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WATER USE AND SODIUM CHLORIDE UPTAKE BY APPLE TREES: II. THE RESPONSE TO SOIL OXYGEN DEFICIENCY

D. W. WEST
Plant and Soil
Vol. 50, No. 1 (AUGUST 1978), pp. 51-65
Published by: Springer
Stable URL: http://www.jstor.org/stable/42947173
Page Count: 15
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WATER USE AND SODIUM CHLORIDE UPTAKE BY APPLE TREES: II. THE RESPONSE TO SOIL OXYGEN DEFICIENCY
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Abstract

Apple trees (Malus sylvestris Mill. cv. 'Granny Smith') were grown with divided root systems and were exposed to combinations of soil salinity (90 meq l⁻¹) and partial soil oxygen deficiency (waterlogging) in half root zones to simulate three of the conditions in which these combinations of double stress may occur in the field. Whenever a salinity stress was applied to a root zone, water uptake from that root zone was depressed to approximately 50% of normal levels while water uptake from the non-saline root zone increased by 50% over normal. If a low oxygen stress was superimposed upon the salinity stress, water uptake declined even more (to 30% of normal) and uptake in the non-stressed zone increased proportionately (to 60% above normal non-stress levels). When an oxygen stress was applied to one root zone and a salinity stress to the other, water uptake in the saline zone again dropped by 50% under normal but uptake increased by only 30% in the non-saline zone. With one saline root zone and both root zones waterlogged water uptake dropped to 30% in the zone with the double stress but there was no increase in water uptake from the non-saline oxygen stressed zone. Exposure of a half root zone to salinity resulted in chloride concentrations in the roots increasing 5-fold compared with the non-saline zone. However, the chloride was retained in the roots and not transported to the leaves so that leaf chloride concentrations were not significantly different from non-salinized plants. When a plant was exposed to a waterlogged saline solution in one half root zone, leaf chloride concentration increased more than 4-fold over initial concentration if the other rootzone was not waterlogged and when both saline and non-saline root zones were waterlogged, leaf chloride concentration increased almost 7-fold over initial concentrations. Any exposure of roots to NaCl stress resulted in significantly higher root Cl than occurred in nonsalinized roots.

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