The effect of flooding on the ethanol accumulation in young apple rootstocks was investigated in relation to water tolerance.
Flooding accumulated high quantity of ethanol in the roots of M9 (water sensitive), but no or little accumulation was observed in those of Malus prunifolia (water tolerant). In `Fuji´ apple trees grafted on both rootstocks, ethanol accumulation was also found in the roots of M9, while a slight accumulation in those of Malus prunifolia and in the stems of the trees on either rootstocks.
A severe chlorosis and desiccation was appeared on the leaves of M9 by flooding, while only slight injury in Malus prunifolia. In the M9 roots, O₂ uptake and CO₂ evolution in reponse to flooding were rapidly decreased, however, those of Malus prunifolia gradually declined with time of flooding.
Application of ethanol at concentration of 10 and 15% greatly reduced the stem increment of `Fuji´ apple trees on M9 and Malas prunifolia, but there was no difference between two rootstocks in response to an exogenous ethanol treatment.
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