Abstract
Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant increase in studies of maize under interactive effects of elevated CO2 concentration ([CO2]) and other factors, yet the interactive effects of elevated [CO2] and increasing precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [CO2] i.e., 390, 450 and 550 µmol·mol(-1), and the experiment with 15% increasing precipitation levels was also set based on the average monthly precipitation of 5-9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2], but irrigation have a positive effect on increased of them at each [CO2] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation, and dark respiration (Rd) was increased as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [CO2] may favor to maize when coupled with increasing amount of precipitation in Northeast China.
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Claims 8
Claim · model-written summary
Irrigation under elevated CO2 increased leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize.
- Treatment
- irrigation under elevated [CO2] levelse1
- Outcome
- leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci)e1
- Direction
- increasede1
- Setting
- Jinzhou, Liaoning province, Northeast Chinae0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed”
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
Claim · model-written summary
Elevated CO2 decreased stomatal conductance (Gs) and transpiration rate (Tr) of maize.
- Treatment
- elevated [CO2]e2
- Outcome
- stomatal conductance (Gs) and transpiration rate (Tr)e2
- Direction
- decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e2“the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2]”
Claim · model-written summary
Irrigation increased stomatal conductance (Gs) and transpiration rate (Tr) of maize at each CO2 level.
- Treatment
- irrigatione3
- Outcome
- stomatal conductance (Gs) and transpiration rate (Tr)e2
- Direction
- positive effect on increasede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e2“the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2]”
e3“irrigation have a positive effect on increased of them at each [CO2] level”
Claim · model-written summary
Water use efficiency (WUE) of maize was higher in the natural precipitation treatment than in the irrigation treatment at elevated CO2.
- Treatment
- natural precipitation treatmente4
- Outcome
- water use efficiency (WUE)e4
- Direction
- highere4
- Comparator
- irrigation treatmente4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e4“resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels”
Claim · model-written summary
Elevated CO2 and irrigation increased maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) of maize.
- Treatment
- elevated [CO2] and irrigatione5
- Outcome
- maximum net photosynthetic rate (Pnmax) and light saturation points (LSP)e5
- Direction
- increasede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e5“maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation”
Claim · model-written summary
Elevated CO2 and irrigation increased dark respiration (Rd) of maize.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e5“maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation”
e6“dark respiration (Rd) was increased as well”
Claim · model-written summary
Irrigation under elevated CO2 enhanced plant height, leaf area and aboveground biomass of maize.
- Treatment
- irrigation under elevated [CO2] levelse1
- Outcome
- plant height, leaf area and aboveground biomasse7
- Direction
- enhancede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e7“The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced”
Claim · model-written summary
Irrigation under elevated CO2 improved yield and ear characteristics of maize, except axle diameter.
- Treatment
- irrigation under elevated [CO2] levelse1
- Outcome
- yield and ear characteristicse2
- Direction
- improvede2
- Qualifier
- except axle diametere2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize”
e2“resulting in an improved of yield and ear characteristics except axle diameter”
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See all 289 papers →8 of 9 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.