Water studies on substrates of vegetal origin for epiphytic orchid cultivation

Abstract

Different growing media were compared as to water adsorption and water loss, at Jaboticabal, SP, Brazil, through a three-year period. The objective was to recommend substrates other than tree: fem fiber for cultivation of epiphytic orchids. Two treatments of each substrate were used in each sampling: materials stored in laboratory (without use) and materials exposed to conditions of orchid cultivation under laths (used). Generally, the substrates without use adsorbed less water than used substrates. When materials without use were compared, the tree fem fiber retained initially the greatest quantity of water and the blocks of pressed cocomit bark, the smaliest. However, these blocks gained a great capacity of water adsorption after being used. Charcoal added to the growing media did not cause significant alterations in the studied characteristics. In terms of water relations, the: best growing media to substitute the tree fem fiber were composed by blocks of pressed cocomit bark or by mixtures of this material with charcoal or Eucalyptus grandis bark. Bark of E. grandis alone or in mixture with charcoal did not give good results.