Abstract This study investigates the critical factors influencing shoot and root regeneration from Homalomena gigantea rhizome cuttings, providing valuable insights for rhizome cutting practices for this plant species. Three key experiments were conducted to assess the impact of plant growth regulator (PGR) concentrations, cutting length, and cutting section on regeneration. In the first experiment, different concentrations of α-NAA and BAP were examined, revealing that PGR selection and concentration play a pivotal role in shoot and root induction and plantlet development. The highest success rates were observed at 150 ppm α-NAA and 100 ppm BAP, although there was a trade-off between the quantity and quality of plantlets, emphasizing the need for a balanced plant regulator selection. The second experiment investigated the influence of rhizome cutting length. Longer cuttings, particularly at 5 and 7 cm, consistently led to better shoot and root development, highlighting the importance of selecting appropriate cutting lengths. In the third experiment, cutting sections (apical, middle, and distal) without PGR concentrations were assessed, with all sections showing high regeneration rates. However, the apical section produced the highest-quality plantlets with superior growth parameters, followed by the middle section, while the distal section exhibited lower effectiveness. In summary, these findings underscore the significance of PGR choice and concentration, cutting length, and cutting section for successful regeneration of H. gigantea from rhizome cuttings. These insights provide valuable guidance for enhancing rhizome cuttings methods for this plant species and promoting efficient propagation. (PGR length αNAA α NAA examined development 15 10 tradeoff trade off cm lengths apical, (apical assessed However highestquality parameters effectiveness summary H propagation 1

Resumo Este estudo investiga os fatores críticos que influenciam a regeneração de brotos e raízes a partir de cortes de rizoma de H. gigantea, fornecendo insights valiosos para as práticas de corte de rizoma. Três experimentos foram conduzidos para avaliar o impacto das concentrações de reguladores vegetais, comprimento do corte e seção de corte na regeneração. No primeiro experimento, diferentes concentrações de α-NAA e BAP foram examinadas, revelando que a seleção e concentração de reguladores vegetais desempenham um papel crucial na indução de brotos e raízes e no desenvolvimento de plântulas. As taxas de sucesso mais altas foram observadas a partir de 150 ppm de α-NAA e 100 ppm de BAP, embora houvesse um equilíbrio entre a quantidade e a qualidade das plântulas, enfatizando a necessidade de uma seleção equilibrada de reguladores vegetais. O segundo experimento investigou a influência do comprimento de corte do rizoma. Cortes mais longos, especialmente com cinco e sete cm, levaram a um melhor desenvolvimento de brotos e raízes, destacando a importância da seleção de comprimentos de corte apropriados. No terceiro experimento, seções de corte (apical, média e distal) sem concentrações de reguladores vegetais foram avaliadas, com todas as seções mostrando altas taxas de regeneração. No entanto, a seção apical produziu plântulas de melhor qualidade com parâmetros de crescimento superiores, seguida pela seção média, enquanto a seção distal apresentou menor eficácia. Em resumo, essas descobertas destacam a importância da escolha e concentração de reguladores vegetais, comprimento de corte e seção de corte para a regeneração bem-sucedida de H. gigantea a partir de cortes de rizoma. Esses insights fornecem orientações valiosas para aprimorar os métodos de corte de rizoma para essa espécie de planta e promover uma propagação eficiente. H αNAA α NAA examinadas 15 10 longos cm apropriados apical, (apical avaliadas entanto superiores eficácia resumo bemsucedida bem sucedida eficiente 1

ABSTRACT Alpinia is considered the largest genus of Zingiberaceae with ca. 250 species occurring in tropical and subtropical Asia, Australia, and Pacific Islands. The historical biogeography of Alpinia was conducted to explain where Alpinia originated and how it migrated to other regions. The phylogeny, divergence times and ancestral area reconstruction of Alpinia were performed by using the molecular data based on the comprehensive taxon sampling. Our results provide an objective approach to understand the historical biogeography of Alpinia. The genus originated in Asia during the Late Cretaceous ca. 69 Ma and started to diverge after the K-Pg boundary during the early Paleocene with the presence and development of the tropical rainforest and a warm, moist climate. Alpinia migrated to Malesia and then dispersed to Australasia. The molecular analyses supported the diversification of Alpinia in Asia and Malesia. Additionally, the Indian Alpinia has likely a common ancestor with Renealmia and Aframomum, and it is possible that after originating in Asia, Alpinia migrated from Asia to India then to Africa during the early period of collision between the Indian subcontinent and Eurasia to form the common ancestor of Indian Alpinia, Renealmia, and Aframomum. Our phylogeny provides a framework for studies in biogeography, comparative ecology, and evolution.