Norms Establishment of the Diagnosis and Recommendation Integrated System at Preflowering in Pineapple (Ananas comosus L.) and Its Verification in Case of Nutrient Omission Trial by Two Consecutive Crops

This study was conducted to (i) establish the diagnosis and recommendation integrated system (DRIS) for the macronutrient and micronutrient status of pineapple at the preflowering stage and (ii) verify the reliability of the established norms for macronutrients. We collected 86 pineapple leaves at sites +1 and +3 from 86 fields of pineapples grown in acid sulfate soil (ASS) and analyzed their nutrient content. Findings revealed the establishment of 12 and 20 nutrient ratios for DRIS norms at pineapple leaf sites +1 and +3. Based on omission fertilization of N, P, K, Ca, and Mg at the first crop, the DRIS index of N, P, K, and Mg was inadequate in treatments lacking the corresponding nutrients, whereas the DRIS index in the treatment fully fertilized with N, P, K, Ca, and Mg was negative and lower at the +3 leaf position. In the second crop, the DRIS norms were highly reliable via the negative DRIS index when fertilizing without N, P, K, Ca, and Mg. By contrast, when fertilizing with N, P, K, Ca, and Mg, the DRIS index was positive or less negative. The DRIS norms established that position +3 is robust and suitable for evaluating the pineapple macronutrient status.