The Influence of CO2 Enrichment on Growth, Nutrient Content and Biomass Allocation of Maranthes corymbosa

1993 ◽  
Vol 41 (2) ◽  
pp. 195 ◽  
Author(s):  
CA Berryman ◽  
D Eamus ◽  
GA Duff

Seedlings of Maranthes corymbosa Blume, an evergreen tree of tropical Australia and Indonesia were grown for 32 weeks under conditions of ambient and elevated (700 μmol CO2 mol-1) CO2 in tropical northern Australia. Seedlings were exposed to ambient temperature, vapour pressure deficit and photon flux density fluctuations. Rates of germination and percentage germination were not affected by elevated CO2. Total plant biomass, height growth, total plant leaf area, numbers of leaves and branches and specific leaf weight were significantly increased by elevated CO2. Root:shoot ratio and foliar P, K, Mg, Mn and Ca levels were unaffected but foliar nitrogen levels were decreased by elevated CO2, Nutrient-use-efficiency was unaffected for phosphorus, magnesium, manganese, calcium and potassium but nitrogen-use-efficiency increased in response to elevated CO2.

2019 ◽  
Vol 46 (7) ◽  
pp. 684 ◽  
Author(s):  
Camilo Rey-Sanchez ◽  
Juan M. Posada

Individual leaves have a unique instantaneous photosynthetic photon flux density (PPFD) at which net photosynthetic light use efficiency (ϵL, the ratio between net photosynthesis and PPFD) is maximised (PPFDϵmax). When PPFD is above or below PPFDϵmax, efficiency declines. Thus, we hypothesised that heterogeneous PPFD conditions should increase the amount of time leaves photosynthesise at a PPFD different than PPFDϵmax and result in reduced growth. To date, this prediction has not been rigorously tested. Here, we exposed seedlings of Abatia parviflora Ruiz & Pav to light regimes of equal total daily irradiance but with three different daily time courses of PPFD: constant PPFD (No_H), low heterogeneity (Low_H) and high heterogeneity (High_H). Mean ϵL, leaf daily photosynthesis and plant growth were all significantly higher in No_H and Low_H plants than in High_H plants, supporting our hypothesis. In addition, mean ϵL was positively related to final plant biomass. Unexpectedly, High_H plants had more etiolated stems and more horizontal leaves than No_H and Low_H plants, possibly due to exposure to low PPFD in the morning and afternoon. In conclusion, PPFD heterogeneity had an important effect on average ϵL, photosynthesis and growth, but also on allocation and plant morphology.


Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 397 ◽  
Author(s):  
Virupax C. Baligar ◽  
Marshall K. Elson ◽  
Alex-Alan F. Almeida ◽  
Quintino R. de Araujo ◽  
Dario Ahnert ◽  
...  

Cacao (Theobroma cacao L.) was grown as an understory tree in agroforestry systems where it received inadequate to adequate levels of photosynthetic photon flux density (PPFD). As atmospheric carbon dioxide steadily increased, it was unclear what impact this would have on cacao growth and development at low PPFD. This research evaluated the effects of ambient and elevated levels carbon dioxide under inadequate to adequate levels of PPFD on growth, physiological and nutrient use efficiency traits of seven genetically contrasting juvenile cacao genotypes. Growth parameters (total and root dry weight, root length, stem height, leaf area, relative growth rate and net assimilation rates increased, and specific leaf area decreased significantly in response to increasing carbon dioxide and PPFD. Increasing carbon dioxide and PPFD levels significantly increased net photosynthesis and water-use efficiency traits but significantly reduced stomatal conductance and transpiration. With few exceptions, increasing carbon dioxide and PPFD reduced macro–micro nutrient concentrations but increased uptake, influx, transport and nutrient use efficiency in all cacao genotypes. Irrespective of levels of carbon dioxide and PPFD, intraspecific differences were observed for growth, physiology and nutrient use efficiency of cacao genotypes.


1986 ◽  
Vol 64 (12) ◽  
pp. 2993-2998 ◽  
Author(s):  
Steven F. Oberbauer ◽  
Nasser Sionit ◽  
Steven J. Hastings ◽  
Walter C. Oechel

Three Alaskan tundra species, Carex bigelowii Torr., Betula nana L., and Ledum palustre L., were grown in controlled-environment chambers at two nutrition levels with two concentrations of atmospheric CO2 to assess the interactive effects of these factors on growth, photosynthesis, and tissue nutrient content. Carbon dioxide concentrations were maintained at 350 and 675 μL L−1 under photosynthetic photon flux densities of 450 μmol m−2 s−1 and temperatures of 20:15 °C (light:dark). Nutrient treatments were obtained by watering daily with 1/60- or 1/8- strength Hoagland's solution. Leaf, root, and total biomass were strongly enhanced by nutrient enrichment regardless of the CO2 concentration. In contrast, enriched atmospheric CO2 did not significantly affect plant biomass and there was no interaction between nutrition and CO2 concentration during growth. Leaf photosynthesis was increased by better nutrition in two species but was unchanged by CO2 enrichment during growth in all three species. The effects of nutrient addition and CO2 enrichment on tissue nutrient concentrations were complex and differed among the three species. The data suggest that CO2 enrichment with or without nutrient limitation has little effect on the biomass production of these three tundra species.


1991 ◽  
Vol 71 (1) ◽  
pp. 245-252 ◽  
Author(s):  
J. Jiao ◽  
M. J. Tsujita ◽  
B. Grodzinski

At three stages of flowering shoot development, varying the irradiance and CO2 levels had a similar effect on the whole-plant net CO2 exchange rate (NCER) of Samantha rose plants. At 22 °C, the NCER was saturated at 1000 μmol m−2 s−1 photosynthetically active radiation (PAR). The duration of the light period was also important in determining daily carbon (C) gain. When roses were exposed to a constant daily radiant energy dose of 17.6 μmol m−2 provided either as a 12-h irradiation interval at 410 μmol m−2 s−1 PAR or 24 h of irradiation at 204 μmol m−2 s−1 PAR, the plants exposed to 24 h of continuous irradiation at the lower photon flux density retained 80% more C. Under saturating irradiance, the net photosynthetic rate at an enriched (1000 μL L−1) CO2 level was almost double that at ambient (350 μL L−1) CO2. However, plants grown at ambient and enriched CO2 levels had similar whole-plant NCERs when compared at the same assay CO2 level. Under CO2 enrichment the flower stem was longer and thicker but the flower bud size at harvest was not significantly different to that of roses grown at the ambient CO2 level. Key words: CO2 enrichment, daily carbon gain, net CO2 exchange rate, radiation, Rosa hybrida


1996 ◽  
Vol 23 (5) ◽  
pp. 593 ◽  
Author(s):  
BE Medlyn

The distribution of nitrogen among compounds involved in photosynthesis varies in response to changes in environmental conditions such as photon flux density. However, the extent to which the nitrogen distribution within leaves adjusts in response to increased atmospheric CO2 is unclear. A model was used to determine the nitrogen distribution which maximises photosynthesis under realistic light regimes at both current and elevated levels of CO2, and a comparison was made with observed leaf nitrogen distributions reported in the literature. The model accurately predicted the distribution of nitrogen within the photosynthetic system for leaves grown at current levels of CO2, except at very high leaf nitrogen contents. The model predicted that, under a doubling of CO2 concentration from its current level, the ratio of electron transport capacity to Rubisco activity (Jmax : Vcmax) should increase by 40%. In contrast, measurements of Jmax : Vcmax taken from the literature show a slight but non-significant increase in response to an increase in CO2. The discrepancy between predicted and observed Jmax : Vcmax suggests that leaf nitrogen distribution does not acclimate optimally to elevated CO2. Alternatively, the discrepancy may be due to effects of CO2 which the model fails to take into account, such as a possible decrease in the conductance to CO2 transfer between the intercellular spaces and the sites of carboxylation at elevated CO2.


1984 ◽  
Vol 14 (3) ◽  
pp. 343-350 ◽  
Author(s):  
Leslie C. Tolley ◽  
B. R. Strain

Mathematical growth analysis techniques were used to assess the effects of atmospheric carbon dioxide enrichment on growth and biomass partitioning of Liquidambarstyraciflua L. (sweetgum) and Pinustaeda L. (loblolly pine) seedlings. Plants were grown from seed under high (1000 μmol•m−2•s−1) and low (250 μmol•m−2•s−1) photosynthetic photon flux density at CO2 concentrations of 350, 675, and 1000 μL•L−1 for 84 or 112–113 days. Elevated atmospheric CO2 concentration significantly increased height, leaf area, basal stem diameter, and total dry weight of sweetgum seedlings grown under high irradiance and to a lesser extent under low irradiance. Increases in dry matter accumulation were associated with early CO2 enhancement of net assimilation rate, but increases in amount of leaf surface area contributed more towards maintenance of larger size as seedlings aged. For sweetgum seedlings in particular, reduction of growth by low irradiance under normal atmospheric CO2 was compensated for by growing plants with elevated CO2. In contrast, elevated CO2 concentration produced no significant increase in growth of loblolly pine seedlings.


1980 ◽  
Vol 7 (1) ◽  
pp. 89 ◽  
Author(s):  
GA Constable ◽  
HM Rawson

Net photosynthesis, dark respiration and the response to photon flux density were measured on cotton leaves grown in a glasshouse. Leaves at four positions on the plant were examined from their unfolding until 70 days later. Photosynthesis and transpiration per unit of leaf area were unaffected by leaf position and, in all leaves, peak photosynthesis of about 110 ng CO2 cm-2 s-1 was attained 13-15 days after leaf unfolding, when the leaf was 75-90% of maximum area. Photosynthesis was maintained at this rate for only 12 days before declining linearly to values 20% of the maximum when leaves were 70 days old. Transpiration followed a similar pattern reaching a maximum of about 13 �g H2O cm-2 s-1 at 2 kPa vapour pressure deficit (VPD) at 13 days. Stomatal and internal conductances changed in parallel as leaves aged, with the consequence that internal CO2 concentration and water use efficiency remainedessentially constant at 220�ll-1 and 16.8 ng CO2 (�g H2O kPa VPD-1)-1 respectively. Youngest and oldest leaves saturated at lowest light levels (400-800 pE m-2 s-1) while 16-18- day-old leaves had light saturation at 1100 �E m-2 s-1. The initial slope of the light response curves increased as leaves expanded up to 10 days age then remained constant at 0.25 ng CO2 cm-2 (pE m-2)-1. Dark respiration reached a maximum of 1.5 ng CO2 mg-1 s-1 5 days after leaf unfolding, when leaf dry weight was increasing most rapidly. The relationship between the consistent pattern of gas exchange with age and the pattern of morphological development is discussed, along with internal factors associated with age-dependent photosynthesis.


2020 ◽  
Vol 17 (17) ◽  
pp. 4421-4441
Author(s):  
June Skeeter ◽  
Andreas Christen ◽  
Andrée-Anne Laforce ◽  
Elyn Humphreys ◽  
Greg Henry

Abstract. Thermokarst features are widespread in ice-rich regions of the circumpolar Arctic. The rate of thermokarst lake formation and drainage is anticipated to accelerate as the climate warms. However, it is uncertain how these dynamic features impact the terrestrial Arctic carbon cycle. Methane (CH4) and carbon dioxide (CO2) fluxes were measured during peak growing season using eddy covariance and chambers at Illisarvik, a 0.16 km2 thermokarst lake basin that was experimentally drained in 1978 on Richards Island, Northwest Territories, Canada. Vegetation in the basin differs markedly from the surrounding dwarf-shrub tundra and included patches of tall shrubs, grasses, and sedges with some bare ground and a small pond in the centre. During the peak growing season, temperature and wind conditions were highly variable, and soil water content decreased steadily. Basin-scaled net ecosystem CO2 exchange (NEE) measured by eddy covariance was −1.5 [CI95 %±0.2] g C−CO2 m-2d-1; NEE followed a marked diurnal pattern with no day-to-day trend during the study period. Variations in half-hourly NEE were primarily controlled by photosynthetic photon flux density and influenced by vapour pressure deficit, volumetric water content, and the presence of shrubs within the flux tower footprint, which varied with wind direction. Net methane exchange (NME) was low (8.7 [CI95 %±0.4] mgCH4m-2d-1) and had little impact on the growing season carbon balance of the basin. NME displayed high spatial variability, and sedge areas in the basin were the strongest source of CH4 while upland areas outside the basin were a net sink. Soil moisture and temperature were the main environmental factors influencing NME. Presently, Illisarvik is a carbon sink during the peak growing season. However, these results suggest that rates of growing season CO2 and CH4 exchange rates may change as the basin's vegetation community continues to evolve.


Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 816
Author(s):  
Jianfeng Zheng ◽  
Peidian Gan ◽  
Fang Ji ◽  
Dongxian He ◽  
Po Yang

This study was conducted to compare the effects of broad spectrum during the whole seedling period and photon flux density (PFD) in the healing stage on the growth and energy use efficiency of grafted tomato (Lycopersicon esculentum Mill.) transplants in a plant factory. Fluorescent lights, white LED lights, and white plus red LED lights were applied at the growth processes of grafted tomato transplants from germination of rootstock and scion to post-grafting. Three levels of PFD (50, 100, 150 μmol m−2 s−1) were set in the healing stage under each kind of light quality. The results indicated that the growth and quality of grafted tomato transplants under different broad spectrums were influenced by the ratio of red to blue light (R/B ratio) and the ratio of red to far-red light (R/FR ratio). A higher R/B ratio was beneficial to total dry matter accumulation, but excessive red light had a negative effect on the root to shoot ratio and the seedling quality index. The higher blue light and R/FR ratio suppressed stem extension synergistically. The LED lights had good abilities to promote plant compactness and leaf thickness in comparison with fluorescent lights. The plant compactness and leaf thickness increased with the increase in daily light integral in the healing stage within a range from 2.5 to 7.5 mol m−2 d−1 (PFD, 50 to 150 μmol m−2 s−1). Compared to fluorescent lights, the LED lights showed more than 110% electrical energy saving for lighting during the whole seedling period. Higher PFD in the healing stage did not significantly increase the consumption of electric power for lighting. White plus red LED lights with an R/B ratio of 1.2 and R/FR ratio of 16 were suggested to replace fluorescent lights for grafted tomato transplants production considering the high quality of transplants and electrical energy saving, and PFD in the healing stage was recommended to be set to 150 μmol m−2 s−1.


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