Klein, I., Institute of Horticulture, ARO, The Volcani Center, Bet Dagen, 50250, Israel
Fanberstein, L., Institute of Horticulture, ARO, The Volcani Center, Bet Dagen, 50250, Israel
Viner, L., Extension Service, Ministry of Agriculture, Raanana, Israel

The leaf macroelement profile of fruiting shoots of persimmon was characterized by a modified diagnostic and recommendation integrated system (DRIS), using SLW as a primary determinant of leaf mineral content. Leaf N, P, Ca, and Mg content was positively and linearly correlated with SLW when expressed on leaf area basis (μg mm-2). Potassium had a negative and higher correlation to SLW when expressed on %DW basis. Mineral ratios relevant for the DRIS analysis were calculated using all four possible combinations of Area (A) and Weight (W) expressions (A/A, A/W, W/A and W/W) and correlated with leaf SLW. The particular expressions chosen for the DRIS analysis were based on their highest correlation to SLW and included N/K, P/K and Ca/Mg, based on the A/W expression of the respective nutrients and the reciprocal expression (W/A) for all other ratios. Derivation of DRIS norms were based on the mineral profile of highly exposed shoots (SLW of 15.0±0.3 mg cm-2). Calculated indices of gradually less exposed shoots (SLW of 3.8-18.9 mg cm-2) revealed a strong exponential imbalance of N, K and P (increasingly positive) vs Ca and Mg (increasingly negative). The calculated Nutritional Imbalance Index (NII) value of leaves decreased exponentially as shoot leaf SLW decreased. The modified DRIS analysis detected successfully a distinct mineral profile of highly vigorous fruiting 'water shoots', as compared to regular fruiting shoots of comparable SLW. © 1993 Kluwer Academic Publishers.