Spectral quality is an important factor for in vitro development of explants in a bioreactor system. Based on the need to optimize micropropagation for E. grandis × E. urophylla clones, the aim of the study was to assess the spectral quality of in vitro multiplication in temporary immersion bioreactor (TIB). The tissue used to generate the explants (i.e., the nodal segment with 1 cm of length and two axillary bud without leaves) was previously in vitro established and multiplied, it derived from ministumps of E. grandis × E. urophylla clone grown in a semi-hydroponic system. The spectral quality of in vitro multiplication was assessed through five light sources (i.e., fluorescent lamp, red, green, blue, and yellow cellophane). Morphological and anatomical features of tissues grown in TIB were evaluated at 90 days. Based on the results, yellow and blue spectral qualities were the most suitable to be adopted for in vitro multiplication of E. grandis × E. urophylla, since they enabled lesser hyperhydricity, favors high number of shoots per explant and shoot length, as well as thicker mesophyll and spongy parenchyma; arise as an alternative for large-scale production of eucalypts clonal plants.

光谱质量是生物反应器系统中外植体体外发育的重要因素。基于优化E. grandis  ×  E. urophylla克隆微繁殖的需要，本研究的目的是评估临时浸入式生物反应器 (TIB) 中体外繁殖的光谱质量。用于产生外植体的组织（即长度为 1 cm 的节段和两个无叶腋芽）是先前在体外建立和繁殖的，它来自E. grandis  ×  E. urophylla 的小茎在半水培系统中生长的克隆。通过五种光源（即荧光灯、红色、绿色、蓝色和黄色玻璃纸）评估体外增殖的光谱质量。在 90 天时评估了在 TIB 中生长的组织的形态学和解剖学特征。根据结果​​，黄色和蓝色光谱质量最适合用于E. grandis  ×  E. urophylla 的体外繁殖，因为它们能够实现较少的超水合，有利于每个外植体的枝条数量和枝条长度高，以及较厚的叶肉和海绵状薄壁组织；作为大规模生产桉树无性系植物的替代品而出现。