Enhanced Micropropagation of Lachenalia ‘Rainbow Bells’ and ‘Riana’ Bulblets Using a Temporary Immersion Bioreactor Compared with Solid Medium Cultures

This study evaluated the effect of the culture system (temporary immersion bioreactor (TIB) vs. solid culture) on the micropropagation efficiency of two Lachenalia cultivars, ‘Rainbow Bells’ and ‘Riana’. Morphological and biochemical responses were analyzed under different immersion frequencies (15 min every 24 h, 15 min every 8 h, and 5 min every 8 h) and on solid medium. TIB, regardless of the immersion frequency, was more efficient in terms of biomass growth (3.27–3.95-fold increase) and the number of obtained bulblets (17.80–19.08 bulbs). The response to culture conditions was genotype-dependent. ‘Rainbow Bells’ exhibited higher biomass growth and bulblet number, whereas ‘Riana’ produced fewer but heavier bulblets (4.39 and 2.09 of biomass growth, 23.19 and 9.97 bulbs per 1 g, 0.23 and 0.31 g per bulb, respectively, for ‘Rainbow Bells’ and Riana’). The most effective bulblet multiplication was obtained under the 1 × 15 min regime for ‘Rainbow Bells’; the same frequency promoted bulblet enlargement in ‘Riana’. Principal component analysis (PCA) explained 77% of total variance, revealing strong genotype separation: ‘Rainbow Bells’ clustered with traits linked to growth intensity and phenolic accumulation, while ‘Riana’ correlated with bulb storage parameters. The results support the use of TIBs to improve Lachenalia micropropagation, bulb quality, and future automation, and indicate that further research should focus on optimizing culture parameters for each genotype.