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The Diagnostic Recommendation and Integrated System (DRIS) is a unique statistical tool and dual ratio concept employed to diagnose nutrient imbalance and identify most yield limiting nutrients. In present study a reliable data bank of nutrient concentration versus fruit yield was developed from survey of litchi orchards grown in lower Himalayas (Uttarakhand, India). Firstly the DRIS norms were established for various nutrient ratios which obtained from the high-yield population (HYP) and then they were used to compute DRIS indices in low yielding population (LYP). Sixty-six nutrient expressions were selected as DRIS ratio norms from HYP and were found to provide statistically significant variance ratios and lower co-efficient of variations. The important nutrient ratio expressions identified in the backdrop of greater physiological significance in fruiting terminals (FT) of litchi are: P/N (0.292), Ca/N (1.274), Mg/N (0.438), P/Mg (0.667), Ca/S (10.08), Zn/S (116.7), Fe/Cu (17.13) and Cu/B (0.252) whereas for non-fruiting terminals (NFT) that expressions are N/P (3.185), K/N (0.942), Cu/N (13.60), P/Zn (0.017), K/Mg (2.250), Ca/Mg (3.417) and Cu/Zn (0.727). The nutrient element S followed by Zn, Mo and B in FT whereas in NFT, S followed by Mo, B and Zn are most common yield-limiting nutrients in LYP of litchi.
Keywords: DRIS, Litchi, Nutrient ratios, Nutrient imbalance index, Yield limiting nutreint.