The optimal CO2 concentrations for the growth of three perennial grass species

Abstract

BackgroundGrasslands are one of the most representative vegetation types accounting for about 20% of the global land area and thus the response of grasslands to climate change plays a pivotal role in terrestrial carbon balance. However, many current climate change models, based on earlier results of the doubling-CO2 experiments, may overestimate the CO2 fertilization effect, and as a result underestimate the potentially effects of future climate change on global grasslands when the atmospheric CO2 concentration goes beyond the optimal level. Here, we examined the optimal atmospheric CO2 concentration effect on CO2 fertilization and further on the growth of three perennial grasses in growth chambers with the CO2 concentration at 400, 600, 800, 1000, and 1200 ppm, respectively.ResultsAll three perennial grasses featured an apparent optimal CO2 concentration for growth. Initial increases in atmospheric CO2 concentration substantially enhanced the plant biomass of the three perennial grasses through the CO2 fertilization effect, but this CO2 fertilization effect was dramatically compromised with further rising atmospheric CO2 concentration beyond the optimum. The optimal CO2 concentration for the growth of tall fescue was lower than those of perennial ryegrass and Kentucky bluegrass, and thus the CO2 fertilization effect on tall fescue disappeared earlier than the other two species. By contrast, the weaker CO2 fertilization effect on the growth of perennial ryegrass and Kentucky bluegrass was sustained for a longer period due to their higher optimal CO2 concentrations than tall fescue. The limiting effects of excessively high CO2 concentrations may not only associate with changes in the biochemical and photochemical processes of photosynthesis, but also attribute to the declines in stomatal conductance and nitrogen availability.ConclusionsIn this study, we found apparent differences in the optimal CO2 concentrations for the growth of three grasses. These results suggest that the growth of different types of grasses may respond differently to future elevated CO2 concentrations through the CO2 fertilization effect, and thus potentially alter the community composition and structure of grasslands. Meanwhile, our results may also be helpful for improving current process-based ecological models to more accurately predict the structure and function of grassland ecosystems under future rising atmospheric CO2 concentration and climate change scenarios.

Elevated CO2 concentration induces photosynthetic down-regulation with changes in leaf structure, non-structural carbohydrates and nitrogen content of soybean

“…6), confirming that this down-regulation of leaf photosynthesis may be attributed to the decline of stomatal conductance through reducing stomatal openness when soybean plants exposed to high CO 2 concentrations. Additionally, the less regular stomatal distribution pattern on the adaxial leaf surface of soybean plants as evidenced by the larger Lhat (d) at higher CO 2 concentrations may contribute to the decline of stomatal conductance through increasing the average distance of CO 2 diffusion from stomata to chloroplasts [47, 63]. Overall, the fewer stomata and smaller stomatal pore aperture, as well as the more irregular spatial distribution patterns at high CO 2 concentrations may partially explain the decline of stomatal conductance in the current study.…”

“…Several previous studies have documented that different plants features with different optimal CO 2 concentrations for plant growth [47, 63] and thus plants with high optimal CO 2 concentrations will suffer less from climate change and meanwhile benefit the most from the CO 2 fertilization effect due to high nitrogen and water use efficiency [24]. Exploring the mechanisms of CO 2 fertilization effect on crops is critical to estimating global agriculture yield under climatic change [64].…”

Respiratory CO2 Combined With a Blend of Volatiles Emitted by Endophytic Serendipita Strains Strongly Stimulate Growth of Arabidopsis Implicating Auxin and Cytokinin Signaling

“…In this context, CO 2 -response curves of photosynthesis and biomass production usually reach a point at which further increase in CO 2 is no longer accompanied by a higher leaf net photosynthetic rate or plant growth. For C3 plants, including Arabidopsis , the maximal plant response is typically obtained at a CO 2 level around 1000 ppm ( Xu, 2015 ; Zheng et al, 2018 ). With this saturation point in mind and based on CO 2 -fertilization applications in horticulture, 1500 ppm CO 2 was added to the 4-L glass reaction vessel.…”

Molecular and Physiological Alterations in Chickpea under Elevated CO2 Concentrations

“…This may be attributed to the elevated CO 2 fertilization effect and higher nitrogen and water use efficiency ( Körner et al. 2005 , Zheng et al. 2018 ).…”