Determination of norms and limitation of Nutrients for Orange by the Compositional Nutrient Diagnosis (CND) method

Nutrients status in plants with high yield can be a real benchmark for evaluating the growth and desirable nutrient status in the plant. The first step in the implementation of each nutritional diagnosis method is determining norms. The aims of this study were determining norms, rang of optimum concentration and limitation of nutrients for orange by compositional nutrient diagnosis method.
Material and This study was conducted in 30 citrus orchards in the tropical and semi-tropical regions of Kohgiluyeh and Boyer-Ahmad Province. The base of selecting these orchards was the similarity in age and variety, with different yield. Composite samples of soil and leaf were taken by standard method and analyzed by using appropriate laboratory methods. The yield of each orchard was determined at the harvest time. Norms of nutrients were determined by compositional nutrient diagnosis method.
By using the model of cumulative variance ratio function of nutrients and solving cumulative third-rank function related to 10 nutrients along and also remaining concentration, the yield related to each of them was calculated with unit of ton per hectare as 15.83 for nitrogen, 14.17 for phosphorus, 18.90 for potassium, 14.27 for calcium, 7.69 for magnesium, 15.44 for manganese, 13.84 for zinc, 13.51 for iron, 15.33 for copper, 14.78 for boron and 16.71 for remained nutrients (Rd). Based on average of optimal yield, the goal yield was determined as 14.62 ton per hectare and with attention to the goal yield, 43% of the selected orchards were located in high-yield subpopulation and 57% of them were located in low-yield subpopulation. This was confirmed by Cate-Nelson method. Compositional nutrients diagnosis norms were estimated as: V*N = 3.12± 0.192 ,V*P = 0.47± 0.227, V*K = 2.8± 0.179, V*Ca = 3.36± 0.156, V*Mg = 0.96± 0.131, V*Mn= -3.35± 0.269, V*Zn = -4.16± 0.136, V*Fe = -2.67± 0.354 , V*Cu = -4.92± 0.115, V*B = -2.39± 0.235 and V*Rd = 6.79± 0.066. Optimal range of nutrients for orange to achieve yield of about 15 ton per hectare were determined as 2.38±0.335 for nitrogen, 0.17±0.033 for phosphorus, 1.73± 0.235 for potassium, 3.02 ± 0.415 for calcium, 0.27 ± 0.040 for magnesium, 38.21 ± 11.44 for manganese, 16.38 ± 2.52 for zinc, 77.7± 31.57 for iron, 7.63 ± 1.04 for copper and 98.54 ± 29.24 for boron.
Imbalance of nutrients such as boron and some cations can be one of the reasons of locating 57% of orchards in low-yield subpopulation. In this way, results showed that the concentration of boron in some samples was higher than norm while, the deficiency of four elements, including magnesium, zinc, iron, and calcium is more common in these areas of the province, which it can be a reason for decreasing of yield.