Indirect in vitro organogenesis of Hancornia speciosa Gomes

Abstract

Hancornia speciosa Gomes is a fruit species belonging to the Apocynaceae family and holds social, cultural and economic potential mostly due to its use in composition of many food industry products and the consumption its fruits in natura. Several aspects regarding their propagation need further studies, since the species is undergoing a continuous process of domestication. The objective was to obtain an in vitro protocol for indirect organogenesis and rooting with subsequent acclimatization of H. speciosa plants. To obtain indirect organogenesis, internodal segments were inoculated in WPM culture medium gelled with 7 g L^-1 agar, added with 30 g L^-1 sucrose, 0.4 g L ^-1 PVP, and supplied with different concentrations of 2,4-D (0.0; 2.46; 7.38; 12.30; and 17.22 µM), BAP (0.0; 4.92; 9.84; 14.76; and 19.68 µM), and TDZ (0.0; 4.92; 9.84; 14.76; and 19.68 µM). For the in vitro rooting, shootings with approximately 6.0 cm diameter length kept for 15 days in WPM medium with no plant growth regulator and, afterwards, subjected to treatments with different auxins (Control; 9.84 µM IBA; 9.84 µM NAA; and 9.84 µM IAA) as well as the combination among them, in order to verify their effects on percentage of rooting (%), number of roots, and average length of the largest root (cm). The formation of calluses was observed in all explants subjected to the concentrations of the regulators tested. The highest shooting regeneration occurred with 7.38 µM 2,4-D (73%). The highest percentage of shoot rooting (80%) and roots with the largest length (1.3 cm) were found in the culture medium with the combination of 4.92 µM NAA and 4.92 µM IBA. The in vitro regeneration of H. speciosa is feasible. The acclimatization of rooted shoots in Trospstrato® was accomplished with successful and 100% survival of plant material was observed during this stage.