Introduction: Plants should undergo a hardening process in the nursery to improve the survival of forest plantations in degraded areas.
Purpose of the study: The effect of three levels of irrigation was evaluated in the hardening stage on some morphological and physiological variables of Pinus oaxacana.
Materials and Methods: The treatments evaluated were three levels of irrigation and a control treatment. Irrigation was performed when the containers reduced their saturation weight by 30 % (frequent), 40-45% (medium) and 45-50% (low); in the control treatment, irrigation was applied every two or three days. The study used a randomized complete block design; each treatment consisted of 100 plants.
Results and Discussion: Morphological indicators with significant differences (P ≤ 0.05) among treatments were root collar diameter, shoot dry weight, and total dry weight. The physiological indicators using the root growth potential test showed no significant differences. Plants with frequent irrigation had greater diameter, shoot dry weight, and total dry weight.
Conclusions: A reduction of irrigation between 30 to 45 % in P. oaxacana allows the production of hardened plants, with greater possibility of success at the time of transplantation in the field.