Establishment of nutrients optimal range for nutritional diagnosis of mandarins based on DRIS and CND methods

ABSTRACT

The aim of this work was to establish for the first time nutrient optimal range (NOR) for mandarins in Tunisia using two methods: Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND). The study was performed using data from 120 mandarin’s commercial orchards, in several locations in Tunisia. Yield data and leaf nutrient content from 2011 to 2014 cropping season were compiled in a database. Leaf samples consist of spring flush leaves (7–8 months old) collected from nonfruiting terminals. The two methods were effective to diagnose the plant nutritional status based on the effectiveness of the chi-square-tested method. The two methods showed the nutrient imbalances of the studied commercial orchards. Phosphorus (P) and iron (Fe) showed higher frequencies as the most required nutrients by the plant. The found norms were then compared to the norms used in other countries. The new norms for mandarins are different because some norms in the literature do not take into account the different species of citrus, and they were adopted in different pedoclimatic conditions. So, adopting the new leaf nutrient norms is key for ensuring productivity in mandarin citrus orchards in Tunisia.

KEYWORDS:

• Leaf standards
• macronutrients
• micronutrients
• mineral nutrition
• mediterranean conditions