In protected cultivation, increasing the light level via supplementary lighting (SL) is critical to improve external quality, especially in periods with low light availability. Despite wide applications, the effect of light quality remains understated. In this study, the effect of SL quality and nutrient solution electrical conductivity (EC) on growth and flowering of three bromeliad species was investigated. Treatments included solar light, and this supplemented with R90B10 [90% red (R) and 10% blue (B)], R80B20 (80% R and 20% B), and R70B30 (70% R and 30% B). These were combined with an EC of 1 and 2 dS m^-l. Irrespective of the light treatment, the higher EC promoted growth, inflorescence emergence, and development in Aechmea fasciata (Lindl.) Baker, whereas adverse effects were noted in Guzmania and Vriesea. The higher EC-induced negative effect in Guzmania and Vriesea was slightly alleviated by SL. With few notable exceptions, SL exerted limited effects on photosynthetic functionality. Depending on the species, SL improved external quality traits. In all species, SL increased root and inflorescence weight and stimulated biomass allocation to generative organs. It also accelerated inflorescence emergence and promoted inflorescence development. In this way, the time to commercial development stage was considerably shortened. These effects were more prominent at R80B20 and R70B30. Under those conditions, for instance, inflorescence emergence occurred 3–5 weeks earlier than in the control, depending on the species. In conclusion, SL with increased B proportion leads to shorter production period owing to faster emergence and improved development of the inflorescence and is recommended for commercial use.

Photosynthesis of plantlets in tissue culture containers is not considered important, compared to photosynthesis of ex vitro plants, due to the exogenous source of carbohydrates present in tissue culture media. However, CO₂ starvation can generate a burst of reactive oxygen species (ROS). We examined this phenomenon in tissue culture, since CO₂ levels may become very low during the light period. The research was carried out with lily scales, regenerating adventitious bulblets, and with Arabidopsis seedlings. CO₂ starvation was achieved by placing a small vial of concentrated KOH solution in the culture container. CO₂ removal reduced the growth of regenerated lily bulblets by 33% or 23%, with or without sucrose in the medium, respectively. In Arabidopsis seedlings, CO₂ removal decreased growth by 50% or 78% in the presence or absence of sucrose in the medium, respectively. Therefore, the addition of sucrose as a replacement for photosynthesis resulted in only partial recovery of growth. Staining with nitroblue tetrazolium (NBT) showed little to no ROS in ex vitro growing seedlings, while abundant ROS were detected in seedlings grown under in vitro CO₂ starvation. Seedlings grown under normal tissue culture conditions (no CO₂ withdrawal) showed low levels of ROS. In lily tissue culture, CO₂ starvation decreased the maximum quantum efficiency of photosystem II (F_v/F_m) from 0.69 to 0.60, and in Arabidopsis from 0.76 to 0.62. F_v/F_m of ex vitro lily and Arabidopsis seedlings was 0.77 and 0.79, respectively. This is indicative of a disturbance in photosynthesis functionality and the occurrence of in vitro stress under reduced CO₂ concentrations. We conclude that poor growth, in the absence of CO₂, was partly due to strongly reduced photosynthesis, while the detrimental effects were most likely due to a burst of ROS.

Essential oil compositions of the leaves of Azadirachta indica growing in the tropical areas in the south of Iran was obtained by hydrodistillation and analysed by GC and GC-MS. The oil yield of air dried leaves was 0.1 % (w/w). Total of 16 components represented 96.2 % of the total oil were identified. The major components of the oil were: γ-elemene (20.8 %), germacrene-B (20.3%), trans-caryophyllene (13.5 %), hexadecanal (12.8 %), and methyl linoleat (10.5 %). The classification of indentified compounds showed that the sesquieterpene hydrocarbons (69.0 %) constituted the major fraction of the oil, followed by oxygenated sesquiterpens (1.4 %). However, other compounds comprised 25.9 % of the total constituents.

In micropropagation of lily, preferably bulblets should be produced: Because bulblets are compact and robust, they are much easier to handle and to plant in soil than shoots. In this review, the various factors that determine bulblet growth in vitro are discussed. Gibberellins, jasmonates (JA) and abscisic acid (ABA) are the major identified plant growth regulators (PGRs) for storage organ formation. They also play a major role in lily bulblet growth in vitro. Growth conditions such as temperature and light (quantity and quality) strongly affect lily bulblet growth in tissue culture. Moderate abiotic stresses are introduced as new tool to improve storage organ formation in vitro. The amounts of endogenous carbohydrates (starch) in the explant and exogenous carbohydrates in the medium (sucrose) influence bulblet growth in vitro. It is also discussed how compounds present in the medium or in the scale-explants are translocated to the regenerating bulblet.