| Abstract: | Abstract The Diagnostic and Recommendation Integrated System (DRIS) was employed for interpreting nutrient analyses of leaf tissue of guava fruit trees (Psidium guajava L.) cultivated in Punjab, northwest India. Standard reference DRIS norms were established for various nutrient ratios and used to compute DRIS indices, which assessed nutrient balance and order of limitation to yield. The DRIS evaluation and sufficiency range approach were equally effective and in agreement for diagnosing deficiencies of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), manganese (Mn), zinc (Zn), and copper (Cu). The results also show that the position of leaf tissue sampled does not have a major effect on the DRIS diagnosis. Nutrient sufficiency ranges derived from DRIS norms were 1.41–1.65, 0.10–0.17, 0.51–0.97, 1.16–2.12, 0.31–0.51, 0.18–0.28% for N, P, K, Ca, magnesium (Mg), and S and were 105–153, 58–110, 15–29, and 6–16 mg Kg?1 for iron (Fe), Mn, Zn, and Cu, respectively. According to these sufficiency ranges 35, 62, 51, 75, 70, and 68% of samples were sufficient, and 4, 29, 36, 9, 10, and 22% of samples were low in N, P, K, Ca, Mg, and S, respectively. More than 50 and 2% of the guava trees selected for sampling was found to deficient in N and P, respectively. For micronutrients, 15, 6, and 7% of samples were found to be low in Mn, Zn, and Cu. |
