Abstract
Further increasing wheat productivity is more challenging due to consistently rising temperatures. Heat stress negatively affects both grain number per m2 (GN) and average grain weight (AGW). It is not clear whether the sensitivity of these components differ, nor whether it would be related to the relevance of the component for determining unstressed yield in the particular cultivar. The aim of this study was to elucidate the plasticity of GN and AGW in response to heat waves at pre-anthesis; and post-anthesis under different source-sink ratios. The field experiments were carried out in two different locations of Catalonia (NE Spain). We selected two contrasting genotypes (Pistolo and Sublim) for the relevance of GN and AGW and analysed in detail (i) the causes for their differences in AGW and (ii) their GN and AGW responses to heat wave stress (HT). The HT treatments were imposed in the field using portable tents with transparent polyethylene films at either at booting (pre-AN HT) or 15 days after anthesis (post-AN HT) for 7 days, with a delta in maximum temperature of c. 5ºC. In addition, we increased source-sink ratios in the control and post-AN HT treatments by removing all spikelets on one side of the spike (de-graining) 14 days after anthesis. Pistolo had always less but heavier grains than Sublim. The differences in AGW were constitutive, rather reflecting a trade-off with GN, as there was no scarcity of resources to satisfy the demands of the growing grains in any of the two cultivars. Exposing the crops to heat stress at pre- and post-anthesis resulted in yield penalties, but yield was more sensitive to pre-AN HT than to post-AN HT, consistently across both locations and genotypes. The reduction of GN per spike was mainly mediated through grain abortion rather than through mortality of floret primordia. The reduction of AGW caused by post-AN HT was not related to source strength changes, but due to a direct effect reducing potential grain weight (PGW) per se. There seemed to be a trend for the cultivar constitutively producing more grains having less sensitivity of GN to pre-AN HT, and for the cultivar constitutively having heavier grains having less sensitivity of AGW to post-AN HT. The reduction of AGW caused by post-AN HT was not related to source strength changes, but due to a direct effect reducing potential grain weight. The plasticity of a yield component in response to heat stress was inversely related to the relevance of that component for yield determination in unheated conditions. Our result would open an opportunity for breeders to select for improved sink-strength through either higher GN or higher PGW depending on the timing and frequency of the most damaging heat waves.
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Claims 12
Claim · model-written summary
Pistolo produced fewer grains than Sublim.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Pistolo had always less but heavier grains than Sublim.”
Claim · model-written summary
Pistolo produced heavier grains than Sublim.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Pistolo had always less but heavier grains than Sublim.”
Claim · model-written summary
Average grain weight differences were constitutive and reflected a tradeoff with grain number.
- Taxon
- wheat
Triticum aestivumt0 - Outcome
- differences in AGWe0
- Qualifier
- no scarcity of resourcese0
- Comparator
- GNe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“The differences in AGW were constitutive, rather reflecting a trade-off with GN, as there was no scarcity of resources to satisfy the demands of the growing grains in any of the two cultivars.”
Claim · model-written summary
Pre-anthesis heat lowered wheat yield.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- pre-AN HTe0
- Outcome
- yielde0
- Direction
- penaltiese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Exposing the crops to heat stress at pre- and post-anthesis resulted in yield penalties, but yield was more sensitive to pre-AN HT than to post-AN HT, consistently across both locations and genotypes.”
Claim · model-written summary
Post-anthesis heat lowered wheat yield.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- post-AN HTe0
- Outcome
- yielde0
- Direction
- penaltiese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Exposing the crops to heat stress at pre- and post-anthesis resulted in yield penalties, but yield was more sensitive to pre-AN HT than to post-AN HT, consistently across both locations and genotypes.”
Claim · model-written summary
Yield was more sensitive to pre-anthesis than post-anthesis heat across locations and genotypes.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- pre-AN HTe0
- Outcome
- yielde0
- Direction
- more sensitivee0
- Qualifier
- consistently across both locations and genotypese0
- Comparator
- post-AN HTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“yield was more sensitive to pre-AN HT than to post-AN HT, consistently across both locations and genotypes.”
Claim · model-written summary
Grain number reduction per spike arose mainly through grain abortion.
- Taxon
- wheatTriticum aestivumt0
- Organ / stage
- graine0
- Outcome
- reduction of GN per spikee0
- Qualifier
- grain abortion rather than through mortality of floret primordiae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“The reduction of GN per spike was mainly mediated through grain abortion rather than through mortality of floret primordia.”
Claim · model-written summary
Post-anthesis heat reduced average grain weight by directly lowering potential grain weight.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- post-AN HTe0
- Outcome
- reduction of AGWe0
- Qualifier
- direct effect reducing potential grain weight (PGW) per see0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“The reduction of AGW caused by post-AN HT was not related to source strength changes, but due to a direct effect reducing potential grain weight (PGW) per se.”
Claim · model-written summary
The higher grain-number cultivar tended to have lower grain-number sensitivity to pre-anthesis heat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- pre-AN HTe0
- Outcome
- sensitivity of GNe0
- Direction
- lesse0
- Qualifier
- There seemed to be a trende0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“There seemed to be a trend for the cultivar constitutively producing more grains having less sensitivity of GN to pre-AN HT”
Claim · model-written summary
The heavier-grain cultivar tended to have lower grain-weight sensitivity to post-anthesis heat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- post-AN HTe0
- Outcome
- sensitivity of AGWe0
- Direction
- lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“for the cultivar constitutively having heavier grains having less sensitivity of AGW to post-AN HT.”
Claim · model-written summary
Yield-component heat plasticity was inversely related to its importance for yield without heat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- heat stresse0
- Outcome
- plasticity of a yield componente0
- Direction
- inversely relatede0
- Comparator
- unheated conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“The plasticity of a yield component in response to heat stress was inversely related to the relevance of that component for yield determination in unheated conditions.”
Claim · model-written summary
The authors suggest breeding for higher grain number or potential grain weight according to local heat-wave timing.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- select for improved sink-strength through either higher GN or higher PGWe0
- Qualifier
- depending on the timing and frequency of the most damaging heat wavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“wheat”
e0“Our result would open an opportunity for breeders to select for improved sink-strength through either higher GN or higher PGW depending on the timing and frequency of the most damaging heat waves.”
The same questions in other papers
heat · yield · Triticum aestivum (wheat)Positive and negative results
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