Micropropagation of Guadua Chacoensis (rojas) Londono & P. M. Peterson

ABSTRACT The bamboo productive chain is still incipient in Brazil, and the low supply of plantlets due to low-efficient conventional propagation methods presents a significant bottleneck to its development. This study aimed to establish a micropropagation protocol for Guadua chacoensis. Explants from donor plants cultivated under controlled environment showed less contamination, if compared to explants from plants grown in the field. The contamination rate was even lower when 2 mL L-1 of Plant Preservative Mixture (PPM™) were added to the culture medium, leading to a higher establishment rate. The obtained cultures were then multiplied using either in vitro-derived nodal segments or clump division in the presence of increasing contents (0 mM, 10 mM, 20 mM, 30 mM or 40 mM) of 6-Benzylaminopurine (BAP). The number of shoots increased with increasing BAP concentrations, but this also resulted in a reduced rooting rate and root length. Plants acclimatized under 0 %, 35 % or 65 % of shading showed a dynamic maximum quantum yield of photosystem II (Fv/Fm), which initially decreased within the first seven days after the transfer to ex vitro conditions, but then increased until reaching stable values of 0.775 after 17 days. Additionally, the shading improved the plant survival rates, if compared to those under non-shaded conditions, which presented photoinhibition and photodamage symptoms.