Water Deficit Modulates the CO2 Fertilization Effect on Plant Gas Exchange and Leaf-Level Water Use Efficiency: A Meta-Analysis

Elevated atmospheric CO2 concentrations ([eCO2]) and soil water deficits significantly influence gas exchange in plant leaves, affecting the carbon-water cycle in terrestrial ecosystems. However, it remains unclear how the soil water deficit modulates the plant CO2 fertilization effect, especially for gas exchange and leaf-level water use efficiency (WUE). Here, we synthesized a comprehensive dataset including 554 observations from 54 individual studies and quantified the responses for leaf gas exchange induced by e[CO2] under water deficit. Moreover, we investigated the contribution of plant net photosynthesis rate (Pn) and transpiration rates (Tr) toward WUE in water deficit conditions and e[CO2] using graphical vector analysis (GVA). In summary, e[CO2] significantly increased Pn and WUE by 11.9 and 29.3% under well-watered conditions, respectively, whereas the interaction of water deficit and e[CO2] slightly decreased Pn by 8.3%. Plants grown under light in an open environment were stimulated to a greater degree compared with plants grown under a lamp in a closed environment. Meanwhile, water deficit reduced Pn by 40.5 and 37.8%, while increasing WUE by 24.5 and 21.5% under ambient CO2 concentration (a[CO2]) and e[CO2], respectively. The e[CO2]-induced stimulation of WUE was attributed to the common effect of Pn and Tr, whereas a water deficit induced increase in WUE was linked to the decrease in Tr. These results suggested that water deficit lowered the stimulation of e[CO2] induced in plants. Therefore, fumigation conditions that closely mimic field conditions and multi-factorial experiments such as water availability are needed to predict the response of plants to future climate change.

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Elevated CO<sub>2</sub>, increased leaf-level productivity, and water-use efficiency during the early Miocene

Climate of the Past ◽

10.5194/cp-16-1509-2020 ◽

2020 ◽

Vol 16 (4) ◽

pp. 1509-1521

Author(s):

Tammo Reichgelt ◽

William J. D'Andrea ◽

Ailín del C. Valdivia-McCarthy ◽

Bethany R. S. Fox ◽

Jennifer M. Bannister ◽

...

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Water Use ◽

Leaf Gas Exchange ◽

Atmospheric Co2 ◽

Early Miocene ◽

Intrinsic Water Use Efficiency ◽

Leaf Level ◽

Fertilization Effect ◽

Use Efficiency

Abstract. Rising atmospheric CO2 is expected to increase global temperatures, plant water-use efficiency, and carbon storage in the terrestrial biosphere. A CO2 fertilization effect on terrestrial vegetation is predicted to cause global greening as the potential ecospace for forests expands. However, leaf-level fertilization effects, such as increased productivity and water-use efficiency, have not been documented from fossil leaves in periods of heightened atmospheric CO2. Here, we use leaf gas-exchange modeling on a well-preserved fossil flora from early Miocene New Zealand, as well as two previously published tropical floras from the same time period, to reconstruct atmospheric CO2, leaf-level productivity, and intrinsic water-use efficiency. Leaf gas-exchange rates reconstructed from early Miocene fossils, which grew at southern temperate and tropical latitudes when global average temperatures were 5–6 ∘C higher than today, reveal that atmospheric CO2 was ∼450–550 ppm. Early Miocene CO2 was similar to projected values for 2040 CE and is consistent with an Earth system sensitivity of 3–7 ∘C to a doubling of CO2. The Southern Hemisphere temperate leaves had higher reconstructed productivity than modern analogs, likely due to a longer growing season. This higher productivity was presumably mirrored at northern temperate latitudes as well, where a greater availability of landmass would have led to increased carbon storage in forest biomass relative to today. Intrinsic water-use efficiency of both temperate and tropical forest trees was high, toward the upper limit of the range for modern trees, which likely expanded the habitable range in regions that could not support forests with high moisture demands under lower atmospheric CO2. Overall, early Miocene elevated atmospheric CO2 sustained globally higher temperatures, and our results provide the first empirical evidence of concomitant enhanced intrinsic water-use efficiency, indicating a forest fertilization effect.

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Excessive nitrogen application under moderate soil water deficit decreases photosynthesis, respiration, carbon gain and water use efficiency of maize

Plant Physiology and Biochemistry ◽

10.1016/j.plaphy.2021.07.014 ◽

2021 ◽

Author(s):

Huanli Xing ◽

Wenbin Zhou ◽

Chao Wang ◽

Li Li ◽

Xiangnan Li ◽

...

Keyword(s):

Water Use Efficiency ◽

Soil Water ◽

Water Deficit ◽

Water Use ◽

Carbon Gain ◽

Soil Water Deficit ◽

Nitrogen Application ◽

Use Efficiency

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Boron Supply and Water Deficit Consequences in Young ParicÃ¡ (Schizolobium parahyba var. amazonicum) Plants

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha44110136 ◽

2016 ◽

Vol 44 (1) ◽

pp. 250-256 ◽

Cited By ~ 1

Author(s):

Bianca do Carmo SILVA ◽

PÃªola Reis de SOUZA ◽

Daihany Moraes CALLEGARI ◽

Vanessa Ferreira ALVES ◽

Allan Klynger da Silva LOBATO ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Stomatal Conductance ◽

Gas Exchange ◽

Water Use Efficiency ◽

Water Deficit ◽

Water Use ◽

Electrolyte Leakage ◽

Tolerance Mechanism ◽

Schizolobium Parahyba ◽

Use Efficiency

Boron (B) is a very important nutrient required by forest plants; when supplied in adequate amounts, plants can ameliorate the negative effects of abiotic stresses. The objective of this study was to (i) investigate gas exchange, (ii) measure oxidant and antioxidant compounds, and (iii) respond how B supply acts on tolerance mechanism to water deficit in young Schizolobium parahyba plants. The experiment employed a factorial that was entirely randomised, with two boron levels (25 and 250 Âµmol L-1, simulating conditions of sufficient B and high B, respectively) and two water conditions (control and water deficit). Water deficit induced negative modifications on net photosynthetic rate, stomatal conductance and water use efficiency, while B high promoted intensification of the effects on stomatal conductance and water use efficiency. Hydrogen peroxide and electrolyte leakage of both tissues suffered non-significant increases after B high and when applied water deficit. Ascorbate levels presented increases after water deficit and B high to leaf and root. Our results suggested that the tolerance mechanism to water deficit in young Schizolobium parahyba plants is coupled to increases in total glutathione and ascorbate aiming to control the overproduction of hydrogen peroxide and alleviates the negative consequences on electrolyte leakage and gas exchange. In relation to B supply, this study proved that sufficient level promoted better responses under control and water deficit conditions.

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