Allocation of nitrogen to cell walls decreases photosynthetic nitrogen-use efficiency


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  • 1Nitrogen (N) is an essential limiting resource for plant growth, and its efficient use may increase fitness. We investigated photosynthetic N-use efficiency (photosynthetic capacity per unit N) in relation to N allocation to Rubisco and to cell walls in Polygonum cuspidatum Sieb. et Zucc. which germinated in May (early germinators) and August (late germinators).
  • 2There was a significant difference between early and late germinators in photosynthetic capacity as a function of leaf N content per unit area. Higher photosynthetic N-use efficiency in late germinators was caused primarily by a larger allocation of N to Rubisco.
  • 3Nitrogen allocation to cell walls was smaller in late germinators. The shorter growth period in late germinators was associated with higher photosynthetic capacity, which was achieved by allocating more N to photosynthetic proteins at the expense of cell walls.
  • 4The trade-off between N allocation to photosynthesis and to structural tissues suggests that plants change N allocation to increase either the rate or duration of carbon assimilation. Such plastic change would help plants maintain themselves and cope with environmental changes.