Giuliano Rigo, Thiago Sanches Ornellas, Francisco Sebastian Montoya Serrano, Fernanda Espíndola Assumpção Bastos, Miguel Pedro Guerra, Rosete Pescador
Abstract The bamboo Dendrocalamus asper (Schult. & Schult. f.) Backer ex K. Heyne has high economic potential; however, the large-scale production of planting material remains a major limitation. To improve the micropropagation protocol for this species, the effects of different arrangements of individualized culms and culm clusters during the multiplication phase, as well as subsequent in vitro rooting and further acclimatization were evaluated. Multiplication rate, oxidation, albinism, and total plant production were assessed over 180 days (d). These evaluations were complemented by anatomical analyses of the organogenetic process and by quantification of total soluble sugars. The use of four clusters containing three culms per flask, cultured in MS medium supplemented with 15.0 µM BAP, proved to be the most efficient treatment, resulting in the highest mean multiplication rate (1.22 shoots·culm⁻ 1 ), improved utilization of the culture medium, and enhanced culm development. The lowest oxidation rates were observed in treatments with intermediate cluster sizes, while the incidence of albino culms increased with higher numbers of culms per cluster. During the rooting phase (40 d), plantlets produced new roots and leaves, followed by acclimatization for 50 d. Acclimatization exhibited a sequential adaptation pattern, characterized by root elongation, increases in leaf number, root number, and culm height. Overall, the optimal configuration for in vitro multiplication of D. asper consisted of four clusters of three culms per flask. For successful ex vitro establishment, culm individualization combined with 40 d of in vitro rooting and 50 d of acclimatization is recommended.