Exploring relationship between morphological characters with in vitro initiation ability and optimizing in vitro propagation of Vanda orchids

Abstract

The cultivation of Vanda orchids in Indonesia faces challenges due to their slow growth, leading to a reliance on importing varieties from foreign countries. Our primary objectives were understanding the relationship between morphological characters and in vitro propagation success and establishing mass in vitro propagation technology from initiation to maturation stages. Additionally, we explored the influence of genotypes, explant types, and media during the initiation stage, alongside evaluating the media's role in the proliferation, regeneration, and maturation of plantlets. A well-defined protocol was developed for the culture induction, multiplication, rejuvenation, and development of Vanda orchids. Established correlations highlight the correlation between floral structure colors and the effectiveness of explant initiation. The optimal medium for culture initiation was Murashige & Skoog (MS) with the addition of 0.75 mg/l thidiazuron (TDZ) and 0.25 mg/l 6-benzyl amino purine (BAP), particularly effective by using rachis explants with the best response found in V. ‘Nilareta Agrihorti’, which exhibited organogenic callus and adventitious shoots within 58 days. During the proliferation stage, culturing 0.5 cm clumps on MS medium with 1 and 2 mg/l BAP resulted in a substantial 3.30 and 2.83 times increasing in clump weight, respectively, and a multiplication rate of 4.30 and 3.83, respectively. MS was added with 0.3 mg/l meta-topoline for shoot regeneration, achieving an average shoot growth percentage of up to 89% during the third subculture period. Half-strength MS medium was combined with 100 g/l banana extract, demonstrating superior plantlet performance during maturation. These findings represent a significant advancement in Vanda hybrid propagation technology, holding promise for cultivating and commercializing these unique orchid varieties in Indonesia and international market.