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Revista mexicana de ciencias forestales

versão impressa ISSN 2007-1132

Rev. mex. de cienc. forestales vol.9 no.50 México Nov./Dez. 2018 


Seed production and biological potential of three Pinus species in Durango

Oscar Omar Santos Sánchez1  * 

Marco Aurelio González Tagle1 

Ricardo López Aguillón1 

1Facultad de Ciencias Forestales, Universidad Autónoma de Nuevo León. México.


This comparative study reveals the biological potential and the production of seeds of superior trees. It allows to compare the behavior of three species in the years 2013 and 2015. The characterization of the cones was made by registering the dimensions of trees of each species in both years, comparing increases or decreases in diameter and length from 2013 to 2015. Pinus engelmannii showed an increase in length of 17 mm and an increase in diameter of 19 mm, Pinus durangensis decreased 20 mm in length and increased 23 mm in diameter, and Pinus cooperi grew 4 mm in length and 13 mm in diameter. The size of the cone is related to the biological potential and the production of seed (developed seeds, DS). The biological potential of Pinus engelmannii proved to be the highest in both years, the Pinus durangensis species registered an increase from 2013 to 2015 in the same sense as Pinus cooperi. In terms of the seed production variable (developed seeds, DS) the Pinus engelmannii species exhibited no significant difference from one year to the next; however, there were no significant differences in Pinus cooperi and P. durangensis between 2013 and 2015.

Key words: Plus tree; cone; Pinus; biological potential; production; seed


Este estudio comparativo da a conocer el potencial biológico y la producción de semillas de árboles superiores. Permite comparar el comportamiento de tres taxa de Pinus en los años 2013 y 2015. Se realizó la caracterización de sus conos a partir de sus dimensiones en ambos años, y se compararon los incrementos o decrementos en diámetro y longitud. Pinus engelmannii presentó un aumento en longitud de 17 mm y en diámetro de 19 mm; Pinus durangensis decreció 20 mm en longitud y aumentó 23 mm en diámetro. Pinus cooperi ganó 4 mm en longitud y 13 mm en diámetro. El tamaño del cono se relaciona con el potencial biológico y la producción de semilla (semillas desarrolladas, SD). En Pinus engelmannii el potencial biológico fue más alto en ambos años; Pinus durangensis y P. cooperi registraron un incremento de 2013 a 2015. Respecto a la producción de semillas (semillas desarrolladas, SD), no hubo diferencia significativa entre años Pinus engelmannii; Pinus cooperi y P. durangensis si se obtuvieron. La comparación de la producción de semilla en el género Pinus ayuda a conocer si existen diferencias significativas entre años de producción, áreas y especies, y así determinar que factores influyen en esa variación y como reducen la viabilidad y cantidad de semilla en los bosques.

Palabras clave: Árboles superiores; cono; Pinus; potencial biológico; producción; semilla

In Mexico, seeds for plant production programs are collected mainly from natural stands, which are not subjected to management for increasing the genetic gain of the seed, and, in a smaller scale, from seedbed areas where poorly formed trees are eliminated and only those trees that may have a better genetic quality are left (Prieto and Martínez, 2006).

The analysis of cones and seeds makes it possible to assess the physical and biological characteristics of a specific batch in order to assign a value to it (Bonner, 1993). Furthermore, it is a helpful tool for determining the amount and quality of the seeds produced in a particular area. This allows estimating the latter’s productivity for utilization as sources of seed-producing germplasm for forest plant production programs.

Since the national demand of forest seeds grows year after year, the production of high quality germplasm must be increased through the establishment of seedbed areas and seed orchards to ensure the availability of permanent sources of germplasm with a 5 to 50 % increase in genetic gain, according to the genetic improvement strategy implemented.

In the seed orchards, the materials for propagation ―seeds or shoots―, are obtained from superior (Plus or elite) trees. In general, seed orchards are generated from a selection of 40 to 60 trees (Droppelmann, 2012).

Plus trees are selected according to various techniques, and their selection depends on such factors as: a) the characteristics of the growth of the species; b) the current forest management situation, and c) the variability and the hereditary pattern of the relevant features, according to the objectives of the forest genetic improvement program (Zobel and Talbert, 1988).

The present study will allow comparing the seed production of three species of the genus Pinus of the state of Durango in two seed-producing years: 2013 and 2015. Its objectives were to determine which of these species has the highest seed production index, to describe the behavior of the dimensions of their cones, and to compare their biological potential.

Pinus engelmannii Carrière is a native species of Mexico, specifically of the Sierra Madre Occidental (Wester Sierra Madre). Its mean height ranges between 15 and 25 m, and its DBH, between 60 and 80 cm; it has perennial leaves; it blooms in winter, and its cones mature from late October to mid-December (Conafor, 2014). It occurs as part of Quercus and conifer forests, between the geographical coordinates 21°50’ and 31°15’ N, and 103°45’ and 110°35’ W. Its natural distribution is limited to the states of Chihuahua, Sonora, Sinaloa, Durango, and Zacatecas (Conafor, 2014).

Pinus durangensis Martínez is native to the Sierra Madre Occidental of Mexico. Its height ranges between 30 and 40 m, and its diameter, between 50 and 80 cm; it has perennial leaves that grow in fascicles of 6, 5, or 7, but only in rare occasions 4 or 8, in the same branchlet, and are thin or moderately thick, 14 to 30 cm long, 0.6 to 1 mm wide, and 0.6 to 0.7 mm thick. Its cones are reddish brown, slightly curved, of an ovoid shape, 6 to 10 cm long, generally occurring in groups of two or three but sometimes individually, and they are semi-persistent for several months. This species is distributed to the northeast of the Sierra Madre Occidental, between Chihuahua, Sonora and Durango, at an altitude of 2 500 to 2 700 m, on very deep, silty clayey loam soils of a brown to reddish brown hue, with a pH of 6 to 7, with a moderate to high organic matter content (5 to 10 %); soils rich in nitrogen, silicon and humus that are permeable and deep, and rich in calcium and potassium but poor in phosphorus; at a temperature of 9 to 17 °C; with precipitations of 600 to 1 200 mm. It is resistant to frost and intolerant to drought (Conafor, 2014).

Pinus cooperi C. E. Blanco is found exclusively in the Sierra Madre Occidental of Mexico. Its height ranges between 15 and 35 m, and its diameter, between 30 and 80 cm; its leaves grow in fasciles of 3 to 5, mostly 5, and only rarely in fasciles of 6, and they are thick and of a dark or ashen green hue. This species is distributed in Zacatecas, Sinaloa, Durango, Chihuahua and Sonora (Conafor, 2014).

The present study was carried out in the El Salto region, in Pueblo Nuevo, Durango (Figure 1). This region is located in the Sierra Madre Occidental, in the southwest of the state of Durango, north of the municipality of Pueblo Nuevo. It can be accessed from Km 100 of the Durango-Mazatlán road, at an altitude of 2 538 masl.

Figure 1 Location of the study area, El Salto, Pueblo Nuevo, Durango.  

75 Plus trees were selected during the execution of the genetic improvement program in the charge of the Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias, INIFAP) (National Institute for Research on Forest, Agriculture and Livestock) in Durango, in 2008. For this purpose, the best phenotypic characteristics ―a straight, clean stem; thin branches, and a small crown; cone production; color of the leaves, and height and diameter― were considered and compared to those of their four neighbors within a radius of 10 to 15 m, with a spacing of over 100 m in order to reduce the likelihood of kinship between them (Callahan, 1964).

The selected individuals corresponded to 25 specimens of each taxon. In the samplings, it was observed that not all individuals produced cones and seeds; therefore, the number of individuals was smaller (Table 1).

Table 1 Comparison of the variables Biological Potential (BP) and Developed Seed (DS), and of the dimensions of the cone (Length and Diameter) for the three species in 2013-2015. 

Species Variable year N Mean (+ -)
Pinus engelmannii Carrière Developed Seed (DS) 2013 3 48.37 10.7
2015 3 48 13.5
Biological Potential (BP) 2013 3 136.9 27.8
2015 3 135.7 26.3
Length 2013 3 11.16 2.85
2015 3 11.33 2.52
Diameter 2013 3 4.14 0.68
2015 3 4.33 0.58
Pinus durangensis Martínez Developed Seed (DS) 2013 7 29.83 21.3
2015 16 62.13 25.9
Biological Potential (BP) 2013 7 86.6 24.9
2015 16 113.6 19.8
Length 2013 7 7.83 1.51
2015 16 7.63 1.31
Diameter 2013 7 3.46 0.83
2015 16 3.69 0.48
Pinus cooperi C.E. Blanco Developed Seed (DS) 2013 10 37.16 14.1
2015 18 57.94 20.7
Biological Potential (BP) 2013 10 85.78 29.6
2015 18 109.3 16.3
Length 2013 10 7.79 1.65
2015 18 7.83 0.79
Diameter 2013 10 3.59 0.41
2015 18 3.72 0.46

A random sample of 12 cones was obtained from each tree; the characterization and dissection of the cones, the extraction of the seeds, and the analysis of the seeds and scales were carried out according to the methodology of Bramlett et al. (1977), adapted by Alba-Landa et al. (2000). The fertile scales and the developed seeds were identified; the biological potential (BP) was estimated using the following formula:

BP=No. of fertile scales ×2

The length and diameter of the cones were measured using a FW-V8 digital caliper calibrated in millimeters, with a precision of 0.001 mm.

The biological potential is the maximum capacity of a cone to contain fully developed seeds (Figure 2).

Figure 1 Classification of the scales of a dissected cone. Lower infertile scales (A), fertile scales (B), and upper infertile scales (C). 

The seed production efficiency (DS) was estimated according to the formula:

DS=Total of full seeds/BP


DS = Total number of developed seeds

BP = Biological potential

The values of the means were considered in order to make a comparison and determine the differences between two seed-producing years in the same production areas for the three studied species and even at specimen level.

Furthermore, this study detected significant differences between the seed-production variables (Developed Seed DS), since it determines the actual number of seeds, unlike the Biological Potential, which refers to the maximum capacity of each species to develop full seeds in each cavity or shell in the fertile scales. However, a cone with a high biological potential may not always yield a large number of fully developed seeds.

An ANOVA variance analysis was performed using the Statistical Package for the Social Sciences (SPSS), version 24. The Kolmogorov-Smirnov normality test was applied to the seed production data per species for the two study years.

Table 1 summarizes the descriptions of the variables for the studied species for the years 2013 and 2015.

Table 2 shows the (ANOVA) statistics produced in order to determine the differences between the species in terms of seed production (DS) from 2013 to 2015.

Table 2 Summary of the variance analysis for the studied species based on the seed production (DS) variable. 

Species Sum of squares Gl Mean Squares F Sig
Pinus engelmannii Carrière 0.202 1 0.202 0.001 0.972
Pinus durangensis Martínez 5079.25 1 5079.25 8.323 0.009
Pinus cooperi C. E. Blanco 2777.1 1 2777.1 7.951 0.009

In general, the biological potential (BP) of the three Pinus taxa increased from 2013 to 2015. When it was compared across time, the BP of Pinus durangensis increased by 23.76 %, and that of Pinus cooperi, by 21.61 %, while Pinus engelmannii exhibited no increase from one year to the other (Table 1).

When comparing only the biological potential (PB), regardless of the time, Pinus engelmannii showed the highest value in the comparison of means, with a

difference of 21.80 %, with respect to the other species (Table 1).

In terms of the developed seed (DS), there was a significant difference in both Pinus cooperi and Pinus durangensis between 2013 and 2015, with an increase in seed production of 51.98 % for P. durangensis and of 49.67 % for P. cooperi, while Pinus engelmannii exhibited no differences (Table 2).

In their comparison of three regions of the state of Durango, Bustamante-García et al. (2012) registered a significant difference in seed production for Pinus engelmannii.

Alba-Landa et al. (2003) compared the biological potential and seed production efficiency of Pinus hartwegii Lindl. from two provenances in Mexico and found differences in both variables; this confirms that the differences in seed production and biological potential may be affected by various environmental, phenotypic of genotypic factors.

According to Bramlett et al. (1977), specific clones in seed orchards exhibit little variation in seed-producing potential; however, this potential differs from the average for the species. López-Upton and Donahue (1995) point out significant differences between sites for the seed-producing potential of Pinus greggii Engelm.

Alba-Landa et al. (2000) document no significant differences between sites for Pinus oaxacana; however, the present study determined that the seed-producing potential may vary significantly on an annual basis at the level of specimens. Boyer (1987) registered considerable variation in seed production in Pinus palustris Mill. between years and localities.

This agrees with the findings of Spurr and Barnes (1982), who state that the characteristics of the seeds of a given species vary significantly according to the habitat. Thus, the differences are determined by the environmental conditions of each site and to the genetic conditions of each taxon.

Since the studied taxa are located in a region that shares the same environmental and topographic characteristics, the behavior of Pinus engelmannii in regard to all the variables may be ascribed to its adaptability to environmental changes, as it is widely distributed in Zacatecas, Sinaloa, Durango, Chihuahua and Sonora, unlike the other studied species.

This adaptability of P. engelmannii (Conafor, 2014) renders it more tolerant to the modification of the various factors that affect or enhance seed production, which include the level of moisture, temperature, rainfalls, soil nutrients and pollination.

Pinus engelmannii is a species with a stable seed production, unlike Pinus cooperi and Pinus durangensis.


To the Universidad Autónoma de Nuevo León (UANL) for their suport, formation and help. To the Instituto Tecnológico of El Salto for having helped in the laboratory analysis and for having lend the licenses for the collections made at their properties.


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Received: March 22, 2018; Accepted: September 27, 2018

Conflict of interests

Los autores declaran no tener conflicto de intereses.

Contribution by author

Oscar Omar Santos Sánchez: data collection at the field, cone analysis at the laboratory, development of the research study, data collection and analysis, structuring and writing of the manuscript; Marco Aurelio González Tagle: statistical analysis, review of the study areas, general review of the document, final corrections, variables selection and review of the manuscript; Ricardo López Aguillón: review of the project and of the data collection, samplings planning, variables selection and review of the manuscript.

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