Propagation of Dyckia vicentensis, an endemic bromeliad of the Pampa biome, Brazil

Rejane Flores Letícia Cezar Kraetzig Paola Zuquetto Flôres Diuliana Nadalon Pereira Henrique Mallmann Büneker Joseila Maldaner Caroline Lançanova Viero Marisa Ana Strahl About the authors

Abstract

Dyckia vicentensis is an endemic species of the southwestern region of Rio Grande do Sul (RS, Brazil), which presents high ornamental and economic value. Thus, the aim of this study was to test in vitro and ex vitro conditions for its propagation. For in vitro germination, disinfested seeds were inoculated on Murashige and Skoog medium with different salt concentrations and containing or not active charcoal. The ex vitro emergence of the seeds was evaluated using different compositions of substrates. Results showed that the propagation of D. vicentensis could be successfully performed in vitro on medium with 50% salt concentration or ex vitro using commercial substrate. The seedlings showed good adaptation during acclimatization in a greenhouse, although the in vitro germinated plants presented higher survival rate, number of leaves, and biomass in relation to those grown in ex vitro substrate. This is the first study carried out on the propagation of D. vicentensis, which may be used to subsidize its propagation and conservation.

Key words:
Bromeliaceae; germination; in vitro culture; ornamental plant; substrates

Resumo

Dyckia vicentensis, uma espécie endêmica do sudoeste do Rio Grande do Sul (RS, Brazil), possui alto valor ornamental e econômico. Assim, o objetivo deste estudo foi testar condições in vitro ou ex vitro para a sua propagação. Para a germinação in vitro, as sementes foram desinfestadas e inoculadas em meio de Murashige e Skoog (MS) com diferentes concentrações de sais minerais e contendo ou não carvão ativo. A emergência de plântulas, em condições ex vitro, foi avaliada em diferentes composições de substratos. Os resultados mostraram que a propagação de D. vicentensis pode ser realizada em condições in vitro, utilizando meio de cultura com 50% da concentração de sais do meio MS, e também em condições ex vitro, em substrato comercial. Em geral, as plântulas mostraram uma boa adaptação durante a aclimatização em casa de vegetação, embora aquelas germinadas in vitro tenham apresentado maior taxa de sobrevivência, maior numero de folhas e biomassa em relação às plântulas oriundas da germinação em substrato. Este estudo é pioneiro para D. vicentensis e poderá fornecer subsídios para propagação e conservação dessa espécie.

Palavras-chave:
Bromeliaceae; germinação; cultivo in vitro; planta ornamental; substratos

The Bromeliaceae family is known for its recent adaptive radiation (Zanella et al. 2012Zanella CM, Janke A, Palma-Silva C, Kaltchuk-Santos E, Pinheiro FG, Paggi GM, Soares LES, Goetze M, Büttow MV & Bered F (2012) Genetics, evolution and conservation of Bromeliaceae. Genetics and Molecular Biology 35: 1020-1026.). It likely originated in the Andean region and subsequently spread throughout the millennia, reaching tropical forests about 200,000 years ago. Currently, this family is widely distributed in the American continent. In Brazil, the bromeliads include 43 genera and 1,341 species (Forzza et al. 2014Forzza RC, Costa A, Siqueira Filho JA, Martinelli G, Monteiro RF, Santos-Silva F, Saraiva DP & Paixão-Souza B (2014) Bromeliaceae. Lista de espécies da flora do Brasil. Jardim Botânico do Rio de Janeiro, Rio de Janeiro. Available at <http://floradobrasil.jbrj.gov.br/2012/FB000066>. Access on 18 November 2016.
http://floradobrasil.jbrj.gov.br/2012/FB...
; Alves et al. 2015Alves M, Trovó M, Forzza RC & Viana P (2015) Overview of the systematics and diversity of Poales in the Neotropics with emphasis on the Brazilian flora. Rodriguésia 66: 305-328.), which represent almost 40% of the diversity of the family.

Bromeliads have high ornamental and economic value (Zanella et al. 2012Zanella CM, Janke A, Palma-Silva C, Kaltchuk-Santos E, Pinheiro FG, Paggi GM, Soares LES, Goetze M, Büttow MV & Bered F (2012) Genetics, evolution and conservation of Bromeliaceae. Genetics and Molecular Biology 35: 1020-1026.) due to their lush shapes and colors. In addition to their easy maintenance and adaptability, they can be used for interior decoration and landscaping. According to SEBRAE (2015)Serviço Brasileiro de Apoio às Micro e Pequenas Empresas - SEBRAE (2015) Plantas e flores ornamentais do Brasil: série estudos mercadológicos. SEBRAE, Brasília. 44p., the production and marketing of ornamental plants (including bromeliads) is one of the most dynamic and promising segments of the Brazilian agribusiness. In this reality, the state of Rio Grande do Sul (RS) is the second most important region of Brazilian floriculture.

The Bromeliaceae family is also characterized by high ecological value and degree of endemism since 1,172 species are endemic to Brazil (Alves et al. 2015Alves M, Trovó M, Forzza RC & Viana P (2015) Overview of the systematics and diversity of Poales in the Neotropics with emphasis on the Brazilian flora. Rodriguésia 66: 305-328.). However, this family is the second plant group in absolute number of endangered species (202 spp.) (Rio Grande do Sul 2014Rio Grande do Sul (2014) Decreto nº 52.109, de 1º de dezembro de 2014. Lei nº 11.520 de 03 de agosto de 2000, que dispõe das espécies da flora nativa ameaçadas de extinção no estado do Rio Grande do Sul. Assembleia legislativa, Porto Alegre, RS, 1º de dezembro de 2014. Available at <http://www.al.rs.gov.br/filerepository/repLegis/arquivos/DEC%2052.109.pdf> Access on 22 August 2016.
http://www.al.rs.gov.br/filerepository/r...
; Alves et al. 2015Alves M, Trovó M, Forzza RC & Viana P (2015) Overview of the systematics and diversity of Poales in the Neotropics with emphasis on the Brazilian flora. Rodriguésia 66: 305-328.). The main threats to bromeliads are the loss of habitats due to the degradation of native forests, since most have epiphytic habit, and the predatory removal of individuals in nature (Santos et al. 2005Santos AJ, Bittencourt AM & Nogueira AS (2005) Aspectos econômicos da cadeia produtiva das bromélias na região metropolitana de Curitiba e Litoral paranaense. Floresta 35: 409-417.) for commercialization. Although this practice is illegal in Brazil, it still occurs in some regions (Negrelle et al. 2012Negrelle RRB, Mitchell D & Anacleto A (2012) Bromeliad ornamental species: conservation issues and challenges related to commercialization. Acta Scientiarum. Biological Sciences 34: 91-100.; Negrelle & Anacleto 2012Negrelle RRB & Anacleto A (2012) Extrativismo de bromélias no estado do Paraná. Ciência Rural 42: 981-986.).

These data highlight the urgent need for studies aiming at developing strategies for the cultivation and conservation of the existing germplasm, especially those endemic and/or endangered species. In addition, the production and use of native plants with ornamental potential can contribute to the valorization and conservation of regional biodiversity. It is an economically and ecologically viable option and contributes to the conservation of natural ecosystems (Santos et al. 2005Santos AJ, Bittencourt AM & Nogueira AS (2005) Aspectos econômicos da cadeia produtiva das bromélias na região metropolitana de Curitiba e Litoral paranaense. Floresta 35: 409-417.; Stumpf et al. 2009Stumpf ET, Romano CM Barbieri RL, Heiden G, Fischer SZ & Corrêa LB (2009) Características ornamentais de plantas do Bioma Pampa. Revista Brasileira de Horticultura Ornamental 15: 49-62.). However, a great number of species of native flora are little studied, hindering the use of management techniques and their sustainable use.

The genus Dyckia Schult. & Schult. f. (subfam. Pitcairnioideae) comprises about 164 species (Gouda et al. 2012Gouda EJ, Butcher D & Gouda CS (2012) Encyclopaedia of Bromeliads. Vol. 3. University Botanic Gardens, Utrecht. Available at < http://encyclopedia.florapix.nl/>. Access on 21 January 2017.
http://encyclopedia.florapix.nl/...
) spread across the southern and southeastern regions of South America (Benzing 2000Benzing DH (2000) Bromeliaceae: profile of an adaptive radiation. Cambridge University Press, Cambridge. 690p.). In Rio Grande do Sul (southern Brazil), this genus is considered to have the highest diversity, with 29 species (Strehl 2008Strehl T (2008) New bromeliads, genus Dyckia, from Rio Grande do Sul, Brazil. Bromeliaceae 42: 8-22.; Büneker et al. 2013Büneker HM, Pontes RC, Soares KP, Witeck-Neto L & Longhi SJ (2013) Uma nova espécie reófita de Dyckia (Bromeliaceae, Pitcairnioideae) para a flora do Rio Grande do Sul, Brasil. Revista Brasileira de Biociências 11: 284-289.) and several endemic species (Hmeljevski et al. 2007Hmeljevski KV, Reis A, Reis MS, Rogalski JM, Daltrini-Neto C & Lenzi M (2007) Resultados preliminares da biologia reprodutiva de Dyckia ibiramensis Reitz (Bromeliaceae): uma espécie rara e endêmica de Santa Catarina. Revista Brasileira de Biociências 5: 267-269.; Büneker et al. 2015Büneker HM, Witeck-Neto L & Soares KP (2015) Dyckia pontesii (Bromeliaceae, Pitcairnioideae), uma nova espécie do Rio Grande do Sul, Brasil. Rodriguésia 66: 499-504.; Gomes-da-Silva et al. 2017Gomes-da-Silva J, Amorim AM & Forzza RC (2017) Distribution of the xeric clade species of Pitcairnioideae (Bromeliaceae) in South America: a perspective based on areas of endemism. Journal of Biogeography 44: 1994-2006.), among which is D. vicentensis Strehl.

D. vicentensis is endemic to the Pampa biome, occurring especially in rocky outcrops in the southwestern region of RS. The name of the species is a tribute to the municipality São Vicente do Sul (RS, Brazil), where it was collected for the first time (Strehl 2008Strehl T (2008) New bromeliads, genus Dyckia, from Rio Grande do Sul, Brazil. Bromeliaceae 42: 8-22.). The great ornamental potential of this species is that its inflorescences are composed of showy flowers, with coloration varying from yellow to red (Fig. 1a,b) and with potential to be grown in parks or gardens.

Figure 1
Plants of Dyckia vicentensis in nature (a) and detail of inflorescence (b); plantlet rustication in a greenhouse after 60 days of planting (c); general aspect of plants after 180 days of planting (d); rusticated plantlets transferred to strays containing commercial substrates (e).(Bars: c = 1.0 cm; d = 2.3 cm; e = 3.0 cm)

The Pampa biome, which is restricted to the southern half of RS, contains a high level of genetic diversity and several wild ornamental species (Stumpf et al. 2009Stumpf ET, Romano CM Barbieri RL, Heiden G, Fischer SZ & Corrêa LB (2009) Características ornamentais de plantas do Bioma Pampa. Revista Brasileira de Horticultura Ornamental 15: 49-62.). However, several factors have contributed to the drastic reduction of this biome, such as the expansion of areas for agriculture (especially for soybean cultivation), the indiscriminate use of agrochemicals, and the presence of exotic species. Thus, D. vicentensis specie is distributed in endangered biome, is endemic or have a relict distribution, therefore threatening the survival of many members of this family. Today, this specie is on the endangered category of the official list of Brazilian plant species threatened with extinction (Rio Grande do Sul 2014Rio Grande do Sul (2014) Decreto nº 52.109, de 1º de dezembro de 2014. Lei nº 11.520 de 03 de agosto de 2000, que dispõe das espécies da flora nativa ameaçadas de extinção no estado do Rio Grande do Sul. Assembleia legislativa, Porto Alegre, RS, 1º de dezembro de 2014. Available at <http://www.al.rs.gov.br/filerepository/repLegis/arquivos/DEC%2052.109.pdf> Access on 22 August 2016.
http://www.al.rs.gov.br/filerepository/r...
).

The propagation of the other species of the genus Dyckia is done using seeds (Pompelli & Guerra 2004Pompelli MF & Guerra MP (2004) Ex situ conservation of Dyckia distachya: an endangered bromeliad from South Brazil. Brazilian Society of Plant Breeding 4: 273-279; Vieira et al. 2007Vieira DM, Socolowski F & Takaki M (2007) Germinação de sementes de Dyckia tuberosa (Vell.) Beer (Bromeliaceae) sob diferentes temperaturas em luz e escuro. Revista Brasileira de Botânica 30: 183-188.; Aoyama et al. 2012Aoyama EM, Gontijo AB & Faria DV (2012) Propagação em Bromeliaceae: germinação de sementes e cultivo in vitro. Enciclopédia Biosfera 8: 1452- 2012.). However, to this date there are no reports on the physiology of germination aimed at the propagation of D. vicentensis plants, which is fundamental knowledge to subsidize their conservation. Thus, this study focused on evaluating the viability of the propagation of D. vicentensis using seeds. For this, the culture media for in vitro germination and different substrates in the emergency of seedlings were tested.

Seed-containing capsules were collected from natural populations in the municipality of Alegrete (RS, Brazil) and cool-stored under refrigeration at 4 ± 2 ºC according to Pompelli & Guerra (2004)Pompelli MF & Guerra MP (2004) Ex situ conservation of Dyckia distachya: an endangered bromeliad from South Brazil. Brazilian Society of Plant Breeding 4: 273-279. For disinfestation, the seeds were immersed in 70% (v/v) ethanol solution for 3 min followed by 30 min immersion with agitation in 1.0% sodium hypochlorite (v/v) plus two drops of commercial detergent per 100 mL solution. The seeds were then rinsed five times in sterile and distilled water. These disinfected seeds were used for in vitro germination and emergence assay in different substrates.

For in vitro germination, the disinfected seeds were inoculated into glass culture tubes containing 2 mL of the solidified culture Murashige & Skoog (MS; Murashige & Skoog 1962Murashige T & Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiologia Plantarum 15: 473-497.) with 50 or 100% of salt concentrations and supplemented or not with activated charcoal (1.0 g L-1). All media were added with 100 mg L-1 myo-inositol, 30 g L-1 sucrose, and 7 g L-1 agar. The pH was adjusted to 5.8 using HCl or NaOH (1N) prior to autoclaving at 121 ºC and 1.15 kg cm-2 for 20 min.

After inoculation (one seed per flask), the seeds were incubated in a growth room at 25±2ºC under a 16/8 h light/dark cycle with 35 µmol m-2 s-1 h of irradiance provided by 40 W cool-white fluorescent tubes. The percentage of germination and seedlings production were assessed every 3 days until the stabilization of results. The criterion used for germination was radicle protrusion (1.0 mm).

To evaluate the best condition for seedling emergency, five compositions of substrates were tested: i) commercial substrate (Carolina Soil II; Santa Cruz do Sul, RS, Brazil); ii) commercial substrate + bark of pine + charcoal + granite fragments (3:1:1:1, v/v/v); iii) commercial substrate + granite fragments (1:1, v/v); iv) bark of pine + charcoal + granite fragments (1:1:1, v/v/v) and v) granite fragments. All substrates were autoclaved for 30 min for disinfection. After this, the amount of 500 cm3 of each substrate was placed inside plastic containers (1000 cm3) with transparent covers and moistened with distilled and autoclaved water before sowing. Substrates were chosen considering D. vicentensis has rupicolous habitat (Strehl 2008Strehl T (2008) New bromeliads, genus Dyckia, from Rio Grande do Sul, Brazil. Bromeliaceae 42: 8-22.).

After sowing, the material was kept in the growth room at 25±2 ºC under a 16/8 h light/dark cycle with 35 µmol m-2 s-1 h of irradiance provided by 40 W cool-white fluorescent tubes. Irrigation was done every three days with distilled and autoclaved water using a sprinkler. Evaluations were carried out every three days depending on the percentage of seedling emergence until results stabilized.

After 65 days, seedlings from in vitro germination and ex vitro emergency in different substrates were transferred to plastic trays (52 × 26 × 4 cm) containing Carolina Soil II substrate and kept in a greenhouse for rustication. Irrigation was done every three days with distilled and autoclaved water using a sprinkler. The survival rate (%) of all plants was evaluated after 60 days of planting. After 180 days, plants (n = 10) originated from in vitro germination and ex vitro emergency were evaluated for the number of leaves per plant and dry biomass (DW; g plant-1). After this phase, all plants were transferred to larger trays (36 × 22 × × 7 cm) containing the same substrate and maintained in a greenhouse for growth and development.

The experimental design was completely randomized. Four replicates and each replicate in in vitro germination and ex vitro emergency consisted of 25 seeds (100 seeds per treatment). All data were subjected to analysis of variance (ANOVA; P ≤ 0.05) followed by Tukey's multiple range test.

Regardless of the treatment, the start of in vitro germination occurred four days after inoculation of seedsand stabilization occurred at 13 days. These results indicate that D. vicentensis presents viable seeds without dormancy and with high in vitro germinative potential, which seems to be a characteristic of this genus. For example, in D. distachya, Pompelli & Guerra (2004)Pompelli MF & Guerra MP (2004) Ex situ conservation of Dyckia distachya: an endangered bromeliad from South Brazil. Brazilian Society of Plant Breeding 4: 273-279 observed the extrusion of the first leaves three days after seed inoculation and seedling development after 30 days.

Both salt concentrations and activated charcoal influenced D. vicentensis seed germination and seedling development (Tab. 1). The culture media with 50% of salt concentration and with 100% of salts plus activated charcoal were the most efficient treatments favoring seed germination and seedling development after 13 days in vitro (Tab. 1). In other bromeliads, such as Vriesea recurvata, the reduction of MS salt concentrations and the active charcoal (5 g L-1) were beneficial for in vitro germination, development, and acclimatization of the plants (Sasamori et al. 2016Sasamori MH, Endres Júnior D & Droste A (2016) Baixas concentrações de macronutrientes beneficiam a propagação in vitro de Vriesea incurvata (Bromeliaceae), uma espécie endêmica da Floresta Atlântica, Brasil. Rodriguésia 67: 1071-1081.). However, in other species of Dyckia, such as D. distachya (Pompelli & Guerra 2005Pompelli CF & Guerra MP (2005) Enraizamento in vitro e ex vitro de Dyckia distachya Hassler, sob diferentes concentrações de AIB. Floresta e Ambiente 12: 42-49.) and D. maritima (Silva et al. 2008Silva ALL, Franco ETH, Dornelles EB & Gesing JPA (2008) Micropropagação de Dyckia maritima Baker - Bromeliaceae. Iheringia 63: 135-138.), the MS medium with 100% salt concentration was used for in vitro germination. This suggests that the requirement of nutrients for germination of seedling development is species-dependent.

Table 1
Effect of salt concentration of MS culture and activated charcoal on the percentage of germination and seedling of Dyckia vicentensis , after 13 days in vitro .

The seedlings (i.e., genotypes) of D. vicentensis obtained in this study were derived from seeds representing the genetic variability in the populations of the collection region, as recommended by Pompelli & Guerra (2005)Pompelli CF & Guerra MP (2005) Enraizamento in vitro e ex vitro de Dyckia distachya Hassler, sob diferentes concentrações de AIB. Floresta e Ambiente 12: 42-49.. Thus, in vitro germination was adequate for this species, since it favored the germination of a large number of plants using a small space and in a short period. In addition, aseptic seedlings have been produced, which may be used for other in vitro techniques (Mercier & Kerbauy 1997Mercier H & Kerbauy GB (1997) Micropropagation of ornamental bromeliads (Bromeliaceae). Biotechnology in Agriculture and Forestry 40: 43-57.) such as clonal propagation of genotypes with ornamental potential.

Moreover, substrate has a great impact on the germination process and development of seedlings because factors such as texture, airing, and water retention capacity can vary among different substrates (Estevan et al. 2010Estevan DA, Faria RT, Vieira AOS, Mota TD & Takahashi LSA (2010) Germinação de sementes de duas bromélias em diferentes substratos. Científica 38: 7-13.). In D. vicentensis, seedlings were visualized after 13 days of planting the seeds in all substrates, and the stabilization of the number of seedlings occurred only after 35 days of planting. In this period, the highest percentage of emergency (100% plantlets) was observed with the use of commercial substrate (Tab. 2).

Table 2
Effect of different substrates on the percentage of seedling emergency of Dyckia vicentensis after 35 days of planting the seeds.

The use of a suitable substrate is essential for the production of high quality seedlings, although most of the study was carried out with epiphytic bromeliads (Ferreira et al. 2007Ferreira CA, Paiva PDO, Rodrigues TM, Ramos DP, Carvalho JC & Paiva R (2007) Desenvolvimento de mudas de bromélia [Neoregelia cruenta (R. Graham) L. B. Smith] cultivadas em diferentes substratos e adubação foliar. Ciência e Agrotecnologia 31: 666-671.) and not in relation to bromeliads that occur exclusively in rocky outcrops, such as D. vicentensis. Seedling emergence is favored in substrates with greater water retention, such as the commercial substrate used in this study, whose water retention capacity is 55%. In addition, it has a slightly acidic pH (around 5.5), which is a characteristic of the soils (Reinert et al. 2007Reinert DJ, Reichert JM, Dalmolin RSD, Azevedo AC & Pedron FA (2007) Principais solos da depressão central e Campanha do Rio Grande do Sul: guia de excursão. Depto. Solos/UFSM, Santa Maria. 47p.) where it occurs naturally.

Other advantages of the use of commercial substrates are the fact that they have a suitable composition and are free of pathogens, avoiding possible sanitary problems as emphasized by Kämpf (2000)Kämpf AN (2000) Seleção de materiais para uso como substrato. In: Kämpf AN & Fermino MH (eds.) Substratos para plantas: a base da produção vegetal em recipientes. Gênesis, Porto Alegre. Pp. 139-145.. Similarly, in other bromeliads such as Neoregelia cruenta (R. Graham) L.B. Smith, which is an epiphyte of large trees, although it also occurs on the ground, the commercial substrate showed the best results for height, leaf number, and aerial biomass of plants (Ferreira et al. 2007Ferreira CA, Paiva PDO, Rodrigues TM, Ramos DP, Carvalho JC & Paiva R (2007) Desenvolvimento de mudas de bromélia [Neoregelia cruenta (R. Graham) L. B. Smith] cultivadas em diferentes substratos e adubação foliar. Ciência e Agrotecnologia 31: 666-671.). On the other hand, more drained substrates containing sphagnum, coconut fiber, or washed river sand were more favorable for seed germination of Dyckia pectinata Smith & Reitz (Estevan et al. 2010Estevan DA, Faria RT, Vieira AOS, Mota TD & Takahashi LSA (2010) Germinação de sementes de duas bromélias em diferentes substratos. Científica 38: 7-13.).

Thus, these results indicate that although D. vicentensis occurs naturally in rocky and highly drained soils, seed germination seems to depend on a greater availability of water. It is likely that adequate water conditions for seed germination do not always occur in nature due to the climatic changes observed in the Pampa biome. Consequently, the establishment of new populations of D. vicentensis is reduced. In fact, according to Pompelli (2006)Pompelli MF (2006) Germinação de Dyckia encholirioides var encholirioides (Bromeliaceae, Pitcairnioideae). Floresta e Ambiente 13: 1-9., high germinative potential observed in this genus, unlike what happens in nature where it finds other barriers, is probably because of the physical nature that decreases germination. This has also been observed in other bromeliads, which have high percentages of in vitro germination, although the reverse occurs in nature (Mercier & Kerbauy 1995Mercier H & Kerbauy GB (1995) The importance of tissue culture technique for conservation of endangered Brazilian bromeliads from Atlantic rain forest canopy. Selbyana 16: 147-149.).

In general, the seedlings derived from in vitro germination or in substrates showed good adaptation to environmental conditions in the greenhouse (Fig. 1c), with 96% and 82.3% survival rate (P ≤ 0.05) after 60 days of planting, respectively. In addition, the conditions used in this study favored the rooting of seedlings (Fig. 1d), which probably influenced positively the higher survival rate of the plants in a greenhouse. Notably, unlike the epiphytic bromeliads, in the genus Dyckia, the root system is well developed and functional (Pita & Menezes 2002Pita PB & Menezes NL (2002) Anatomia da raiz de espécies de Dyckia Schult. f. e Encholirium Mart. Ex Schult. & Schult. f. (Bromeliaceae, Pitcairnioideae) da Serra do Cipó (Minas Gerais, Brasil), com especial referência ao velame. Revista Brasileira de Botânica 25: 25-34.), hence the importance of the appropriate substrate for its development.

After 180 days in a greenhouse, the plants from the in vitro culture presented a larger number of leaves and higher DW (mean of 7.9 leaves and 200 mg plant-1) in relation to those germinated in ex vitro conditions (mean of 6.4 leaves and 76 mg plant-1) (P ≤ 0.05). After this phase, plants were transferred to larger trays (Fig. 1e) and then destined for ex situ conservation in a conserved area in the municipality of São Vicente do Sul (RS, Brazil).

Several studies have shown the advantages of in vitro cultivation of other species of Dyckia (Pompelli & Guerra 2005Pompelli CF & Guerra MP (2005) Enraizamento in vitro e ex vitro de Dyckia distachya Hassler, sob diferentes concentrações de AIB. Floresta e Ambiente 12: 42-49.; Silva et al. 2008Silva ALL, Franco ETH, Dornelles EB & Gesing JPA (2008) Micropropagação de Dyckia maritima Baker - Bromeliaceae. Iheringia 63: 135-138.). Moreover, in a recent study carried out by Sasamori et al. (2016)Sasamori MH, Endres Júnior D & Droste A (2016) Baixas concentrações de macronutrientes beneficiam a propagação in vitro de Vriesea incurvata (Bromeliaceae), uma espécie endêmica da Floresta Atlântica, Brasil. Rodriguésia 67: 1071-1081. with Vriesea incurvata (Bromeliaceae), the in vitro germinated plantlets also showed high survival rate during acclimatization. In this study, it was also found that the reduction of all macronutrients (25%) or of the nitrogen salts (25%) was beneficial for both plantlets development and survival during acclimatization (97%). In D. vicentensis, the plants derived from in vitro germination presented higher survival rate and superior biomass in relation to those germinated in substrates, which may be justified by the higher supply of minerals, carbohydrates, and vitamins present in vitro.

Due to the high degree of threat of extinction of the native bromeliads, studies related to their biology, propagation, and management together with the creation of areas of environmental protection for the in situ conservation should be priority actions. According to Barroso et al. (2007)Barroso CM, Klein GN, De Barros IBI, Franke LB & Delwing AB (2007) Considerações sobre a propagação e o uso ornamental de plantas raras ou ameaçadas de extinção no Rio Grande do Sul, Brasil. Revista Brasileira Horticultura Ornamental 13: 91-94., the cultivation of bromeliads is an emergency solution, since it protects part of the genetic structure of the populations of the anthropic impacts in their natural environment, which ensures the survival of the species and its subsequent reintroduction into nature. In general, the cultivation of native ornamental plants can constitute a strategy of valorization and conservation of biodiversity, in addition to being an excellent alternative of income for small farmers.

In conclusion, the results of the present study showed that in vitro or ex vitro germination are useful tools for D. vicentensis propagation, an endangered bromeliad species of the Pampa biome. Plant propagation can be successfully performed in vitro using MS medium with 50% salt concentration or, alternatively, ex vitro using commercial substrate. However, in vitro germination presents advantages over the use of commercial substrates, such as higher speed and uniformity during germination, the production of aseptic and vigorous seedlings with higher number of leaves and biomass, together with greater survival rate of the plants in a greenhouse.

In this study, the seedlings produced (about 300 plants) are genotypes collected in a region of natural occurrence, which could be used to subsidize the conservation of this species by maintaining the genetic variability of natural populations. In addition, the plants produced can be also used for clonal propagation programs, ecophysiological and/or genetic studies, plant production and reintroduction into the wild, as well as genetic breeding.

References

  • Alves M, Trovó M, Forzza RC & Viana P (2015) Overview of the systematics and diversity of Poales in the Neotropics with emphasis on the Brazilian flora. Rodriguésia 66: 305-328.
  • Aoyama EM, Gontijo AB & Faria DV (2012) Propagação em Bromeliaceae: germinação de sementes e cultivo in vitro Enciclopédia Biosfera 8: 1452- 2012.
  • Barroso CM, Klein GN, De Barros IBI, Franke LB & Delwing AB (2007) Considerações sobre a propagação e o uso ornamental de plantas raras ou ameaçadas de extinção no Rio Grande do Sul, Brasil. Revista Brasileira Horticultura Ornamental 13: 91-94.
  • Benzing DH (2000) Bromeliaceae: profile of an adaptive radiation. Cambridge University Press, Cambridge. 690p.
  • Büneker HM, Witeck-Neto L & Soares KP (2015) Dyckia pontesii (Bromeliaceae, Pitcairnioideae), uma nova espécie do Rio Grande do Sul, Brasil. Rodriguésia 66: 499-504.
  • Büneker HM, Pontes RC, Soares KP, Witeck-Neto L & Longhi SJ (2013) Uma nova espécie reófita de Dyckia (Bromeliaceae, Pitcairnioideae) para a flora do Rio Grande do Sul, Brasil. Revista Brasileira de Biociências 11: 284-289.
  • Estevan DA, Faria RT, Vieira AOS, Mota TD & Takahashi LSA (2010) Germinação de sementes de duas bromélias em diferentes substratos. Científica 38: 7-13.
  • Ferreira CA, Paiva PDO, Rodrigues TM, Ramos DP, Carvalho JC & Paiva R (2007) Desenvolvimento de mudas de bromélia [Neoregelia cruenta (R. Graham) L. B. Smith] cultivadas em diferentes substratos e adubação foliar. Ciência e Agrotecnologia 31: 666-671.
  • Forzza RC, Costa A, Siqueira Filho JA, Martinelli G, Monteiro RF, Santos-Silva F, Saraiva DP & Paixão-Souza B (2014) Bromeliaceae. Lista de espécies da flora do Brasil. Jardim Botânico do Rio de Janeiro, Rio de Janeiro. Available at <http://floradobrasil.jbrj.gov.br/2012/FB000066>. Access on 18 November 2016.
    » http://floradobrasil.jbrj.gov.br/2012/FB000066
  • Gomes-da-Silva J, Amorim AM & Forzza RC (2017) Distribution of the xeric clade species of Pitcairnioideae (Bromeliaceae) in South America: a perspective based on areas of endemism. Journal of Biogeography 44: 1994-2006.
  • Gouda EJ, Butcher D & Gouda CS (2012) Encyclopaedia of Bromeliads. Vol. 3. University Botanic Gardens, Utrecht. Available at < http://encyclopedia.florapix.nl/>. Access on 21 January 2017.
    » http://encyclopedia.florapix.nl/
  • Hmeljevski KV, Reis A, Reis MS, Rogalski JM, Daltrini-Neto C & Lenzi M (2007) Resultados preliminares da biologia reprodutiva de Dyckia ibiramensis Reitz (Bromeliaceae): uma espécie rara e endêmica de Santa Catarina. Revista Brasileira de Biociências 5: 267-269.
  • Kämpf AN (2000) Seleção de materiais para uso como substrato. In: Kämpf AN & Fermino MH (eds.) Substratos para plantas: a base da produção vegetal em recipientes. Gênesis, Porto Alegre. Pp. 139-145.
  • Mercier H & Kerbauy GB (1995) The importance of tissue culture technique for conservation of endangered Brazilian bromeliads from Atlantic rain forest canopy. Selbyana 16: 147-149.
  • Mercier H & Kerbauy GB (1997) Micropropagation of ornamental bromeliads (Bromeliaceae). Biotechnology in Agriculture and Forestry 40: 43-57.
  • Murashige T & Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiologia Plantarum 15: 473-497.
  • Negrelle RRB & Anacleto A (2012) Extrativismo de bromélias no estado do Paraná. Ciência Rural 42: 981-986.
  • Negrelle RRB, Mitchell D & Anacleto A (2012) Bromeliad ornamental species: conservation issues and challenges related to commercialization. Acta Scientiarum. Biological Sciences 34: 91-100.
  • Pita PB & Menezes NL (2002) Anatomia da raiz de espécies de Dyckia Schult. f. e Encholirium Mart. Ex Schult. & Schult. f. (Bromeliaceae, Pitcairnioideae) da Serra do Cipó (Minas Gerais, Brasil), com especial referência ao velame. Revista Brasileira de Botânica 25: 25-34.
  • Pompelli CF & Guerra MP (2005) Enraizamento in vitro e ex vitro de Dyckia distachya Hassler, sob diferentes concentrações de AIB. Floresta e Ambiente 12: 42-49.
  • Pompelli MF & Guerra MP (2004) Ex situ conservation of Dyckia distachya: an endangered bromeliad from South Brazil. Brazilian Society of Plant Breeding 4: 273-279
  • Pompelli MF (2006) Germinação de Dyckia encholirioides var encholirioides (Bromeliaceae, Pitcairnioideae). Floresta e Ambiente 13: 1-9.
  • Reinert DJ, Reichert JM, Dalmolin RSD, Azevedo AC & Pedron FA (2007) Principais solos da depressão central e Campanha do Rio Grande do Sul: guia de excursão. Depto. Solos/UFSM, Santa Maria. 47p.
  • Rio Grande do Sul (2014) Decreto nº 52.109, de 1º de dezembro de 2014. Lei nº 11.520 de 03 de agosto de 2000, que dispõe das espécies da flora nativa ameaçadas de extinção no estado do Rio Grande do Sul. Assembleia legislativa, Porto Alegre, RS, 1º de dezembro de 2014. Available at <http://www.al.rs.gov.br/filerepository/repLegis/arquivos/DEC%2052.109.pdf> Access on 22 August 2016.
    » http://www.al.rs.gov.br/filerepository/repLegis/arquivos/DEC%2052.109.pdf
  • Santos AJ, Bittencourt AM & Nogueira AS (2005) Aspectos econômicos da cadeia produtiva das bromélias na região metropolitana de Curitiba e Litoral paranaense. Floresta 35: 409-417.
  • Sasamori MH, Endres Júnior D & Droste A (2016) Baixas concentrações de macronutrientes beneficiam a propagação in vitro de Vriesea incurvata (Bromeliaceae), uma espécie endêmica da Floresta Atlântica, Brasil. Rodriguésia 67: 1071-1081.
  • Serviço Brasileiro de Apoio às Micro e Pequenas Empresas - SEBRAE (2015) Plantas e flores ornamentais do Brasil: série estudos mercadológicos. SEBRAE, Brasília. 44p.
  • Silva ALL, Franco ETH, Dornelles EB & Gesing JPA (2008) Micropropagação de Dyckia maritima Baker - Bromeliaceae. Iheringia 63: 135-138.
  • Strehl T (2008) New bromeliads, genus Dyckia, from Rio Grande do Sul, Brazil. Bromeliaceae 42: 8-22.
  • Stumpf ET, Romano CM Barbieri RL, Heiden G, Fischer SZ & Corrêa LB (2009) Características ornamentais de plantas do Bioma Pampa. Revista Brasileira de Horticultura Ornamental 15: 49-62.
  • Vieira DM, Socolowski F & Takaki M (2007) Germinação de sementes de Dyckia tuberosa (Vell.) Beer (Bromeliaceae) sob diferentes temperaturas em luz e escuro. Revista Brasileira de Botânica 30: 183-188.
  • Zanella CM, Janke A, Palma-Silva C, Kaltchuk-Santos E, Pinheiro FG, Paggi GM, Soares LES, Goetze M, Büttow MV & Bered F (2012) Genetics, evolution and conservation of Bromeliaceae. Genetics and Molecular Biology 35: 1020-1026.

Publication Dates

  • Publication in this collection
    Oct-Dec 2018

History

  • Received
    30 June 2017
  • Accepted
    29 Oct 2017
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