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11.
Over two seasons in c. 600 ppm CO2, oak had lower stomatal conductancein CO2-enriched compared to amblent air. Beech showed no responseto CO2 concentration on sunny days. Mirroring this pattern,exposure to elevated CO2 reduced whole-shoot hydraulic conductanceper unit leaf area in oak, but not in beech. Key words: Climate change, Fagaceae, gas exchange, trees, water relations 相似文献
12.
The lack of control of water loss in micropropagated plants is not related to poor cuticle development 总被引:2,自引:0,他引:2
To assess if cuticular transpiration could contribute significantly to the high rates of water loss often observed in micropropagated plants after transfer to the nursery, it was tested whether adaxial cuticular water permeance (P) of leaves grown in vitro was higher than that of leaves grown ex vitro. For four species of micropropagated plants with hypostous leaves ( Delphinium elatum hybrid, Doronicum hybrid, Hosta sieboldiana var. elegans, Rodgersia pinnata ), P was determined with two independent techniques which gave similar results. Minimum adaxial overall conductance was measured with the same methods for a Heuchera hybrid which had amphistomatous leaves. Leaves of all species except Heuchera lost 36–65% of their original weight within 25 min after excision. Detached leaves whose abaxial surfaces had been coated lost only 25–38% of their original weight within 5–9 h. Permeances (P) were between 1 × 10−5 m s−1 and 1 × 10−4 m s−1 , which was within the range of typical values found with leaves grown ex vitro. From these results and a critical assessment of the literature it is concluded that there is no evidence that P of micropropagated plants was high enough to contribute significantly to the desiccation problem at the transfer stage. 相似文献
13.
Tree physiological responses to above-ground herbivory directly modify below-ground processes of soil carbon and nitrogen cycling 总被引:7,自引:0,他引:7
Edward Ayres James Heath Malcolm Possell Helaina I. J. Black Gerhard Kerstiens Richard D. Bardgett 《Ecology letters》2004,7(6):469-479
Above‐ground herbivory is ubiquitous in terrestrial ecosystems, yet its impacts on below‐ground processes and consequences for plants remain ambiguous. To examine whether physiological responses of individual trees may potentially modify soil nutrient availability, we subjected Fagus sylvatica L. (European beech) and Abies alba Mill. (silver fir) to simulated foliar herbivory over two growing seasons. Above‐ground herbivory enhanced N mineralization and inorganic N availability in the soil. The total input of C from the plant roots to the soil is not known; however, carbon sequestration in the soil, measured using stable isotopic techniques, was unaffected by herbivory. Fagus responded to herbivory by producing larger leaves, with increased photosynthetic capacity and N content, which largely compensated for the loss of biomass; Abies exhibited no such response. We conclude that despite large interspecific differences in the growth response, tree physiological responses to foliar herbivory are capable of directly modifying soil biological processes. 相似文献
14.