Boron fertilization in pêra rio sweet orange affected by citrus variegated chlorosis. / Adubação boratada em pomar de laranja Pêra Rio afetado pela clorose variegada dos citros.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Citrus crop is extremely dependent on an adequate mineral nutrition to reach bigger levels of production to fewer costs, especially under adverse conditions, as in the case of occurrence of citrus variegated chlorosis (CVC). In this context, boron directly influences the production because it provides a bigger root growth, what increases the volume of the explored soil by the roots, maximizes the use of water and fertilizers, as well as because it is directly involved in the cell wall biosynthesis, what contributes to the increase of the general resistance of the plant. The current study was developed from a field experiment and conducted in the period of September/2001 to August/2002, in a commercial field area located in the city of Comendador Gomes (state of MG). Pêra Rio variety grafted on Limão Cravo was used in the eighth year of production, cultivated in Typic Haplustox. The aim of the study was to evaluate the use of boron sources applied to soil in different dosages and its influence in the production and quality of the citrus affected by CVC. Plant nutritional condition, soil chemical attribute evaluations, productivity, and technical and physical attributes of the fruits were evaluated. The sources used were: ulexite fine, ulexite granular, colemanite fine, boric acid and fused boron phosphate, in 1, 2, 3 and 4 kg ha-1 rates. The experimental design used was completely randomized, with 5X4 factorial, besides two additional treatments (control and fused magnesium phosphate), in four replications. The evaluation of the nutritional state was done by leaf chemical analysis sampled six months after the application of the treatments. The chemical attributes of the soil were evaluated through analysis of samples collected eleven months after the application of the treatments, at a depth of 0- 20cm. The production was evaluated on the occasion of the harvest, as well as the technological and physical attributes of the fruits. The results showed that all boron sources promoted significative increases on the leaf boron contents. The higher increase was promoted by boric acid and ulexite fine sources. However didn´t happen source and dose influences on leaf contents of P, Ca e Mg. The boron soil contents remained higher than the level considerate suitable. The higher soil boron content was observed when sources with low solubility like colemanite and fused boron phosphate were applied. Productivity and fruit physical attributes didn´t were influenced by boron sources and dosages in plants with higher incidence of CVC. With the boron doses increase diminish the fruit juice contents.

ASSUNTO(S)

fertilization citrus produção agrícola laranja soil chemical. citrus variegated chlorosis clorose-variegada-dos citros adubação agricultural production boro química do solo. boron

ACESSO AO ARTIGO

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