Net Assimilation Rate

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Bill Shipley - One of the best experts on this subject based on the ideXlab platform.

  • Net Assimilation Rate specific leaf area and leaf mass ratio which is most closely correlated with relative growth Rate a meta analysis
    Functional Ecology, 2006
    Co-Authors: Bill Shipley
    Abstract:

    Summary 1Data were compiled consisting of 1240 observations (614 species) from 83 different experiments published in 37 different studies, in order to quantify the relative importance of Net Assimilation Rate (NAR, g cm−2 day−1), specific leaf area (SLA, cm2 g−1) and leaf mass ratio (LMR, g g−1) in determining relative growth Rate (RGR, g g−1 day−1), and how these change with respect to daily quantum input (DQI, moles m−2 day−1) and growth form (herbaceous or woody). 2Each of ln(NAR), ln(SLA) and ln(LMR) were sepaRately regressed on ln(RGR) using mixed model regressions in order to partition the between-experiment and within-experiment variation in slopes and intercepts. DQI and plant type were then added to these models to see if they could explain some of the between-experiment variation in the relative importance of each growth component. 3LMR was never strongly related to RGR. In general, NAR was the best general predictor of variation in RGR. However, for determining RGR the importance of NAR decreased, and the importance of SLA increased, with decreasing daily quantum input in experiments containing herbaceous species. This did not occur in experiments involving woody species.

  • trade offs between Net Assimilation Rate and specific leaf area in determining relative growth Rate relationship with daily irradiance
    Functional Ecology, 2002
    Co-Authors: Bill Shipley
    Abstract:

    Summary 1 Three sepaRate experiments were conducted, involving 27 herbaceous species and 14 woody species aged 15–30 days, in order to determine the relative importance of Net Assimilation Rate (NAR), specific leaf area (SLA) and leaf weight ratio (LWR) in explaining interspecific variations in relative growth Rate. 2 Daily quantum inputs were 31·12 mol m−2 day−1 in the first experiment and 33·17 mol m−2 day−1 in the second and third experiments. This is about twice the typical irradiance of most other experiments in this area, but only about 85% of the daily photon flux in nature. Plants were cultivated in hydroponic sand culture in a solution containing 5·8 mm nitrogen. 3 RGR was strongly and positively correlated with NAR in all three experiments. RGR was weakly and negatively correlated with SLA, while the correlation between RGR and LWR was weak and variable. 4 These results are compared to those already published in the literature: the commonly reported result that interspecific variation in RGR is determined primarily by SLA is partly due to the low irradiance used in most experiments, and the relative importance of SLA and NAR changes depending on irradiance. 5 A hypothesis is proposed in which direct and indirect effects of SLA on each of NAR and RGR are decomposed, and which leads to a trade-off between SLA and NAR as a function of daily irradiance.

  • Trade‐offs between Net Assimilation Rate and specific leaf area in determining relative growth Rate: relationship with daily irradiance
    Functional Ecology, 2002
    Co-Authors: Bill Shipley
    Abstract:

    Summary 1 Three sepaRate experiments were conducted, involving 27 herbaceous species and 14 woody species aged 15–30 days, in order to determine the relative importance of Net Assimilation Rate (NAR), specific leaf area (SLA) and leaf weight ratio (LWR) in explaining interspecific variations in relative growth Rate. 2 Daily quantum inputs were 31·12 mol m−2 day−1 in the first experiment and 33·17 mol m−2 day−1 in the second and third experiments. This is about twice the typical irradiance of most other experiments in this area, but only about 85% of the daily photon flux in nature. Plants were cultivated in hydroponic sand culture in a solution containing 5·8 mm nitrogen. 3 RGR was strongly and positively correlated with NAR in all three experiments. RGR was weakly and negatively correlated with SLA, while the correlation between RGR and LWR was weak and variable. 4 These results are compared to those already published in the literature: the commonly reported result that interspecific variation in RGR is determined primarily by SLA is partly due to the low irradiance used in most experiments, and the relative importance of SLA and NAR changes depending on irradiance. 5 A hypothesis is proposed in which direct and indirect effects of SLA on each of NAR and RGR are decomposed, and which leads to a trade-off between SLA and NAR as a function of daily irradiance.

Xuefei Li - One of the best experts on this subject based on the ideXlab platform.

  • Net Assimilation Rate determines the growth Rates of 14 species of subtropical forest trees
    PLOS ONE, 2016
    Co-Authors: Bernhard Schmid, Xuefei Li, Fei Wang, C Timothy E Paine
    Abstract:

    Growth Rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that geneRate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange Rates. After calculating individual biomass trajectories, we estimated relative growth Rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), Net Assimilation Rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic Rate and leaf nitrogen content. Photosynthetic Rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.

C Timothy E Paine - One of the best experts on this subject based on the ideXlab platform.

  • Net Assimilation Rate determines the growth Rates of 14 species of subtropical forest trees
    PLOS ONE, 2016
    Co-Authors: Bernhard Schmid, Xuefei Li, Fei Wang, C Timothy E Paine
    Abstract:

    Growth Rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that geneRate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange Rates. After calculating individual biomass trajectories, we estimated relative growth Rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), Net Assimilation Rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic Rate and leaf nitrogen content. Photosynthetic Rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.

Hans Lambers - One of the best experts on this subject based on the ideXlab platform.

  • variation in relative growth Rate of 20 aegilops species poaceae in the field the importance of Net Assimilation Rate or specific leaf area depends on the time scale
    Plant and Soil, 2005
    Co-Authors: Rafael Villar, Pilar Panadero, Francisco Arenas, Teodoro Marañón, Jose Luis Quero, Hans Lambers
    Abstract:

    Field experiments reporting the relative growth Rate (RGR) patterns in plants are scarce. In this study, 22 herbaceous species (20 Aegilops species, Amblyopyrum muticum and Triticum aestivum) were grown under field conditions to assess their RGR, and to find out if the differences in RGR amongst species were explained by morphological or physiological traits. Plants were cultivated during two months, and five harvests (every 13–19 days) were carried out. Factors explaining between-species differences in RGR varied, depending on whether short (13–19 days) or longer periods (62 days) were considered. RGR for short periods (4 growth periods of 13–19 days each) showed a positive correlation with Net Assimilation Rate (NAR), but there was no significant correlation with leaf area ratio (LAR) (with the exception of the first growth period). In contrast, when growth was investigated over two months, RGR was positively correlated with morphological traits (LAR, and specific leaf area, SLA), but not with physiological traits (NAR). A possible explanation for these contrasting results is that during short growth periods, NAR exhibited strong variations possibly caused by the variable field conditions, and, consequently NAR mainly determined RGR. In contrast, during a longer growth period (62 days) the importance of NAR was not apparent (there was no significant correlation between RGR and NAR), while allocation traits, such as LAR and SLA, became most relevant.

Yue Li - One of the best experts on this subject based on the ideXlab platform.

  • responses of Net Assimilation Rate to elevated atmospheric co2and temperature at different growth stages in a double rice cropping system
    Journal of Applied Ecology, 2020
    Co-Authors: Runan Li, Bin Wang, Yue Li
    Abstract:

    Effects of elevated atmospheric CO2 concentration and temperature on rice dry matter accumulation vary in planting regions and cropping systems. It remains unclear how dry matter productivity responds to factorial combination of elevated CO2 and temperature in the double rice cropping system of China. Field experiments were conducted using open-top chambers (OTC) to simulate different scenarios of elevated CO2 and/or temperature for three rotations of double rice in Jingzhou, Hubei Province. Liangyou 287 and Xiangfengyou 9 were used as rice cultivar for early rice and late rice, respectively. There were five treatments: UC, paddy field without OTC covering; CK, OTC with the similar temperature and CO2 concentration to field environment; ET, OTC with 2 ℃ temperature elevation; EC, OTC with 60 μmol·mol-1 CO2 elevation; ETEC, OTC with simu-ltaneous 2 ℃ temperature elevation and 60 μmol·mol-1 CO2 elevation. We measured aboveground biomass, leaf area index (LAI) and Net Assimilation Rate (NAR) of dry matter under different treatments. Our results showed that elevated CO2 and/or temperature had no significant effects on NAR from transplanting to jointing, increased NAR from jointing to heading, but decreased NAR from heading to maturity (except for EC treatment in early rice). Elevated CO2 and/or temperature promoted leaf area development at all growth stages, with ETEC showing the highest increase in LAI except at maturity. Warming and CO2 enrichment jointly promoted dry matter accumulation at heading, with ETEC increasing aboveground biomass by 10.3%-39.8% and 23.6%-34.4% compared with CK in early rice and late rice, respectively. At maturity of early rice, elevated temperature partly offset the positive effects of elevated CO2 on aboveground biomass, as shown by a reduction of 3.2%-14.1% under ETEC compared with EC. Contrarily at maturity of late rice, co-elevation of CO2 and temperature further increased aboveground biomass, showing a synergistic interaction. Results from regression analysis showed that warming and CO2 enrichment had positive effects on NAR at vegetative stages of double rice, while warming showed negative effects on NAR at reproductive stages. Considering the dissimilarities in growth characteristics, growing periods and ambient temperature, elevated CO2 and temperature might increase dry matter production in the Chinese double rice cropping system.