Resumo

BLANCO-MACIAS, F. et al. Comparison between CND norms and boundary-line approach nutrient standards: Opuntia ficus-indica L. case. Rev. Chapingo Ser.Hortic [online]. 2009, vol.15, n.2, pp.217-223. ISSN 2007-4034.

It is a need to know optimum concentrations and/or optimum ranges of nutrients useful for correct diagnosis and improvements of nutrient status of cultivated plants. Recognizing the need to develop correct nutritional standards, it is convenient to improve or to ensure the reliability of those already determined. Having in mind that aim, boundary-line approach standards were developed taking into account data acquired from a field experiment to study the effects of three fertilization treatments on yield of Opuntia ficus-indica L. The developed boundary-line approach standards were compared with already developed compositional nutrient diagnosis norms for N, P, K, Ca, and Mg concentrations in one-year old cladodes, and cladodes fresh matter as yield in order to define correct nutrient standards. The developed boundary-line approach optimum nutrient concentrations (associated to estimated maximum yield) for Opuntia ficus-indica L. are: N = 1.42%, P = 0.38%, K = 4.55%, Ca = 2.83% and Mg = 1.41%. Results suggest that boundary-line approach estimated standards could be trustful and that lower and upper concentrations of the boundary-line approach sufficiency nutrient ranges could be also reliable as well as those for compositional nutrient diagnosis norms.

Palavras-chave : plant nutrition; CND norms; BLA standards.