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Agronomy QUESTION #2045
Question 1
The 'critical concentration' of a nutrient in plant tissue is defined as:
  • The concentration above which toxicity symptoms appear
  • The tissue concentration below which yield is reduced by 10% relative to maximum yield, used to diagnose deficiency and calibrate fertilizer recommendations✔️
  • The minimum concentration detectable by laboratory analysis
  • The concentration at which a nutrient first becomes visible in a spectroscopic analysis
Correct Answer Explanation
Critical concentration (or critical level) is the tissue nutrient concentration below which a 10% yield reduction occurs (some definitions use 5%). It is determined through nutrient response experiments and tissue analysis. It forms the basis for plant tissue testing diagnostic programs and fertilizer recommendations in modern agronomy.