Abstract
Nitrogen fertilizer and planting density are key factors affecting rice yield and nitrogen utilization efficiency. There is still a need to optimize nitrogen fertilizer and planting density management for high yield. We studied the effects of different quantities of nitrogen application (N0 0 kg ha−1, N1 120 kg ha−1, N2 180 kg ha−1) and planting density (low-density: 18.8 hills m−2; high-density: 37.5 hills m−2) on rice yield, photosynthetic characteristics, antioxidant system, and nitrogen use efficiency. ANOVA results indicated that most tested traits were affected by environment, planting density, N application, and their interactions. Comparing the results of low-density planting, high-density planting increased the panicle number by 21.12% but decreased the grain number per panicle and yield by 3.97% and 22.48%, respectively. Similarly, the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively, while HIn (N harvest index) increased by 1.32%. Compared to no N application, N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment; and increased by 17.15%, 29.09%, and 128.94% in the N2 treatment, respectively. N application significantly increased net photosynthetic rates and enzyme activities of antioxidant antioxidases. Compared with N1, N2 decreased REn (apparent recovery efficiency of N), AEn (agronomic N use efficiency), and PFPn by 8.98%, 11.80%, and 25.14%, respectively, while, compared with N0, N1 increased HIn by 8.50%. It was observed that nitrogen fertilizer and planting density had an interaction effect on the net photosynthetic rate, antioxidant enzyme activities, and PFPn and HIn. Given a comprehensive consideration, it is best to apply nitrogen at a rate of 120 kg ha−1 at the planting density of 37.5 hills m−2 for high grain yield and high N use efficiency in our experimental site.
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Claims 20
Claim · model-written summary
Most tested rice traits were affected by environment, density, nitrogen and their interactions.
- Taxon
- Rice
Oryza sativat0 - Outcome
- most tested traitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most tested traits were affected by environment, planting density, N application, and their interactions”
t0“Rice”
Claim · model-written summary
High-density planting increased panicle number by 21.12%.
- Taxon
- RiceOryza sativat0
- Treatment
- high-density plantinge0
- Outcome
- panicle numbere0
- Direction
- increasede0
- Value
- 21.12%e0
- Comparator
- Different Fertilizer N Inputs and Planting Densityt0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high-density planting increased the panicle number by 21.12%”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting decreased grain number per panicle by 3.97%.
- Taxon
- RiceOryza sativat0
- Treatment
- high-density plantinge0
- Outcome
- grain number per paniclee0
- Direction
- decreasede0
- Value
- 3.97%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high-density planting increased the panicle number by 21.12% but decreased the grain number per panicle and yield by 3.97% and 22.48%, respectively”
t0“Rice”
Claim · model-written summary
High-density planting decreased yield by 22.48%.
- Taxon
- RiceOryza sativat0
- Treatment
- high-density plantinge0
- Outcome
- yielde0
- Direction
- decreasede0
- Value
- 22.48%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high-density planting increased the panicle number by 21.12% but decreased the grain number per panicle and yield by 3.97% and 22.48%, respectively”
t0“Rice”
Claim · model-written summary
High-density planting decreased SOD activity by 8.20%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- superoxide dismutase (SOD)e0
- Direction
- decreasede0
- Value
- 8.20%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting decreased CAT activity by 6.99%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- catalase (CAT)e0
- Direction
- decreasede0
- Value
- 6.99%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting decreased POD activity by 16.41%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- peroxidase (POD)e0
- Direction
- decreasede0
- Value
- 16.41%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting decreased APX activity by 14.28%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- ascorbate peroxidase (APX) activitiese0
- Direction
- decreasede0
- Value
- 14.28%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting decreased PFPn by 5.73%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- PFPn (partial factor productivity of nitrogen)e0
- Direction
- decreasede0
- Value
- 5.73%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PFPn (partial factor productivity of nitrogen) decreased by 8.20%, 6.99%, 16.41%, 14.28%, and 5.73%, respectively”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
High-density planting increased HIn by 1.32%.
- Taxon
- RiceOryza sativat0
- Treatment
- planting densityt0
- Outcome
- HIn (N harvest index)e0
- Direction
- increasede0
- Value
- 1.32%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“HIn (N harvest index) increased by 1.32%”
t0“Rice under Different Fertilizer N Inputs and Planting Density”
Claim · model-written summary
N1 increased panicle number by 9.92% versus no nitrogen.
- Taxon
- RiceOryza sativat0
- Treatment
- N1 treatmente0
- Outcome
- panicle numbere0
- Direction
- increasede0
- Value
- 9.92%e0
- Comparator
- no N applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to no N application, N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment”
t0“Rice”
Claim · model-written summary
N1 increased grain number per panicle by 17.64%.
- Taxon
- RiceOryza sativat0
- Treatment
- N1 treatmente0
- Outcome
- grain number per paniclee0
- Direction
- increasede0
- Value
- 17.64%e0
- Comparator
- no N applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to no N application, N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment”
t0“Rice”
Claim · model-written summary
N1 increased yield by 37.83%.
- Taxon
- RiceOryza sativat0
- Treatment
- N1 treatmente0
- Outcome
- yielde0
- Direction
- increasede0
- Value
- 37.83%e0
- Comparator
- no N applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to no N application, N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment”
t0“Rice”
Claim · model-written summary
N2 increased panicle number by 17.15%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased by 17.15%, 29.09%, and 128.94% in the N2 treatment, respectively”
t0“Grain Yield, Nitrogen Use Efficiency and Antioxidant Enzymes of Rice”
Claim · model-written summary
N2 increased grain number per panicle by 29.09%.
- Taxon
- RiceOryza sativat0
- Treatment
- N2 treatmente0
- Outcome
- grain number per paniclee0
- Direction
- increasede0
- Value
- 29.09%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment; and increased by 17.15%, 29.09%, and 128.94% in the N2 treatment, respectively”
t0“Rice”
Claim · model-written summary
N2 increased yield by 128.94%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N application treatments increased the panicle number, grain number per panicle, and yield by 9.92%, 17.64%, and 37.83% in the N1 treatment; and increased by 17.15%, 29.09%, and 128.94% in the N2 treatment, respectively”
t0“Rice”
Claim · model-written summary
N application significantly increased net photosynthetic rates and antioxidant enzyme activities.
- Taxon
- RiceOryza sativat0
- Treatment
- N applicatione0
- Outcome
- net photosynthetic rates and enzyme activities of antioxidant antioxidasese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N application significantly increased net photosynthetic rates and enzyme activities of antioxidant antioxidases”
t0“Rice”
Claim · model-written summary
N2 lowered REn, AEn and PFPn relative to N1 by 8.98%, 11.80% and 25.14%, respectively.
- Taxon
- RiceOryza sativat0
- Treatment
- N2e0
- Outcome
- REn (apparent recovery efficiency of N), AEn (agronomic N use efficiency), and PFPne0
- Direction
- decreasede0
- Value
- 8.98%, 11.80%, and 25.14%e0
- Comparator
- N1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with N1, N2 decreased REn (apparent recovery efficiency of N), AEn (agronomic N use efficiency), and PFPn by 8.98%, 11.80%, and 25.14%, respectively”
t0“Rice”
Claim · model-written summary
N1 increased HIn by 8.50% relative to N0.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“compared with N0, N1 increased HIn by 8.50%”
t0“Rice”
Claim · model-written summary
The authors recommend 120 kg ha−1 nitrogen at 37.5 hills m−2 for high yield and nitrogen-use efficiency.
- Taxon
- RiceOryza sativat0
- Outcome
- apply nitrogen at a rate of 120 kg ha−1 at the planting density of 37.5 hills m−2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it is best to apply nitrogen at a rate of 120 kg ha−1 at the planting density of 37.5 hills m−2 for high grain yield and high N use efficiency in our experimental site”
t0“Rice”
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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.