Abstract
In order to compare the differences of physiological responses of cucumber seedlings under the Ca(NO3)2and NaCl stress,the effects of two iso-osmotic salts on growth,photosynthetic characteristics,reactive oxygen level,antioxidant enzymes activity and cations absorption of cv.‘Jinchun No.2'(salt sensitive cultivar) cucumber seedlings cultivated hydroponically were investigated.The results showed that NaCl inhibited the growth of both shoots and roots of cucumberseedlings,whereas the inhibiting effect by Ca(NO3)2was mainly on shoots,but not on roots.The results of photosynthetic gas exchange parameters indicate that NaCl stress restricted the entry of CO2from environment into mesophyll cells resulting in reduction of photosynthetic rate.According to analysis of chlorophyll a fluorescence parameters,the capacity of carbon assimilation of cucumber seedlings was also inhibited by NaCl stress.However,Ca(NO3)2stress only affected the entry of CO2,but did not significantly affect the capacity of carbon assimilation.The portion of excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex) was enhanced by both Ca(NO3)2and NaCl,which led to an increase of the production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2) in cucumber seedling leaves.The increase of Ex,O-· 2production rate and H2O2content by NaCl stress was more than that by Ca(NO3)2.Changes of antioxidant enzymes activity of cucumber seedling leaves were different between Ca(NO3)2and NaCl stress.For example,the activity of peroxidase(POD) and catalase(CAT) was increased,but the activity of superoxide dismutase(SOD) in leaves was reduced by NaCl stress.However,the activity of antioxidant enzymes such as SOD,POD,CAT was all enhanced by Ca(NO3)2.We speculated that reactive oxygen species(ROS) quenching was limited under NaCl stress,leading to its accumulation and the serious lipid peroxidation.However,ROS was eliminated by antioxidant enzymes under Ca(NO3)2 stress,so the lipid peroxidation damage by Ca(NO3)2stress was less than that by NaCl.Besides,NaCl stress remarkably increased accumulation of Na+,leading to reduction of ratio of K/Na,Mg/Na and Ca/Na in each plant organ of cucumber seedlings,and disturbing of ionic equilibrium in plants.Ca(NO3)2increased Ca2+accumulation in cucumber seedlings,but decreased K+and Mg2+content,which reduced ratio of K/Ca and Mg/Ca,and also disturbed ionic equilibrium in plants.However,the injury to cucumber seedlings by excessive Na+was more severe than by excessive Ca2+.Our results suggested that physiological responses of cucumber seedlings under the iso-osmotic Ca(NO3)2and NaCl stress were different.NaCl stress increased the accumulation of Na+in cucumber seedlings,which not only restricted the entry of CO2from environment into mesophyll cells,but also reduced carbon assimilation.Because of limitation of ROS quenching,the rapid accumulation of ROS duo to the rise of excess energy in PSⅡ reaction center might activate lipid peroxidation damage,and reduce the growth and photosynthetic performances of cucumber seedlings.Carbon assimilation capacity of cucumber seedlings was not significantly affected by Ca(NO3)2,because that ROS could be removed by antioxidant system in a timely manner without causing lipid peroxidation damage and significant reduction of photosynthetic rate as well as growth of cucumber seedling.
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Claims 20
Claim · model-written summary
Cucumber seedlings: growth of both shoots and roots inhibited under NaCl.
- Taxon
- cucumber
Cucumis sativust0 - Treatment
- NaCle0
- Outcome
- growth of both shoots and rootse0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“NaCl inhibited the growth of both shoots and roots of cucumberseedlings”
Claim · model-written summary
Cucumber seedlings: shoots inhibiting under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e0
- Outcome
- shootse0
- Direction
- inhibitinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“the inhibiting effect by Ca(NO3)2was mainly on shoots,but not on roots”
Claim · model-written summary
Cucumber seedlings: entry of CO2from environment into mesophyll cells restricted under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- entry of CO2from environment into mesophyll cellse0
- Direction
- restrictede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“NaCl stress restricted the entry of CO2from environment into mesophyll cells resulting in reduction of photosynthetic rate”
Claim · model-written summary
Cucumber seedlings: photosynthetic rate reduction under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- photosynthetic ratee0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“NaCl stress restricted the entry of CO2from environment into mesophyll cells resulting in reduction of photosynthetic rate”
Claim · model-written summary
Cucumber seedlings: capacity of carbon assimilation inhibited under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- capacity of carbon assimilatione0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“capacity of carbon assimilation of cucumber seedlings was also inhibited by NaCl stress”
Claim · model-written summary
Cucumber seedlings: capacity of carbon assimilation did not significantly affect under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e0
- Outcome
- capacity of carbon assimilatione0
- Direction
- did not significantly affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“Ca(NO3)2stress only affected the entry of CO2,but did not significantly affect the capacity of carbon assimilation”
Claim · model-written summary
Cucumber seedlings: excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex) enhanced under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e0
- Outcome
- excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex)e0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“portion of excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex) was enhanced by both Ca(NO3)2and NaCl”
Claim · model-written summary
Cucumber seedlings: excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex) enhanced under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex)e0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“portion of excessive energy in photosystem Ⅱ(PSⅡ) reaction center(Ex) was enhanced by both Ca(NO3)2and NaCl”
Claim · model-written summary
Cucumber seedlings: production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2) increase under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e1
- Outcome
- production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2)e0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“increase of the production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2) in cucumber seedling leaves”
e1“the inhibiting effect by Ca(NO3)2was mainly on shoots,but not on roots”
Claim · model-written summary
Cucumber seedlings: production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2) increase under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle1
- Outcome
- production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2)e0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“increase of the production rate of superoxide anion radical(O-· 2) and content of hydrogen peroxide(H2O2) in cucumber seedling leaves”
e1“NaCl inhibited the growth of both shoots and roots of cucumberseedlings”
Claim · model-written summary
Cucumber seedlings: Ex,O-· 2production rate and H2O2content increase under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- Ex,O-· 2production rate and H2O2contente0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“The increase of Ex,O-· 2production rate and H2O2content by NaCl stress was more than that by Ca(NO3)2”
Claim · model-written summary
Cucumber seedlings: activity of peroxidase(POD) and catalase(CAT) increased under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle1
- Outcome
- activity of peroxidase(POD) and catalase(CAT)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“activity of peroxidase(POD) and catalase(CAT) was increased”
e1“NaCl inhibited the growth of both shoots and roots of cucumberseedlings”
Claim · model-written summary
Cucumber seedlings: activity of superoxide dismutase(SOD) reduced under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- activity of superoxide dismutase(SOD)e0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“activity of superoxide dismutase(SOD) in leaves was reduced by NaCl stress”
Claim · model-written summary
Cucumber seedlings: activity of antioxidant enzymes such as SOD,POD,CAT enhanced under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e0
- Outcome
- activity of antioxidant enzymes such as SOD,POD,CATe0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“activity of antioxidant enzymes such as SOD,POD,CAT was all enhanced by Ca(NO3)2”
Claim · model-written summary
Cucumber seedlings: accumulation of Na+ increased under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle0
- Outcome
- accumulation of Na+e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“NaCl stress remarkably increased accumulation of Na+”
Claim · model-written summary
Cucumber seedlings: ratio of K/Na,Mg/Na and Ca/Na reduction under NaCl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- NaCle1
- Outcome
- ratio of K/Na,Mg/Na and Ca/Nae0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“reduction of ratio of K/Na,Mg/Na and Ca/Na in each plant organ”
e1“NaCl inhibited the growth of both shoots and roots of cucumberseedlings”
Claim · model-written summary
Cucumber seedlings: Ca2+accumulation increased under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e0
- Outcome
- Ca2+accumulatione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“Ca(NO3)2increased Ca2+accumulation in cucumber seedlings”
Claim · model-written summary
Cucumber seedlings: K+and Mg2+content decreased under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e1
- Outcome
- K+and Mg2+contente0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“decreased K+and Mg2+content”
e1“the inhibiting effect by Ca(NO3)2was mainly on shoots,but not on roots”
Claim · model-written summary
Cucumber seedlings: ratio of K/Ca and Mg/Ca reduced under Ca(NO3)2.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Ca(NO3)2e1
- Outcome
- ratio of K/Ca and Mg/Cae0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“reduced ratio of K/Ca and Mg/Ca”
e1“the inhibiting effect by Ca(NO3)2was mainly on shoots,but not on roots”
Claim · model-written summary
Cucumber seedlings: injury to cucumber seedlings more severe under excessive Na+.
- Taxon
- cucumberCucumis sativust0
- Treatment
- excessive Na+e0
- Outcome
- injury to cucumber seedlingse0
- Direction
- more severee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“injury to cucumber seedlings by excessive Na+was more severe than by excessive Ca2+”
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