Abstract
L.) production. Much attention has been directed toward plant responses to heat or drought stress. However, maize reproductive stage responses to combined heat and drought remain less explored. Therefore, this study aimed to quantify the impact of optimum daytime (30°C, control) and warmer daytime temperatures (35°C, heat stress) on pollen germination, morpho-physiology, and yield potential using two maize genotypes ("Mo17" and "B73") under contrasting soil moisture content, that is, 100% and 40% irrigation during flowering. Pollen germination of both genotypes decreased under combined stresses (42%), followed by heat stress (30%) and drought stress (19%). Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control. Genotype "Mo17" reduced its green leaf area to minimize the water loss, which appears to be one of the adaptive strategies of "Mo17" under stress conditions. The leaf reflectance of both genotypes varied across treatments. Vegetation indices associated with pigments (chlorophyll index of green, chlorophyll index of red edge, and carotenoid index) and plant health (normalized difference red-edge index) were found to be highly sensitive to drought and combined stressors than heat stress. Combined drought and heat stresses caused a significant reduction in yield and yield components in both Mo17 (49%) and B73 (86%) genotypes. The harvest index of genotype "B73" was extremely low, indicating poor partitioning efficiency. At least when it comes to "B73," the cause of yield reduction appears to be the result of reduced sink number rather than the pollen and source size. To the best of our awareness, this is the first study that showed how the leaf-level spectra, yield, and quality parameters respond to the short duration of independent and combined stresses during flowering in inbred maize. Further studies are required to validate the responses of potential traits involving diverse maize genotypes under field conditions. This study suggests the need to develop maize with improved tolerance to combined stresses to sustain production under increasing temperatures and low rainfall conditions.
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Claims 16
Claim · model-written summary
Combined stress decreased pollen germination by 42%.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pollen germination of both genotypes decreased under combined stresses (42%)”
t0“maize (Zea mays L.)”
Claim · model-written summary
Heat stress decreased pollen germination by 30%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“followed by heat stress (30%)”
e1“Pollen germination of both genotypes decreased under combined stresses (42%), followed by heat stress (30%)”
t0“maize (Zea mays L.)”
Claim · model-written summary
Drought stress decreased pollen germination by 19%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pollen germination of both genotypes decreased under combined stresses (42%), followed by heat stress (30%) and drought stress (19%)”
t0“maize (Zea mays L.)”
Claim · model-written summary
Stomatal conductance and transpiration were comparable under control and heat stress.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and transpiration were comparable between control and heat stress”
t0“maize (Zea mays L.)”
Claim · model-written summary
Combined stress decreased stomatal conductance by 83% versus control.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control”
t0“maize (Zea mays L.)”
Claim · model-written summary
Combined stress decreased transpiration by 72% versus control.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control”
t0“maize (Zea mays L.)”
Claim · model-written summary
Drought decreased stomatal conductance by 52% versus control.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control”
t0“maize (Zea mays L.)”
Claim · model-written summary
Drought decreased transpiration by 47% versus control.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and transpiration were comparable between control and heat stress but significantly decreased under combined stresses (83% and 72%) and drought stress (52% and 47%) compared with the control”
t0“maize (Zea mays L.)”
Claim · model-written summary
Mo17 reduced green leaf area under stress.
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Genotype "Mo17" reduced its green leaf area to minimize the water loss”
t0“maize (Zea mays L.)”
Claim · model-written summary
Leaf reflectance varied across treatments in both genotypes.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leaf reflectance of both genotypes varied across treatments”
t0“maize (Zea mays L.)”
Claim · model-written summary
Pigment and plant health vegetation indices were more sensitive to drought and combined stress than heat.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Vegetation indices associated with pigments (chlorophyll index of green, chlorophyll index of red edge, and carotenoid index) and plant health (normalized difference red-edge index) were found to be highly sensitive to drought and combined stressors than heat stress”
t0“maize (Zea mays L.)”
Claim · model-written summary
Combined stress significantly reduced yield and yield components by 49% in Mo17.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Combined drought and heat stresses caused a significant reduction in yield and yield components in both Mo17 (49%) and B73 (86%) genotypes”
t0“maize (Zea mays L.)”
Claim · model-written summary
Combined stress significantly reduced yield and yield components by 86% in B73.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Combined drought and heat stresses caused a significant reduction in yield and yield components in both Mo17 (49%) and B73 (86%) genotypes”
t0“maize (Zea mays L.)”
Claim · model-written summary
B73 had an extremely low harvest index.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The harvest index of genotype "B73" was extremely low”
t0“maize (Zea mays L.)”
Claim · model-written summary
The authors attribute B73 yield reduction chiefly to reduced sink number.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the cause of yield reduction appears to be the result of reduced sink number rather than the pollen and source size”
e1“At least when it comes to "B73,"”
t0“maize (Zea mays L.)”
Claim · model-written summary
The authors recommend developing maize with improved tolerance to combined stress.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“develop maize with improved tolerance to combined stresses to sustain production”
t0“maize (Zea mays L.)”
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