Abstract
Low temperature and overcast rain are harmful to directly seeding early rice, it can hinder rice growth and lower rice biomass during the seedling stage, which in turn lowers rice yield. Farmers usually use N to help rice recuperate after stress and minimize losses. However, the effect of N application on the growth recovery for rice seedlings after such low temperature stress and its associated physiological changes remain unclearly. Two temperature settings and four post-stress N application levels were used in a bucket experiment to compare B116 (strong growth recovery after stress) with B144 (weak growth recovery). The results showed that the stress (average daily temperature at 12°C for 4 days) inhibited the growth of rice seedlings. Compared to the zero N group, the N application group’s seedling height, fresh weight and dry weight significantly increased after 12 days. In particular, the increases in all three growth indicators were relatively higher than that of N application at normal temperature, indicating the importance of N application to rice seedlings after low temperature stress. The antioxidant enzyme activity of rice seedlings increased significantly after N application, which reduced the damaging effect of ROS (reactive oxygen species) to rice seedlings. At the same time, the soluble protein content of seedlings showed a slow decrease, while the H 2 O 2 and MDA (malondialdehyde) content decreased significantly. Nitrogen could also promote nitrogen uptake and utilization by increasing the expression of genes related to NH4+ and NO3− uptake and transport, as well as improving the activity of NR (nitrate reductase) and GS (glutamine synthetase) in rice. N could affect GA 3 (gibberellin A3) and ABA (abscisic acid) levels by regulating the anabolism of GA 3 and ABA. The N application group maintained high ABA levels as well as low GA 3 levels from day 0 to day 6, and high GA 3 levels as well as low ABA levels from day 6 to day 12. The two rice varieties showed obvious characteristics of accelerated growth recovery and positive physiological changes by nitrogen application after stress, while B116 generally showed more obvious growth recovery and stronger growth-related physiological reaction than that of B144. The N application of 40 kg hm -2 was more conducive to the rapid recovery of rice growth after stress. The above results indicated that appropriate N application promoted rice seedling growth recovery after low temperature stress mainly by increasing the activities of antioxidant enzymes and nitrogen metabolizing enzymes as well as regulating the levels of GA 3 and ABA. The results of this study will provide a reference for the regulation of N on the recovery of rice seedling growth after low temperature and weak light stress.
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Claims 14
Claim · model-written summary
Low temperature stress (average daily temperature 12°C for 4 days) inhibited growth of rice seedlings.
- Taxon
- rice
Oryza sativae0 - Treatment
- average daily temperature at 12°C for 4 dayse0
- Outcome
- growth of rice seedlingse0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the stress (average daily temperature at 12°C for 4 days) inhibited the growth of rice seedlings”
Claim · model-written summary
N application significantly increased seedling height, fresh weight and dry weight after 12 days compared with the zero N group.
- Taxon
- riceOryza sativat0
- Treatment
- N applicatione0
- Outcome
- seedling height, fresh weight and dry weighte0
- Direction
- increasede0
- Comparator
- zero N groupe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the zero N group, the N application group’s seedling height, fresh weight and dry weight significantly increased after 12 days”
t0“rice seedlings”
Claim · model-written summary
The increases in seedling growth indicators with N application after low temperature stress were relatively higher than with N application at normal temperature.
- Taxon
- riceOryza sativat0
- Treatment
- N applicatione0
- Outcome
- increases in all three growth indicatorse0
- Direction
- highere0
- Comparator
- N application at normal temperaturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increases in all three growth indicators were relatively higher than that of N application at normal temperature”
t0“rice seedlings”
Claim · model-written summary
Antioxidant enzyme activity of rice seedlings increased significantly after N application.
- Taxon
- riceOryza sativae0
- Treatment
- N applicatione0
- Outcome
- antioxidant enzyme activitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The antioxidant enzyme activity of rice seedlings increased significantly after N application”
Claim · model-written summary
Soluble protein content of rice seedlings showed a slow decrease.
- Taxon
- riceOryza sativat0
- Outcome
- soluble protein contente0
- Direction
- slow decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the soluble protein content of seedlings showed a slow decrease”
t0“rice seedlings”
Claim · model-written summary
H2O2 and MDA content of rice seedlings decreased significantly.
- Taxon
- riceOryza sativat0
- Outcome
- H 2 O 2 and MDA (malondialdehyde) contente0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the H 2 O 2 and MDA (malondialdehyde) content decreased significantly”
t0“rice seedlings”
Claim · model-written summary
Nitrogen increased the expression of genes related to NH4+ and NO3− uptake and transport in rice.
- Taxon
- riceOryza sativat0
- Treatment
- Nitrogene0
- Gene
- genes related to NH4+ and NO3− uptake and transporte0
- Outcome
- expressione0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen could also promote nitrogen uptake and utilization by increasing the expression of genes related to NH4+ and NO3− uptake and transport”
t0“rice seedlings”
Claim · model-written summary
Nitrogen improved the activity of nitrate reductase (NR) and glutamine synthetase (GS) in rice.
- Taxon
- riceOryza sativae0
- Treatment
- Nitrogene0
- Gene
- NR (nitrate reductase) and GS (glutamine synthetase)e0
- Outcome
- activitye0
- Direction
- improvinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen could also promote nitrogen uptake and utilization by increasing the expression of genes related to NH4+ and NO3− uptake and transport, as well as improving the activity of NR (nitrate reductase) and GS (glutamine synthetase) in rice”
Claim · model-written summary
N is asserted to affect GA3 and ABA levels by regulating the anabolism of GA3 and ABA.
- Taxon
- riceOryza sativat0
- Treatment
- Ne0
- Outcome
- GA 3 (gibberellin A3) and ABA (abscisic acid) levelse0
- Qualifier
- regulating the anabolism of GA 3 and ABAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N could affect GA 3 (gibberellin A3) and ABA (abscisic acid) levels by regulating the anabolism of GA 3 and ABA”
t0“rice seedlings”
Claim · model-written summary
With N application, rice seedlings had high ABA and low GA3 levels from day 0 to day 6.
- Taxon
- riceOryza sativat0
- Treatment
- N applicatione0
- Outcome
- ABA levels as well as low GA 3 levelse0
- Direction
- high ABA levels as well as low GA 3 levelse0
- Qualifier
- from day 0 to day 6e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N application group maintained high ABA levels as well as low GA 3 levels from day 0 to day 6”
t0“rice seedlings”
Claim · model-written summary
With N application, rice seedlings had high GA3 and low ABA levels from day 6 to day 12.
- Taxon
- riceOryza sativat0
- Treatment
- N applicatione0
- Outcome
- GA 3 levels as well as low ABA levelse0
- Direction
- high GA 3 levels as well as low ABA levelse0
- Qualifier
- from day 6 to day 12e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N application group maintained high ABA levels as well as low GA 3 levels from day 0 to day 6, and high GA 3 levels as well as low ABA levels from day 6 to day 12”
t0“rice seedlings”
Claim · model-written summary
Rice variety B116 showed more obvious growth recovery and stronger growth-related physiological reaction than B144 after N application.
- Taxon
- riceOryza sativat0
- Material
- B116e0
- Outcome
- growth recovery and stronger growth-related physiological reactione0
- Direction
- more obviouse0
- Comparator
- B144e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B116 generally showed more obvious growth recovery and stronger growth-related physiological reaction than that of B144”
t0“rice seedlings”
Claim · model-written summary
N application of 40 kg hm -2 was more conducive to rapid recovery of rice growth after stress.
- Taxon
- riceOryza sativae0
- Treatment
- N application of 40 kg hm -2e0
- Outcome
- rapid recovery of rice growth after stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N application of 40 kg hm -2 was more conducive to the rapid recovery of rice growth after stress”
Claim · model-written summary
Appropriate N application promoted rice seedling growth recovery after low temperature stress mainly by increasing activities of antioxidant and nitrogen metabolizing enzymes and regulating GA3 and ABA levels.
- Taxon
- riceOryza sativae0
- Treatment
- N applicatione0
- Outcome
- rice seedling growth recovery after low temperature stresse0
- Qualifier
- increasing the activities of antioxidant enzymes and nitrogen metabolizing enzymes as well as regulating the levels of GA 3 and ABAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“appropriate N application promoted rice seedling growth recovery after low temperature stress mainly by increasing the activities of antioxidant enzymes and nitrogen metabolizing enzymes as well as regulating the levels of GA 3 and ABA”
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