interactions between drought, aba application and supplemental uv-ag贵宾会

to test whether drought and aba application alter the effects of enhanced uv-b on the growth and biomass allocation of populus yunnanensis dode, cuttings were growth in pots at two aba levels, two watering regimes and two uv-b levels for one growth season. exposure to enhanced uv-b radiation significantly decreased plant growth and photosynthesis under well-watered conditions, but these effects were obscured by drought, which alone caused growth reduction. drought may contribute to masking the effects of uv-b radiation. the accumulation of uv-b absorbing compounds and the increase of the aba content induced by drought could reduce the effectiveness of uv-b radiation. aba application did not have large direct effects on biomass accumulation and allocation. evidence for interactions between uv-b and aba was detected for only a few measured traits. therefore, there was little evidence to support a pivotal role for aba in regulating a centralized whole plant response to enhanced uv-b. yet, we recorded an aba-induced decrease in stomatal conductance (gs) and increase in uv-b absorbing compounds and carbon isotope composition (δ13c) in response to enhanced uv-b. the allometric analysis reveled that regression models between root and shoot biomass in response to enhanced uv-b are different for plants under well-watered and drought conditions. enhanced uv-b led to a significant displacement of the allometric regrssion line under well-watered condition, while allometric trajectories for both uv-b regimes did not differ significantly under drought condition.