Effect of girdling on gas exchanges and leaf mineral content in the "independence" nectarine
2001
Di Vaio, C. | Petito, A. | Buccheri, M.
The aim of this work was to analyze the physiological modifications induced by girdling, and to evaluate their effects on the gas exchanges and mobility of the mineral elements in peach leaves. On 15 trees, sixty 1-yr-old shoots were chosen, thirty of which were girdled (a ring of bark 1 cm thick was removed), and 30 were used as control. The fruits were removed from half the girdled shoots and from the same number of control shoots. The following data were taken from all shoots: measurements of gas exchanges, analysis of leaf mineral content, analysis of leaf and shoot characteristics, analysis of fruit characteristics. In the girdled shoots a reduction in their development, an improvement in fruit quality and earlier ripening was noted. Girdling, breaking off the phloematic flow, causes a store of elaborated sap in the portion of the shoot over the girdling that inhibits the photosynthetic activity of the leaves. On the girdled shoots the presence of fruit, which is a sink for nutritive elements, promotes photosynthesis and transpiration. Transpiration and the store of mineral elements [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] in the leaves appeared closely connected. Indeed, after a reduction in the transpiration rate of the leaves of the girdled shoots, there was a decrease in the store of all the mineral elements analyzed. Our observations confirmed the check of gas exchanges due to girdling and due to the presence of fruit, and show that girdling has a clear effect on the nutritional state of the leaves.
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