Genetic variation and phenotypic plasticity in the seasonal shoot growth pattern of Pinus pseudostrobus

Global warming has increased the stress conditions faced by natural populations of forest species. Genetic variation (GV) and phenotypic plasticity (PP) of adaptive traits are the main mechanisms by which these species survive the in situ effects of environmental fluctuation including a higher frequency of stressful events. This study evaluated the level of GV and PP in annual shoot growth and bud phenology traits such as bud flush and bud set date in 44 families of Pinus pseudostrobus from central Mexico established in an open-pollinated progeny trial replicated at two sites with different soil and climate conditions. Results showed wide GV in seasonal shoot growth pattern and strong genetic control in bud phenology traits. Shoot growth, particularly activation and formation of terminal bud, and shoot growth during wintertime, showed an adaptive relationship with climate conditions of origin site of families, particularly with moisture availability and aridity index. Despite the significant effect of test site on shoot growth, families exhibited consistent performance across sites for most traits, except for wintertime shoot growth (WSG) which showed a significant genotype x environment interaction. PP in WSG showed moderate genetic control and positive relationship with productivity (total height). The adaptive value of the GV and PP of shoot growth traits could allow P. pseudostrobus populations to mitigate the negative impacts of environmental fluctuations associated with global warming and provide competitive advantages in productivity for domestication purposes.