ISHS Acta Horticulturae 343: Physiological Basis of Postharvest Technologies
LEAF AREA, XYLEM CYCLING AND CA STATUS IN APPLES |
| Authors: | A. Lang, R.K. Volz |
| Abstract:
Low Ca concentrations at harvest predispose apple fruit to physiological disorders during storage and advance fruit senescence. Tree factors regulating Ca partitioning into apples are poorly understood, however, although the presence of large numbers of subtending spur and bourse leaves can improve Ca uptake by fruit (Jones and Samuelson, 1983; Ferree and Palmer, 1982; Volz et al., 1992). It has been suggested that the transpirational pull from these nearby leaves is somehow able to direct Ca towards the fruit. Recently it has been shown that the familiar diumal pattern of fruit shrinkage and expansion in apples (Tromp, 1979) occurs as a result of reversals of xylem sap flow between fruit and tree (Lang, 1990). Because Ca is known to move exclusively in the xylem system (Marschner, 1983) it is possible that the effect of nearby leaves on fruit Ca nutrition is in some way linked to the xylem reversal patterns. Our study explores this link. | |
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