Abstract
BACKGROUND AND AIMS: Flooding slows seed germination, imposes fatalities and delays seedling establishment in direct-seeded rice. This study describes responses of contrasting rice genotypes subjected to flooding or low oxygen stress during germination and discusses the basis of tolerance shown by certain cultivars. METHODS: In one set of experiments, dry seeds were sown in soil and either watered normally or flooded with 10 cm of water. Seedling survival and shoot and root growth were assessed and seed portions of germinating seedlings were assayed for soluble sugars and starch concentrations. The whole germinating seedlings were assayed for amylase and peroxidase activities and for ethylene production. Activities of enzymes associated with anaerobic respiration were examined and gene expression was analysed separately with seeds germinating under different amounts of dissolved oxygen in dilute agar. KEY RESULTS: Flooding during germination reduced survival but to a lesser extent in tolerant genotypes. Starch concentration in germinating seeds decreased while sugar concentration increased under flooding, but more so in tolerant genotypes. Amylase activity correlated positively with elongation (r = 0.85 for shoot and 0.83 for root length) and with plant survival (r = 0.92). Tolerant genotypes had higher amylase activity and higher RAmy3D gene expression. Ethylene was not detected in seeds within 2 d after sowing, but increased thereafter, with a greater increase in tolerant genotypes starting 3 d after sowing. Peroxidase activity was higher in germinating seeds of sensitive genotypes and correlated negatively with survival. CONCLUSIONS: Under low oxygen stress, tolerant genotypes germinate, grow faster and more seedlings survive. They maintain their ability to use stored starch reserves through higher amylase activity and anaerobic respiration, have higher rates of ethylene production and lower peroxidase activity as germinating seeds and as seedlings. Relevance of these traits to tolerance of flooding during germination and early growth is discussed.
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Claims 16
Claim · model-written summary
Flooding reduced survival, less strongly in tolerant genotypes.
- Taxon
- rice
Oryza sativat0 - Material
- tolerant genotypese0
- Treatment
- Flooding during germinatione0
- Outcome
- survivale0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Flooding during germination reduced survival but to a lesser extent in tolerant genotypes”
t0“rice”
Claim · model-written summary
Flooding decreased seed starch concentration, more in tolerant genotypes.
- Taxon
- riceOryza sativat0
- Material
- tolerant genotypese0
- Organ / stage
- germinating seedse0
- Treatment
- floodinge0
- Outcome
- Starch concentratione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Starch concentration in germinating seeds decreased while sugar concentration increased under flooding, but more so in tolerant genotypes”
t0“rice”
Claim · model-written summary
Flooding increased seed sugar concentration, more in tolerant genotypes.
- Taxon
- riceOryza sativat0
- Material
- tolerant genotypese0
- Treatment
- floodinge0
- Outcome
- sugar concentratione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sugar concentration increased under flooding, but more so in tolerant genotypes”
t0“rice”
Claim · model-written summary
Amylase activity correlated positively with shoot elongation at r = 0.85.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Amylase activity correlated positively with elongation (r = 0.85 for shoot”
t0“rice”
Claim · model-written summary
Amylase activity correlated positively with root elongation at r = 0.83.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“0.83 for root length) and with plant survival”
t0“rice”
t1“Amylase activity correlated positively with elongation”
Claim · model-written summary
Amylase activity correlated positively with plant survival at r = 0.92.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and with plant survival (r = 0.92)”
t0“rice”
t1“Amylase activity correlated positively with elongation”
Claim · model-written summary
Tolerant genotypes had higher amylase activity.
- Taxon
- riceOryza sativat0
- Material
- Tolerant genotypese0
- Outcome
- amylase activitye0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tolerant genotypes had higher amylase activity”
t0“rice”
Claim · model-written summary
Tolerant genotypes had higher RAmy3D expression.
- Taxon
- riceOryza sativat0
- Material
- Tolerant genotypese0
- Gene
- RAmy3De0
- Outcome
- RAmy3D gene expressione0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tolerant genotypes had higher amylase activity and higher RAmy3D gene expression”
t0“rice”
Claim · model-written summary
Ethylene was undetected during the first two days.
- Taxon
- riceOryza sativat0
- Organ / stage
- seedse0
- Outcome
- Ethylene was not detectede0
- Qualifier
- within 2 d after sowinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ethylene was not detected in seeds within 2 d after sowing”
t0“rice”
Claim · model-written summary
Ethylene increased later, more in tolerant genotypes from day three.
- Taxon
- riceOryza sativat0
- Material
- tolerant genotypese0
- Outcome
- Ethylenee1
- Direction
- greater increasee0
- Qualifier
- starting 3 d after sowinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased thereafter, with a greater increase in tolerant genotypes starting 3 d after sowing”
t0“rice”
t1“Amylase activity correlated positively with elongation”
e1“Ethylene was not detected in seeds within 2 d after sowing”
Claim · model-written summary
Sensitive genotypes had higher seed peroxidase activity.
- Taxon
- riceOryza sativat0
- Material
- sensitive genotypese0
- Organ / stage
- germinating seedse0
- Outcome
- Peroxidase activitye0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Peroxidase activity was higher in germinating seeds of sensitive genotypes”
t0“rice”
Claim · model-written summary
Peroxidase activity correlated negatively with survival.
- Taxon
- riceOryza sativat0
- Gene
- Peroxidasee1
- Outcome
- survivale0
- Direction
- negativelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“correlated negatively with survival”
t0“rice”
t1“Amylase activity correlated positively with elongation”
e1“Peroxidase activity was higher in germinating seeds of sensitive genotypes”
Claim · model-written summary
Under low oxygen, tolerant genotypes germinated.
- Taxon
- riceOryza sativat0
- Material
- tolerant genotypese0
- Treatment
- low oxygen stresse0
- Outcome
- germinatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under low oxygen stress, tolerant genotypes germinate”
t0“rice”
Claim · model-written summary
Under low oxygen, tolerant genotypes grew faster.
- Taxon
- riceOryza sativat0
- Material
- tolerant genotypese0
- Outcome
- grow fastere0
- Direction
- fastere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tolerant genotypes germinate, grow faster”
t0“rice”
Claim · model-written summary
Under low oxygen, more tolerant seedlings survived.
- Taxon
- riceOryza sativat0
- Outcome
- seedlings survivee0
- Direction
- moree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“more seedlings survive”
t0“rice”
Claim · model-written summary
Tolerant genotypes maintained starch use through higher amylase and anaerobic respiration.
- Taxon
- riceOryza sativat0
- Gene
- amylasee0
- Outcome
- ability to use stored starch reservese0
- Qualifier
- anaerobic respiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They maintain their ability to use stored starch reserves through higher amylase activity and anaerobic respiration”
t0“rice”
The same questions in other papers
processing · survival · Oryza sativa (rice)Positive and negative results
1 in the opposite direction
- positive
flooding · survival · Oryza sativa (rice)Positive and negative results
4 papers in the same direction as this paper · 7 in the opposite direction
- positive
- positive
- positive
8 papers more in this group
See all 12 papers →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.