In the present study, the applicability of four wide-spectrum light-emitting diodes (LEDs) emitting warm light (AP67, AP673L, G2, and NS1) was determined for the micropropagation of five popular ornamental plant species: Chrysanthemum × grandiflorum, Gerbera jamesonii, Heuchera × hybrida, Ficus benjamina, and Lamprocapnos spectabilis. Plantlets were grown in a growth room with a 16-h photoperiod. The photosynthetic photon flux density was set at 62-65 μmol m −2 s −1. The composition of the media and subculture timing were adjusted to the needs of each species tested. The results were compared to the cool daylight-emitting fluorescent (FL) control (TLD 36W/54). In most of the species studied (except for F. benjamina), the highest propagation ratios, or ratios similar to the FL control, were observed under the red-and far-red-abundant G2 LEDs. NS1 spectrum (with the highest proportion of blue and green light) was also efficient for G. jamesonii and L. spectabilis, and it provided a similar propagation ratio as the FL control. Light quality affected shoot length, number of leaves, callus regeneration, and the biosynthesis of chlorophyll. This influence, however, was species-dependent. Lighting conditions did not affect the dry matter and rooting in most of the species tested, except for G. jamesonii. The substitution of FLs with G2 LEDs can result in a 50% reduction of annual electricity costs, while the application of NS1 lamps can generate savings of up to 75%. In conclusion, the G2 LED lighting system seemed to be the most suitable in terms of propagation efficiency, plantlet quality, and cost reduction.

Four narcissus cultivars were forced under artificial light using fluorescent lamps which emitted white (307 -770 nm), blue (393 -580 nm), red (540 -760 nm), yellow (450 -750 nm), or green (387 -680 nm) light. The photosynthetic photon flux density was 12.5 µmol m -2 s -1 , with a 6 h photoperiod. Light colour (wavelength) had no significant effect on flowering date, or on the number of flowers collected (P < 0.05). Narcissus bulbs exposed to blue light (393 -580 nm) formed shorter, more rigid shoots of lower weight with 13 -40% shorter leaves.

In vitro tissue culture technique, especially micropropagation, is attracting increasing attention in the production of ornamental plants. This technique will probably dominate the horticultural market in the near future. Light is one of the several factors affecting the success of in vitro plant tissue cultures. It directly affects the widely understood morphogenetic response of the explant, i.e., the ability of the explant to grow or regenerate, produce roots, etc. Lighting conditions provided during the in vitro stage may also greatly affect the plant vigor after transferring to nonsterile conditions. Moreover, the necessity of providing artificial light significantly contributes to the total cost of maintaining tissue cultures (related to energy consumption and the need to cool down the heat generated by lamps). Light quantity (intensity) and quality (spectral composition) are the two main parameters that determine its influence on in vitro cultures. This impact depends on the species and other accompanying factors. The aim of this mini-review is to summarize information on the influence of light on the morphogenetic and biochemical response of explants of some selected ornamental plant species grown under in vitro conditions.

Among many challenges in chrysanthemum cross-breeding, the access to viable pollen for hybridization of cultivars distant in location and different in flowering time is required. Low pollen viability along with incompatibility are mainly responsible for low seed set in modern chrysanthemum cultivars. The aim of the study was to test various temperatures and periods of pollen storage of Chrysanthemum × morifolium in order to elaborate the method of chrysanthemum pollen preservation for cross-breeding purposes. In the first experiment, in vitro pollen germination of four cultivars was investigated following storage at 20 °C, 4 °C, −20 °C, and −80 °C, for one, four, and eight weeks. The second experiment focused on in vivo seed set after one week pollen treatment with 20 °C, 4 °C, −20 °C, and −80 °C (three pollen donor cultivars tested). Pollen in vitro germinability, as well as seed set efficiency, was generally low and cultivar dependent. Independent of the period of storage, stored pollen germinability was lower (5.30–6.63%) than fresh pollen (8.15%). Incubation of pollen in −80 °C significantly increased pollen germinability (9.80%), as well as seed set efficiency in comparison to control (19.28% and 10.21%, respectively) provided the cultivars are compatible. Among cultivars, the highest germinability of pollen was found in ‘Brda’ and ‘Donna’ (8.2% and 8.23%, respectively), while ‘Bydgoszczanka’ showed the lowest germinability (2.97%). There were also pollen genotype dependent effects in in vivo seed set efficiency, which was highest in ’Brda’ (17.57%) and much lower in ‘Jutrzenka’ and ‘Polka’ (1.34% and 0.39%, respectively), which contributed to the incompatibility of crossed cultivars rather than pollen viability.