The flow of water into fruit trees. I. Resistances to water flow through roots and stems

Abstract

SUMMARY Relative conductivity ( K ) to water in healthy apple trees ranged from maximum values of 18.2 cm 3 .100 s ‐1 .cm length.0.001 Pas.kPa ‐1 .cm ‐2 xylem area, for major suberized roots to values of 1.6 for 1‐yr‐old twigs. The values for equivalent parts of healthy cherry trees were 26.3 and 3.3. Trees with roots affected by the larvae of the fruit tree root weevil ( Leptopius squalidus ) which causes either chronic growth decline or sudden wilting and death, had values as low as 1% of healthy trees, in those parts of the tree showing wilting and lack of growth. Water flow under pressure into the root systems of healthy apple trees increased linearly with increases in pressure from 200 to 800 kPa. Flows into dormant and active root systems respectively were 0.6 and 1.7 cm 3 .100 s ‐1 . 100 cm 2 root surface area. 100 kPa ‐1 .