Abstract
Precise quantification of plant nitrogen (N) nutrition status is essential for crop N management. The concept of critical N concentration (Nc) has been widely used for assessment of plant N status. This study aimed to develop a new winter wheat Nc dilution curve based on leaf area duration (LAD). Four field experiments were performed on different cultivars with different N fertilization modes in the Yangtze River basin and Yellow River basin in China. Results showed that the increase in LAD with increasing cumulative thermal time took the shape of an “S” type curve; whereas shoot N concentration decreased with increasing LAD, according to a power function. Both LAD and shoot N concentration increased with increasing N application. The new LAD based Nc dilution curve was determined and described as Nc = 1.6774 LAD−0.37 when LAD > 0.13. However, when LAD ≤ 0.13, Nc was constant and can be calculated by the equation when LAD = 0.13. The validation of Nc dilution curve with dataset acquired from independent experiments confirmed that N nutrition index (NNI) predictions based on the newly established Nc dilution curve could precisely diagnose N deficiency at different plant growth stages. The integrated N nutrition index (NNIinte), which was obtained by the weighted mean of NNI, was used to estimate shoot N concentration, shoot dry matter, LAD, and yield using regression functions. The linear relationships between NNIinte and these growth variables were well correlated. These results provided enough evidence that the new LAD–based Nc dilution curve could effectively and precisely diagnoses N deficiency in winter wheat crops.
Highlights
Nitrogen (N) is a major nutritional element required for crop growth and productivity (Eickhout et al, 2006)
The objectives of this study were to develop a N concentration (Nc) dilution curve based on Leaf area duration (LAD) for winter wheat which combines the merits of shoot dry matter- and Leaf area index (LAI)-based Nc curves and to test the curve through evaluation of the effects of N deficiency on growth variables and yield
This study has developed a new Nc dilution curve based on LAD in winter wheat, which combines the merits of shoot dry matter- and LAI-based Nc curve
Summary
Nitrogen (N) is a major nutritional element required for crop growth and productivity (Eickhout et al, 2006). In-season N diagnosis and management in crop production is an important agronomic practice for ensuring food security and environmental sustainability (Ata-Ul-Karim et al, 2016a,b). N is an integral component of chlorophyll and protein related with plant vigor, yield and quality and appropriate N fertilizer application is imperative for improving crop production and for increasing the processing quality of grain in cereals (Wang et al, 2002; Zhu et al, 2003). Wheat Critical Nitrogen Dilution Curve studies have shown a strong relationship between N status and wheat yield and quality. Accurate estimation of crop N status and precision N management has become pressing study topics for crop growers and scientists
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