Response of wheat seedlings to low O2 concentrations in nutrient solution: II. K +/Na+ selectivity of root tissues9

C. J. Thomson, B. J. Atwell, H. Greenway

    Research output: Contribution to journalArticlepeer-review


    This paper reports the effects of low O2 concentration (0-01, 0-055, and 0115 mol m~3) in nutrient solutions on K+/Na + selectivity of growing and mature root tissues of 6- to 8-d-old, intact, wheat (Triticum aeslivum cv. Gamenya) seedlings.
    Increases in anaerobic catabolism and decreases in O2 uptake, K+ uptake and K+/Na + selectivity were all more pronounced and/or occurred at higher external O2 concentrations in the apex (0-2 mm) than in the expanding tissues (2—4 mm); these growing tissues were, in turn, more affected than the expanded tissues of the roots (4—12 mm).
    Selectivity for K+ over Na + in roots and shoots was particularly sensitive to O2 deficiency. For example, in apical tissues (0-2 mm) K + /Na+ selectivity was already reduced at 0-115 mol m ~3 O2, yet at this O2 concentration there was no effect on either growth or (K+/Na +) uptake.
    Upon transfer from 001 to 0-26 mol m" 3 O2, a detailed study of the 12 mm root tips showed that 70% of these tips regained high (K+ +Na +) concentrations and K+/Na +ratios. In contrast, there was no recovery in the remaining 30% of the 12 mm root tips. Net K.+ transport to the shoots during the period after re-aeration was negative for the population as a whole. The severity of these effects supports the view that the root tips and the stele were more susceptible to O2 deficiency than was the cortex of the fully-developed root tissues.
    Original languageEnglish
    Pages (from-to)993-999
    Number of pages7
    JournalJournal of Experimental Botany
    Issue number9
    Publication statusPublished - Sept 1989


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