Study of the Nutritional Status in Thomson navel sweet orange orchards from East of Mazandaran by using the Compositional Nutrient Diagnosis (CND) method

In order to study the nutritional status of orange orchards, Thompson navel sweet orange in north of Iran (east of Mazandaran province) through CND method, 133 orchards were studied in summer (August). After selecting and as signing 30 trees in each orchard, plant samples were taken from the trees in a proper time to determine concentration of the elements and their average yield was measured in the harvest season. By using the cumulative distribution function (CDF) of nutrients variance ratio model in this work, 27 orchards were considered as the high yielding group and 106 orchards were considered as the low yielding group. By solving the third-degree cumulative function equations related to the elements, the related yields were calculated and the cut-off yield was determined 58 ton ha-1. The norms were calculated for 10 elements from average concentrations of high yield groups: N 2.32±0.24%; P 0.17±0.01%; K 1.74±0.24%; Ca 3.38±0.94%; Mg 0.41± 0.08%; Mn 40±18 mg kg-1; Zn 45.8±25 mg kg-1; Fe 199.4±78 mg kg-1; Cu 14±6.7 mg kg-1; B 80±36 mg kg-1.  Measured norms showed that K, P and Mn showed more deficiency in the orchards, respectively.