Abstract
ABSTRACTTo evaluate the acclimation of water transport properties to soil nutrient conditions, morphological and hydraulic traits were measured in 4-year-old potted saplings of Japanese red pine that were grown under differing nutrient conditions for 3 years. To compare recovery from severe drought stress under differing nutrient conditions, the well-watered saplings were subjected to drought treatments of almost Ψ50 by stopping irrigation; this is equivalent to the xylem water potential at which 50% loss of hydraulic conductivity occurs. After resuming daily watering, the xylem water potential and gas exchange rate were measured. Whole-plant transpirational demand from large total-leaf area tended to be high for plants under high-nutrient conditions. However, no differences were observed in water transport properties, such as the conducting area, hydraulic efficiency, and cavitation resistance, suggesting that acclimation of the hydraulic architecture did not occur when plants were grown under sufficient soil moisture conditions. The root dry weight tended to be large and the belowground dry mass to root dry mass (T/R ratio) tended to be low for plants under high-nutrient conditions. Plants grown under high-nutrient conditions recovered their gas exchange rate and leaf-specific hydraulic conductance slightly during the month following severe drought stress by irrigation. The recovery of Japanese red pine appears to vary under different levels of nutrient availability probably because of the influence of root water absorption capacity.
Published Version
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