A protocol for obtaining bulbs via in vitro organogenesis was developed for tarda tulip (Tulipa tarda Stapf). Scale explants were obtained from bulbs formed at the base of seedlings or from adventitious bulbs that developed from callus tissue forming on stolons or on germinating seeds. Some explants were subjected to chilling at 5°C for 12 wk. The culture media contained 3 or 6% sucrose and was supplemented with either no growth regulators, either 0.5 μM 6-benzyl-aminopurine (BAP) or 18.9 or 94.6 μM abscisic acid (ABA). Cultures were maintained in the dark at 20°C. Callus tissue developed mainly on media without growth regulators or with BAP. Callus was formed from up to 96% of explants derived from non-chilled adventitious bulbs that were treated with 3% sucrose and 0.5 μM BAP. Less callus was formed from chilled explants compared with non-chilled explants. Newly formed adventitious bulbs appeared on the explants via direct and indirect organogenesis. The media with BAP promoted the formation of adventitious bulbs at a rate of 56–92% from non-chilled explants, whereas a maximum rate of 36% was observed from chilled explants. ABA inhibited the induction of adventitious bulbs and callus. The adventitious bulbs obtained in these experiments contained a meristem, which was evidence that they had developed properly.

The present study provides an efficient cryopreservation protocol for Tulipa tarda cultured in vitro. Apices were excised from bulblets cultivated on MS medium, supplemented with 60 or 90 g l^− 1 sucrose. Half of the bulblets were subjected to a cold treatment at 5 °C for 10 weeks, before exposure of the apices to loading solution (LS) and plant vitrification solution 2 (PVS2). Ten weeks after rewarming and culture on recovery medium, 100% regrowth rates were obtained for cold treated explants cultured on 60 g l^− 1 sucrose after 30 and 60 min exposure to PVS2. Cold treatment significantly improved the recovery rates of most of the cryopreserved apical meristems while an enrichment of the culture medium with higher sucrose concentration (90 g l^− 1) did not improve regrowth of the apices.

Cryopreservation of vegetatively propagated plant material is an increasingly widely used method for the efficient and safe storage of germplasm resources around the world. In Poland, there are currently four cryobanks in use for long-term plant protection programs. However, plant tissues propagated in vitro constitute only a small portion of the accessions stored in them. To date, cryogenic storage techniques have been developed and adopted in this country for ornamental plants (roses, chrysanthemums, and geophytes), crop species (potato and garlic), forest tree species (the genera Quercus and Fraxinus ), and some ferns. Polish researchers have used suspension cultures of Gentiana spp. and shoot tips of Lamprocapnos spectabilis to improve cryopreservation knowledge. A better understanding of the benefits of cryopreservation and its widespread implementation in plant biodiversity conservation programs is required. The objective of this review is to provide a concise synthesis of the scientific contributions, current status, and applications of cryogenic techniques for the conservation of in vitro culture-derived plant tissues in Poland. First, the results contributing to research that has been achieved using cell suspensions and advances related to the use of nanoparticles and plant extracts to improve cryopreservation efficiency are discussed. Then, the applications and advances in cryopreservation of ornamental plants (roses, radiomutants, plant chimeras, Lamprocapnos spp., and geophytes), crop species (potato and garlic), forest trees, and ferns are summarized.

This study was conducted to investigate the effect of various horticultural substrates (compost, peat-coconut, peat TS1, flower soil, lowmoor peat) and a foliar spray of chlormequat (at a concentration of 1380 mg dm-3) on the growth and flowering of the marigold cultivars belonging to two species: Tagetes erecta - ʻMarvel Mixtureʼ and ʻTaishan Orangeʼ, and Tagetes patula - ʻDurango Redʼ and ʻBonanza Flameʼ. The obtained results show that the plants grown in peat TS1 and peat-coconut were taller, had longer internodes and leaves, and thicker stems than the plants grown in the other substrates. Chlormequat significantly reduced the height of ʻMarvel Mixtureʼ (in peat TS1), ʻTaishan Orangeʼ (in lowmoor peat) and ‘Bonanza Flameʼ (in peat-coconut). The use of chlormequat also accelerated the development of flower heads in ʻTaishan Orangeʼ (in lowmoor peat).

Micropropagation via organogenesis of Lachenalia viridiflora W. F. Barker, a native endangered plant from South Africa, is presented in this study. Leaves, collected from in vivo plants, were a source for culture initiation to obtain three types of explants (leaf, bulb, callus). They were grown on Murashige and Skoog (MS) medium supplemented with two concentrations of sucrose (3 or 6%, marked as S3 and S6) and different concentrations of benzylaminopurine (BA) (0.0–5.0 μM) and naphthalene acetic acid (NAA) (0.0–0.5 μM). The results demonstrated that bulbing was more efficient on media with 3% sucrose and this process was closely related to explant type—irrespective of media type twice more adventitious bulbs (5.1–5.6) were regenerated on leaf and bulb explants than on callus (2.6). The highest value of adventitious bulb number was recorded for interaction: leaf × S3/2.5 BA/0.5 NAA (9.3 bulbs per explant). Irrespective of media type, the higher the number of adventitious bulbs (obtained from leaf and bulb explants), the lower their diameter. Moreover, adventitious bulbs regenerated from bulb explants formed the longest leaves (18.9 mm) and in the greatest percentage (52.3%). The highest biomass weight increase indicator (50 times) was recorded for interaction: leaf × S6/2.5 BA/0.25 NAA. Various combinations of plant growth regulators favor biomass increase.

The aim of the present study was to estimate the endogenous abscisic acid (ABA) content in tulip ‘Apeldoorn’ torpedo and mature somatic embryos. Moreover, the effect of exogenous ABA and/or its inhibitor fluridone on somatic embryo maturation and conversion into plantlets was investigated. Torpedo-stage somatic embryos were subcultured on media containing 5 μM of picloram and 1 μM of 6-benzyl-aminopurine (BAP)—control, and combinations of ABA (0 or 10 μM) and/or fluridone (0 or 30 μM) for 1 week. Then, the torpedo embryos were transferred to a maturation medium containing 0.25 μM of α-naphthaleneacetic acid (NAA) and 2.5 μM of BAP, without ABA and fluridone treatment, and cultivated under darkness or light for ten weeks. Endogenous ABA content (first time measured in tulip somatic embryos) was evaluated by ELISA test. The obtained results revealed that the highest level of endogenous ABA, at 17.45 nmol g⁻¹ dry weight (DW), was recorded in torpedo-stage of tulip embryo development, only after 1 week of ABA treatment, and was nearly 10 times higher in comparison with the control. Simultaneous addition of ABA and fluridone to the medium resulted in the lowering of the ABA concentration to 9.58 nmol g⁻¹ DW. During ten weeks of maturation of the embryos, the endogenous ABA content in mature tissue of tulip somatic embryo considerably decreased to an amount 0.87–1.33 nmol g⁻¹ DW (irrespective of ABA and fluridone treatment) and did not differ significantly from control (0.59 nmol g⁻¹ DW). Exogenous ABA and fluridone significantly decreased the growth value of fresh weight (FW) of the tulip torpedo-shaped and mature embryos under light conditions. Percentage of the DW of the torpedo embryos treated with exogenous ABA was significantly higher (15.43–17.02) in comparison with the control (10.87). Three to three and a half times more malformed mature embryos were noted under light conditions than in darkness, irrespective of ABA and fluridone treatment. The highest percentage of mature embryos forming shoots (conversion) was observed under light conditions in the control and after fluridone treatment (26 and 20%, respectively).