Biostimulants as an Alternative to Synthetic Growth Regulators in the Micropropagation of Hippeastrum

The genus Hippeastrum (Amaryllidaceae) is very popular worldwide for its attractive, colourful flowers. The aim of the research was to evaluate the possibility of replacing synthetic growth regulators added to the media with biostimulants of natural origin on the micropropagation and acclimatisation efficiency of several Hippeastrum genotypes. The effect of the biostimulants on the starch and fructan content of the bulbils after a 10-week in vitro culture was also investigated. The addition of biostimulant Goteo to the MS medium in vitro resulted in increased plantlet weight, leaf length and root number for most of the genotypes tested. The Folium biostimulant, not previously used in in vitro plant culture media showed positive effects, especially on leaf length. The use of Goteo during plant acclimatisation significantly improved root growth parameters, indicating its potential in minimising stress associated with the change from in vitro to ex vitro conditions. Higher starch content was detected in the bulbils of clone 0017-01 and the highest fructan content in the bulbils of clone 18 H. × chmielii. The use of the Folium biostimulant, consisting mainly of amino acids, reduced sugar accumulation, which may have been due to a shift in carbon allocation from storage processes to photosynthesis. The results confirm that biostimulants based on natural ingredients can be an alternative to synthetic growth regulators in the micropropagation of Hippeastrum and possibly other ornamental plants, what will be an input to further development of sustainable horticulture production.