Evaluating Nitrogen Fertilizer Utilization Efficiency and Analyzing Its Relationship with Nitrogen Nutrition Index in Lettuce

Document Type : Full Paper


1 Ph.D, Irrigation and Reclamation Engineering Department, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.

2 Horticulture Department, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.


Improving nitrogen utilization efficiency (NUtE) is one of the most important challenges in the agricultural sector. The NUtE index, which is the amount of dry biomass (g) produced per nitrogen absorbed (g) by the plant, is influenced by factors such as climate and nitrogen nutrition status. Therefore, providing management strategies to increase NUtE should be performed by taking into account the nitrogen status of the plant. In this study, relationships between nitrogen nutrition index (NNI) and NUtE in lettuce were extracted based on the concept of critical nitrogen concentration. For this purpose, two experiments were conducted in the research greenhouse of the college of Agriculture and Natural Resources, University of Tehran, located in Karaj, Iran, with six N fertilizer treatments. Then, NUtE and NNI were calculated for all treatments. The results showed that the NNI varied from 0.70 to 1.22 and 0.60 to 1.23 for the first and second experiments, respectively. The NUtE decreased due to the increase in fertilizer application rate. Also, application of nitrogen fertilizer more than the plant uptake capacity led to a decrease in the nitrogen uptake efficiency (NUpE). The relationship between NUtE and NNI for different dry biomass values was investigated. The results showed that at constant NNI values, NUtE increased non-linearly with increasing dry biomass production. Also, the critical nitrogen utilization efficiency curve (NUtEc) discriminated well between different N treatments. Under the optimal nitrogen nutrition conditions (NNI = 1), the critical value of NUtE for lettuce was equal to 24 (g g-1 N).


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Articles in Press, Accepted Manuscript
Available Online from 13 December 2023
  • Receive Date: 18 December 2022
  • Revise Date: 03 September 2023
  • Accept Date: 04 October 2023