AN ORGANOGENIC in vitro SYSTEM FOR THE CONSERVATION AND MASS PRODUCTION OF Haworthia truncata

Abstract

Haworthia truncata, a species from South Africa, is characterized by truncated leaves at its flat and translucent apex, making it a species with great ornamental value. The objective of this research was to develop a micropropagation protocol for Haworthia truncata, for its future application on massive production of the species. A completely random design was established with 16 treatments for the induction of calluses with 12 repetitions for the combination of thidiazuron (TDZ) and 1-naphthaleneacetic acid (NAA), and five treatments for 6-benzylaminopurine (BA).  For the induction of shoots and roots 16 treatments were established with five repetitions. Therefore, we developed an efficient and rapid in vitro micropropagation system where the formation of multiple calluses was achieved from different sections of leaves. Leaves were submerged in Murashige and Skoog (MS) 0.5X and 1X media, supplemented with two concentrations of NAA (1 mg L^-1 and 2 mg L^-1), each one combined with TDZ (1 mg L^-1 or 2 mg L^-1). A second experiment was carried out for the induction of callus in a 0.5X MS basal medium, adding 0.1, 0.5, 1.0, 2.0, and 4.0 mg L^-1 BA. The induction stage of shoots used basal medium 0.5X MS. The growth regulators used were 0, 0.5, 1.0, 2.0, and 4.0 mg L^-1 BA; and 0.1 and 1 mg L^-1 NAA. The highest percentage of callus induction was observed with the growth regulators 1 mg L^-1 NAA+1 mg L^-1 TDZ and 2 mg L^-1 NAA+1 mg L^-1 TDZ. When BA was used, the highest percentage of callus emerged in 0.5 mg L^-1 BA. The treatment of 4 mg L^-1 BA showed the highest number of shoots 140 d after sowing. For the acclimatization of plants in substrate there was a survival of 80-90%. An efficient organogenic system with culture medium for H. truncata mass production is shown in this study.