Morpho-physiological response to drought of progenies of Pinus taeda L. contrasting in mean growth rate

BULFE, N.; FERNÁNDEZ M.E.

NEW FORESTS

SPRINGER

Lugar: Berlin; Año: 2016 vol. 47 p. 431 - 451

0169-4286

Potential trade-offs between growth and water stress resistance in Pinus taedaL. families, and the ecophysiological processes involved were evaluated. Families of high(HG) and low (LG) growth rate were subject to moderate and severe water stress. Familiesonly differed in growth under the high water availability condition (control treatment),declining exponentially to similar values in all families under drought. HG families presented higher absolute growth but lower relative growth than LG families. Hydraulicconductivity of branches decreased at high air saturation deficit (D) even with high soilwater content due to high vulnerability to cavitation (mean P50 = 1.7 MPa) and poorstomatal control of water potential in all families (which was even lower in LG). LGfamilies presented higher carbon fixation capacity (per unit leaf area) but this could not bereflected in absolute growth due to their higher biomass allocation to roots compared to HGfamilies. HG2 family allocated more biomass to leaves than the other families, increasingits whole capacity of C fixation. HG1 family had a differential allocation to the stem,probably increasing whole hydraulic conductance and capacitance, and therefore having anefficient way of providing water to the leaves. Our results does not support the hypothesisof a tradeoff between growth and drought resistance in Pinus taeda, but that there aredifferent combinations of traits, as those of HG families, leading to high absolute growthwhen soil water availability is high, and low growth?but similar to that of LG families?under water deficit conditions.