Journal of Applied Horticulture. 2003: 5(2): 76-80

Evaluation of DRIS and CND indexes for effective nutrient management in Muscat grapevines (Vitis vinefera)

Kumar, P S S; Geetha, S A; Savithri, P; Mahendran, P P; Ragunath, K P

Department of Soil Science and Agricultural Chemistry, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore - 641 003, India.

The Compositional Nutrient Diagnosis (CND) and Diagnosis and Recommendation Integrated System (DRIS) nutrient index ranges were derived from a Muscat grape database to relate nutrient concentration and indexes with berry yield. A Muscat grape database of 188 observations on commercial yields and N, P, K, Ca, Mg, Na, S, B, Zn, Cu, Fe and Mn were taken. The proportion of low-yield specimens in the survey population was computed at inflection point of variance ratio function and was associated with a Cate and Nelson statistical value (r2) of 4.7 that was confirmed in the validation subpopulation. Critical CND nutrient indexes were found to be symmetrical about zero as follows: -0.45 to +0.45 for CND/N, -0.39 to +0.39 for CND/P, -0.45 to +0.45 for CND/K, -0.93 to +0.93 for CND/Na, -0.45 to +0.45 for CND/Ca, -0.33 to +0.33 for CND/Mg, -0.60 to +0.60 for CND/S, -1.02 to +1.02 for CND/B, -0.58 to +0.58 for CND/Zn, -0.78 to +0.78 for CND/Cu, -0.55 to +0.55 for CND/Fe, -0.16 to +0.16 for CND/Mn and -0.49 to +0.49 for CND/R12. Summing squared critical nutrient indexes also gave a CND rr of 4.76, the minimum CND imbalance index for high-yield targets (>21.1 Mg ha-1). The yield-index relationship was close with CND (R2=0.806) compared with DRIS (R2=0.664). The Zn concentration was poorly related to yield (R2=0.31). Hence, CND appeared to be the most sensitive diagnosis for early detection of Zn stress in Muscat grape than DRIS and could be instrumental in adjusting fertilization to crop needs after crop emergence and the CND index was the most closely related to berry yield.