Why do the deficiency symptoms of nitrogen appear first in the senescent leaves?
GeneralClass 12AllAnswered 27 Mar 2026
Answer
Nitrogen is a mobile element in plants, meaning it can be remobilized from older tissues to younger, actively growing regions. During nitrogen deficiency, nitrogenous compounds in senescent (older) leaves are degraded, and nitrogen is exported to young developing tissues. Therefore, deficiency symptoms like chlorosis (yellowing) appear first in older leaves while younger leaves remain relatively normal until the deficiency becomes severe.
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