Abstract
The objective of this study was to determine how the rice plant responds to combinations of temperature and photoperiod. Both temperature and photoperiod are important for normal completion of the life cycle, but there has been little study of their combined effects in rice. Controlled temperature and photoperiod experiments were conducted in growth cabinets using 4 temperatures; 35/18, 35/26.5, 35/35 and 40.5/18°C day/night. There were 4 photoperiods of 8, 10, 12 and 14 hours. Light was provided by cool white fluorescent tubes. The day temperature periods corresponded to the photoperiods. Four varieties were selected: Kangni-27 and Dokribasmati from Dokri, Pakistan; Caloro from California, U.S.A.; and Bluebonnet-50 from Texas, U.S.A. Growth characteristics, net photosynthesis rates, and flowering were measured and chlorophyll a and b, carotenoid, carbohydrate and ash concentrations were determined. The effect of photoperiod on flowering was most pronounced at 35/26.5. The delays in flowering at 14 hours for this temperature were 30, 30, 21 and 63 days in Kangni, Caloro, Dokri and Bluebonnet compared to the optimum, photoperiod which varied among varieties. The delays observed at 35/18 were 23, 14, 6 and 2 days. At 35/26.5 all varieties showed a significant photoperiodic effect on flowering, but at 35/18, Dokri and Bluebonnet did not show a significant photoperiodic effect. 35/35 was most unsatisfactory for flowering. A similar but less serious effect was found at 40.5/18. Final dry matter production was high at 35/35 and 40.5/18; an increase of 3 to 8 g per pot was noted at these temperatures compared with 35/26.5 and 35/18. There was an increase of about 5 g per pot at maturity for each increase of 2 hours in photoperiod. Panicle characteristics were generally unaffected by temperature, but there were some photoperiod effects. At the 12-hour photoperiod panicles of all varieties were 2 to 4 cm longer than at other photoperiods and at 10-and 12-hour photoperiods there were 10 to 32 more spikelets per panicle than at 8 and 14 hours. Sterility was very high at 35/35 (95%) and 40.5/18 (69%). Average sterility at 35/18 and 35/26.5 was about 36%. There was 8 to 24% less sterility at 10- and 12-hour photoperiod compared with 8 or 14 hours. Hundred-grain weight was unaffected by photoperiod or temperature. High numbers of tillers were consistently observed at 40.5/18 and 35/18 and low numbers at 35/35. The differences varied with the stage of growth. Plants at 14-hour photoperiod had consistently more tillers than those at other photoperiods. Kangni and Dokri had higher numbers of tillers than Caloro and Bluebonnet. Leaf development was fastest at 40.5/18 and the 12-hour photoperiod. This was especially so at 6 and 8 weeks. Kangni and Dokri had faster development than Caloro and Bluebonnet. Plant height was 2 to 5 cm greater at 2 weeks at 35/26.5 and 35/35 but at 4, 6 and 8 weeks, plant height was greater at 35/18. The shortest plants were observed at 40.5/18. The rate of net photosynthesis on a leaf blade weight basis was highest at 2 weeks in all varieties at all photoperiods and temperatures. The rate generally declined with the aging of plants. The greatest decline at 8 weeks, compared to 2 weeks, was 71% in Dokri and least was 65% in Bluebonnet. Except at 2 weeks, the highest rate of photosynthesis was at 40.5/18 but at 6 and 8 weeks there were also high rates at 35/35. The rate was consistently higher in plants growing in the 8-hour photoperiod. The rate was higher in the 8-hour photoperiod compared to the 14-hour by 28 and 25% at 6 and 8 weeks respectively. Both Caloro and Bluebonnet had higher net photosynthetic rates than Kangni and Dokri. In all varieties chlorophyll and carotenoid content declined with age. Both chlorophyll and carotenoid were high at 40.5/18 at all stages. Chlorophyll concentration was also high at 35/18 at 2, 4 and 6 weeks. A definite correlation between chlorophyll content and photosynthesis was not shown, but there was a significant correlation between chlorophyll and fresh weight at all temperatures and photoperiods except at 2 weeks. Total water soluble carbohydrate and total ash content did not show definite trends according to stages of growth. No relationship could be shown between floral initiation and combined carbohydrate and ash content.
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Claims 20
Claim · model-written summary
The photoperiod effect on flowering was most pronounced at 35/26.5 and was significant in all varieties at that temperature.
- Taxon
- rice
Oryza sativae0 - Treatment
- photoperiode1
- Outcome
- effect of photoperiod on floweringe1
- Direction
- most pronouncede1
- Qualifier
- all varietiese2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“The effect of photoperiod on flowering was most pronounced at 35/26.5”
e2“At 35/26.5 all varieties showed a significant photoperiodic effect on flowering”
Claim · model-written summary
At 35/26.5, 14-hour photoperiod delayed flowering by 30, 30, 21 and 63 days in Kangni, Caloro, Dokri and Bluebonnet compared with the optimum photoperiod.
- Taxon
- riceOryza sativae0
- Material
- Kangni, Caloro, Dokri and Bluebonnete1
- Treatment
- 14 hourse1
- Outcome
- delays in floweringe1
- Direction
- delayse1
- Value
- 30, 30, 21 and 63 dayse1
- Qualifier
- 35/26.5e2
- Comparator
- optimume1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“The delays in flowering at 14 hours for this temperature were 30, 30, 21 and 63 days in Kangni, Caloro, Dokri and Bluebonnet compared to the optimum, photoperiod which varied among varieties”
e2“The effect of photoperiod on flowering was most pronounced at 35/26.5”
Claim · model-written summary
At 35/18, flowering was delayed by 23, 14, 6 and 2 days.
- Taxon
- riceOryza sativae0
- Treatment
- 35/18e1
- Outcome
- delays observede1
- Direction
- delayse1
- Value
- 23, 14, 6 and 2 dayse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“The delays observed at 35/18 were 23, 14, 6 and 2 days”
Claim · model-written summary
At 35/18, Dokri and Bluebonnet showed no significant photoperiodic effect on flowering.
- Taxon
- riceOryza sativae0
- Material
- Dokri and Bluebonnete1
- Treatment
- 35/18e1
- Outcome
- photoperiodic effecte1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“but at 35/18, Dokri and Bluebonnet did not show a significant photoperiodic effect”
Claim · model-written summary
At 35/35, flowering was most unsatisfactory; a similar but less serious effect was found at 40.5/18.
- Taxon
- riceOryza sativae0
- Treatment
- 35/35e1
- Outcome
- floweringe1
- Direction
- most unsatisfactorye1
- Qualifier
- A similar but less serious effect was found at 40.5/18e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“35/35 was most unsatisfactory for flowering”
e2“A similar but less serious effect was found at 40.5/18”
Claim · model-written summary
Final dry matter production was higher at 35/35 and 40.5/18 by 3 to 8 g per pot than at 35/26.5 and 35/18.
- Taxon
- riceOryza sativae0
- Treatment
- 35/35 and 40.5/18e1
- Outcome
- Final dry matter productione1
- Direction
- increasee1
- Value
- 3 to 8 g per pote1
- Comparator
- 35/26.5 and 35/18e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Final dry matter production was high at 35/35 and 40.5/18; an increase of 3 to 8 g per pot was noted at these temperatures compared with 35/26.5 and 35/18”
Claim · model-written summary
Each 2-hour increase in photoperiod increased dry matter at maturity by about 5 g per pot.
- Taxon
- riceOryza sativae0
- Treatment
- increase of 2 hours in photoperiode1
- Outcome
- dry mattere2
- Direction
- increasee1
- Value
- about 5 g per pote1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“There was an increase of about 5 g per pot at maturity for each increase of 2 hours in photoperiod”
e2“Final dry matter production was high at 35/35 and 40.5/18; an increase of 3 to 8 g per pot was noted at these temperatures compared with 35/26.5 and 35/18”
Claim · model-written summary
The 12-hour photoperiod gave panicles 2 to 4 cm longer than other photoperiods and 10 to 32 more spikelets per panicle at 10 and 12 hours than at 8 and 14 hours.
- Taxon
- riceOryza sativae0
- Treatment
- 12-hour photoperiode1
- Outcome
- paniclese1
- Direction
- longere1
- Value
- 2 to 4 cme1
- Qualifier
- 10 to 32 more spikelets per paniclee2
- Comparator
- other photoperiodse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“At the 12-hour photoperiod panicles of all varieties were 2 to 4 cm longer than at other photoperiods”
e2“at 10-and 12-hour photoperiods there were 10 to 32 more spikelets per panicle than at 8 and 14 hours”
Claim · model-written summary
Sterility was very high at 35/35 (95%) and 40.5/18 (69%), and averaged about 36% at 35/18 and 35/26.5.
- Taxon
- riceOryza sativae0
- Treatment
- 35/35e1
- Outcome
- Sterilitye1
- Direction
- very highe1
- Value
- 95%e1
- Qualifier
- about 36%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Sterility was very high at 35/35 (95%) and 40.5/18 (69%)”
e2“Average sterility at 35/18 and 35/26.5 was about 36%”
Claim · model-written summary
Between 10 and 12 hours of photoperiod, sterility was 8 to 24% lower than at 8 or 14 hours.
- Taxon
- riceOryza sativae0
- Treatment
- 10- and 12-hour photoperiode1
- Outcome
- sterilitye1
- Direction
- lesse1
- Value
- 8 to 24%e1
- Comparator
- 8 or 14 hourse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“There was 8 to 24% less sterility at 10- and 12-hour photoperiod compared with 8 or 14 hours”
Claim · model-written summary
Hundred-grain weight was unaffected by photoperiod or temperature.
- Taxon
- riceOryza sativae0
- Treatment
- photoperiod or temperaturee1
- Outcome
- Hundred-grain weighte1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Hundred-grain weight was unaffected by photoperiod or temperature”
Claim · model-written summary
Tiller numbers were high at 40.5/18 and 35/18 and low at 35/35; plants at 14-hour photoperiod had more tillers.
- Taxon
- riceOryza sativae0
- Treatment
- 40.5/18 and 35/18e1
- Outcome
- numbers of tillerse1
- Direction
- Highe1
- Qualifier
- Plants at 14-hour photoperiod had consistently more tillerse2
- Comparator
- 35/35e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“High numbers of tillers were consistently observed at 40.5/18 and 35/18 and low numbers at 35/35”
e2“Plants at 14-hour photoperiod had consistently more tillers than those at other photoperiods”
Claim · model-written summary
Leaf development was fastest at 40.5/18 and the 12-hour photoperiod; Kangni and Dokri developed faster than Caloro and Bluebonnet.
- Taxon
- riceOryza sativae0
- Treatment
- 40.5/18 and the 12-hour photoperiode1
- Outcome
- Leaf developmente1
- Direction
- fasteste1
- Qualifier
- Kangni and Dokri had faster development than Caloro and Bluebonnete2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Leaf development was fastest at 40.5/18 and the 12-hour photoperiod”
e2“Kangni and Dokri had faster development than Caloro and Bluebonnet”
Claim · model-written summary
Plant height was 2 to 5 cm greater at 2 weeks at 35/26.5 and 35/35, and greater at 35/18 at 4, 6 and 8 weeks; plants were shortest at 40.5/18.
- Taxon
- riceOryza sativae0
- Treatment
- 35/26.5 and 35/35e1
- Outcome
- Plant heighte1
- Direction
- greatere1
- Value
- 2 to 5 cme1
- Qualifier
- The shortest plants were observed at 40.5/18e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Plant height was 2 to 5 cm greater at 2 weeks at 35/26.5 and 35/35 but at 4, 6 and 8 weeks, plant height was greater at 35/18”
e2“The shortest plants were observed at 40.5/18”
Claim · model-written summary
Net photosynthesis per leaf blade weight was highest at 2 weeks and declined with plant age, by 71% in Dokri over 2 to 8 weeks.
- Taxon
- riceOryza sativae0
- Organ / stage
- leaf bladee1
- Outcome
- rate of net photosynthesise1
- Direction
- declinede2
- Value
- 71%e3
- Qualifier
- least was 65% in Bluebonnete3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“The rate of net photosynthesis on a leaf blade weight basis was highest at 2 weeks in all varieties at all photoperiods and temperatures”
e2“The rate generally declined with the aging of plants”
e3“The greatest decline at 8 weeks, compared to 2 weeks, was 71% in Dokri and least was 65% in Bluebonnet”
Claim · model-written summary
Net photosynthesis was highest at 40.5/18 except at 2 weeks, and higher in Caloro and Bluebonnet than in Kangni and Dokri.
- Taxon
- riceOryza sativae0
- Treatment
- 40.5/18e1
- Outcome
- rate of photosynthesise1
- Direction
- higheste1
- Qualifier
- Both Caloro and Bluebonnet had higher net photosynthetic rates than Kangni and Dokrie2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Except at 2 weeks, the highest rate of photosynthesis was at 40.5/18 but at 6 and 8 weeks there were also high rates at 35/35”
e2“Both Caloro and Bluebonnet had higher net photosynthetic rates than Kangni and Dokri”
Claim · model-written summary
Chlorophyll and carotenoid content declined with age in all varieties and were high at 40.5/18.
- Taxon
- riceOryza sativae0
- Outcome
- chlorophyll and carotenoid contente1
- Direction
- declinede1
- Qualifier
- high at 40.5/18e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“In all varieties chlorophyll and carotenoid content declined with age”
e2“Both chlorophyll and carotenoid were high at 40.5/18 at all stages”
Claim · model-written summary
A definite correlation between chlorophyll content and photosynthesis was not shown, but chlorophyll correlated significantly with fresh weight at all temperatures and photoperiods except at 2 weeks.
- Taxon
- riceOryza sativae0
- Treatment
- all temperatures and photoperiodse1
- Outcome
- correlation between chlorophyll and fresh weighte1
- Qualifier
- A definite correlation between chlorophyll content and photosynthesis was not showne1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“A definite correlation between chlorophyll content and photosynthesis was not shown, but there was a significant correlation between chlorophyll and fresh weight at all temperatures and photoperiods except at 2 weeks”
Claim · model-written summary
Total water soluble carbohydrate and total ash content showed no definite trends with growth stage, and no relationship with floral initiation.
- Taxon
- riceOryza sativae0
- Outcome
- Total water soluble carbohydrate and total ash contente1
- Qualifier
- No relationship could be shown between floral initiation and combined carbohydrate and ash contente2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“Total water soluble carbohydrate and total ash content did not show definite trends according to stages of growth”
e2“No relationship could be shown between floral initiation and combined carbohydrate and ash content”
Claim · model-written summary
The rate of photosynthesis was consistently higher in the 8-hour photoperiod, by 28 and 25% over the 14-hour photoperiod at 6 and 8 weeks.
- Taxon
- riceOryza sativae0
- Treatment
- 8-hour photoperiode2
- Outcome
- ratee1
- Direction
- highere1
- Value
- 28 and 25%e2
- Comparator
- 14-houre2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“how the rice plant responds to combinations of temperature and photoperiod”
e1“The rate was consistently higher in plants growing in the 8-hour photoperiod”
e2“The rate was higher in the 8-hour photoperiod compared to the 14-hour by 28 and 25% at 6 and 8 weeks respectively”
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