Low vapour pressure deficit affects nitrogen nutrition and foliar metabolites in silver birch.
Air humidity indicated as vapour pressure deficit (VPD) is directly related to transpiration and stomatal function of plants. We studied the effects of VPD and nitrogen (N) supply on leaf metabolites, plant growth, and mineral nutrition with young micropropagated silver birches (Betula pendula Roth.) in a growth chamber experiment. Plants that were grown under low VPD for 26 d had higher biomass, larger stem diameter, more leaves, fewer fallen leaves, and larger total leaf area than plants that were grown under high VPD. Initially, low VPD increased height growth rate and stomatal conductance; however, the effect was transient and the differences between low and high VPD plants became smaller with time. Metabolic adjustment to low VPD reflected N deficiency. The concentrations of N, iron, chlorophyll, amino acids, and soluble carbohydrates were lower and the levels of starch, quercetin glycosides, and raffinose were higher in the leaves that had developed under low VPD compared with high VPD. Additional N supply did not fully overcome the negative effect of low VPD on nutrient status but it diminished the effects of low VPD on leaf metabolism. Thus, with high N supply, the glutamine to glutamate ratio and starch production under low VPD became comparable with the levels under high VPD. The present study demonstrates that low VPD affects carbon and nutrient homeostasis and modifies N allocation of plants.
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland jenna.lihavainen@uef.fi.
Jenna
J
Lihavainen
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 1627, 70211 Kuopio, Finland.
Viivi
V
Ahonen
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
Sarita
S
Keski-Saari
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
Sari
S
Kontunen-Soppela
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
Elina
E
Oksanen
University of Eastern Finland, Department of Environmental and Biological Sciences, PO Box 111, 80101 Joensuu, Finland.
Markku
M
Keinänen
D029662:Betula / Q000254:growth & development / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D006813:Humidity; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D054046:Plant Stomata / Q000378:metabolism; D018526:Plant Transpiration / Q000502:physiology
D009584:Nitrogen
Air humidity; Betula; VPD.; amino acids; carbohydrates; flavonoids; metabolite profiling; mineral nutrients; nitrogen; pendula; starch