Abstract
As temperature rises above 18-22ºC, the observed decrease in the duration of deposition of dry matter in the kernel is not accompanied by a compensating increase in the rate of grain filling with the result that grain weight (and yield) is diminished at high temperature. Reduced starch content accounts for most of the reduction in grain dry matter at high temperature. Responses to temperature in the low temperature range, 20-30ºC (the LTR), could possibly be ascribed to the temperature response characteristics of the reaction catalysed by soluble starch synthase (SSS), the enzyme synthesising starch. However, the rate of cell enlargement and the rate of accumulation of nitrogen in the grain also do not increase much as temperature rises, so other explanations are conceivable for the temperature responses in the LTR. Variation amongst cultivars of wheat in tolerance of high temperature is evident in the LTR. At temperatures above 30ºC (in the high temperature range (HTR) between 30 and 40ºC), even for short periods, the rate of starch deposition is slower than that observed at lower temperatures, an effect which is carried over after transfer from high to lower temperatures. This response is attributable to a reduction in the activity, possibly due to thermal denaturation, of SSS. Several forms of SSS are found in cereal endosperm, and some forms may be more tolerant of high temperature than others. Loss of enzyme activity at high temperature is swift, but is partly restored some time after transfer from hot to cool conditions. There appear to be two distinct mechanisms of response to elevated temperature, both resulting in a reduced grain weight through reduced starch deposition, but one of them is important only in the range of temperature above 30ºC.
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Claims 12
Claim · model-written summary
Above 18-22ºC, duration of dry matter deposition in wheat kernels decreased.
- Taxon
- Wheat
Triticum aestivumt0 - Treatment
- temperature rises above 18-22ºCe0
- Outcome
- duration of deposition of dry matter in the kernele0
- Direction
- decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As temperature rises above 18-22ºC, the observed decrease in the duration of deposition of dry matter in the kernel”
t0“Wheat”
Claim · model-written summary
Grain filling rate did not compensate as temperature rose.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- rate of grain fillinge0
- Direction
- not accompanied by a compensating increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“not accompanied by a compensating increase in the rate of grain filling”
t0“Wheat”
Claim · model-written summary
High temperature diminished grain weight and yield.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- high temperaturee0
- Outcome
- grain weight (and yield)e0
- Direction
- diminishede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain weight (and yield) is diminished at high temperature”
t0“Wheat”
Claim · model-written summary
Reduced starch content accounted for most loss of grain dry matter at high temperature.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- reduction in grain dry mattere0
- Qualifier
- Reduced starch contente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced starch content accounts for most of the reduction in grain dry matter at high temperature.”
t0“Wheat”
Claim · model-written summary
Cell enlargement rate did not increase much as temperature rose.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- temperature risese0
- Outcome
- rate of cell enlargemente0
- Direction
- do not increase muche0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the rate of cell enlargement and the rate of accumulation of nitrogen in the grain also do not increase much as temperature rises”
t0“Wheat”
Claim · model-written summary
Grain nitrogen accumulation rate did not increase much as temperature rose.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- temperature risese0
- Outcome
- rate of accumulation of nitrogen in the graine0
- Direction
- do not increase muche0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the rate of cell enlargement and the rate of accumulation of nitrogen in the grain also do not increase much as temperature rises”
t0“Wheat”
Claim · model-written summary
Wheat cultivars varied in high temperature tolerance in the low temperature range.
- Taxon
- wheatTriticum aestivume0
- Material
- cultivars of wheate0
- Outcome
- tolerance of high temperaturee0
- Direction
- Variatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Variation amongst cultivars of wheat in tolerance of high temperature is evident in the LTR.”
Claim · model-written summary
Above 30ºC, starch deposition was slower than at lower temperatures.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- temperatures above 30ºCe0
- Outcome
- rate of starch depositione0
- Direction
- slowere0
- Comparator
- lower temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At temperatures above 30ºC (in the high temperature range (HTR) between 30 and 40ºC), even for short periods, the rate of starch deposition is slower than that observed at lower temperatures”
t0“Wheat”
Claim · model-written summary
Reduced starch deposition persisted after transfer to lower temperatures.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- rate of starch depositione1
- Direction
- slowere1
- Qualifier
- carried over after transfer from high to lower temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an effect which is carried over after transfer from high to lower temperatures”
e1“the rate of starch deposition is slower than that observed at lower temperatures”
t0“Wheat”
Claim · model-written summary
Heat reduced soluble starch synthase activity, possibly through denaturation.
- Taxon
- WheatTriticum aestivumt0
- Gene
- soluble starch synthase (SSS)e1
- Outcome
- reduction in the activitye0
- Qualifier
- possibly due to thermal denaturatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This response is attributable to a reduction in the activity, possibly due to thermal denaturation, of SSS.”
e1“soluble starch synthase (SSS), the enzyme synthesising starch”
t0“Wheat”
Claim · model-written summary
Some endosperm SSS forms may be more heat tolerant than others.
- Taxon
- WheatTriticum aestivumt0
- Organ / stage
- cereal endosperme0
- Gene
- SSSe0
- Outcome
- more tolerant of high temperaturee0
- Direction
- more tolerante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Several forms of SSS are found in cereal endosperm, and some forms may be more tolerant of high temperature than others.”
t0“Wheat”
Claim · model-written summary
Enzyme activity was lost rapidly at high temperature and partly restored after cooling.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- enzyme activitye0
- Direction
- Losse0
- Qualifier
- partly restored some time after transfer from hot to cool conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Loss of enzyme activity at high temperature is swift, but is partly restored some time after transfer from hot to cool conditions.”
t0“Wheat”
The same questions in other papers
heat · yield · Triticum aestivum (wheat)Positive and negative results
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