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Agronomy QUESTION #2058
Question 1
The crop coefficient (\(K_c\)) in the FAO-56 approach changes across crop growth stages. Which sequence correctly represents the typical \(K_c\) pattern for a cereal crop like wheat?
  • Constant throughout the season
  • Low at initial stage → increases during crop development → peaks at mid-season → declines at late season (senescence/maturation)✔️
  • High at initial stage → decreases linearly to harvest
  • Peaks at germination then remains constant through grain fill
Correct Answer Explanation
In FAO-56 methodology, \(K_c\) follows a characteristic curve: \(K_{c,ini}\) (low, sparse cover) → \(K_{c,mid}\) (peak, full canopy, maximum ET) → \(K_{c,end}\) (lower, senescence, stomatal closure). For wheat: \(K_{c,ini} \approx 0.3\), \(K_{c,mid} \approx 1.15\), \(K_{c,end} \approx 0.25–0.4\). This drives irrigation scheduling calculations.