Ammonium application mitigates the effects of elevated carbon dioxide on the carbon/nitrogen balance of Phoebe bournei seedlings

2021 ◽  
Author(s):  
Xiao Wang ◽  
Xiaoli Wei ◽  
Gaoyin Wu ◽  
Shengqun Chen

Abstract The study of plant responses to increases in atmospheric carbon dioxide (CO2) concentration is crucial to understand and to predict the effect of future global climate change on plant adaptation and evolution. Increasing amount of nitrogen (N) can promote the positive effect of CO2, while how N forms would modify the degree of CO2 effect is rarely studied. The aim of this study was to determine whether the amount and form of nitrogen (N) could mitigate the effects of elevated CO2 (eCO2) on enzyme activities related to carbon (C) and N metabolism, the C/N ratio, and growth of Phoebe bournei (Hemsl.) Y.C. Yang. One-year-old P. bournei seedlings were grown in an open-top air chamber under either an ambient CO2 (aCO2) (350 ± 70 μmol•mol−1) or an eCO2 (700 ± 10 μmol•mol−1) concentration and cultivated in soil treated with either moderate (0.8 g per seedling) or high applications (1.2 g per seedling) of nitrate or ammonium. In seedlings treated with a moderate level of nitrate, the activities of key enzymes involved in C and N metabolism (i.e., Rubisco, Rubisco activase and glutamine synthetase) were lower under eCO2 than under aCO2. By contrast, key enzyme activities (except GS) in seedlings treated with high nitrate or ammonium were not significantly different between aCO2 and eCO2 or higher under eCO2 than under aCO2. The C/N ratio of seedlings treated with moderate or high nitrate under eCO2was significantly changed compared with the seedlings grown under aCO2, whereas the C/N ratio of seedlings treated with ammonium was not significantly different between aCO2 and eCO2. Therefore, under eCO2, application of ammonium can be beneficial C and N metabolism and mitigate effects on the C/N ratio.

2019 ◽  
Vol 48 (4) ◽  
pp. 935-944 ◽  
Author(s):  
Yu Chen ◽  
Laurent Serteyn ◽  
Zhenying Wang ◽  
KangLai He ◽  
Frederic Francis

Abstract In the current context of global climate change, atmospheric carbon dioxide (CO2) concentrations are continuously rising with potential influence on plant–herbivore interactions. The effect of elevated CO2 (eCO2) on feeding behavior of corn leaf aphid, Rhopalosiphum maidis (Fitch) on barley seedlings Hordeum vulgare L. was tracked using electrical penetration graph (EPG). The nutrient content of host plant and the developmental indexes of aphids under eCO2 and ambient CO2 (aCO2) conditions were also investigated. Barley seedlings under eCO2 concentration had lower contents of crude protein and amino acids. EPG analysis showed the plants cultivated under eCO2 influenced the aphid feeding behavior, by prolonging the total pre-probation time of the aphids (wandering and locating the feeding site) and the ingestion of passive phloem sap. Moreover, fresh body weight, fecundity and intrinsic population growth rate of R. maidis was significantly decreased in eCO2 in contrast to aCO2 condition. Our findings suggested that changes in plant nutrition caused by eCO2, mediated via the herbivore host could affect insect feeding behavior and population dynamics.


HortScience ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. 687-690 ◽  
Author(s):  
James Bunce

Soil water deficits remain one of the most important factors reducing the yield of crop plants and may become even more limiting with changes in the global climate and competition for fresh water resources. Soil water deficits reduce plant growth partly by reducing photosynthesis. However, it remains unclear how important non-stomatal factors are in limiting photosynthesis under moderate water stress and whether rising atmospheric carbon dioxide may alter which processes limit photosynthesis under water stress. The conductance to CO2 from the substomatal air space to the site of carboxylation inside chloroplasts in C3 plants is now termed mesophyll conductance. Because of the competition between CO2 and O2 for RuBisco, the carbon dioxide concentration at the chloroplast can be estimated from the O2 sensitivity of photosynthesis, providing a new method of estimating mesophyll conductance. It has also recently been realized that partial stomatal closure resulting from water stress can often be reversed by exposing leaves to low CO2. This provides a new means of assessing the non-stomatal component of the inhibition of photosynthesis by water stress. These methods were applied to four C3 species and revealed that mesophyll conductance decreased substantially with water stress in two of the four species and that reopening of stomata did not eliminate the reduction in photosynthesis caused by moderate water stress at either the current ambient or elevated CO2 concentrations.


2021 ◽  
pp. 5-16
Author(s):  
Kneev Sharma ◽  
Dimitre Karamanev

Understanding the fundamental relationship between atmospheric carbon dioxide concentration and temperature rise is essential for tackling the problem of climate change that faces us today. Misconceptions regarding the relationship are widespread due to media and political influences. This investigation aims to address the popular misconception that CO2 concentration directly and naturally leads to global temperature rise. While anthropogenic CO2 emissions seem to affect the rising global atmospheric temperature with a confidence of 95%, it falters when the historical relationship using ice core data is studied. This investigation uses two statistical approaches to determine an accurate range and direction for this important relationship. Through a combined approach, it was found that historically CO2 concentration in the last 650 000 years lags global temperature rise by 1020-1080 years with a maximum correlation coefficient of 0.8371-0.8372. This result is important for the investigation of climate change.


Our Nature ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Krishna Prasad Bhattarai ◽  
Tej Narayan Mandal

Global climate change is a major problem generated by increasing concentration of carbon dioxide in the atmosphere. Forests and their soils are major sink of carbon and thus constitute an effective role in the global carbon cycle. Present study was conducted to quantify and compare the amount of carbon stock in litterfall, fine root and soil between Tarai Sal forest and Hill Sal forest of eastern Nepal. Carbon stock in litter and fine root was estimated by ash content method and in soil by multiplying the value of soil organic carbon, bulk density and soil depth. Carbon stock in litterfall was higher (3.94 Mg ha-1) in TSF than HSF (3.26 Mg ha-1) and in fine root (0-5 mm size) in 0-30 cm soil depth it was higher in HSF (2.76 Mg ha-1) than TSF (2.19 Mg ha-1). In soil (0-30 cm depth) the value was higher in HSF (58.23 Mg ha-1) than TSF (50.81Mg ha-1). Tarai Sal forest accumulated higher carbon stock in the litterfall and lower in fine root than Hill Sal forest which was mainly attributed to the amount of litterfall and fine root biomass rather than organic carbon concentration. In Tarai Sal forest the carbon stock in soil was relatively low than Hill Sal forest that may be due to the higher net uptake and mineralization of carbon in the situation of higher growth rate of plant. These outcomes verified that the forest plays important role for mitigation of global warming by storing the atmospheric carbon dioxide in plant parts and the soil. So, it concludes that conserving the considerable quantity of carbon in forests is inevitable for proper forest management.


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