Abstract
(1) High night temperatures (minimum temperature in range 22-25 $^\circ$C), could contribute to the lower yields of maize crops grown in the humid tropics compared with temperate areas because of higher rates of respiration. (2) Overnight respiration losses of whole plants were measured in a young maize crop grown in the humid tropic zone of Western Nigera. In an older crop, overnight leaf respiration was measured. (3) In the younger plants, respiration rates initially were high (c. 15% overnight reduction in dusk plant dry weight) but they declined to c. 5% by 27 days after emergence (d.a.e.). Overnight leaf respiration caused 4% reduction in dusk lamina dry weight. Nightly dry weight losses by whole plants averaged 40% of daily dry weight gain. (4) Assuming a value of 12 mg g$^{-1}$ per 12 h with a Q$_{10}$ of 2 for the maintenance component of respiration for the period 11 to 27 d.a.e., overnight dry weight loss could be reduced to 37% and 35% of daily gain for a 10 $^\circ$C and 20 $^\circ$C decrease in night minimum temperature. Such dry weight conservation, if maintained through the remaining period of crop growth could give yield increases of 200 and 300 kg ha$^{-1}$ respectively, and at best. c. 5% improvement on Experimental Station yields of elite varieties. (5) On this basis it appears that high night temperatures are of minor importance in explaining yield differences between the humid tropics and temperate zones.
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Claims 10
Claim · model-written summary
Young maize initially lost about 15% of dusk plant dry weight overnight.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the younger plants, respiration rates initially were high (c. 15% overnight reduction in dusk plant dry weight)”
t0“Maize”
Claim · model-written summary
Maize overnight respiration declined to about 5% by 27 days after emergence.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but they declined to c. 5% by 27 days after emergence (d.a.e.).”
e1“In the younger plants, respiration rates initially were high (c. 15% overnight reduction in dusk plant dry weight)”
t0“Maize”
Claim · model-written summary
Overnight maize leaf respiration reduced dusk lamina dry weight by 4%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overnight leaf respiration caused 4% reduction in dusk lamina dry weight.”
t0“Maize”
Claim · model-written summary
Nightly maize whole-plant dry weight losses averaged 40% of daily dry weight gain.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nightly dry weight losses by whole plants averaged 40% of daily dry weight gain.”
t0“Maize”
Claim · model-written summary
A 10 degree decrease in minimum night temperature could reduce maize overnight dry weight loss to 37% of daily gain under the stated maintenance assumptions.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overnight dry weight loss could be reduced to 37% and 35% of daily gain for a 10 $^\circ$C and 20 $^\circ$C decrease in night minimum temperature.”
t0“Maize”
Claim · model-written summary
A 20 degree decrease in minimum night temperature could reduce maize overnight dry weight loss to 35% of daily gain under the stated maintenance assumptions.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overnight dry weight loss could be reduced to 37% and 35% of daily gain for a 10 $^\circ$C and 20 $^\circ$C decrease in night minimum temperature.”
t0“Maize”
Claim · model-written summary
Maintaining dry weight conservation following a 10 degree night cooling could increase maize yield by 200 kg per hectare.
- Treatment
- 10 $^\circ$Ce1
- Outcome
- yielde0
- Direction
- increasese0
- Value
- 200e0
- Qualifier
- if maintained through the remaining period of crop growthe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such dry weight conservation, if maintained through the remaining period of crop growth could give yield increases of 200 and 300 kg ha$^{-1}$ respectively”
e1“10 $^\circ$C and 20 $^\circ$C decrease in night minimum temperature”
t0“Maize”
Claim · model-written summary
Maintaining dry weight conservation following a 20 degree night cooling could increase maize yield by 300 kg per hectare.
- Treatment
- 20 $^\circ$Ce1
- Outcome
- yielde0
- Direction
- increasese0
- Value
- 300 kg ha$^{-1}$e0
- Qualifier
- if maintained through the remaining period of crop growthe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such dry weight conservation, if maintained through the remaining period of crop growth could give yield increases of 200 and 300 kg ha$^{-1}$ respectively”
e1“10 $^\circ$C and 20 $^\circ$C decrease in night minimum temperature”
t0“Maize”
Claim · model-written summary
The calculated conservation would at best improve elite maize Experimental Station yields by about 5%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at best. c. 5% improvement on Experimental Station yields of elite varieties.”
t0“Maize”
Claim · model-written summary
The authors infer that high night temperature contributes only modestly to maize yield differences between humid tropical and temperate zones.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high night temperatures are of minor importance in explaining yield differences between the humid tropics and temperate zones.”
t0“Maize”