STUDIES ON PLANT PROPAGATION USING THE AERO-HYDROPONIC METHOD

Experiments to compare rooting in aero-hydroponics and conventional media with or without overhead misting were performed. Rooting percentage, number of roots per rooted cutting and total root length of Ficus benjamina and ChrysanthemumX morifolium were greater in aero-hydroponics than in either solid medium. Rooting percentage of Ficus, number of roots, and root length were greater without mist than under mist in aero-hydroponics while the converse was true for perlite-vermiculite.

Cuttings of Ficus benjamina and ChrysanthemumX morifolium were rooted in aero-hydroponics to study the effect of dissolved oxygen concentrations in the range 8 mg·l^-1 (ambient saturation) to 0 mg·l^-1. The results of this study indicate that dissolved oxygen is essential to root formation and root growth. Oxygen affected the timing of rooting,rooting percentage,number of roots,and root length. Based on the rooting performance of the immersed segment of cuttings in stirred and unstirred units, it was apparent that the dissolved oxygen concentration of greatest physiological interest is at the interface between the cutting's stem surface and the water.

A 60-fold increase in ethylene content in the stem of Chrysanthemum held in aero-hydroponics was observed under anoxic conditions during the 8–12 days necessary for adventitious root formation. Ethylene content was highest in the immersed portion of the cuttings, but there was substantial ethylene produced by anoxic, misted portions of the cutting above the liquid. The elevated concentrations of ethylene in anoxic cuttings may have beneficial and/or detrimental effects of practical importance in horticultural propagation. Oxygenation of the medium may reduce adverse effects of ethylene on the cuttings.