Revista Mexicana de Ciencias Forestales Vol. 13 (69)

Enero – Febrero (2022)

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Efectos del pretratamiento con Trichoderma y Bacillus en la germinación de semillas de Agave victoriae-reginae T. Moore

Effects of Trichoderma and Bacillus pre-treatments on the germination of Agave victoriae-reginae T. Moore seeds

Francisco Castillo Reyes1

David Castillo Quiroz1*

Jesús Eduardo Sáenz Ceja2

Agustín Rueda Sánchez3

J. Trinidad Sáenz Reyes4

Fecha de recepción/Reception date: 24 de agosto de 2021

Fecha de aceptación/Acceptance date: 26 de noviembre de 2021


1Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Campo Experimental Saltillo. México.

2Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México. México.

3 Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Campo Experimental Centro Altos de Jalisco. México.

4 Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias Campo Experimental Uruapan.  México.

*Autor para correspondencia; correo-e:


La aplicación de tratamientos pregerminativos es fundamental para mejorar las tasas de germinación de las semillas de especies forestales, entre los cuales el uso de microorganismos es uno de ellos. En este estudio se evaluó el porcentaje de germinación de semillas de Agave victoriae-reginae tratadas con Trichoderma spp. y Bacillus spp. Se probaron tres tratamientos: T1 (Trichoderma), T2 (Bacillus) y T3 (Testigo), con tres repeticiones de 100 semillas cada una. Las semillas se sumergieron en una solución de 1 × 106 UFC (tratamientos T1 y T2), y en agua corriente (T3), luego se sembraron sobre Sphagnum peat moss y se registró el porcentaje de germinación diariamente. La germinación comenzó a los 5 días después de la siembra, lo que significa que las semillas no presentaron latencia. Entre el 8° y 12° día se registró un aumento acelerado de la germinación en los tres casos, hasta que la el proceso finalizó a los 26 días, con 85 % de germinación total para semillas tratadas con Trichoderma, 86.7 % con Bacillus y 74 % con el testigo. Se observó un efecto significativo del tratamiento sobre el porcentaje de germinación; incluso el uso de ambos microorganismos aceleró el proceso de germinación con respecto al testigo. Estos resultados sugieren que el uso de Trichoderma spp y Bacillus spp. como tratamientos pregerminativos puede mejorar la germinación de A. victoriae-reginae y su conservación a largo plazo, lo que contribuye a la permanencia de esta especie en peligro de extinción.

Palabras clave: Agave, especie en riesgo, latencia, noa, tratamiento pregerminativo, viabilidad de semilla.


Application of germinative treatments is key to improve germination rates of forest species seeds, among which is found the use of microorganisms. In this study, the percentage of germination of Agave victoriae-reginae seeds treated with Trichoderma spp, and Bacillus spp was evaluated. Three treatments were tested: T1 (Trichoderma), T2 (Bacillus), and T3 (control), with three replications of 100 seeds each one. The seeds were immersed in a solution 1 × 106 CFU (treatments T1 and T2), and water in T3, then they were sowed, and the germination percentage was recorded daily. The germination began 5 days before the sown, which indicated that seeds did not present dormancy. Between 8° and 12° day an accelerated increase of germination was recorded in the three cases, until it ended at day 26, with 85 % as total germination for seeds treated with Trichoderma spp., 86.7 % with Bacillus spp., and 74 % with control. A significant effect of treatment on the germination percentage was found; even the use of both microorganisms accelerated the germination process compared to control. These results suggest that the use of Trichoderma spp, and Bacillus spp. as pregerminative treatments can improve the germination of A. victoriae-reginae and its long-term conservation, which contributes to the preservation of this endangered species.

Key words: Agave, endangered species, dormancy, noa, germinative treatment, seed viability.


The collection and commercialization of non-timber forest resources is one of the main economic activities in the arid and semi-arid zones of northeastern Mexico (Castillo et al., 2015). However, the inadequate management of the exploited species, as well as clandestine collection, have had effects on the diversity, the area of distribution and the abundance of these species, to the extent of leading them to different levels of risk of extinction (Durán and Núñez, 2015). Among the threatened species in Mexico is Agave victoriae-reginae T. Moore (Asparagaceae) (Tropicos, 2019), known as “noa” or “queen’s agave”, a perennial species, endemic to the Chihuahuan Desert, distributed in northern Mexico, in the states of Coahuila, Durango and Nuevo León (Durán and Núñez, 2015).

From its peculiar beauty, this species has been the focus of attention by collectors for ornamental use (González et al., 2011). This situation has led this taxon to be included in the Official Mexican Standard NOM-059-SEMARNAT-2010 under the category of "endangered species" (Semarnat, 2010), as well as in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) (CITES, 2017). Therefore, the assisted reproduction of A. victoriae-reginae seedlings and the subsequent reforestation in their habitat constitutes an alternative to mitigate the loss of natural populations.

Germination is the most crucial stage of the plant cycle, as it depends on a set of environmental conditions and resources such as soil and nutrients, which limit or promote the establishment of the seedling on a substrate, and on a broader scale, the regeneration of a plant population (Donohue et al., 2005). Therefore, understanding the germination process is key to improving nursery production (Barnett and Varela, 2004) and thus promoting the conservation of forest populations.

Maturity, viability (period during which seeds retain their germination capacity) and dormancy (inability to germinate under optimal environmental conditions and resources) are intrinsic factors on which seed germination depends, as well as extrinsic factors such as temperature, substrate, light intensity and humidity (Khurana and Singh, 2001; Doria, 2010). The use of pregerminative treatments allows to accelerate and homogenize germination, among which are mechanical, thermal and chemical scarification, dehydration, imbibition, and the use of growth regulators (Cubillos et al., 2011; Hernández et al., 2017).

There is evidence that certain microorganisms have the ability to stimulate seedling germination and growth (Cubillos et al., 2011). On the one hand, the use of fungi such as Trichoderma spp. reduces the mechanical resistance of the testa in the seeds and facilitates the breaking of dormancy (Delgado-Sánchez et al., 2013). On the other hand, the use of bacteria such as Bacillus spp. allows the solubilization of nutrients such as phosphates, which improves the nutrition of the embryos (Cabra et al., 2017).

In general, the use of pregerminative treatments in seeds of Agave species has been limited and has focused on evaluating the effect of environmental conditions such as temperature in eight species of this genus, including Agave lechuguilla Torr. and Agave cupreata Trel. et Berger (Ramírez et al., 2012), the origin of the seed in Agave potatorum Zucc. (Rangel et al., 2015), or the substrate in A. victoriae-reginae (Sánchez et al., 2017). Furthermore, in this genus, the use of microorganisms as germination facilitators has not been evaluated. Therefore, the objective of this study was to evaluate the effect of pregerminative treatments with Trichoderma spp. and Bacillus spp. on the percentage of germination of seeds of A. victoriae-reginae. The hypothesis of this research is that the use of Trichoderma spp. and Bacillus spp. as pregerminative treatments, the GP can be increased compared to sowing without these microorganisms.

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Materials and Methods

Studied species

Agave victoriae-reginae T. Moore. Small, compact plant, simple or furrowed or cespitose, acaulescent with short stem (highly variable under cultivation). Short, green leaves with striking white markings, generally very intertwined, 15-20 (-25) × 4-6 cm. linear ovate, rounded at the apex, stiff, thick, flat to concave at the top, rounded to sharp at the bottom; corneal margin white, generally toothless, 2-5 cm wide, continuous to base; terminal spines 1-3, 1.5-3 cm long, trine-conical, subulate, very broad at the base, with broad base, widely concave on the upper face, with rounded keels below, black: inflorescence spiky, erect 3-5 m high, densely flowered in the upper half of the axis, the peduncle with long attenuated deltoid chartaceous bracts; flowers in pairs or short triads, forked, sturdy pedicels, 40-46 mm long; thickly fusiform, with a short neck; shallow tube, extended, 3 × 8-10 mm; tepals almost equal, 18-20 × 5-6 mm, linear, rounded apiculate, spreading, then enveloping the filaments in the post-anthesis and erect, the interior strongly keeled, filaments 45-50 mm long, inserted at the edge of the tube; anthers 18-21 mm long, yellow or tan, centric or eccentric; capsules ovoid to oblong, 17-20 × 10-13 mm, rounded at the base, apiculate: seed 3-5 × 2.5-3.5 mm, hemispherical to lacriform, veined on both sides, lower marginal wing (Gentry, 1982).

Germplasm collection

A mass harvest of A. victoriae-reginae seeds was carried out directly from the capsules that indicated the dehiscence of specimens (plants) from the botanical garden of the La Sauceda Experimental Site, which belongs to the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) (National Institute of Forest, Agricultural and Livestock Research (INIFAP ), located in the Ramos Arizpe municipality, state of Coahuila, between 101°18'58.45'' W and 25°50'48.45'' N, at 1 024 masl. The environmental conditions for this place according to the Köppen climatic classification, modified by García (1973), the climate is predominantly dry, semi-warm and temperate (BWK) with an average annual temperature of 18.5 °C and average annual rainfall of 198.7 mm; annual average evaporation of 1 349 mm (Díaz et al., 2007). The germplasm was collected in 2018 and stored in a transparent plastic container (10x10 cm) and hermetic at room temperature (25 °C average) for a year, within the Saltillo Experimental Field of INIFAP, in the Saltillo municipality, Coahuila.

Pregerminative treatments

Three pregerminative treatments were applied to the seeds: T1 (Consortium of Trichoderma species), T2 (Consortium of Bacillus species) and T3 (control based on only direct running tap water). The microorganisms were purchased in the form of commercial biostimulant complexes; for Trichoderma, it was PrevenceTM (Trichoderma harzianum Rifal (1969) T. asperellum Samuels, Lieckf. & Nirenberg and T. yunnanense Z. F.Yu & K. Q. Zhang, equivalent to 1 × 1012 spores ml-1) and for Bacillus it was Bioshield-RTM (Bacillus subtilis (Ehrenberg 1835) Cohn 1872, B. amyloliquefaciens Priest et al., 1987, B. licheniformis (Weigmann 1898) Chester 1901, B. megaterium de Bary 1884 and B. mycoides Flügge 1886, equivalent to 1 × 109 CFU ml-1). Agave seeds were soaked in a final solution composed of 1 × 106 CFU for one minute, and then allowed to dry at room temperature.

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Experimental design

A completely random experimental design was used with three replications of 100 seeds each. The seeds treated with the microorganisms were sown in 25 × 10 cm transparent plastic containers with a cover, and Sphagnum peat moss (PremierTM) was used as substrate in a 5 cm thick layer moistened at field capacity. After sowing, each of the containers was kept at a temperature of 26 ± 2 °C and conditions of 12 h light and 12 h of darkness, under laboratory conditions.

The number of germinated seeds was recorded every 24 hours to determine the germination percentage (PG), which was calculated using the equation:


GP = Germination percentage (%)

SG = Number of germinated seeds

ST = Total number of seeds

Statistical analysis

An analysis of covariance was performed to evaluate the effect of pregerminative treatments and the time after sowing on the GP of the treated seeds (α = 0.05), using the statistical package R (3.4.3) (R Core Team, 2017).

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The analysis of covariance showed that the treatment and the time had a significant influence on the germination of the seeds (Table 1). the Trichoderma and Bacillus consortium (P <0.001) treatment determined a final PG statistically higher than control, with an increase in germination of 14.8 % and 17.1 %, respectively. The germination time after sowing also influenced GP (P <0.001), as during the first days a notable increase in germination was observed, to follow afterwards a stabilization trend after the 12th day of sowing.

Table 1. Effect of the treatment and time in the germination percentage of Agave victoriae-reginae T. Moore.

Variation factor




F value

P value



2 989

1 495





34 515

34 515



Treatment - time








8 479


GL=degrees of freedom; SC= sum of squares; PSC= SC  average.

Germination of A. victoriae seeds began on the 5th day after sowing, with 29.6 %, 19.6 % and 12.6 % for the seeds treated with Trichoderma spp., Bacillus spp. and control, respectively. Between the 8th and 12th day, an exponential increase in germination was observed, and later, the increase in germination began a relative stabilization period until the end of 26 days, when the GP reached 85 % for seeds treated with Trichoderma spp., 86.7 % with Bacillus spp. and 74 % with the control treatment (tap water) (Figure 1).

Figure 1. Percentage of germination of seeds of Agave victoriae-reginae T. Moore according to the treatment with respect to time.

The type of treatment did not influence the germination time (P> 0.345), since the three treatments followed similar temporal trajectories, but there was significant evidence that the use of microorganisms accelerated the GP in the first days, for example, on the 5th day, the GP with Trichoderma spp. was 29.7 %, a figure higher than that registered with the control on the 10th day (28 %). Also in the last days of germination, the control reached a GP of 74 % at 26 days, while with microorganisms this value was exceeded at 17 days (79.3 % with Trichoderma spp. and 77 % with Bacillus spp.). During the first 12 days, there were significant differences between the three treatments. After this period, the GPs with the microorganisms were similar, but they did differ in contrast to the control.


The total GP of the three treatments were higher than those calculated for Agave mapisaga Trel. (70 %) and A. angustifolia Haw. subsp. tequilana (F.A.C. Weber), with 28 % germination (Ramírez et al., 2016), in which no pre-germination treatments with microorganisms were used. Also, the seeds of A. victoriae-reginae were viable after one year of being collected. Since metabolic processes such as perspiration and metabolisms that cause natural aging occur in stored seeds, and, consequently, viability tends to decrease over time (Moncaleano et al., 2013), it is possible that if A. victoriae-reginae seeds are sown during the year of collection, they might achieve higher GPs. However, the results of this study suggest that it is possible to store the seeds for at least one year, and have acceptable GPs.

In addition, under the environmental conditions during the experiment, it can be stated that seeds did not show dormancy, characteristic of other Agave species from arid areas, such as Agave lechuguilla Torr. (Freeman et al., 1977) and Agave parryi Engelm. var. parryi (Freeman, 1975). The absence of dormancy in the evaluated seeds in this study is similar to that known for seeds stored for two years of Agave salmiana Otto ex Salm-Dyck, which had lower dormancy than those sown in the same year of collection; such differences are attributable to the effect of the storage temperature (Peña et al., 2006).

The germination start time was similar to that reported in another study with A. victoriae-reginae (Sánchez et al., 2017), which varied between 3 and 4 days. The time after sowing significantly influenced the GP in which significant differences were identified between the three treatments before 12 days, expressed in a period of acceleration of germination; meanwhile, in the second half of the evaluated time there were no differences between Bacillus spp. and Trichoderma spp., but they were found with the control. This behavior is similar to that of other Agave species, with a fast-growth period followed by a saturation of the germination curve (Ramírez et al., 2012; Ramírez et al., 2016).

The increase in GP during the first days of the experiment could be attributed to the fact that the largest seeds could have been the first to germinate, as they were genotypically the most vigorous (Sánchez et al., 2011). Another factor could be the high moisture due to the covered container used, which favored the ideal humidity conditions to promote germination (Castillo et al., 2014).

The response of A. victoriae-reginae to the microorganisms added as pregerminative treatments was satisfactory, indicating that the use of Trichoderma spp. and Bacillus spp. can improve the nursery production of this species. These results coincide with those recorded in Opuntia streptacantha Lem, another plant from semi-arid areas, in which fungi have the ability to dissolve the testa, without affecting the endocarp, which facilitates the emergence of the embryo (Delgado-Sánchez et al., 2010). In addition, fungi and bacteria release radical exudates, among which are sugars, mucilage, organic acids and amino acids, which can provide nutrients for the embryos, and even promote the subsequent growth of seedlings (Ahmad et al., 2008; Gómez et al., 2013).

In addition, some of the biocomposites produced by these inoculants, such as antimicrobial substances or that stimulate the seedling's immune system, inhibit the development of phytopathogens, which represents an advantage for new seedlings (Guillén et al., 2006). Therefore, the management of Trichoderma spp. and Bacillus spp., widely used in agriculture (Moreno et al., 2018), is highly recommended to promote the germination of A. victoriae-reginae seeds, since they increase the GP.

In forest plantations with coniferous species, the incorporation of microorganisms such as mycorrhizae has also shown increases in seedling survival (Gómez et al., 2013). This confirms the great role that microorganisms play during the first stages of the life cycle of plant species such as pine trees and also agaves, through biotic interactions such as mutualism (Sieber, 2007). For this reason, it is of vital importance to introduce this type of microorganisms in the production of forest species in nurseries (Ortega et al., 2004).

Because the seeds of A. victoriae-reginae respond favorably to the use of Trichoderma spp. and Bacillus spp., the nursery production of this species is feasible, which means a great opportunity for the recovery of the populations of this endangered species. In subsequent studies, it will be important to evaluate the effect of other environmental conditions, such as humidity, temperature and light, on the germination of the seeds of this species and others at risk.


The germination of seeds of A. victoriae-reginae responded favorably to treatment with Trichoderma spp. and Bacillus spp., increasing the PG. These characteristics represent a great opportunity for the assisted reproduction of this species at risk and the recovery of natural populations in the long term.

Conflict of interests

The authors declare no conflict of interest.

Contribution by author

Francisco Castillo Reyes: experimental design, data analysis, writing of the manuscript, David Castillo Quiroz: germplasm collection, direction and establishment of the experiment, taking parameters, writing and review of the manuscript. Jesús Eduardo Sáenz Ceja, Agustín Rueda Sánchez and J. Trinidad Sáenz Reyes: data analysis, writing and review of the manuscript.


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