'Universidad Autonoma de Zacatecas - Francisco Garcia Salinas'
Abstract
The appraisal of soil fertility and the assessment of plant mineral requirements are fundamental for crop management. This study was conducted to determine nutrient norms and to identify significant nutrient interactions in nopal (Opuntia ficus-indica). Preliminary compositional nutrient diagnosis (CND) norms were developed from a small database as means and standard deviations of row-centered log ratios (Vx) of
five nutrients (N, P, K, Ca, and Mg) and a filling value, R, which comprises all nutrients not chemically analyzed and quantified in nopal plants. Preliminary CND norms are: *
N V = -1.13336 ±0.0766, * VP = -2.26110 ±0.1093, * VK = 0.36715 ±0.2329, * VCa = 0.37021 ±0.1047, * VMg = -0.7257 ±0.1413, and * VR5 = 3.38281 ±0.0833. These norms qualify yields higher than 35 kg pl-1 (fresh matter of cladodes oneyear old) registered in an experimental plot with a plant density of 10000 plants per hectare, and are associated to 0.97% N, 0.31% P, 4.47% K, 4.37% Ca, and 1.47% Mg. Four important nutrient interactions were evidenced through principal component analyses: Ca-Mg, Ca-N, Mg-N, and K-P
