Respostas de dendróbio borboleta (Dendrobium phalaenopsis Fitzgerald) à luminosidade e substratos

Abstract

The aim of this work was to evaluate the influence of light and alternative substrates to xaxim on acclimatization, development and flowering of Dendrobium Phalaenopsis var. "semi-alba” (Orchidaceae). The experiment was conducted in the area of Jardinocultura of FCA/UFGD from October 2007 to August 2008. The plants used were 4 years old and produced by in vitro sowing, acclimatized in nurseries with coverings that provide 12800, 8300, 6200, 5300, 4500 lux of light intensities. The plants were planted in plastic pots containing as substrate charcoal, coconut fiber or a mixture of carbon + fiber coconut. It was used a randomized completely design and the treatments were arranged in split-plot, the plots were the 5 levels of light intensity conditions and the subplots the 3 substrates, with 10 repetitions. During the experimental period there were evaluated the increments in weight, in number, diameter and length of pseudobulbs, the number of keikis produced, the length of the floral stem, number of flower buds, flower diameter and the duration of the flowering period. There was a positive increase in the number and height of pseudobulbs and the number of keikis produced, but there were no significant differences between the treatments for these characteristics. There were observed a decrease in the weight and diameter of pseudobulbs and the length of the roots. Under the conditions in which the work was conducted it is recommended that this orchid can be produced in nursery under 12800 lux using charcoal as substrate, since the largest number of plants with flowers, number of flower buds for plant, diameter and length of the flora stem and the number of keikis were produced under these conditions.