Seedling emergence capacity and morphological traits are under strong genetic control in the resin tree Pinus oocarpa

Pinus oocarpa is a widely distributed species essential for resin production in Mexico, where demand surpasses supply. This study aimed to identify differences and variation levels of seedling emergence capacity and morphological traits in resin-producing high-yield P. oocarpa trees and estimate their genetic control. Seeds from 72 open-pollinated families were planted using a randomized complete block experimental design. Differences between families were determined and pooled using cluster analysis. We recorded wide differences in seed emergence capacity and morphological traits (cotyledon number and length, and hypocotyl length), allowing to establish three family groups. We also calculated the contribution of the variation sources to the total variance and genetic parameters involved. Our data evidenced high genetic control for all tested variables. We found a moderate and positive genetic correlation between cotyledon length, cotyledon number, and hypocotyl length. We also found a high negative genetic correlation between emergence capacity and hypocotyl length. At the phenotypic level, we found a high and significant correlation between cotyledon length and number. Grouping P. oocarpa into families should aid decision-making for sexual propagation since a high propagation capacity of the high-yield trees is essential for genetic improvement programs. Moreover, we demonstrate that the heritability of the emergence capacity and other morphological traits is high; these traits can be useful for the early selection of high-yield families.