Abstract
Plant photosynthesis and biomass production are closely associated traits but critical to unfavorable environmental constraints such as salinity and drought. The relationships among stress tolerance, photosynthetic mechanisms, biomass and ethanol yield were assessed in Phragmites karka. The growth parameters, leaf gas exchange and chlorophyll fluorescence of P. karka were studied when irrigated with the control and 100 and 300 mM NaCl in a nutrient solution and water deficit conditions (drought, at 50% water holding capacity). The plant shoot fresh biomass was increased in the low NaCl concentration; however, it significantly declined in high salinity and drought. Interestingly the addition of low salinity increased the shoot biomass and ethanol yield. The number of tillers was increased at 100 mM NaCl in comparison to the control treatment. High salinity increased the photosynthetic performance, but there were no significant changes in drought-treated plants. The saturated irradiance (Is) for photosynthesis increased significantly in low salinity, but it declined (about 50%) in high salt-stressed and (about 20%) in drought-treated plants compared to the control. The rates of dark respiration (Rd) and compensation irradiance (Ic) were decreased significantly under all treatments of salinity and drought, with the exception of unchanged Rd values in the control and drought treatments. A-Ci curve analyses revealed a significant improvement in the Jmax, Vc, max, and triose-phosphate utilization (TPU) at lower salinity levels but decreased at 300 mM NaCl and drought treatments compared to the control. In the chlorophyll fluorescence parameters (Fv/Fm, maximum photochemical quantum yield of PSII, and Y(NO)), the non-photochemical yields were not affected under the salt and drought treatments, although an effective photochemical quantum yield (YII) and electron transport rate (ETR) were significantly enhanced in water deficit compared to control plants. P. karka regulates an efficient photosynthesis mechanism to grow in saline and arid areas and can therefore be used as a sustainable biofuel crop.
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Claims 18
Claim · model-written summary
Low salt increased shoot fresh biomass.
Not reportedComparator
Verbatim
e0“The plant shoot fresh biomass was increased in the low NaCl concentration”
Claim · model-written summary
High salinity reduced shoot fresh biomass.
Not reportedTaxonComparatorOutcome
Verbatim
e0“it significantly declined in high salinity and drought”
Claim · model-written summary
Drought reduced shoot fresh biomass.
Not reportedTaxonComparatorOutcome
Verbatim
e0“it significantly declined in high salinity and drought”
Claim · model-written summary
Low salinity increased ethanol yield.
Not reportedTaxonComparator
Verbatim
e0“the addition of low salinity increased the shoot biomass and ethanol yield”
Claim · model-written summary
At 100 mM NaCl, tiller number increased relative to control.
Not reportedTaxon
Verbatim
e0“The number of tillers was increased at 100 mM NaCl in comparison to the control treatment”
Claim · model-written summary
High salinity increased photosynthetic performance.
Not reportedTaxonComparator
Verbatim
e0“High salinity increased the photosynthetic performance”
Claim · model-written summary
Drought did not significantly change photosynthetic performance.
Not reportedTaxonComparatorOutcome
Verbatim
e0“there were no significant changes in drought-treated plants”
Claim · model-written summary
Low salinity significantly increased photosynthetic saturated irradiance.
Not reportedTaxonComparator
Verbatim
e0“The saturated irradiance (Is) for photosynthesis increased significantly in low salinity”
Claim · model-written summary
High salt reduced photosynthetic saturated irradiance by about 50%.
Not reportedTaxonComparatorOutcome
Verbatim
e0“it declined (about 50%) in high salt-stressed”
Claim · model-written summary
Drought reduced photosynthetic saturated irradiance by about 20%.
Not reportedTaxonOutcomeDirection
Verbatim
e0“(about 20%) in drought-treated plants compared to the control”
Claim · model-written summary
Salinity decreased dark respiration and compensation irradiance.
- Treatment
- salinitye0
- Outcome
- dark respiration (Rd) and compensation irradiance (Ic)e0
- Direction
- decreasede0
Not reportedTaxonComparator
Verbatim
e0“The rates of dark respiration (Rd) and compensation irradiance (Ic) were decreased significantly under all treatments of salinity and drought”
Claim · model-written summary
Drought decreased compensation irradiance.
Not reportedTaxonComparator
Verbatim
e0“compensation irradiance (Ic) were decreased significantly under all treatments of salinity and drought”
Claim · model-written summary
Drought left dark respiration unchanged.
Not reportedTaxon
Verbatim
e0“unchanged Rd values in the control and drought treatments”
Claim · model-written summary
Low salinity improved Jmax, Vc max and TPU.
- Treatment
- lower salinity levelse0
- Outcome
- Jmax, Vc, max, and triose-phosphate utilization (TPU)e0
- Direction
- improvemente0
Not reportedTaxonComparator
Verbatim
e0“a significant improvement in the Jmax, Vc, max, and triose-phosphate utilization (TPU) at lower salinity levels”
Claim · model-written summary
At 300 mM NaCl, Jmax, Vc max and TPU decreased.
Not reportedTaxonOutcome
Verbatim
e0“decreased at 300 mM NaCl and drought treatments compared to the control”
Claim · model-written summary
Drought decreased Jmax, Vc max and TPU.
Not reportedTaxonOutcome
Verbatim
e0“decreased at 300 mM NaCl and drought treatments compared to the control”
Claim · model-written summary
Salt and drought did not affect non-photochemical yields.
Not reportedTaxonComparator
Verbatim
e0“the non-photochemical yields were not affected under the salt and drought treatments”
Claim · model-written summary
Water deficit enhanced effective photochemical quantum yield and electron transport rate.
Verbatim
e0“an effective photochemical quantum yield (YII) and electron transport rate (ETR) were significantly enhanced in water deficit compared to control plants”
The same questions in other papers
drought · physiology: photosynthesis · Viridiplantae (plants)Positive and negative results
3 in the opposite direction
- negative
- negative
- negative
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.