Resposta do bambu gigante Dendrocalamus giganteus à adubação de nitrogênio, fósforo e potássio

Abstract

Bamboo is known as a plant of the thousand uses, having potentiality in the most diferente scopes. However, there are few studies on the management of bamboo fertilization under Brazilian conditions. The objective of this work is to evaluate the response of the giant bamboo Dendrocalamus giganteus Wallich ex Munro to the application of nitrogen (N), phosphorus (P) and potassium (K). The experiment is located in the experimental area of the Federal Technology University of Paraná, campus Dois Vizinhos, where the soil is classified as Red Nitosol. The useful area of the experiment is 1.6 ha, consisting of 240 plants divided into 12 plots. The area was divided in 3 experiments, each containing 4 plots, with doses of each of the nutrients (N, P and K). In experiment 1, 0, 40, 80, 120 and 160 kg of N ha-1 were used; In experiment 2: 0, 40, 80, 120 and 160 kg of P2O5 ha-1 and in experiment 3: 0, 30, 60, 90 and 120 kg of K2O ha-1. The inventory of plants was carried out, with the following evaluations: a) crown area; B) number of stems and shoots; C) height and lap circumference of stems and shoots d) number of stems dead. For the evaluation of the N, P and K content in the leaf tissue samples of leaves of the aerial part of the plants were collected. The leaves were dried, ground and underwent a process of acid digestion for the extraction of nutrients. The determination of the K content was carried out in a flame spectrophotometer, the P content in a UV-Visible spectrophotometer (882nm) and the N content with semi-micro kjeldahl distillation and titration. The results were evaluated through analysis of variance using statistical software R and when significant, the effects of quantitative treatments were compared through regression analysis. There was no significant response to the inventory evaluations of the bamboo plants, except for the variable number of shoots smaller than 10 cm, with a significant response for N and P doses, and for the variable number of dead shoots, which presented a significant dose response From N. N contents in leaf tissue varied between 0.4 and 1.9% and also presented a significant response. P levels were not significant and ranged from 0.109 to 0.241%. P levels were not significant and ranged from 0.109 to 0.241%. The K contents weresignificant and varied between 0,58-1,17%. Excess N may have caused toxicity to stalks causing death or even overgrowth, which are more susceptible to tipping. There was also a negative influence on the development of new shoots, which may also be related to plant physiology. Because it is a perennial species, the evaluation time between fertilization and evaluations is still short, requiring future evaluations to obtain more concrete results on the experiment. It is also suggested the adequacy of inventory techniques and new studies on sample standardization for foliar tissue analysis.