Abstract
The objective of this work was to analyze the responses of maize plants to combinations of various plant densities and nitrogen rates considering their canopy apparent photosynthesis (CAP) and assimilate redistribution characters by 13CO2 stable isotope tracing. In this study, maize plants were grown at various planting densities (6.75, 8.25, 9.75, and 11.25 pl m-2) and N application rates (0, 180, 270, 360, and 540 kg ha-1) during 2013–2015 in Shandong, China. The maize varieties Denghai618 and Denghai605 were used as the study materials. At the community level, grain yield (GY) was maximized at a density of 9.75 pl m-2 with a 270–360 kg ha-1 N rate during the 3 study years. The CAP and leaf area index (LAI) was both enhanced significantly by increased density and N rate, while the yield improvement was more associated with the increase in CAP. By contrast, excess N had inhibitory effects and decreased the GY consequently. Increased N supply weakened the decreased KNP and TKW caused by enhanced density mainly by decreasing the retention of 13C-photosynthates in the stem and promoting 13C-photosynthate reallocation to reproductive organs. The GY, biomass, CAP, LAI and 13C-photosynthate reallocation ratio to different organs all responded more intensively to density than N rate, though the response degree differed between varieties. Based on our results, greater CAP, higher use of reserves and more 13C-photosynthate distribution to ears are all vital for the further improvement of maize GY under different density and N rate combinations.
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Claims 13
Claim · model-written summary
Maize grain yield was maximized at 9.75 pl m-2 with a 270-360 kg ha-1 N rate in Shandong, China.
- Treatment
- a density of 9.75 pl m-2 with a 270–360 kg ha-1 N ratee0
- Outcome
- grain yield (GY)e0
- Direction
- maximizede0
- Setting
- Shandong, Chinae1
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“grain yield (GY) was maximized at a density of 9.75 pl m-2 with a 270–360 kg ha-1 N rate”
e1“in Shandong, China”
Claim · model-written summary
Canopy apparent photosynthesis and LAI were significantly enhanced by increased planting density.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“The CAP and leaf area index (LAI) was both enhanced significantly by increased density and N rate”
Claim · model-written summary
Canopy apparent photosynthesis and LAI were significantly enhanced by increased N rate.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“The CAP and leaf area index (LAI) was both enhanced significantly by increased density and N rate”
Claim · model-written summary
Yield improvement was more associated with the increase in CAP.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“the yield improvement was more associated with the increase in CAP”
Claim · model-written summary
Excess N had inhibitory effects and decreased grain yield.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“excess N had inhibitory effects and decreased the GY”
Claim · model-written summary
Increased N supply weakened the decrease in KNP and TKW caused by enhanced density.
- Treatment
- Increased N supplye0
- Outcome
- decreased KNP and TKW caused by enhanced densitye0
- Direction
- weakenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“Increased N supply weakened the decreased KNP and TKW caused by enhanced density”
Claim · model-written summary
Increased N supply decreased the retention of 13C-photosynthates in the stem.
- Treatment
- Increased N supplye0
- Outcome
- retention of 13C-photosynthates in the steme1
- Direction
- decreasinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“Increased N supply weakened the decreased KNP and TKW caused by enhanced density”
e1“decreasing the retention of 13C-photosynthates in the stem”
Claim · model-written summary
Increased N supply promoted 13C-photosynthate reallocation to reproductive organs.
- Treatment
- Increased N supplye0
- Outcome
- 13C-photosynthate reallocation to reproductive organse1
- Direction
- promotinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“Increased N supply weakened the decreased KNP and TKW caused by enhanced density”
e1“promoting 13C-photosynthate reallocation to reproductive organs”
Claim · model-written summary
Grain yield and biomass responded more intensively to planting density than to N rate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“The GY, biomass, CAP, LAI and 13C-photosynthate reallocation ratio to different organs all responded more intensively to density than N rate”
Claim · model-written summary
CAP and LAI responded more intensively to planting density than to N rate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“The GY, biomass, CAP, LAI and 13C-photosynthate reallocation ratio to different organs all responded more intensively to density than N rate”
Claim · model-written summary
The 13C-photosynthate reallocation ratio to different organs responded more intensively to planting density than to N rate.
- Treatment
- densitye0
- Outcome
- 13C-photosynthate reallocation ratio to different organse0
- Direction
- higherinferrede0
- Comparator
- N ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“The GY, biomass, CAP, LAI and 13C-photosynthate reallocation ratio to different organs all responded more intensively to density than N rate”
Claim · model-written summary
The degree of response differed between varieties.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“though the response degree differed between varieties”
Claim · model-written summary
Greater CAP, higher use of reserves and more 13C-photosynthate distribution to ears are vital for further improving maize grain yield.
- Outcome
- further improvement of maize GYe0
- Qualifier
- greater CAP, higher use of reserves and more 13C-photosynthate distribution to earse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Maize”
e0“greater CAP, higher use of reserves and more 13C-photosynthate distribution to ears are all vital for the further improvement of maize GY”
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See all 2,185 papers →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.