Abstract
Global climate change is increasing the frequency of concurrent heat and drought events, highlighting the urgent need to elucidate their synergistic effects on crop root function and nutrient uptake. We subjected maize plants to normal condition (CK), heat stress (H), drought stress (D), and combined heat and drought stress (HD) at the 12 th fully expanded leaf stage (V12) for five days. The root-to-shoot ratio decreased under H but increased under D. Both single stresses induced “low-cost” root anatomical changes. Under HD, however, these anatomical alterations were most pronounced. They coincided with the strongest oxidative damage, the greatest suppression of root respiration, and the most severe cellular energy deficit. This energy limitation downregulated key nitrogen assimilation enzymes (NR, GS, and GOGAT) and impaired the compensatory upregulation of glutamate dehydrogenase observed under single stresses. Consequently, root nitrogen uptake efficiency declined by 9.0%, 10.4%, and 18.0% under H, D, and HD, respectively. Total plant nitrogen accumulation was lowest under HD, with nitrogen allocation increasingly skewed toward the shoot. Grain yield also lowest under HD. Collectively, these findings demonstrate that combined heat and drought cause oxidative damage, which in turn worsens the energy deficit in roots and suppresses nitrogen assimilation, thereby reducing nitrogen acquisition efficiency in maize.
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Claims 15
Claim · model-written summary
Heat decreased maize root-to-shoot ratio.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The root-to-shoot ratio decreased under H but increased under D.”
e1“We subjected maize plants to normal condition (CK), heat stress (H), drought stress (D), and combined heat and drought stress (HD) at the 12 th fully expanded leaf stage (V12) for five days.”
t0“maize”
Claim · model-written summary
Drought increased maize root-to-shoot ratio.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The root-to-shoot ratio decreased under H but increased under D.”
e1“We subjected maize plants to normal condition (CK), heat stress (H), drought stress (D), and combined heat and drought stress (HD) at the 12 th fully expanded leaf stage (V12) for five days.”
t0“maize”
Claim · model-written summary
Single stresses induced low-cost root anatomical changes.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both single stresses induced “low-cost” root anatomical changes.”
t0“maize”
Claim · model-written summary
Combined stress produced the most pronounced root anatomical changes.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under HD, however, these anatomical alterations were most pronounced.”
t0“maize”
Claim · model-written summary
Combined stress caused the strongest oxidative damage.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They coincided with the strongest oxidative damage, the greatest suppression of root respiration, and the most severe cellular energy deficit.”
t0“maize”
e1“combined heat and drought stress (HD)”
Claim · model-written summary
Combined stress caused the greatest suppression of root respiration.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They coincided with the strongest oxidative damage, the greatest suppression of root respiration, and the most severe cellular energy deficit.”
t0“maize”
e1“combined heat and drought stress (HD)”
Claim · model-written summary
Combined stress caused the most severe cellular energy deficit.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“They coincided with the strongest oxidative damage, the greatest suppression of root respiration, and the most severe cellular energy deficit.”
t0“maize”
e1“combined heat and drought stress (HD)”
Claim · model-written summary
Energy limitation downregulated NR, GS, and GOGAT.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This energy limitation downregulated key nitrogen assimilation enzymes (NR, GS, and GOGAT) and impaired the compensatory upregulation of glutamate dehydrogenase observed under single stresses.”
t0“maize”
Claim · model-written summary
Energy limitation impaired compensatory glutamate dehydrogenase upregulation.
- Gene
- glutamate dehydrogenasee0
- Outcome
- compensatory upregulation of glutamate dehydrogenasee0
- Qualifier
- energy limitatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This energy limitation downregulated key nitrogen assimilation enzymes (NR, GS, and GOGAT) and impaired the compensatory upregulation of glutamate dehydrogenase observed under single stresses.”
t0“maize”
Claim · model-written summary
H reduced maize root nitrogen uptake efficiency by 9.0%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Consequently, root nitrogen uptake efficiency declined by 9.0%, 10.4%, and 18.0% under H, D, and HD, respectively.”
t0“maize”
Claim · model-written summary
D reduced maize root nitrogen uptake efficiency by 10.4%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Consequently, root nitrogen uptake efficiency declined by 9.0%, 10.4%, and 18.0% under H, D, and HD, respectively.”
t0“maize”
Claim · model-written summary
HD reduced maize root nitrogen uptake efficiency by 18.0%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Consequently, root nitrogen uptake efficiency declined by 9.0%, 10.4%, and 18.0% under H, D, and HD, respectively.”
t0“maize”
Claim · model-written summary
Total maize nitrogen accumulation was lowest under combined stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total plant nitrogen accumulation was lowest under HD, with nitrogen allocation increasingly skewed toward the shoot.”
t0“maize”
Claim · model-written summary
Combined stress increasingly skewed nitrogen allocation toward the shoot.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total plant nitrogen accumulation was lowest under HD, with nitrogen allocation increasingly skewed toward the shoot.”
t0“maize”
Claim · model-written summary
Maize grain yield was lowest under combined stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yield also lowest under HD.”
t0“maize”
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8 of 9 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.