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Insufficient and excessive N fertilizer input reduces maize root mass across soil types
Field Crops Research ( IF 5.6 ) Pub Date : 2021-04-15 , DOI: 10.1016/j.fcr.2021.108142
Raziel A. Ordóñez , Michael J. Castellano , Gerasimos N. Danalatos , Emily E. Wright , Jerry L. Hatfield , Lee Burras , Sotirios V. Archontoulis

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.



中文翻译:

氮肥投入不足和过量会降低土壤类型上的玉米根系质量

量化玉米根系对氮肥,土壤质地和天气的反应对于理解复杂的土壤-根系植物过程至关重要。我们在美国爱荷华州进行了为期2年x 4个地点(砂含量范围:5-95%)x N处理(范围:0至336 kg N ha -1)的田间试验,以确定(1)根系性状的响应氮肥,以及(2)开发通用功能,以帮助了解和预测根质量和根冠比(R:S)。在灌浆初期至中期,使用土壤核心方法收集深根样品(0-210 cm,增量为30 cm),并定量分析根质量,长度以及氮和碳的浓度。另外,测量了产量和枝条生物量。根系性状和产量对氮肥输入的反应不同。根重最大为168 kg N ha-1 ; 零氮肥和过量氮肥分别使根质量降低了33%和17%。氮肥仅在土壤最上层30 cm处显着影响根系性状。在干燥的一年中,土壤质地会影响根系性状(根团质量与淤泥和粘土呈正相关),而在潮湿的一年中则不会,这表明土壤水分压倒了质地的影响。组合数据(N比率x位置x年份)显示R:S比率与产量之间呈负相关。这产生了一组新的方程式(例如,上限R:S = e (–1.5 – 0.04 *收益率)),可以代替文献中使用的恒定R:S方法。通常测量的产量综合了环境,管理和遗传变异的影响;因此,所提出的方程式可以被广泛应用。这项研究提供的证据表明,在不同的矿质氮营养水平下,不同的植物性状得到了最大化。结果可以增强生物物理模型和R:S比的预测。

更新日期:2021-04-15
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