Germination Capacity Versus Germination Rate: A Physiological Trade-Off Dependent on the Germination Environment in Three Mexican Conifers

Seed germination is a key factor in the success of forest regeneration and nursery production; however, its performance depends on the interactions among seed physiology, pre-germination treatments, and environmental conditions. We evaluated how eight pre-germination treatments and two contrasting environments affected germination capacity, vigor, and kinetics in seed lots (provenances) of Pinus hartwegii, P. montezumae, and P. pseudostrobus. The seeds were subjected to hydration, H2O2, mechanical scarification, or GA3 treatments and were germinated in a controlled chamber and a greenhouse; the responses were analyzed using generalized linear mixed models. Species × environment interactions were significant for all germination parameters. Final germination was higher in the greenhouse than in the chamber (81% vs. 72%), while germination was faster in the chamber. P. pseudostrobus achieved the highest germination rate (96%), P. montezumae showed the greatest stability across environments, and P. hartwegii exhibited a relatively stable final germination capacity across environments but greater kinetic sensitivity. Among the treatments evaluated, 2% H2O2 and 200 mg L−1 GA3 showed the most favorable balance between germination capacity and rate, while scarification accelerated germination but reduced its final percentage.