Altitudinal Genetic Variation of Pinus oocarpa Seedling Emergence in the Southern Mountains, Oaxaca, Mexico

Abstract

Pinus oocarpa is the most important conifer for resin production in Mexico, so superior resin trees were selected in the Southern Mountains of Oaxaca, Mexico. The objective was to determine the variation and differences among provenances and among trees according to the parameters of seedling emergence and the number of cotyledons, and their relationship with elevation and climatic variables. The seedling emergence of four replicates of 20 seeds from 80 trees was counted daily. For the emergence parameters, provenance contributed 42.02% to the total variance, tree 29.19% and error 28.79%. Only tree (11.71%) and error (88.29%) contributed to the total variance of the cotyledon number. The effect of provenance (p ≤ 0.0006) and tree (p ≤ 0.0001) was significant for all variables evaluated. Higher-elevation provenances and trees had higher emergence values. The emergence parameters were positively associated with tree elevation. Climatic variables related to precipitation and temperature were negatively related to the emergence parameters. The results allow for the selection of phenotypes without emergence problems to establish seed orchards.

Geographic and Climatic Variation in Resin Components and Quality of Pinus oocarpa in Southern Mexico Provenances

“…On the contrary, the percentage of turpentine of all the provenances was lower than that reported (12.7 to 14.55%) for the same species [29,31]. Therefore, it can be affirmed that the rosin content of El Tizne, San Pedro, Las Tejas and Sesteadero is high in reference to previous studies [5,23,29].…”

“…[21]. Therefore, in 2019, the National Institute of Forestry, Agriculture, and Livestock Research initiated a broader research project to improve the resin production of this species in Mexico, through the selection of high-yield resin provenances and phenotypes [22,23].…”

“…In countries such as Mexico, where FGI for resin production is poorly developed [15], the first step is to select superior provenances and trees [24]. The study of provenances can provide insight into the levels and distribution of genetic variation, which is indispensable for genetic improvement [23]. The resin components (rosin and turpentine), quality and genetic gain of resin yield of P. merkusii Jungh.…”

“…For Mexican pine species and in particular for P. oocarpa, the relationship between resin characteristics with geographic and climatic variables has not been studied. However, geographic and environmental factors influence the number of cotyledons, seed emergence parameters and tree growth of this species [23,37,38]. Knowledge of the relationship between resin characteristics and geographic and climatic factors is important to guide the collection of seeds to establish resin-producing plantations [18,23].…”

“…However, geographic and environmental factors influence the number of cotyledons, seed emergence parameters and tree growth of this species [23,37,38]. Knowledge of the relationship between resin characteristics and geographic and climatic factors is important to guide the collection of seeds to establish resin-producing plantations [18,23].…”