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Dormancy overcoming in seeds of Myrciaria glomerata O. Berg.

Superação de dormência de sementes de Myrciaria glomerata O. Berg

Cleberton Correia Santos Silvia Correa Santos Fernanda Pinto Daiane Mugnol Dresch Silvana de Paula Quintão Scalon Elissandra Pacito Torales About the authors

Abstract

Myrciaria glomerata O. Berg. (Myrtaceae) is a fruit tree native to the Brazilian Atlantic Forest with potential for use as food and medicine, besides having good ecological potential. However, this species is limited by low germination rates. Thus, this study aimed to evaluate different methods to overcome dormancy in seeds of M. glomerata and to improve seedling vigor. For this, two experiments were conducted. In Experiment 1, seven treatments were tested: a control treatment, immersion in water at 100 ºC for 30 seconds, immersion in concentrated sulfuric acid (H2SO4) for 1 and 5 minutes, immersion in an aqueous solution of gibberellic acid (GA3) at the concentrations of 250 and 500 mg L-1 for 24 h, and seeds homogenized with an aqueous solution of Stimulate® at a concentration of 5 mL kg-1 seed. In Experiment 2, six doses of Stimulate® were tested: 0, 5, 10, 15, 20, 25, and 30 mL kg-1 seed. The immersion of seeds in 250 and 500 mg L-1 GA3 contributes to increase germination rates, seed length, fresh mass, and dry mass compared to the control and the other methods tested. Immersions in water at 100 ºC and in H2SO4 are not recommended for M. glomerata. The treatment with Stimulate® at 15–25 mL kg-1 seed increased all characteristics analyzed. Immersion in 250 mg L-1 GA3 and Stimu-late® at 20–25 mL kg-1 seed efficiently stimulated seeds to overcome dormancy in M. glomerata, as well as improved seedling vigor.

Index terms
gibberellic acid; Stimulate®; physiological quality; germination

Resumo

Myrciaria glomerata O. Berg. (Myrtaceae) é uma frutífera nativa da Mata Atlântica com potencial alimentício, medicinal e ecológico, mas com baixa taxa de germinação. Objetivou-se com este trabalho avaliar diferentes métodos na superação da dormência de sementes e no vigor de plântulas de M. glomerata. Foram realizados dois experimentos. No experimento 1, foram testados sete tratamentos: controle; imersão em água a 100 ºC por 30 segundos; imersão em ácido sulfúrico concentrado (H2SO4) por 1 e 5 minutos; imersão em solução aquosa de ácido giberélico (AG3) 250 e 500 mg L-1 e imersão em solução aquosa com 5 mL de Stimulate® kg-1 de sementes. No experimento 2, foram testadas sete doses de Stimulate®: 0; 5; 10; 15; 20; 25 e 30 mL kg-1 de sementes. A imersão das sementes em 250 e 500 mg L-1 AG3 contribui na velocidade de germinação e maior comprimento, massas frescas e secas, em comparação às do controle e aos outros métodos testados. A imersão em água a 100 ºC e em H2SO4 não é recomendada para M. glomerata. As doses de 20 a 25 mL de Stimulate® kg-1 de sementes proporcionam incremento para todas as características anali-sadas. Imersão em AG3, na concentração de 250 mg L-1, e doses de 15 a 25 mL de Stimulate® kg-1 de sementes são eficientes para a superação da dormência de sementes e o vigor de plântulas de M. glomerata.

Termos para indexação
ácido giberélico; Stimulate®; qualidade fisiológica; germinação

Introduction

Myrciaria glomerata O. Berg. (commonly known in Brazil as “cabeludinha”, Myrtaceae) is a fruit tree species classified as early secondary in the ecological succession (CAMARGOS et al., 2013 CAMARGOS, V.L.; MARTINS, S.V.; RIBEIRO, G.A.; CARMO, F.M.S.; SILVA, A.F. Influência do fogo no banco de sementes do solo em floresta estacional semidecidual. Ciência Florestal, Santa Maria, v.23, n.1, p.19-28, 2013. ). It is native to the Brazilian AtlanticForest, with natural occur-rence in different phytophysiognomies in the phytogeographic domains ofthe Cerrado, Amazon rainforest, and Caatinga (SOBRAL et al., 2015 SOBRAL, M.; PROENÇA, C.; SOUZA, M.; MAZINE, F.; LUCAS, E. Myrtaceae in lista de espécies da flora do Brasil. Jardim Botânico do Rio de Janeiro, 2015. Disponível em: http://www.floradobrasil.jbrj.gov.br/jabot/floradobrasil/FB10787. Acesso em: 20 abr. 2022.
http://www.floradobrasil.jbrj.gov.br/jab...
).

The fruits of Myrciaria glomerata can be consumed in natura, consisting of globose berries with a thick peel in “canary yellow” color that contain one or two large seeds with astringent taste (LORENZI, 2002 LORENZI, H. Árvores brasileiras: manual de identificação e cultivo de plantas arbóreas nativas do Brasil. 3.ed. Nova Odessa: Instituto Plantarun, 2002. v.1, 368p. ) and anti-inflammatory property(PACHECO-SILVA; DONATO, 2016 PACHACO-SILVA, N.V;/ DONATO, A.M. Morpho-anatomy of the leaf of Myrciaria glomerata. Revista Brasileira de Farmacognosia, São Paulo, v.26, n.3, p.275-280, 2016. ). In addition, its seedlings can be inserted into agroforestry systems and/or recovery programs for degraded areas. Considering the importance of the species, its ex situ cultivation aimed at conservation and sustainable exploitation is necessary.

Although M. glomerata is propagated by its seeds, they have low germination potential (PINTO et al., 2017 PINTO, F.; SANTOS, S.C.; REZENDE, R.K.S.; DAMIANI, C.R. Germinação de sementes e calogênese in vitro de Plinia glomerata (O. Berg) Amshoff. Revista Brasileira de Plantas Medicinais, Botucatu, v.19, n.2, p.205-211, 2017. ), depending on the dormancy mechanism or seed quality. The occurrence of seeds that do not germinate or present low germination evenunder apparently favorable environmental conditions is common in native species, as there arefew technical descriptions in the literature. These seeds are considered dormant and may need additional treatment to germinate according to their physiological quality. We emphasize that studies aimed at establishing techniques for thephysiological management of seeds are important for the subsequent production of seedlings. According to Taiz et al. (2017) TAIZ, L.; ZEIGER, E.; MOLLER, I.; MURPHY, A. Fisiologia e desenvolvimento vegetal. 6.ed. Porto Alegre: Artmed, 2017. 888 p. , germination is affected by different hormones, being promoted by some and inhibited by others.

Biostimulants/bioregulators such gibberel-lins in the form of gibberellic acid (GA3) and Stimulate®, which consists of cytokinin, gibberellic acid, and butyric indole acid, for example, are used as germination promoters for triggering embryogrowth, weakening the endosperm layer surrounding the embryo, and mobilizing energy reserves (SKUBACZ;DASZKOWSKA, 2017 SKUNACZ, A.; DASZKOWSKA-GOLEC, A. Seed dormancy: the complex process regulated by abscisic acid, gibberellins, and other phytohormones that makes seed germination work. Phytohormones – signaling mechanisms and crosstalk in plant development and stress responses. 2017. [S.l.]: IntechOpen, 2017. ; TAIZ et al., 2017 TAIZ, L.; ZEIGER, E.; MOLLER, I.; MURPHY, A. Fisiologia e desenvolvimento vegetal. 6.ed. Porto Alegre: Artmed, 2017. 888 p. ; SILVA et al., 2021 SILVA, E.C.; VILLA, F.; SILVA, D.F.; POSSENTI, J.C.; SILVA, L.S.; RITTER, G. Araticum accessions: effect of gibberellic acid concentrations and soaking times on seed dormancy overcoming. Revista Caatinga, Mossoró, v.34, n.3, p.614–620, 2019. ), as well as assisting in the development of therootsystem and other processes of plant metabolism and development (SANTIAGO et al., 2019 SANTIAGO, W.R.; GAMA, J.S.N.; TORRES, S.B.; LEITE, M.D.; LEITE, T.S.; NOGUEIRA NETO, F.A. Physiological performance of Physalis angulata L.seeds treated with chemical promoters. Revista Caatinga, Mossoró, v.32, n.3, p.834-840, 2019. ; HOSSEINI et al., 2020 HOSSEINI, M.S.; ZAHEDI, S.M.; HOVEIZEH, N.F.; LI, L.; RAFIEE, M.; FAROOQ, M. Improving seed germination and seedling growth of guava under heat and osmotic stresses by chemical and hormonal seed treatments. Bragantia, Campinas, v.79, n.4, p.512-524, 2020. ). Other methods, such as immersion in sulfuric acid and high temperature water to overcome tegumentary dormancy should also be studied,mainly due to the lack of knowledge on the type of dormancy of the seeds of M. glomerata.

Information on seed placement and seed efficiency, such as choosing the optimal doses of hormones and methods of overcoming physiological or tegumentary dormancy for native species is scarce. We hypothesized that the treatment used in seeds cancontribute to overcome dormancy and improve physiological quality. Thus, the aim of the present study was to test different methods for overcoming dormancy in seeds of M. glomerataand improving seedling vigor.

Material and methods

Two experiments were conducted independently in the Laboratory of Nutrition and Plant Metabolism/Federal University of Grande Dourados (UFGD) between October 2018 and January 2019 (Experiment 1) and October 2019 (Experiment 2). Fruits of M. glomerata were collected from twenty plants belonging to a sixyear orchard located in the area of fruit farming of the UFGD, university city, municipality of Dourados, Mato Grosso do Sul State (MS), Brazil. The fruits were taken to the laboratoryand manually depulped under running water. The mucilage surrounding theseeds was removed using a sieve, with seeds being subsequently dried for 40 min on apaper towel under ambient conditions (25 ± 1 °C and 60% humid-ity relative).

The following procedures were performed for the two experiments:

Seeds were sanitized with 2.5% sodium hypochlorite for 5 min, washed under running water, and distributed on three Germitest® pa-per towels previously moistened with distilled water at a ratio of 2.5 times the mass of the dry paper (BRASIL,2009 BRASIL. Ministério da Agricultura e Reforma Agrária. Regras para análises de sementes. Brasília: SNDA/ DNDV/CLAV, 2009. 399 p. ), being subsequently packed inside transparent plastic boxes (11.5 x 11.5 x 3.5 cm) placed in biochemical Oxygen demand (BOD) incubators at 25 °C under constant white light. The seed moisture con-tent was 47% at the beginning of the experiment. In both experiments, three replicates of 25 seeds were used per treatment.

Taking into consideration the scarcity of in-formation and the limitation of the seeds of M. glomerata, the criteria used by, Dresch et al. (2012) DRESCH, D.M.; SCALON, S.P.Q.; MASETTO, T.E.; VIEIRA, M.C. Germinação de sementes de Campomanesia adamantium (Camb.) O.Berg em diferentes temperaturas e umidades do substrato. Scientia Forestalis, Piracicaba, v.40, n.94, p.223-229, 2012. , who worked with a species belonging to the Myrtaceae family, were adopted for installing theexperiment.

Experiment 1

The experiment consisted of the following treatments: 1) control (no treatment), 2) immersion in water at 100 ºC for 30 seconds, 3) immersion in concentrated sulfuric acid (H2SO4) for 1 minute, 4) immersion in concentrated (98%) sulfuric acid(H2SO4) for 5 minutes, 5) immersion in aqueous solution of GA3 (250 mg L-1) for 24h, 6) immersion in aqueous solution of GA3 (500 mg L-1) for 24h, and 7) homogenization using a solution with 5 mL kg-1 of Stimulate® (seeds were packed in a plastic bag, thesolution was poured in the seeds, and the sample was maintained at rest for 24h).

Experiment 2

The following doses of Stimulate® were tested: 0 (control), 5, 10, 15, 20, 25, and 30 mL kg-1 seeds (according to the description in Exp. 1), with seeds being sown after applying the solution.

Evaluated characteristics

The percentage of normal seedlings and germination speed index were evaluated at 30 days after sowing (DAS), while seed vigor and length were evaluated at 35 DAS for both experiments as follows:

Percentage of normal seedlings: calculated using the number of developed shoots and roots as criterion (BRASIL, 2009 BRASIL. Ministério da Agricultura e Reforma Agrária. Regras para análises de sementes. Brasília: SNDA/ DNDV/CLAV, 2009. 399 p. ).

Germination speed index (GSI): calculated by the sum of the number of seeds sprouted each day divided by the number of days elapsed between sowing and germination, according to Maguire (1962) MAGUIRE, J.D. Speed of germination aid in selection and evaluation for seedling emergence and vigor. Crop Science, Madison, v.2, n.2, p.176-77, 1962. :

G S I = ( G 1 / N 1 ) + ( G 2 / N 2 ) + ( G 3 / N 3 ) + ( G n / N n )

Where: GSI = germination speed index, G1, G2, G3, ..., Gn = number of seedlings com-puted in the first, second, third and last count; and N1, N2, N3, ..., Nn = number of days after sowing in relation to the first, second, third, and last count.

Seedling length: the length of the roots and shoot of the seedlings was measured using a graduated ruler (centimeters) and the results were expressed in cm.

Fresh mass of seedlings: calculated from the weight of roots and shoots after the end of the experiment. The masses were determined in a precision scale (0.0001 g) and the results were expressed in g per seedlings.

Dry mass of seedlings: roots and shoots were placed in paper bags and maintained in an oven regulated at 60 °C for 48 hours. When they reached constant mass, the dry weight was determined in an analytical scale (0.0001 g) and the results were expressed in g per seedlings.

Statistical analysis

A completely randomized experimental designed was used for the two experiments. Germination data were subjected to homogeneity of variance and normal distribution by the Bartlett and Shapiro-Wilk tests, respectively. In Exp. 1, data weresubmitted to analysis of variance (test F, p ≤ 0.05) and averages werecompared using the Scott-Knott test at p ≤ 0.05 for all treatments. InExp. 2, data were submitted to analysis of variance and regression analysis, testing the significance of the linear and quadratic model (p ≤ 0.05) with a coefficient of determination ≥ 0.60. Statistical analysis was performed using the SISVARsoftware (FERREIRA, 2014 FERREIRA, D.F. Sisvar: a guide for its bootstrap procedures in multiple comparisons. Ciência e Agrotecnologia, Lavras, v.38, n.2, p.109-112, 2014. ).

Results

Experiment 1

We observed significant effects of treat-ments regarding the analyzed characteristics, as shown in Tables 1 and 2. Higher values of normal seedlings, GSI, length, fresh mass, and dry mass were obtained by preimbibition of seeds in GA3 at 250 and500 mg L-1, while root dry mass was higher when us-ing GA3 at 250 mg L-1. On the other hand, seeds that were immersed in water at 100 ºC for30 seconds and in sulfuric acid (H2SO4) for 1 and 5 minutes did not germinate (Table 1 and Figure 1), while controls presented low germination rates.

Table 1
Percentage of normal seedlings (NS) and germination speed index (GSI), shoot length (SL), and root length (RL) of treatments for overcoming the dormancy of seeds ofMyrciaria glomerata O. Berg.
Table 2
Fresh mass of shoots (SFM) and roots (RFM) and dry mass of shoots (SDM) and roots (RDM) of seedlings of Myrciaria glomerata O. Berg. subjected to treatments for overcoming seed dormancy at 35 days after sowing.

Figure 1
Visual aspect of seeds of M. glomerata in the control treatment (not treated), immersion in water at 100 ºC for 30 seconds, immersion in concentrated sulfuric acid (H2SO4) for 1 and 5 minutes, immersion in aqueous solution of GA3 (250 e 500 mg L-1) for 24h, and using a solution with 5 mL kg-1 of Stimulate®. Source: the authors.

Experiment 2

The percentage of normal seedlings of M. glomerata responded linearly to increasing doses of Stimulate®, reaching 100% germination with 30 mL kg-1 seeds (Figure 2a). The different doses of Stimulate® had a quadratic effect on GSI, with themaximum value (1.14) being obtained at the concentration of 20.95 mL kg-1 seeds of Stimulate® (Figure 2b).

Figure 2
Percentage of normal seedlings – (a) and germination speed index – (b) (GSI) of seeds of Myrciaria glomerata O. Berg treated with different concentrations of Stimulate® at 30 days after sowing.

Doses of Stimulate® promoted a quadratic effect on shoot length (Figure 3a), root length (Figure 3b), and total length (Figure 3c). Maximum shoot growth (6.08 cm) was observed with Stimulate® at 20.19 mL kg-1 seeds, while maximum root and totallength of seedlings were observed at 24.42 and 26.03 mL kg-1 seeds, respectively.

Figure 3
Shoot length – (a), root length – (b), and total length (c) of seedlings of Myrciaria glomerata O. Berg treated with different concentrations of Stimulate® at 35 days after sowing.

The fresh and dry mass of shoots and roots and total mass showed a quadratic effect as a function of doses of Stimulate® (Figures 4 and 5). The highest values of shoot, root, and total seedling fresh mass were 0.059, 0.186 and 1.553 g per seedlingsat 20.15, 24.22, and 21.37 mL of Stimulate® kg-1 seed, respectively (Figure 4a, b, c). The highest values of dry mass of shoots and roots and total dry mass of seedlings were obtained (0.0205, 0.0833, and 0.6681 g per seedling) at 19.93, 30, and21.42 mL kg-1 seed, respectively (Figure 5).

Figure 4
Shoot fresh mass – (a), root fresh mass – (b), and total fresh mass (c) of seedlings of Myrciaria glomerata O. Berg treated with different concentrations of Stimulate® at 35 days after sowing.

Figure 5
Shoot dry mass (a), root dry mass (b), and total dry mass (c) of seedlings of Myrciaria glomerata O. Berg treated with different concentrations of Stimulate® at 35 days after sowing.

Discussion

Experiment 1

The low germination speed index and seedling heterogeneity of M. glomerata observed for the control treatment may have resulted from an unfavorable balance between endogenous growth promoters and inhibitors. However, the treatment with GA3resulted in a higher number of normal seedlings for promoting cell elongation,which contributes for the seed germination of this species. Treatment with GA contributes to the biosynthesis of the amylase that acts in the starch hydrolysis, being converted into soluble sugars and favoring seedlings formation (BEWLEY et al.,2013 BEWLEY, J.D.; BRADFORD, K.J.; HILHORST, H.W.M.; NONOGAKI, H.L. Seeds: physiology of development, germination and dormancy. 3rd ed. New York: Springer, 2013. ; GARCIA et al., 2021 GARCIA, J.; CASTOLDI, C.T.; ANDRADE, G.C.; COELHO, C.M.; UARROTTA, V.G. Gibberellic acid promotes dormancy-breaking of rice seeds and the formation of abnormal seedlings. Revista de Ciências Agroveterinárias, Florianópolis v.20, n.4, p.278-285, 2021. ).

Thus, the treatment with adequate concentrations of GA3 may result in a more homogenous germination and a higher germination rate in seeds with relatively low endogenous GA3 contents (CORNEA-CIPCIGAN et al., 2020 CORNEA-CIPCIGAN, M.; PAMFIL, D.; SISEA, C.R.; MARGAOAN, R. Gibberellic acid can improve seed germination and ornamental quality of selected Cyclamen species grown under short and long days. Agronomy, Madison, v.10, n.536, p.1-19, 2020. ; SILVA et al., 2021 SILVA, E.C.; VILLA, F.; SILVA, D.F.; POSSENTI, J.C.; SILVA, L.S.; RITTER, G. Araticum accessions: effect of gibberellic acid concentrations and soaking times on seed dormancy overcoming. Revista Caatinga, Mossoró, v.34, n.3, p.614–620, 2019. ). In our study with seeds of M. glomerata treated with low doses of gibberellic acid (250 e 500 mg L-1 GA3) higher values of GSI, length, and biomass were obtained, which is importantas it reduces production costs in the acquisition of this hormone, contributing to overcome dormancy.

Responses regarding GA3 vary according to the species. According to Silva et al. (2019 SILVA, E.C.; VILLA, F.; SILVA, D.F.; POSSENTI, J.C.; SILVA, L.S.; RITTER, G. Araticum accessions: effect of gibberellic acid concentrations and soaking times on seed dormancy overcoming. Revista Caatinga, Mossoró, v.34, n.3, p.614–620, 2019. ), seeds of Annona sylvatica A.St.-Hil pre-imbibed for 24 h with 1,200 mg L-1 of GA3 showed higher GSI. For Psidium guajava L., the use 0.1% GA3 contributes to germination and normal seedlings (HOSSEINI et al., 2020 HOSSEINI, M.S.; ZAHEDI, S.M.; HOVEIZEH, N.F.; LI, L.; RAFIEE, M.; FAROOQ, M. Improving seed germination and seedling growth of guava under heat and osmotic stresses by chemical and hormonal seed treatments. Bragantia, Campinas, v.79, n.4, p.512-524, 2020. ). The physiological effects of plant growth regulators and biostimulants depend on factors such as dose and formulation, plant species, and environmental conditions, including nutrientavailability.

In addition, we reinforce that the immersion in water at 100 ºC and in H2SO4, besides not contributing to overcome dormancy, also hampered germination as 12.67% of normal seedlings were formed in the control treatment. From these results, it ispossible to infer that the dormancy of M. glomerata is physiological and not tegumentary. Generally, H2SO4 and boiling water are mostly used to reduce the hardness of the seed integument and facilitate the subsequent process of imbibition. For M. glomerata, the use of these methods compromised the physical integrity and reserves of seeds, being an unfeasible practice (Figure 1).

Similarly, Pirola et al. (2021) PIROLA, K.; WAGNER JÚNIOR, A.; DOTTO, M.; CASSOL, D.A.; POSSENTI, J.C.; CITADIN, I. Dormancy in native fruit seeds of the Brazilian South Region. Colloquium Agrariae, Presidente Prudente, v.17, n.3, p.21-32, 2021. reported that it is not recommended to use water at 80 ºC and sulfuric acid to overcome the dormancy of seeds of Eugenia uniflora L., Plinia peruviana (Poir.) Govaerts, Plinia cauliflora (Mart.) Kausel, Eugeniainvolucrata DC., Myrcianthes pungens (O. Berg) D. Legrand, and Campomanesia guazumifolia (Cambess.) O. Berg, species belonging to the Myrtaceae family. These authors described that these two methods may have damaged the seed embryo, reducing thegermination potential.

The performance of seeds treated with Stimulate® was lower than expected. Treatment with products containing plant growth regu-lators such as gibberellin, cytokinin, and auxin during germination may improve seed performance in several plantspecies, but the dose may have been low, which prompted us to carry out the second experiment.

Gibberellin causes primary roots to break the tissues that restrain their growth, such as the endosperm and seed and/or fruit tegument, whereas cytokinin and auxins supplement the action of gibberellins, inducing cell division and promotingradicle and shoot growth (FERREIRA et al., 2016 FERREIRA, G.; LA-CRUZ-CHACÓN, I.; GONZÁLEZ-ESQUINCA, A.R. Overcoming seed dormancy in Annona macroprophyllata and Annona purpurea using plant growth regulators. Revista Brasileira de Fruticultura, Jaboticabal, v.38, n.3, p,e-234, 2016. ; TUAN et al., 2018 TUAN, P.A.; KUMAR, R.; REHAL, P.K.; TOORA, P.K.; AYELE, B.T. Molecular mechanisms underlying abscisic acid/gibberellin balance in the control of seed dormancy and germination in cereals. Frontiers in Plant Science, Lausanne, v.9, p.e-668, 2018. ; ATROCH et al., 2020 ATROCH, E.M.A.C.; CAVALCANTE, V.M.V.; ATROCH, A.L.; NASCIMENTO FILHO, F.J. Reguladores de crescimento na germinação de sementes e vigor de plântulas de guaranazeiro. Biodiversidade, Cuiabá, v.19, n.1, p.40-49, 2020. ).

Experiment 2

The results of our study indicate that higher concentrations of Stimulate® should be used to achieve the maximum germination (normal seedlings) of M. glomerata, indicating its physiological effect as a growth regulator in this species. Stimulate®had a synergistic effect due to its balanced composition of plant growth regulators (0.005% indole butyric acid, 0.009% kinetin, and 0.005% GA3). Physiologically, the balance of these hormones act on starch hydrolysis (BEWLEY et al., 2013 BEWLEY, J.D.; BRADFORD, K.J.; HILHORST, H.W.M.; NONOGAKI, H.L. Seeds: physiology of development, germination and dormancy. 3rd ed. New York: Springer, 2013. ), whichfavors the availability of reserves for formation of roots and hypocotyl (SKUBACZ; DASZKOWSKA, 2017 SKUNACZ, A.; DASZKOWSKA-GOLEC, A. Seed dormancy: the complex process regulated by abscisic acid, gibberellins, and other phytohormones that makes seed germination work. Phytohormones – signaling mechanisms and crosstalk in plant development and stress responses. 2017. [S.l.]: IntechOpen, 2017. ; TAIZ et al., 2017 TAIZ, L.; ZEIGER, E.; MOLLER, I.; MURPHY, A. Fisiologia e desenvolvimento vegetal. 6.ed. Porto Alegre: Artmed, 2017. 888 p. ).

This was likely responsible for the higher values of shoot length and shoot and root dry weights, as Stimulate® increases plant growth and development by stimulating cell division, differentiation, and elongation (SANTOS et al., 2013 SANTOS, C.A.C.; PEIXOTO, C.P.; VIEIRA, E.L.; CARVALHO, E.V.; PEIXOTO, V.A.B. Stimulate® na germinação de sementes, emergência e vigor de plântulas de girassol. Bioscience Journal, Uberlândia, v.29, n.2, p.605-616, 2013. ; SMIDERLI etal., 2022 SMIDERLI, O.J.; SOUZA, A.G.; MAIA, S.S.; REIS, N.D.; COSTA, J.S.; PEREIRA, G.S. Do stimulate® and acadian® promote increased growth and physiological indices of Hymenaea courbaril seedlings? Revista Brasileira de Fruticultura, Jaboticabal, v.44, n.2, p.e-872, 2022. ), making it a tool for the improvement of seed and plant physiology. This product can usually be used in the treatment of seeds, but there are also studies on the management of application using other products. In this case, attentionshould be paid to other factors.

Stimulate® presents a cytokinin concentration of 50 mg L-1 kinetin, while the dose of 25 mL kg-1 seeds contained 125 mg L-1 kinetin (DANTAS et al., 2012 DANTAS, A.C.V.L.; QUEIROZ, J.M.O.; VIEIRA, E.L.; ALMEIDA, V.O. Effect of gibberellic acid and the bioestimulant Stimulate® on the initial growth of thamarind. Revista Brasileira de Fruticultura, Jaboticabal, v.34, n.1, p.8-14, 2012. ), indicating a possible phytotoxic effect at higher doses of Stimulate®. On the other hand,the use of this biostimulant at appropriate doses was promising forthe physiology of germination of seeds of M. glomerata. There are few studies in the literature related to the use of Stimulate® specifically in Myrtaceae. Thus, we also describe the responses of other fruit species.

Stimulate® has been used in several crops with satisfactory results regarding shoot growth, as observed for Hymenaea courbaril L. (SMIDERLI et al., 2022). Hormonal treatment in seeds positively contributed to germination and seedling formation of Myrtaceae species (HOSSEINI et al., 2020 HOSSEINI, M.S.; ZAHEDI, S.M.; HOVEIZEH, N.F.; LI, L.; RAFIEE, M.; FAROOQ, M. Improving seed germination and seedling growth of guava under heat and osmotic stresses by chemical and hormonal seed treatments. Bragantia, Campinas, v.79, n.4, p.512-524, 2020. ; PIROLA et al., 2021), which issimilar to what was observed for M. glomerata. For seeds of Physalis angulata L., an increase in the firstgermination count, germination speed index, andseedling formation was observed when seeds were preimbibed in Stimulate® solution 1.50%(SANTIAGO et al., 2019 SANTIAGO, W.R.; GAMA, J.S.N.; TORRES, S.B.; LEITE, M.D.; LEITE, T.S.; NOGUEIRA NETO, F.A. Physiological performance of Physalis angulata L.seeds treated with chemical promoters. Revista Caatinga, Mossoró, v.32, n.3, p.834-840, 2019. ).

These properties are consistent with the higher values obtained for root length and total length of seedlings, as well as with the considerably higher fresh and dry weight observed for M. glomerata in the present study.

Stimulate® is an efficient alternative for obtaining high germination rates and seedling growth in M. glomerata, and the results of this study are important for the establishment of protocols based on physiological management aimed at thepropagation and ex situ cultivation of this species.

Conclusion

Treatment with GA3 (250 mg L-1) and Stimulate® (20-25 mL kg-1 seeds) efficiently over-come dormancy in seeds of Myrciaria glomerata O. Berg., resulting in higher germination rates and seedling vigor.

Acknowledgments

To CAPES for granting the postdoctoral scholarship; and to CNPq and FUNDECT for the financial support.

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Publication Dates

  • Publication in this collection
    25 Nov 2022
  • Date of issue
    2022

History

  • Received
    24 Apr 2022
  • Accepted
    22 Aug 2022
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