RESPONSE OF Pinus pinceana Gordon TO DROUGHT AND HIGH TEMPERATURE STRESS

Abstract

To identify the potential for adaptability of Pinus pinceana Gordon to environmental stress associated with climate change, the effect of drought and high temperature stress on growth and biomass allocation in seedlings from 12 provenances of the species was evaluated under greenhouse conditions. The experimental design included two different temperature environments with an average difference of 2 °C, and two levels of water availability (S₀ = soil water potential above -0.5 Mpa; S₁ = soil water potential below -1.5 Mpa). Both factors caused a reduction (P ≤ 0.05) in shoot growth, biomass accumulation and shoot/root ratio, but the effect of water stress was two to three times higher than temperature stress. The increase in temperature caused a greater thickening of the stem, particularly when combined with water stress. A wide variation among provenances in growth potential and biomass allocation was found in response to stress factors, indicating phenotypic plasticity in their adaptation mechanisms. Under stress conditions, populations from the northern region showed higher reductions in biomass accumulation and shoot/root ratio, but produced more branches than populations from the southern region. These results allow us to postulate that the species has the potential to adapt to climate change, if populations with best response to the predicted stress levels are used in conservation and ecological restoration programs.