Enriched rhizosphere CO2 concentrations can ameliorate the influence of salinity on hydroponically grown tomato plants

M. D. Cramer, S. H. Lips

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    77 Scopus citations


    Our previous work indicated that salinity caused a shift in the predominant site of nitrate reduction and assimilation from the shoot to the root in tomato plants. In the present work we tested whether an enhanced supply of dissolved inorganic carbon (DIC, CO2+ HCO3) to the root solution could increase anaplerotic provision of carbon compounds for the increased nitrogen assimilation in the root of salinity‐stressed Lycopersicon esculentum (L.) Mill. cv. F144. The seedlings were grown in hydroponic culture with 0 or 100mM NaCl and aeration of the root solution with either ambient or CO2‐enriched air (5000 μmol mol−1). The salinity‐treated plants accumulated more dry weight and higher total N when the roots were supplied with CO2‐enriched aeration than when aerated with ambient air. Plants grown with salinity and enriched DIC also had higher rates of NO3 uptake and translocated more NO3 and reduced N in the xylem sap than did equivalent plants grown with ambient DIC. Incorporation of DIC was measured by supplying a 1 ‐h pulse of H14CO3 to the roots followed by extraction with 80% ethanol. Enriched DIC increased root incorporation of DIC 10‐fold in both salinized and non‐salinized plants. In salinity‐stressed plants, the products of dissolved inorganic 14C were preferentially diverted into amino acid synthesis to a greater extent than in non‐salinized plants in which label was accumulated in organic acids. It was concluded that enriched DIC can increase the supply of N and anaplerotic carbon for amino acid synthesis in roots of salinized plants. Thus enriched DIC could relieve the limitation of carbon supply for ammonium assimilation and thus ameliorate the influence of salinity on NO3 uptake and assimilation as well as on plant growth.

    Original languageEnglish
    Pages (from-to)425-432
    Number of pages8
    JournalPhysiologia Plantarum
    Issue number3
    StatePublished - 1 Jan 1995


    • Carbon dioxide
    • Lycopersicon esculentum
    • nitrate
    • nitrate reductase
    • phosphoenolpyruvate carboxylase
    • potassium
    • respiration
    • salinity
    • tomato

    ASJC Scopus subject areas

    • Physiology
    • Genetics
    • Plant Science
    • Cell Biology


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