Abstract
The excessive nitrogen (N) applications, large rainfall variations and poor water-nitrogen couplings are main problems to efficient nitrogen fertilizer uses in spring maize production of Weibei dryland. Critical nitrogen dilution curves under different rainfall scenarios in Weibei dryland were constructed in this study to analyze the feasibilities of diagnosing and evaluating nitrogen nutritional conditions in terms of nitrogen nutrition index (NNI), which would provide a theoretical basis for reasonable nitrogen fertilizations application of dryland maize in response to different rainfalls. The experiment design using Zhengdan 958 (ZD958) and Shaandan 8806 (SD8806) as tested materials was five treatments level, N applied at 0(N0), 75(N1), 150(N2), 270(N3), and 360(N4) kg hm–2 in 2016 and 2017, and at 0(N0), 90(N0), 180(N2), 270(N3), and 360(N4) kg hm–2 in 2018 and 2019, respectively. It was rainy at the ear stage and dry at the grain stage in 2016 and 2018, whereas dry at the ear stage and rainy at the grain stage in 2017 and 2019. Critical nitrogen dilution curve models for spring maize with two precipitation patterns were constructed and verified using the data collected in the four-year position nitrogen fertilization experiment. The results showed that: (1) increased nitrogen fertilizer application significantly increased aboveground biomass and plant N concentrations, and there were significantly different among different treatments. Both critical nitrogen concentrations (Nc) and aboveground biomass conformed the exponential relations with the two precipitation patterns, but there were differences between the parameters of the models for these relations (a. Rainy at the ear stage: Nc = 35.98DM–0.35; b. Dry at the ear stage: Nc = 35.04DM–0.23). The relatively stable model had a linear correlation between the fitted and actual plant N concentrations, which shown that the RMSE and n–RMSE were 1.03 and 5.75% at the ear stage over the rainy years and 1.53 and 6.78% at the ear stage in the dry years, respectively. (2) at the different growth stages, NNI were increased with the increased application, and there were differences in the optimal nitrogen application under different precipitation conditions. The optimum N rate in the form of basal fertilizers was 150–180 kg hm–2, and in the form of top dressing fertilizers was 45–75 kg hm–2 at the ear stage in the rainy years. The nitrogen nutrition index (NNI) was significantly correlated with relative nitrogen uptake (RNupt), as were relative aboveground biomass (RDW) and relative yield (RY). When the NNI was 1.02 at the ear stage in the rainy years, the maximum RY was 0.95; and when the NNI was 1.08 at the ear stage in the dry years, the maximum RY was 0.92. The critical nitrogen dilution curve model and nitrogen nutrition index model constructed in this study were able to accurately predict nitrogen nutrition conditions from jointing stage to maturity stage under the two precipitation patterns of spring maize. They would provide an important guidance for nitrogen diagnosis and fertilization application in maize growing stage.
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Claims 15
Claim · model-written summary
Increasing N application significantly increased aboveground biomass.
- Treatment
- increased nitrogen fertilizer applicatione0
- Outcome
- aboveground biomasse0
- Direction
- increasede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased nitrogen fertilizer application significantly increased aboveground biomass and plant N concentrations”
t0“spring maize”
Claim · model-written summary
Increasing N application significantly increased plant N concentration.
- Treatment
- increased nitrogen fertilizer applicatione0
- Outcome
- plant N concentrationse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased nitrogen fertilizer application significantly increased aboveground biomass and plant N concentrations”
t0“spring maize”
Claim · model-written summary
Critical N concentration and biomass followed an exponential relation in rainy-ear-stage years.
- Outcome
- critical nitrogen concentrations (Nc)e0
- Value
- Nc = 35.98DM–0.35e0
- Setting
- Rainy at the ear stagee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both critical nitrogen concentrations (Nc) and aboveground biomass conformed the exponential relations with the two precipitation patterns, but there were differences between the parameters of the models for these relations (a. Rainy at the ear stage: Nc = 35.98DM–0.35; b. Dry at the ear stage: Nc = 35.04DM–0.23).”
t0“spring maize”
Claim · model-written summary
Critical N concentration and biomass followed a different exponential relation in dry-ear-stage years.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both critical nitrogen concentrations (Nc) and aboveground biomass conformed the exponential relations with the two precipitation patterns, but there were differences between the parameters of the models for these relations (a. Rainy at the ear stage: Nc = 35.98DM–0.35; b. Dry at the ear stage: Nc = 35.04DM–0.23).”
t0“spring maize”
Claim · model-written summary
The rainy-ear-stage model predicted plant N with RMSE 1.03 and n-RMSE 5.75%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“RMSE and n–RMSE were 1.03 and 5.75% at the ear stage over the rainy years”
t0“spring maize”
Claim · model-written summary
The dry-ear-stage model predicted plant N with RMSE 1.53 and n-RMSE 6.78%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“1.53 and 6.78% at the ear stage in the dry years”
e1“RMSE and n–RMSE were 1.03 and 5.75%”
t0“spring maize”
Claim · model-written summary
NNI increased with N application at different growth stages.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at the different growth stages, NNI were increased with the increased application”
t0“spring maize”
Claim · model-written summary
The optimum rainy-ear-stage basal N rate was 150–180 kg hm–2.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The optimum N rate in the form of basal fertilizers was 150–180 kg hm–2”
t0“spring maize”
Claim · model-written summary
The optimum rainy-ear-stage top dressing N rate was 45–75 kg hm–2.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the form of top dressing fertilizers was 45–75 kg hm–2 at the ear stage in the rainy years.”
t0“spring maize”
Claim · model-written summary
NNI correlated significantly with relative N uptake.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nitrogen nutrition index (NNI) was significantly correlated with relative nitrogen uptake (RNupt)”
t0“spring maize”
Claim · model-written summary
NNI correlated significantly with relative aboveground biomass.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nitrogen nutrition index (NNI) was significantly correlated with relative nitrogen uptake (RNupt), as were relative aboveground biomass (RDW) and relative yield (RY).”
t0“spring maize”
Claim · model-written summary
NNI correlated significantly with relative yield.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nitrogen nutrition index (NNI) was significantly correlated with relative nitrogen uptake (RNupt), as were relative aboveground biomass (RDW) and relative yield (RY).”
t0“spring maize”
Claim · model-written summary
At rainy-year ear stage, NNI 1.02 corresponded to maximum relative yield 0.95.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When the NNI was 1.02 at the ear stage in the rainy years, the maximum RY was 0.95”
t0“spring maize”
Claim · model-written summary
At dry-year ear stage, NNI 1.08 corresponded to maximum relative yield 0.92.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when the NNI was 1.08 at the ear stage in the dry years, the maximum RY was 0.92”
t0“spring maize”
Claim · model-written summary
The two precipitation-specific models accurately predicted N nutrition from jointing through maturity.
- Outcome
- accurately predict nitrogen nutrition conditionse0
- Value
- two precipitation patternse0
- Qualifier
- from jointing stage to maturity stagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The critical nitrogen dilution curve model and nitrogen nutrition index model constructed in this study were able to accurately predict nitrogen nutrition conditions from jointing stage to maturity stage under the two precipitation patterns of spring maize.”
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