EFFECTS OF PACLOBUTRAZOL AND CROP-LOAD ON MINERAL ELEMENT CONCENTRATION IN DIFFERENT ORGANS OF “CATHERINE” PEACH TREES

ABSTRACT

The concentration of mineral elements in leaves and shoots of “Catherine” peach [Prunus persica (L.) Batsch.] trees with different crop-loads and treated with or without 2 g paclobutrazol (PP333) was analyzed. For most elements, the concentrations in the leaf varied linearly along the growing season, the concentrations of nitrogen (N), potassium (K), copper (Cu), and zinc (Zn) decreasing, those of calcium (Ca), magnesium (Mg), and manganese (Mn) increasing, while the concentration of iron (Fe) did not follow a clear pattern. PP333 increased concentration of calcium (Ca), Mg, Fe and Mn, and a decrease in K, while the pattern of change of concentration of N varied so that more N was exported from leaves of PP333 treated trees than from untreated trees. Crop-load also affected leaf N, Mg, and Mn concentration, but no effects were observed on K, Ca, and Fe concentration. In terminal shoots, PP333 increased the concentrations of all elements except K and Mg, and the level of cropping induced changes in the behavior of several elements: K, Mg, Fe, Mn, and Cu concentrations increased with crop-load in control trees, while in PP333-treated trees, they either decreased (Fe, Mn, and Cu) or remain unchanged (K and Mg), and phosphorus (P) concentration decreased both in PP333-treated or untreated trees. It is concluded that mineral element distribution among leaves and shoots is affected by PP333 and by the level of cropping.

ACKNOWLEDGMENTS

The authors acknowledge A.L.M. Group for the facilities provided to carry the experiment, particularly Mr. J.M. Soriano, Mr. C. Flamarique, and Dr. J. Negueroles, and Zeneca for gifts of PP333. Thanks are also due to Dr. R.B. Austin and Dr. Gomez Aparisi for helpful discussion of the paper. The work was carried-out under research project CICYT AGR90-0792.