Genetic Variation in Frost Damage and Seed Zone Delineation within an Altitudinal Transect of Pinus Devoniana (P. Michoacana) in Mexico

We explored the patterning of genetic variation among Pinus devoniana Lindl. (also known as P. michoacana Martinez) populations to develop guidelines for seed and seedling movements, intended for improving the matching between genotypes and environments regarding frost tolerance, in reforestation programs. Open-pollinated seed from 16 populations along an altitudinal transect (1600 to 2450 m) were collected near Morelia, State of Michoacan, Mexico. A common-garden provenance test, established with 2.5-year-old seedlings, was assessed for frost resistance conducting a laboratory frost damage test (-9°C). Results indicate that there were significant differences among provenances (P = 0.0261) for frost damage. Variation among provenances was structured as an altitudinal cline, with populations from lower altitudes being the least tolerant to frost. Linear regression statistics suggest that for each increment of 100 m of provenance altitude, there will be a 5.2% decrease in frost damage. We suggest the use of two provisional altitudinal seed zones of 400 m breadth each (lower and upper limits for zone 1:1600 m and 2000 m of altitude; for zone 2:2000 and 2400 m, respectively), and for reforestation of a given site, the use of seedlings originated from seed of the same seed zone or within ±200 m of altitude from the elevation of the reforestation site. Key words: Pinus devoniana, Pinus michoacana, altitudinal genetic variation, provenances, frost damage, frost hardiness, seed zoning, seed and seedling movement guidelines.

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Author(s): Cuauhtemoc Saenz-Romero, B. L. Tapia-Olivares

Section: Genetics and Tree Improvement

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