期刊
FIELD CROPS RESEARCH
卷 267, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.fcr.2021.108142
关键词
Root length; Specific root length; Root carbon; Maize biomass; Nitrogen uptake
类别
资金
- Foundation for Food and Agricultural Research [534264]
- Iowa Crop Improvement Association
- NSF [1830478]
- USDA-NIFA Hatch project [IOW10480]
- Iowa State University Plant Science Institute faculty scholar program
Quantifying maize root response to nitrogen (N) fertilizer, soil texture, and weather is crucial to understanding complex soil-root-plant processes. Different plant traits are maximized at different levels of mineral N nutrition, and new equations have been developed to predict root mass and root to shoot ratio based on the combined data of nitrogen rates, locations, and years.
Quantifying maize root response to nitrogen (N) fertilizer, soil texture, and weather is crucial to understand complex soil-root-plant processes. We performed a 2-year x 4 locations (sand content range: 5-95%) x N treatments (range: 0 to 336 kg N ha- 1) field experiment in Iowa, U.S. to (1) determine the response of root traits to N fertilizer, and (2) develop generalized functions to aid understanding and prediction of root mass and root to shoot (R:S) ratio. Deep root samples (0-210 cm, increments of 30 cm) were collected using the soil core approach at early to middle grain fill period and quantified root mass, length, and N and C concentrations. In addition, yield and shoot biomass was measured. Root traits and yield had different responses to N fertilizer input. Root mass was maximized at 168 kg N ha- 1; zero and excessive N fertilization decreased root mass by 33 and 17 %, respectively. Nitrogen fertilizer significantly affected root traits only in the top 30 cm soil layer. Soil texture affected root traits in a dry year (root mass was positively associated with silt and clay), but not in a wet year, suggesting that soil moisture overwhelms the effect of texture. The combined data (N rates x locations x years) revealed a negative relationship between R:S ratio and yield. This resulted in a new set of equations (e.g., upper bound R:S = e(-1.5 - 0.04*yield)) that can replace the constant R:S approach used in the literature. Yield, which is commonly measured, integrates the effects of environment, management, and genetic variation; hence the proposed equations can be widely applied. This study provides evidence that different plant traits are maximized at different levels of mineral N nutrition. Results can enhance biophysical models and prediction of R: S ratio.
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