Abstract
Growth analyses of transplanted and row‐seeded ‘IR64’ rice ( Oryza sativa L.) grown in the Philippines at six levels of applied N indicated that growth and CO 2 assimilation rates were low during reproductive growth in row‐seeded as compared with transplanted rice. This study sought to quantify the effect on growth of various canopy properties, and to develop a concept for improving yield of direct‐seeded tropical rice. Mathematical relationships among growth parameters were established based on empirical patterns of leaf area index (LAI), foliage N concentration, canopy CO 2 exchange rate (CER), and dry matter accumulation. Patterns of tissue death were used to estimate senescence. Relative foliage expansion rates were calculated from LAI patterns. Across all treatments and most developmental stages, uniform response patterns of foliage expansion, tissue death, and CER to LAI and foliage N concentration were observed. With increasing LAI, the minimum foliage N concentration for foliage expansion and tissue maintenance increased. Cessation of foliage expansion and onset of tissue death depended similarly on foliar N status and LAI. Canopy CO 2 exchange rate was positively correlated to LAI up to a certian LAI optimum, which depended on foliage N concentration (LAI 3‐6 at 10‐40 g N kg −1 ). Further increases in LAI reduced CER. Leaf area limited biomass accumulation during the vegetative growth phase, whereas foliage N concentration became limiting thereafter, in all treatments. Overexpansion of foliage was particularly marked in row‐seeded rice, due to the absence of transplanting shock and the high plant density, leading to an unfavorable respiration/photosynthesis ratio. Simulation suggested higher yield for direct‐seeded lowland rice in a modified plant type with lower LAI and higher foliar N concentration during the reproductive growth phase, lower tillering ability, and higher assimilate storage capacity in the stems.
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Claims 10
Claim · model-written summary
Row-seeded rice had lower growth and carbon assimilation during reproduction than transplanted rice.
- Taxon
- rice
Oryza sativat0 - Organ / stage
- reproductive growthe0
- Outcome
- growth and CO 2 assimilation ratese0
- Direction
- lowe0
- Comparator
- transplanted ricee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“growth and CO 2 assimilation rates were low during reproductive growth in row‐seeded as compared with transplanted rice.”
t0“Rice”
Claim · model-written summary
Foliage expansion, tissue death and canopy exchange followed uniform response patterns to LAI and foliage nitrogen across treatments.
- Taxon
- riceOryza sativat0
- Outcome
- response patterns of foliage expansion, tissue death, and CERe0
- Direction
- uniforme0
- Qualifier
- LAI and foliage N concentratione0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Across all treatments and most developmental stages, uniform response patterns of foliage expansion, tissue death, and CER to LAI and foliage N concentration were observed.”
t0“Rice”
Claim · model-written summary
Minimum foliage nitrogen needed for expansion and maintenance increased with LAI.
- Taxon
- riceOryza sativat0
- Outcome
- minimum foliage N concentratione0
- Direction
- increasede0
- Qualifier
- increasing LAIe0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With increasing LAI, the minimum foliage N concentration for foliage expansion and tissue maintenance increased.”
t0“Rice”
Claim · model-written summary
Foliage expansion cessation and tissue death onset depended on foliar nitrogen and LAI.
- Taxon
- riceOryza sativat0
- Outcome
- Cessation of foliage expansion and onset of tissue deathe0
- Direction
- dependede0
- Qualifier
- foliar N status and LAIe0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cessation of foliage expansion and onset of tissue death depended similarly on foliar N status and LAI.”
t0“Rice”
Claim · model-written summary
Canopy exchange increased with LAI up to an optimum governed by foliage nitrogen.
- Taxon
- riceOryza sativat0
- Outcome
- Canopy CO 2 exchange ratee0
- Direction
- positively correlatede0
- Value
- LAI 3‐6 at 10‐40 g N kg −1e0
- Qualifier
- foliage N concentratione0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy CO 2 exchange rate was positively correlated to LAI up to a certian LAI optimum, which depended on foliage N concentration (LAI 3‐6 at 10‐40 g N kg −1 ).”
t0“Rice”
Claim · model-written summary
Further LAI increases reduced canopy carbon exchange.
- Taxon
- riceOryza sativat0
- Outcome
- CERe0
- Direction
- reducede0
- Qualifier
- increases in LAIe0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Further increases in LAI reduced CER.”
t0“Rice”
Claim · model-written summary
Leaf area limited biomass accumulation in vegetative growth.
- Taxon
- riceOryza sativat0
- Outcome
- biomass accumulatione0
- Qualifier
- vegetative growth phasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area limited biomass accumulation during the vegetative growth phase, whereas foliage N concentration became limiting thereafter, in all treatments.”
t0“Rice”
Claim · model-written summary
Foliage nitrogen concentration limited biomass accumulation after vegetative growth.
- Taxon
- riceOryza sativat0
- Outcome
- biomass accumulatione0
- Qualifier
- foliage N concentration became limiting thereaftere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area limited biomass accumulation during the vegetative growth phase, whereas foliage N concentration became limiting thereafter, in all treatments.”
t0“Rice”
Claim · model-written summary
Row-seeded rice showed marked foliage overexpansion linked to no transplant shock and high density.
- Taxon
- riceOryza sativat0
- Outcome
- Overexpansion of foliagee0
- Qualifier
- absence of transplanting shock and the high plant densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overexpansion of foliage was particularly marked in row‐seeded rice, due to the absence of transplanting shock and the high plant density, leading to an unfavorable respiration/photosynthesis ratio.”
t0“Rice”
Claim · model-written summary
Simulation suggested higher direct-seeded rice yield with lower LAI, higher foliar nitrogen, less tillering and greater stem storage.
- Taxon
- riceOryza sativat0
- Outcome
- higher yielde0
- Qualifier
- lower LAI and higher foliar N concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simulation suggested higher yield for direct‐seeded lowland rice in a modified plant type with lower LAI and higher foliar N concentration during the reproductive growth phase, lower tillering ability, and higher assimilate storage capacity in the stems.”
t0“Rice”