Balanced nutrients application is essential to increase yield, improve quality and prevent contaminations. Orange orchards in the calcareous soil widely suffer from calcium (Ca) and zinc (Zn) deficiencies because they are immobile in plants while there are abundant of calcium carbonate in the soil. In order to supply Ca and Zn for orange fruits, a study was conducted in the south western of Iran. The foliar application of calcium and zinc on yield, calcium, zinc and boron concentration and some quality Characteristics of orange (cv.valencia) was conducted in two growing seasons as a factorial design based on completely randomized block with nine treatments and three replications. Treatments were spraying of calcium chloride at three levels (0, 0.25%, and 0.5%) and foliar of zinc spraying from zinc sulfate at three levels (0, 0.25%, and 0.5%) at fruitlet and repeated twice every 30 days. Results showed that interaction of calcium and zinc on yield has been significant (p≤0.05) and increased Ca and Zn levels in the foliage. Meanwhile, the boron (B) status decreased by Ca application in 0.25% concentration significantly. Ca and Zn foliar treatments both resulted on B reduction in the orange leaves. Since orange orchards in the region shows visual of high boron symptoms, combined Ca and Zn spraying reduced boron toxicity effect rather than solely application.

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