than in white spruce.Elevated CO_(2)also reduced Jmax in white spruce in both measurements while the effect became insignificant at 30%light later in the growing season.However,the effect on black spruce varied with time.Elevated CO_(2)reduced Jmax in black spruce in mid-growing season in all light treatments and the effect became insignificant at 30%light later in the growing season,while it increased Jmax later in the season at 100%and 50%light.These results suggest that both species benefited from elevated CO_(2),and that the responses varied with light supply,such that the response was primarily physiological at 100%and 50%light,while it was primarily morphological at 30%light.展开更多
Changes in the global environment such as ocean acidification （OA） may interact with anthropogenic pollutants including trace metals threatening the integrity of marine ecosystems. We analyze recent studies on the i...Changes in the global environment such as ocean acidification （OA） may interact with anthropogenic pollutants including trace metals threatening the integrity of marine ecosystems. We analyze recent studies on the interactive effects of OA and trace metals on marine organisms with a focus on the physiological basis of these interactions. Our analysis shows that the responses to elevated CO2 and metals are strongly dependent on the species, developmental stage, metal biochemistry and the degree of environmental hypercapnia, and cannot be directly predicted from the CO2-induced changes in metal solubility and speciation. The key physiological functions affected by both the OA and trace metal exposures involve acid-base regulation, pro- tein turnover and mitochondrial bioenergetics, reflecting the sensitivity of the underlying molecular and cellular pathways to CO2 and metals. Physiological interactions between elevated CO2 and metals may impact the organisms＇ capacity to maintain ac- id-base homeostasis and reduce the amount of energy available for fitness-related functions such as growth, development and re- production thereby affecting survival and performance of estuarine populations. Environmental hypercapnia may also affect the marine food webs by altering predator-prey interactions and the trophic transfer of metals in the food chain. However, our under- standing of the degree to which these effects can impact the function and integrity of marine ecosystems is limited due the scar- city of the published research and its bias towards certain taxonomic groups. Future research priorities should include studies of metal x Pco2 interactions focusing on critical physiological functions （including acid-base, protein and energy homeostasis） in a greater range of ecologically and economically important marine species, as well as including the field populations naturally ex- posed （and potentially adapted） to different levels of metals and CO2 in their environments [Current Zoology 61 （4）： 653-668, 2015].展开更多
基金Project supported by the National High Technology Research and Development Program (863 Program) of China(No. 2006AA10A303)the Post-Doctoral Program of Jiangsu Province, China (No. 0602027C)
文摘Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus L.) based on the ecophysiological processes and using a three-layer radiation balance scheme for calculating the radiation interception and absorption by the layers of flowers, pods, and leaves within the canopy. Gaussian integration method was used to calculate photosynthesis of the pod and leaf layers, and the daily total canopy photosynthesis was determined by the sum of photosynthesis from the two layers of green organs. The effects of physiological age, temperature, nitrogen, and water deficit on maximum photosynthetic rate were quantified. Maintenance and growth respiration were estimated to determine net photosynthetic production. Partition index of the shoot in relation to physiological development time was used to calculate shoot dry matter from plant biomass and shoot biomass loss because of freezing was quantified by temperature effectiveness. Testing of the model for dynamic dry matter accumulation through field experiments of different genotypes, sowing dates, and nitrogen levels showed good fit between the observed and simulated data, with an average root mean square error of 10.9% for shoot dry matter. Thus, the present model appears to be reliable for the prediction of photosynthetic production in oilseed rape.
基金by Natural Sciences and Engineering Research Council of Canada Discovery grants to Q.L.Dang(Project No.203198-2013-RGPIN)Lakehead University Graduate Assistantships to J.Marfo.
文摘Aims Black spruce(Picea mariana[Mill.]B.S.P.)and white spruce(Picea glauca[Moench]Voss.)are congeneric species.Both are moderately shade tolerant and widely distributed across North American boreal forests.Methods To understand light effects on their ecophysiological responses to elevated CO_(2),1-year-old seedlings were exposed to 360µmol mol−1 and 720µmol mol−1 CO_(2)at three light conditions(100%,50%and 30%of full light in the greenhouse).Foliar gas exchanges were measured in the mid-and late-growing season.Important Findings Elevated CO_(2)increased net photosynthesis(Pn)and photosynthetic water use efficiency,but it reduced stomatal conductance and transpiration.The stimulation of photosynthesis by elevated CO_(2)was greatest at 50%light and smallest at 100%.Photosynthesis,maximum carboxylation rate(Vcmax)and light-saturated rate of electron transport(Jmax)all decreased with decreasing light.Elevated CO_(2)significantly reduced Vcmax across all light treatments and both species in mid-growing season.However,the effect of elevated CO_(2)became insignificant at 30%light later in the growing season,with the response being greater in black spruce than in white spruce.Elevated CO_(2)also reduced Jmax in white spruce in both measurements while the effect became insignificant at 30%light later in the growing season.However,the effect on black spruce varied with time.Elevated CO_(2)reduced Jmax in black spruce in mid-growing season in all light treatments and the effect became insignificant at 30%light later in the growing season,while it increased Jmax later in the season at 100%and 50%light.These results suggest that both species benefited from elevated CO_(2),and that the responses varied with light supply,such that the response was primarily physiological at 100%and 50%light,while it was primarily morphological at 30%light.
基金This work was in part supported by funds provided by the National Science Foundation award I0S-095107 and UNC Charlotte＇s Faculty Research Grant to I.M.S.
文摘Changes in the global environment such as ocean acidification （OA） may interact with anthropogenic pollutants including trace metals threatening the integrity of marine ecosystems. We analyze recent studies on the interactive effects of OA and trace metals on marine organisms with a focus on the physiological basis of these interactions. Our analysis shows that the responses to elevated CO2 and metals are strongly dependent on the species, developmental stage, metal biochemistry and the degree of environmental hypercapnia, and cannot be directly predicted from the CO2-induced changes in metal solubility and speciation. The key physiological functions affected by both the OA and trace metal exposures involve acid-base regulation, pro- tein turnover and mitochondrial bioenergetics, reflecting the sensitivity of the underlying molecular and cellular pathways to CO2 and metals. Physiological interactions between elevated CO2 and metals may impact the organisms＇ capacity to maintain ac- id-base homeostasis and reduce the amount of energy available for fitness-related functions such as growth, development and re- production thereby affecting survival and performance of estuarine populations. Environmental hypercapnia may also affect the marine food webs by altering predator-prey interactions and the trophic transfer of metals in the food chain. However, our under- standing of the degree to which these effects can impact the function and integrity of marine ecosystems is limited due the scar- city of the published research and its bias towards certain taxonomic groups. Future research priorities should include studies of metal x Pco2 interactions focusing on critical physiological functions （including acid-base, protein and energy homeostasis） in a greater range of ecologically and economically important marine species, as well as including the field populations naturally ex- posed （and potentially adapted） to different levels of metals and CO2 in their environments [Current Zoology 61 （4）： 653-668, 2015].
