Abstract
Near-isogenic lines of wheat were used to investigate the possible yield penalty of dwarfing genes in rainfed environments. Field experiments were conducted over seven years in south-eastern Australia which were characterized by drought becoming progressively more intense as crop maturity approached. Isogenic sets for the Rht1 and Rht2 genes were chosen to cover a range of heights for the tall (rhtrht) lines, from 100 to 130 cm when grown in the absence of drought before anthesis. Rht1 or Rht2 reduced this height by about 23% whereas Rht1 and Rht2 together or Rht3 alone reduced this ceiling height by about 47%. Highest grain yields were achieved by lines with a height between 70 and 100 cm. Although major were usually required to achieve this optimum height, no specific advantage of the major dwarfing genes was found. Likewise, in tall and short isogenic populations, the short populations yielded more than the tall populations even though they all contained Rht1. The expression of the major dwarfing genes and their effect on agronomic characteristics varied depending on the genetic background but general trends were evident. Above-ground dry weight was reduced by 4.4% of the mean weight for each 10 cm reduction in height below 100 cm. Above 100 cm there was little change in above-ground dry weight. Harvest index decreased by 3.7% of the mean value for each 10 cm increase in height above 65 cm. When height was less than 65 cm, harvest index remained constant. Kernel number was more sensitive to variation in height than was kernel weight. In only one of the isogenic sets was there evidence for compensation between kernel number and kernel weight; in four sets, both kernel number and kernel weight matched variation in yield in a positive way.
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Claims 12
Claim · model-written summary
Rht1 or Rht2 reduced height about 23%.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- Rht1 or Rht2e0
- Outcome
- heighte0
- Direction
- reducede0
- Value
- about 23%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rht1 or Rht2 reduced this height by about 23%”
t0“spring wheat”
Claim · model-written summary
Rht1 and Rht2 together or Rht3 alone reduced height about 47%.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- Rht1 and Rht2 together or Rht3 alonee0
- Outcome
- ceiling heighte0
- Direction
- reducede0
- Value
- about 47%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rht1 and Rht2 together or Rht3 alone reduced this ceiling height by about 47%”
t0“spring wheat”
Claim · model-written summary
Highest grain yields occurred at 70 to 100 cm height.
- Taxon
- wheatTriticum aestivumt0
- Material
- linese0
- Outcome
- grain yieldse0
- Direction
- Higheste0
- Qualifier
- between 70 and 100 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Highest grain yields were achieved by lines with a height between 70 and 100 cm”
t0“spring wheat”
Claim · model-written summary
Major dwarfing genes had no specific advantage.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- advantage of the major dwarfing genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no specific advantage of the major dwarfing genes was found”
t0“spring wheat”
Claim · model-written summary
Short isogenic populations yielded more than tall ones.
- Taxon
- wheatTriticum aestivumt0
- Material
- short populationse0
- Outcome
- yieldede0
- Direction
- moree0
- Comparator
- tall populationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the short populations yielded more than the tall populations even though they all contained Rht1”
t0“spring wheat”
Claim · model-written summary
Aboveground dry weight fell 4.4% for each 10 cm decrease below 100 cm.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- heighte0
- Outcome
- Above-ground dry weighte0
- Direction
- reducede0
- Value
- 4.4%e0
- Qualifier
- for each 10 cm reduction in height below 100 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Above-ground dry weight was reduced by 4.4% of the mean weight for each 10 cm reduction in height below 100 cm”
t0“spring wheat”
Claim · model-written summary
Above 100 cm, aboveground dry weight changed little.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- above-ground dry weighte0
- Direction
- little changee0
- Qualifier
- Above 100 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Above 100 cm there was little change in above-ground dry weight”
t0“spring wheat”
Claim · model-written summary
Harvest index fell 3.7% for each 10 cm height increase above 65 cm.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- heighte0
- Outcome
- Harvest indexe0
- Direction
- decreasede0
- Value
- 3.7%e0
- Qualifier
- for each 10 cm increase in height above 65 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Harvest index decreased by 3.7% of the mean value for each 10 cm increase in height above 65 cm”
t0“spring wheat”
Claim · model-written summary
Harvest index remained constant below 65 cm.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- heighte0
- Outcome
- harvest indexe0
- Direction
- remained constante0
- Qualifier
- less than 65 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When height was less than 65 cm, harvest index remained constant”
t0“spring wheat”
Claim · model-written summary
Kernel number was more sensitive to height than kernel weight.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- heighte0
- Outcome
- Kernel numbere0
- Direction
- more sensitivee0
- Comparator
- kernel weighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kernel number was more sensitive to variation in height than was kernel weight”
t0“spring wheat”
Claim · model-written summary
One isogenic set showed compensation between kernel number and weight.
- Taxon
- wheatTriticum aestivumt0
- Material
- isogenic setse0
- Outcome
- compensation between kernel number and kernel weighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In only one of the isogenic sets was there evidence for compensation between kernel number and kernel weight”
t0“spring wheat”
Claim · model-written summary
In four sets, both kernel number and weight varied positively with yield.
- Taxon
- wheatTriticum aestivumt0
- Material
- setse0
- Outcome
- kernel number and kernel weighte0
- Direction
- positivee0
- Qualifier
- variation in yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in four sets, both kernel number and kernel weight matched variation in yield in a positive way”
t0“spring wheat”