Acclimation of leaf nitrogen to vertical light gradient at anthesis in wheat is a whole-plant process that scales with the size of the canopy

Delphine Moreau (1, 2, 3) , Vincent Allard (1, 3) , Oorbessy Gaju (3) , Jacques Le Gouis (1, 3) , M. John Foulkes (3) , Pierre Martres (1, 3)

1 GDEC - Génétique Diversité et Ecophysiologie des Céréales
2 Agroécologie [Dijon]
3 Division of Plant and Crop Sciences, School of Biosciences

Vertical leaf nitrogen (N) gradient within a canopy is classically considered as a key adaptation to the local light environment that would tend to maximize canopy photosynthesis. We studied the vertical leaf N gradient with respect to the light gradient for wheat (Triticum aestivum) canopies with the aims of quantifying its modulation by crop N status and genetic variability and analyzing its ecophysiological determinants. The vertical distribution of leaf N and light was analyzed at anthesis for 16 cultivars grown in the field in two consecutive seasons under two levels of N. The N extinction coefficient with respect to light (b) varied with N supply and cultivar. Interestingly, a scaling relationship was observed between b and the size of the canopy for all the cultivars in the different environmental conditions. The scaling coefficient of the b-green area index relationship differed among cultivars, suggesting that cultivars could be more or less adapted to low-productivity environments. We conclude that the acclimation of the leaf N gradient to the light gradient is a whole-plant process that depends on canopy size. This study demonstrates that modeling leaf N distribution and canopy expansion based on the assumption that leaf N distribution parallels that of the light is inappropriate. We provide a robust relationship accounting for vertical leaf N gradient with respect to vertical light gradient as a function of canopy size.

Domaines: Sciences du Vivant [q-bio]

Delphine Moreau, Vincent Allard, Oorbessy Gaju, Jacques Le Gouis, M. John Foulkes, et al.. Acclimation of leaf nitrogen to vertical light gradient at anthesis in wheat is a whole-plant process that scales with the size of the canopy. Plant Physiology, 2012, 160 (3), pp.1479-1490. ⟨10.1104/pp.112.199935⟩. ⟨hal-01001606⟩