Abstract
Abstract The plant type in high-yielding cultivars (HYC) bred in recent years has tended to change from a higher number of panicles with smaller stems and panicles (panicle number type) to a lower number of panicles with larger stems and panicles (panicle weight type or superpanicle weight type) with a concomitant increase of the contribution ratio of the spikelet number per panicle to the number of spikelets per square meter. Therefore, field experiments were conducted by using twenty-two rice cultivars with different plant types belonging to both japonica and indica ecospecies to analyze cultivar differences in the number of differentiated spikelets per panicle (NDS) and the percentage of degenerated spikelets (PDGS) which determines the number of spikelets per panicle, in relation to the amount of dry matter produced and nitrogen (N) absorbed until and / or during the panicle formation stage. The NDS, number of degenerated spikelets (NDGS) and surviving spike lets per panicle (NSS) were significantly higher in the indica cultivars than in the japonica ones mainly due to the spike lets on the secondary rachis branches. The NDS ranged from 83.9–149.6 and 133.1–229.9 in the japonica and indica cultivars, respectively. The PDGS ranged from 15.3 to 26.8% in the japonica cultivars and 7.2–38.1% in the indica ones with averages of 21.6 and 27.0%, respectively. Correlation showed that the higher NDS increased the number of both NSS and NDGS per panicle and that the latter one significantly increased the PDGS in both indica and japonica cultivar groups. The NSS was not closely related to the PDGS in both ecospecies. The amount of dry matter per productive stem (per stem) at YPS (young panicle stage: young panicle 1–2 mm long on superior stems) or heading and its increase during the period from YPS to heading were correlated with the NDS, and the amount of absorbed N per stem showed similar correlations with the NDS except at YPS. The amount of dry matter or absorbed N per stem at YPS or heading showed a similar range in both ecospecies, but for the same amount of dry matter, the NDS was remarkably higher in the indica than in the japonica cultivars, i.e., SPE-D or SPE-N (production efficiency of the differentiated spikelets per dry matter or N content) was higher in the indica than in the japonica cultivars. SPE-D or SPE-N showed a high and negative correlation with the amount of dry matter or absorbed N per stem at YPS or heading and their increase during the period from YPS to heading in both indica and japonica cultivar groups. These results imply that the increase in the amount of dry matter or absorbed N per stem at YPS and heading also increased the NDS with decreasing SPE-D or SPE-N. We concluded that the changes in the plant type from panicle number to panicle weight type may be brought about by the increase of NDS and NSS with a concomitant decrease in the spikelets production efficiency per amount of dry matter produced and N absorbed per stem irrespective of ecospecies.
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Claims 17
Claim · model-written summary
Indica cultivars had significantly more differentiated spikelets per panicle than japonica cultivars.
- Taxon
- rice
Oryza sativae0t0 - Material
- indica cultivarse0
- Outcome
- NDSe0
- Direction
- highere0
- Comparator
- japonica onese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NDS, number of degenerated spikelets (NDGS) and surviving spike lets per panicle (NSS) were significantly higher in the indica cultivars than in the japonica ones”
t0“rice”
Claim · model-written summary
Indica cultivars had significantly more degenerated and surviving spikelets per panicle than japonica cultivars.
- Taxon
- riceOryza sativae0t0
- Material
- indica cultivarse0
- Outcome
- number of degenerated spikelets (NDGS) and surviving spike lets per panicle (NSS)e0
- Direction
- highere0
- Comparator
- japonica onese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NDS, number of degenerated spikelets (NDGS) and surviving spike lets per panicle (NSS) were significantly higher in the indica cultivars than in the japonica ones”
t0“rice”
Claim · model-written summary
Differentiated spikelets per panicle ranged from 83.9–149.6 in japonica cultivars.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NDS ranged from 83.9–149.6 and 133.1–229.9 in the japonica and indica cultivars, respectively.”
t0“rice”
Claim · model-written summary
Differentiated spikelets per panicle ranged from 133.1–229.9 in indica cultivars.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NDS ranged from 83.9–149.6 and 133.1–229.9 in the japonica and indica cultivars, respectively.”
t0“rice”
Claim · model-written summary
Degenerated spikelet percentage ranged from 15.3 to 26.8% in japonica cultivars, averaging 21.6%.
- Taxon
- riceOryza sativae0t0
- Material
- japonica cultivarse0
- Outcome
- PDGSe0
- Value
- 15.3 to 26.8%e0
- Qualifier
- 21.6e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The PDGS ranged from 15.3 to 26.8% in the japonica cultivars and 7.2–38.1% in the indica ones with averages of 21.6 and 27.0%, respectively.”
t0“rice”
Claim · model-written summary
Degenerated spikelet percentage ranged from 7.2–38.1% in indica cultivars, averaging 27.0%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The PDGS ranged from 15.3 to 26.8% in the japonica cultivars and 7.2–38.1% in the indica ones with averages of 21.6 and 27.0%, respectively.”
t0“rice”
Claim · model-written summary
Higher differentiated spikelet numbers correlated with more surviving and degenerated spikelets.
- Taxon
- riceOryza sativae0t0
- Organ / stage
- paniclee0
- Outcome
- number of both NSS and NDGS per paniclee0
- Direction
- increasede0
- Qualifier
- higher NDSe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the higher NDS increased the number of both NSS and NDGS per panicle”
t0“rice”
Claim · model-written summary
More degenerated spikelets correlated with a significantly higher degenerated spikelet percentage.
- Taxon
- riceOryza sativae0t0
- Material
- indica and japonica cultivar groupse0
- Outcome
- PDGSe0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the latter one significantly increased the PDGS in both indica and japonica cultivar groups.”
t0“rice”
Claim · model-written summary
Surviving spikelet number was not closely related to degenerated spikelet percentage.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NSS was not closely related to the PDGS in both ecospecies.”
t0“rice”
Claim · model-written summary
Dry matter per productive stem at young panicle stage and heading, and its increase between stages, correlated with differentiated spikelet number.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The amount of dry matter per productive stem (per stem) at YPS (young panicle stage: young panicle 1–2 mm long on superior stems) or heading and its increase during the period from YPS to heading were correlated with the NDS”
t0“rice”
Claim · model-written summary
Absorbed nitrogen per stem was similarly correlated with differentiated spikelet number except at young panicle stage.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the amount of absorbed N per stem showed similar correlations with the NDS except at YPS.”
t0“rice”
Claim · model-written summary
Indica and japonica cultivars had similar dry matter and nitrogen amounts per stem at young panicle stage or heading.
- Taxon
- riceOryza sativae0t0
- Organ / stage
- YPS or headinge0
- Outcome
- amount of dry matter or absorbed N per steme0
- Direction
- similar rangee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The amount of dry matter or absorbed N per stem at YPS or heading showed a similar range in both ecospecies”
t0“rice”
Claim · model-written summary
At the same dry matter amount, indica cultivars produced more differentiated spikelets than japonica cultivars.
- Taxon
- riceOryza sativae0t0
- Material
- indicae0
- Outcome
- NDSe0
- Direction
- highere0
- Comparator
- japonica cultivarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for the same amount of dry matter, the NDS was remarkably higher in the indica than in the japonica cultivars”
t0“rice”
Claim · model-written summary
Indica cultivars had greater differentiated spikelet production efficiency per dry matter or nitrogen than japonica cultivars.
- Taxon
- riceOryza sativae0t0
- Material
- indicae0
- Outcome
- SPE-D or SPE-Ne0
- Direction
- highere0
- Comparator
- japonica cultivarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPE-D or SPE-N (production efficiency of the differentiated spikelets per dry matter or N content) was higher in the indica than in the japonica cultivars.”
t0“rice”
Claim · model-written summary
Spikelet production efficiency was negatively correlated with dry matter or nitrogen per stem and their increase from young panicle stage to heading.
- Taxon
- riceOryza sativae0t0
- Organ / stage
- YPS or headinge0
- Outcome
- SPE-D or SPE-Ne0
- Direction
- negative correlatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPE-D or SPE-N showed a high and negative correlation with the amount of dry matter or absorbed N per stem at YPS or heading and their increase during the period from YPS to heading in both indica and japonica cultivar groups.”
t0“rice”
Claim · model-written summary
The authors inferred that increased dry matter or nitrogen per stem increased differentiated spikelets while decreasing production efficiency.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increase in the amount of dry matter or absorbed N per stem at YPS and heading also increased the NDS with decreasing SPE-D or SPE-N.”
t0“rice”
Claim · model-written summary
The authors attributed the shift toward panicle weight types to more differentiated and surviving spikelets with lower production efficiency per dry matter and nitrogen.
- Taxon
- riceOryza sativae0t0
- Outcome
- changes in the plant type from panicle number to panicle weight typee0
- Qualifier
- increase of NDS and NSSe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the changes in the plant type from panicle number to panicle weight type may be brought about by the increase of NDS and NSS with a concomitant decrease in the spikelets production efficiency per amount of dry matter produced and N absorbed per stem irrespective of ecospecies.”
t0“rice”