Normal nutrient ranges by the ChM, DRIS and CND methods and critical level by method of the reduced normal distribution for orange-pera
The use of nutritional diagnoses methods to define ideal and critical nutrient concentrations in plant tissues has proved promising, provided the limits are known. This study determined the normal nutrient ranges for an orange pear population, using the methods mathematical chance (MCh), Integrated Diagnosis and Recommendation (DRIS) and Compositional Nutrient Diagnosis (CND), in addition to the critical level by the reduced normal distribution method. The study was conducted in Bebedouro, São Paulo state, at the Experimental Station of Bebedouro. The total nutrient contents of 50 leaf samples and orange pear yield from an experiment to test applied limestone rates were used as database. For N, the highest value was obtained by MCh class 2 (23.6-24.7 g kg-1), with values similar to those obtained by DRIS (22.1-24.0 g kg-1) and CND (22.1-23.9 g kg-1). Values below these normal ranges agree with the critical level reached (22.7 g kg-1), which is very close to the threshold proposed in the literature. For P, K, Mg, Zn, and B, normal nutrient ranges and critical levels were distant from those reported in the literature. The Ca, Fe, Mn, and Cu values of the normal range and critical level approached the recommended limits, possibly due to a greater variation in the levels. The proposed methods for a population were more appropriate when variation in nutrient content was greater. The amplitude of normal range was narrower than the range of sufficiency levels found in the literature.