DRIS para avaliação nutricional de laranjeira pera no Amazonas

Abstract

The culture of the sweet orange is characterized by being an activity of great social and economic importance in the state of Amazonas, in Brazil as well, but lacks information related to nutritional standards for the Amazon region. In this sense, the objective was to establish sufficiency range (SR), the critical level (CL) and standards through Compositional Nutrient Diagnosis (CND) to assess nutritional status of sweet orange in different phases of development. 120 plots were monitored commercial sweet orange grafted in lemon clove, sampled in citrus-producing region in the Amazon, in the municipalities: Iranduba, Manacapuru, Manaus, Presidente Figueiredo and Rio Preto da Eva between 2010 and 2011. The FS, NC and CND norms for orange fruits with six months of age were established from the set of plots, while the standards for CND orange phase of full flowering and fruit three and six months of age were obtained from orchards with productivity exceeding 25 tonnes ha-1 in the main crop (June 2012). SR, CL and CND standards for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe ), manganese (Mn) and zinc (Zn) were established to sweet oranges in different phases of development. The diagnosis through nutritional standards CND has a low level of agreement compared to nutritional standards proposed by the literature. RS and CL obtained by CND disagree with the CL proposed in the literature for most nutrients. In almost 50% of the plots monitored, P, K, Ca, S, B, Cu and Fe are below critical levels proposed in this paper. The nutritional status of orange varied with foliar sampling period. The concentration of foliar N, P, K and Cu were higher, Ca and Zn in smaller flowering page. It is suggested that the sweet orange has different nutritional requirements among the three phenological stages.