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Four field experiments were established at different locations to study the influence of Zn alone and combined Zn + Fe, Zn + B and Zn + Fe + B applications on leaf and fruit absorption levels by “Gemlik” table olive cultivar ( Olea europea L.) trees. The treatments of every experiment were consisted of control, soil and foliar applications. Soil applied Zn did not have an effect on Zn contents of either the leaves or the fruit in each year of the experiments. Every treatments of foliar applied Zn elevated sufficiently Zn contents of the leaves. Four times foliar application of each dose should be conducted due to more evident increases in the fruit Zn contents. Foliar applications of double and triple combinations of Zn with Fe and B increased significantly Zn, Fe and B concentrations in the olive trees.

Foliar analysis is usually adopted for nutrient diagnosis in fruit trees, particularly citrus trees, but the results are only applicable in the subsequent year. Flowers are a precursor to fruit, and their nutrients should have a direct effect on the yield and fruit quality of a tree. A field experiment was conducted to research the relationship between the nutrient concentrations of flowers and leaves to determine whether flower analysis could be used for nutrient diagnosis in the Satsuma mandarin ( Citrus unshiu Marc .). The point observation method was adopted. Flower and leaf samples were collected from 616 trees in 77 sampling locations in April and September. N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, B and Mo concentrations in the flower and leaf samples were analyzed. The regression analyses between the nutrient concentrations in the flowers and leaves were performed. The results showed that the K, Mn, Cu, Ca and B concentrations in the citrus flowers were significantly correlated with those in the leaves. The N, P, K, Cu and Zn concentrations in the citrus flowers were higher than those in the leaves, whereas the Ca, Mg, Mn and B concentrations were lower in the flowers. Higher coefficients of variation were observed for most of the nutrient concentrations of the citrus flowers, indicating a sensitive response to nutritional status changes. Regression analyses and grade standards showed the flower critical concentrations of K, Ca, Cu, Fe and B to be 2.08%, 0.56%, 13.80 mg/kg, 69.90 mg/kg and 33.20 mg/kg, respectively. These results suggest that floral analysis could be used as an early method of nutrient diagnosis for Satsuma mandarin ( Citrus unshiu Marc. ).

Correlations between macro and micronutrient concentration of olive leaves and those obtained in floral buds at five development stages, were studied in order to evaluate the utility of floral analysis for the diagnosis of the nutritional status of olive orchards. Olive leaves from ‘Arbequina’, ‘Frantoio’, ‘Hojiblanca’, ‘Bella de Espana’ and ‘Picual’ cultivars were taken during July of 2002 and 2003. Samples of floral buds were collected at five development stages: closed bud (E), petal fall (G), G + 15 days, G + 30 days and pit hardening (H). Results showed a lack of signification of the correlation coefficients between leaf and floral analysis for N, P, K, Ca, Mg, B, Zn, Mn, Fe, Cu and Na in both years of the experiment. The few significant correlations obtained were not repeated in both years. Therefore, the results indicate that floral bud mineral analyses cannot substitute the foliar diagnosis to establish the nutritional status of the olive orchards.

Mature ‘on’ and ‘off’ ‘Manzanillo’ olives trees with three healthy branches of 10–12 cm in diameter were selected to determine changes in nitrogen levels in the bearing shoots after foliar application of urea. Each selected branch of each tree received one of the following treatments: (i) control without urea application; (ii) foliar application of urea to all the current-season leaves; and (iii) foliar application of urea to all the one-year-old leaves. Urea was applied in May, four days after full bloom in the ‘on’ year trees. Each treated leaf was immersed in a test tube containing a 4% urea solution and 0.1% Tween 20 for 5 s. Bearing shoots, composed of both one-year stems and leaves and current-season stems and leaves, were collected at intervals from the beginning of the experiment until 64 days after urea application. Nitrogen was determined in stems and leaves from each part of the bearing shoot, and in fruits during the ‘on’ year. Nitrogen uptake from the leaves was rapidly mobilized from the older to the current-season leaves of the bearing shoot, and thereafter to other storage organs of the tree or to the fruit, which is the largest nitrogen sink in the bearing shoot. No translocation of nitrogen from the current-season leaves to older leaves was observed. The rapid translocation of nitrogen from the younger leaves to other storage organs of the tree could explain the insensitivity of leaf analysis to detect excess nitrogen, since mature leaves from current-season shoots must be sampled to determine the nutritional status of the tree. The failure of leaf analysis to detect excess nitrogen may be a cause of nitrogen over-fertilization in olive orchards.

Graft combinations of potato and tomato were cultivated to study the dry matter and mineral nutrient distribution in plants with and without one or two storage organs. N and P entered the fruits and tubers in an order of magnitude roughly comparable to dry matter distribution; K entered them even more liberally than would correspond to their relative dry matter content, whereas Ca and Mg showed a distribution pattern completely different from that of dry matter or N, P and K. Obviously, it is very difficult to bring sizeable quantities of Ca and Mg into fruits and tubers. This observation is discussed with reference to the prevention of so-called calcium and magnesium deficiency disorders in fruits and with regard to possible changes in leaf analysis values obtained for some of the major nutrients.