Optimizing Nitrogen Economy Under Drought: Increased Leaf Nitrogen Is an Acclimation to Water Stress in Willow (Salix Spp.)

Ann Bot. 2011 Nov;108(7):1347-53. doi: 10.1093/aob/mcr227. Epub 2011 Sep 6.

Abstract

Background and aims: The major objective was to identify plant traits functionally important for optimization of shoot growth and nitrogen (N) economy under drought. Although increased leaf N content (area basis) has been observed in dry environments and theory predicts increased leaf N to be an acclimation to drought, experimental evidence for the prediction is rare.

Methods: A pedigree of 200 full-sibling hybrid willows was pot-grown in a glasshouse in three replicate blocks and exposed to two water regimes for 3 weeks. Drought conditions were simulated as repeated periods of water shortage. The total leaf mass and area, leaf area efficiency (shoot growth per unit leaf area, E(A)), area-based leaf N content (N(A)), total leaf N pool (N(L)) and leaf N efficiency (shoot growth per unit leaf N, E(N)) were assessed.

Key results: In the water-stress treatment, shoot biomass growth was N limited in the genotypes with low N(L), but increasingly limited by other factors in the genotypes with greatest N(L). The N(A) was increased by drought, and drought-induced shift in N(A) varied between genotypes (significant G × E). Judged from the E(A)-N(A) relationship, optimal N(A) was 16 % higher in the water-stress compared with the well-watered treatment. Biomass allocation to leaves and shoots varied between treatments, but the treatment response of the leaf : shoot ratio was similar across all genotypes.

Conclusions: It is concluded that N-uptake efficiency and leaf N efficiency are important traits to improve growth under drought. Increased leaf N content (area basis) is an acclimation to optimize N economy under drought. The leaf N content is an interesting trait for breeding of willow bioenergy crops in a climate change future. In contrast, leaf biomass allocation is a less interesting breeding target to improve yield under drought.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acclimatization / physiology*
  • Chimera
  • Dehydration / metabolism*
  • Nitrogen / metabolism*
  • Plant Leaves / chemistry
  • Plant Leaves / metabolism
  • Plant Shoots / metabolism
  • Salix / growth & development
  • Salix / metabolism*

Substances

  • Nitrogen