Propagação in vitro de guadua spp. Nativos da Amazônia Sul- Ocidental, Acre, Brasil

Abstract

The world’s largest native bambu forest is in the state of Acre in the brazilian Amazon. An enormous area high in biodiversity, located just in the brazilian border with Peru and Bolivia and there is in fact a large scale demand on the Guadua’s gender seeding production, due to its versatility and for being such a renewable and sustainable raw material. The goal was to develop a protocol of in vitro propagation using small parts of bamboo plant (nodal segments, leaves and seeds) in laboratory tests of establishment, multiplication, rooting, callus induction and in vitro germination. The experiments were conducted at the morphogenesis and Biomolecular Laboratory from EMBRAPA (Brazilian Agricultural Research Corporation in Acre). The establishment was realized with nodal segments collected from plants stored at the laboratory greenhouse. The nodal segments were disinfected with a systemic fungicide, bactericide, alcohol and sodium hypochlorite. Plant Preservative Mixture (PPM®) was used as a synthetic biocide in concentration of both 0, 2 and 3 mL L-1 in glass tubes with the semisolid Murashige and Skoog (MS) culture medium and 2 mg L-1 of benzylaminopurine (BA) to stimulate the axillary bud break at 15 days of incubation. The variables analyzed were shoot number, and degrees of bacterial and fungal contamination. In vitro multiplication was performed with BA plant growth hormone in concentrations of 0, 2, 4, 6, 8 mg L-1 in glass tubes with MS liquid at 38 days of incubation. The variables analyzed were shoot number, shoot length, multiplication rate, callus and root growth in two consecutive subcultures. Rooting was induced with the indoleacetic (IAA), indolebutyric (IBA) and naphthaleneacetic (NAA) acids in concentrations of 0, 0.5, 1, 2 mg L-1. The variables analyzed were root number, root length, rooting rate at 30 days of incubation. In callus formation was used 2,4-D, Picloram, BA and NAA regulators, with light and no light. It was checked degree of callus, bacterial and fungal contamination. In vitro germination was tested with AG3, BA, MS and WPM culture medium. It was verified degree of plant formation, bacterial and fungal contamination. The establishment using 2 mL L-1 of PPM® was more effective against bacterial and fungal attack, and shoot regeneration was not concentration dependent. The use of BA was effective in increasing the shoot number and the shoot length during the first subculture as compared with the control treatment. The second subculture results showed increased shoot number in all BA concentrations tested, except for the control. Shoot length showed no statistical increase in any of the concentrations used. The in vitro rooting using the auxin IAA demonstrated good root response while IBA and NAA were not response. It was verified 83% of rooting in IAA. Micropropagation of Guadua latifolia nodal segments is best accomplished using 2 mL L-1 of PPM® for establishment, 2 mg L-1 of BA for multiplication, and 0.5 mg L-1 of A IAA for rooting. It is not found callus formation in Guadua cf. angustifolia, and the seed germination of G. latifolia was not develop completely. Keywords: Poaceae. Bamboo. Micropropagation. Callus. Seeds.