Abstract
Light deficiency is a growing abiotic stress in rice production, however, few studies focus on shading effects on grain yield and quality of rice in east China. It is also interesting to investigate proper nitrogen (N) application strategy for alleviating grain yield and quality loss of rice exposed to light deficiency stress. A two-year field experiment was conducted to explore the effects of shading (non-shading and shading from heading to maturity) and panicle N application (NDP, decreased panicle N rate; NMP, medium panicle N rate; NIP, increased panicle N rate) treatments on rice yield- and quality-related characteristics. Compared with non-shading, shading resulted in a 9.5-14.8% yield loss (P<0.05), mainly due to lower filled-grain percentage and grain weight. NMP and NIP had higher (P<0.05) grain yield than NDP under non-shading, and no significant difference was observed in rice grain yield among NDP, NMP, and NIP under shading. Compared with NMP and NIP, NDP achieved a less yield loss under shading because of the increased filled-grain percentage and grain weight. Shading reduced leaf photosynthetic rate after heading, as well as shoot biomass weight at maturity, shoot biomass accumulation from heading to maturity, and nonstructural carbohydrate (NSC) content in the stem at maturity (P<0.05). The harvest index and NSC remobilization reserve of NDP were increased under shading. Shading decreased (P<0.05) percentages of brown rice, milled rice, and head rice, and amylose content, while increased (P<0.05) chalky rice percentage, chalky area, chalky degree, and grain protein. NMP demonstrated a better milling quality under non-shading, while NDP demonstrated under shading. NDP exhibited both lower chalky rice percentage, chalky area, and chalky degree under non-shading and shading, compared with NMP and NIP. NDP under shading decreased amylose content and breakdown, while increased grain protein content and setback, contributing to a similar overall palatability to non-shading. Our results suggested severe grain yield and quality penalty of rice when subjected to shading after heading. NDP improved NSC remobilization, harvest index, and sink-filling efficiency, and alleviated yield loss under shading. Besides, NDP would maintain milling, appearance, and cooking and eating qualities of rice under shading. The proper N management with a decreased panicle N rate could be adopted to mitigate the negative effects of shading on rice grain yield and grain quality.
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Claims 20
Claim · model-written summary
Shading reduced rice yield by 9.5-14.8% compared with non-shading.
Not reportedTaxon
Verbatim
e0“Compared with non-shading, shading resulted in a 9.5-14.8% yield loss (P<0.05)”
Claim · model-written summary
Shade related yield loss was mainly due to lower filled-grain percentage and grain weight.
- Outcome
- filled-grain percentage and grain weighte0
- Direction
- lowere0
- Qualifier
- mainly due to lower filled-grain percentage and grain weighte0
Not reportedTaxon
Verbatim
e0“mainly due to lower filled-grain percentage and grain weight.”
Claim · model-written summary
Under non-shading, NMP and NIP had higher grain yield than NDP.
- Treatment
- NMP and NIPe0
- Outcome
- grain yielde0
- Direction
- highere0
- Qualifier
- under non-shadinge0
- Comparator
- NDPe0
Not reportedTaxon
Verbatim
e0“NMP and NIP had higher (P<0.05) grain yield than NDP under non-shading”
Claim · model-written summary
Under shading, NDP, NMP and NIP did not differ significantly in grain yield.
- Taxon
- rice
Oryza sativae0 - Treatment
- NDP, NMP, and NIPe0
- Outcome
- grain yielde0
- Direction
- no significant differencee0
- Qualifier
- under shadinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no significant difference was observed in rice grain yield among NDP, NMP, and NIP under shading.”
Claim · model-written summary
NDP had less shade-related yield loss than NMP and NIP.
Not reportedTaxon
Verbatim
e0“Compared with NMP and NIP, NDP achieved a less yield loss under shading”
Claim · model-written summary
NDP increased filled-grain percentage and grain weight under shading.
Not reportedTaxonTreatmentComparator
Verbatim
e0“because of the increased filled-grain percentage and grain weight.”
Claim · model-written summary
Shading reduced leaf photosynthetic rate after heading.
Not reportedTaxonComparator
Verbatim
e0“Shading reduced leaf photosynthetic rate after heading”
Claim · model-written summary
Shading reduced shoot biomass weight and accumulation.
- Treatment
- Shadinge0
- Outcome
- shoot biomass weight at maturity, shoot biomass accumulation from heading to maturitye0
- Direction
- reducede0
Not reportedTaxonComparator
Verbatim
e0“Shading reduced leaf photosynthetic rate after heading, as well as shoot biomass weight at maturity, shoot biomass accumulation from heading to maturity”
Claim · model-written summary
Shading reduced stem NSC content at maturity.
- Organ / stage
- stem at maturitye0
- Treatment
- Shadinge0
- Outcome
- nonstructural carbohydrate (NSC) contente0
- Direction
- reducede0
Not reportedTaxonComparator
Verbatim
e0“Shading reduced leaf photosynthetic rate after heading, as well as shoot biomass weight at maturity, shoot biomass accumulation from heading to maturity, and nonstructural carbohydrate (NSC) content in the stem at maturity (P<0.05).”
Claim · model-written summary
NDP increased harvest index and NSC remobilization reserve under shading.
- Treatment
- NDPe0
- Outcome
- harvest index and NSC remobilization reservee0
- Direction
- increasede0
- Qualifier
- under shadinge0
Not reportedTaxonComparator
Verbatim
e0“The harvest index and NSC remobilization reserve of NDP were increased under shading.”
Claim · model-written summary
Shading reduced brown, milled and head rice percentages.
- Treatment
- Shadinge0
- Outcome
- percentages of brown rice, milled rice, and head ricee0
- Direction
- decreasede0
Not reportedTaxonComparator
Verbatim
e0“Shading decreased (P<0.05) percentages of brown rice, milled rice, and head rice”
Claim · model-written summary
Shading reduced amylose content.
Not reportedTaxonComparator
Verbatim
e0“Shading decreased (P<0.05) percentages of brown rice, milled rice, and head rice, and amylose content”
Claim · model-written summary
Shading increased chalky rice percentage, area and degree.
Not reportedTaxonTreatmentComparator
Verbatim
e0“increased (P<0.05) chalky rice percentage, chalky area, chalky degree, and grain protein.”
Claim · model-written summary
Shading increased grain protein.
Not reportedTaxonTreatmentComparator
Verbatim
e0“increased (P<0.05) chalky rice percentage, chalky area, chalky degree, and grain protein.”
Claim · model-written summary
NMP gave better milling quality under non-shading.
Not reportedTaxon
Verbatim
e0“NMP demonstrated a better milling quality under non-shading”
Claim · model-written summary
NDP gave better milling quality under shading.
Not reportedTaxonOutcomeDirection
Verbatim
e0“NDP demonstrated under shading.”
Claim · model-written summary
NDP lowered chalky rice percentage, area and degree compared with NMP and NIP under either light condition.
- Treatment
- NDPe0
- Outcome
- chalky rice percentage, chalky area, and chalky degreee0
- Direction
- lowere0
- Qualifier
- under non-shading and shadinge0
- Comparator
- NMP and NIPe0
Not reportedTaxon
Verbatim
e0“NDP exhibited both lower chalky rice percentage, chalky area, and chalky degree under non-shading and shading, compared with NMP and NIP.”
Claim · model-written summary
Under shading, NDP lowered amylose content and breakdown.
Not reportedTaxonComparator
Verbatim
e0“NDP under shading decreased amylose content and breakdown”
Claim · model-written summary
Under shading, NDP increased grain protein content and setback.
Not reportedTaxonTreatmentComparator
Verbatim
e0“increased grain protein content and setback, contributing to a similar overall palatability to non-shading.”
Claim · model-written summary
Reduced panicle N is recommended to mitigate shade-related yield and quality losses in rice.
- Taxon
- riceOryza sativae0
- Treatment
- decreased panicle N ratee0
- Outcome
- decreased panicle N ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The proper N management with a decreased panicle N rate could be adopted to mitigate the negative effects of shading on rice grain yield and grain quality.”
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