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To determine critical values for macro and micronutrients in main four fruit orchards of Iran, including grape (bidaneh cultivar in Qazvin and east azarbaijan), date palm ( Estamaran in khozestan, kabkab in boushehr,mazafati in south of Kerman and piarom in hormozgan), apple ( red in semirom and golden delicious in west Azarbijan) , 40 orchards were selected. In each of them, 30 unique trees were marked and soil and leaf samples were taken in the right time and two year collected yields of each orchard was recorded in the harvest time. By using the average of measured nutrients norms for the high yielding community the concentration of the 10 studied elements was obtained. These results were confirmed by findings of the multivariate statistical analysis method as well as known Compositional Nnutrients Diagnosis to determine optimum yield for each region. Results showed that yield mean and nutrients levels mean in two yielding group were different. Each crop and each region had its own restricted nutrients which reduced yield. Between cultivar, region and yields were significant differneces for optimum nutrient levels. Nutrients norm for high yielding group were assessed for seedless grape as followed, N: 2.32, P:0.19, K: 2.0, Ca: 2.3, Mg: 0.46, Mn: 176, Zn: 52, Fe: 373, Cu: 12,0, B:64 in Qazvin region while for East Azarbaijan region showed N:2.8, P: 0.64, Mn: 69, Zn: 39, Fe: 104, Cu: 18. The nutreints norms for Valencia orange in south of Fars as N: 3.0, P: 0.17, K: 1.37, Ca:3.3, Mg: 0.36, Mn:23, Zn: 17, Fe: 75, Cu: 7.8, B: 76 and for Thompson Navel orange in Mazandaran region were for N: 2.3, P:0.17, K: 1.73, Ca: 3.3, Mg: 0.41, Mn: 41, Zn: 38, Fe: 199,cu: 14.6 and B: 81. Nutrients norm for red apple orchards in semirom region as N:.17, P: 0.25, K:2.0, Ca:1.9, Mg: 0.38, Mn: 69, Zn: 17, Fe: 188, Cu:6 and B:48 while for golden apple in Urumia were N:1.52, P: 0.24, K: 1.94, Ca: 1.8, Mg: 0.85, Mn: 33, Zn: 25, Fe:101, Cu:12. Nutrients norms for piarom date palm in Hormozgan were N: 1.9, P: 0.4, K: 1.4, Ca: 1.65, Mg: 0.4, Fe: 270, Mn: 44, Zn: 11, Cu:5.7, B: 85 and for Kabkab in Boshehr N:1.5, P: 0.24, K:1.36, Mn: 32, Zn: 20, Fe: 281, Cu: 5.7. for mazafati date palm in south Kerman region; N: 1.4, P: 0.33m K: 0.9, Ca: 1.1 Mg: 0.5, Mn : 55, Zn: 35, Fe: 308, Cu: 11 and B:112. For estamaran cultivar in Khozestan region for N: 1.1, P: 0.28, K: 1.1, Ca: 1.19, Mg:0.31, Mn:230, Zn: 45, Fe:230, Cu: 9 were obtained. These nutrient levels impacted on yields but one or two elements were key role to shrink the yields those are managebale to increase production in low yielding orchrads. Keywords: fruit tress, critical values, Nutritional Management, Reference Norms.
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