Root or shoot nitrate assimilation in terrestrial vascular plants – does it matter?

Mitchell Andrews (Lead / Corresponding author), John A. Raven

    Research output: Contribution to journalReview articlepeer-review

    2 Citations (Scopus)

    Abstract

    Background: Most terrestrial vascular plants can assimilate soil obtained NO3- in their root and shoot. Scope: Data from the literature are collated and analysed with respect to genotype and environmental effects on the partitioning of NO3- assimilation between root and shoot of terrestrial vascular plants. Conclusions: Temperate evergreen woody species in the Ericaceae and Pinaceae carry out most of their NO3- assimilation in the root when growing in low (0.5 mM) up to at least 5 mM soil NO3-. The root is the main site of NO3- assimilation for temperate deciduous woody species and perennial and annual herbaceous legume species at 0.5–1 mM NO3- but for many, shoot assimilation increases in importance with increased NO3- supply. Temperate perennial grasses and annual non-legume species and tropical/ sub-tropical species regardless of life-form, carry out a substantial, usually major proportion of their NO3- assimilation in shoots at NO3- concentrations above 0.5 mM. Furthermore, high NH4+ supply, mycorrhizal infection and infection by parasitic plants can increase the proportion of total plant NO3- assimilation carried out in the shoot while abiotic stress and elevated atmospheric [CO2] can cause this to decrease. Shoot NO3- assimilation is an advantage under non-stress conditions due to its positive effect on leaf expansion but can be a disadvantage under freezing and chilling stress conditions. Increased reliance on root NO3- assimilation at elevated CO2 was associated with increased and conversely decreased plant growth and NO3- assimilation depending on study. Resolution of these different findings across studies is an important area for further research.

    Original languageEnglish
    Pages (from-to)31-62
    Number of pages32
    JournalPlant and Soil
    Volume476
    Early online date31 Jan 2022
    DOIs
    Publication statusPublished - Jul 2022

    Keywords

    • Atmospheric CO
    • Chilling stress
    • Freezing stress
    • Leaf expansion
    • Nitrate reductase
    • pH regulation
    • Photoreduction of nitrate
    • Stress tolerance
    • Xylem sap nitrate
    • δN

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