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991.
Net photosynthetic rate (P
N) and dark respiration rate (R
D) were measured in Vitis vinifera L. cvs. Dimiat 4/24 (23rd subculture), Dimiat 4/38 (22nd subculture), and Italian Riesling 3/47 (22nd subculture) on days 3, 2, and 1 (1st series) before transfer from the in vitro culture and on days 14, 15, 16 (2nd series) and 28, 29, 30 (3rd series) after the transfer. P
N of in vitro and ex vitro plants was strongly affected by irradiance. P
N and R
D of in vitro plantlets were lower and transpiration rate (E) was higher compared to those of ex vitro plantlets. P
N, R
D, and E changed in the course of acclimation. 相似文献
992.
Comparison of Cadmium Effect on Willow and Poplar in Response to Different Cultivation Conditions 总被引:1,自引:0,他引:1
Salix alba L. and Populus×euroamericana cv. Robusta cuttings were grown in 10 μM Cd(NO3)2 (direct treatment) or in Knop solution and afterwards in Cd(NO3)2 (indirect treatment). Cd impact on rooting of directly treated plants and its impact on normally formed roots and shoots
of indirectly treated plants were studied. The cumulative length, number and biomass of willow roots, pigment and starch contents,
leaf net photosynthetic rate and dry mass/leaf area ratio of willow leaves were positively influenced by indirect treatment.
However, indirectly treated poplars were more sensitive to Cd than directly treated ones. Indirect treatment lowered root
Cd uptake in willow, Cd accumulation in cuttings of both species and Cd accumulation in poplar shoots. Cd-caused structural
changes were similar in both species and in both treatments. Root apices, rhizodermis and cortex were the most seriously damaged
root parts. In directly treated willow, the structure of central cylinder (0.5 – 1 cm from apex) remained unchanged in contrast
to indirectly treated plants. Formation of cambium close to the apex indicated shortening of root elongation zone of indirectly
treated plants. Directly Cd-treated poplar roots exhibited unusual defence activity of root apical meristem and accumulation
of darkly stained material around central cylinder.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
993.
Woody plants, carbon allocation and fine roots 总被引:12,自引:2,他引:10
Kurt S. Pregitzer 《The New phytologist》2003,158(3):421-424
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996.
We found that the gradient of a host-specific attractant, cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone) isolated from the roots of spinach triggered encystment followed by germination of zoospores of Aphanomyces cochlioidesat a concentration less than micromolar order. This compound did not affect the growth and reproduction of this phytopathogen up to 10–6 M concentration in the culture medium. We also observed that mastoparan, an activator of heterotrimeric G-protein could inhibit the motility of zoospores and then strikingly effect encystment followed by 60–80% germination of cysts. Concomitant application of cochliophilin A and mastoparan showed stronger encystment followed by 100% germination of cysts. In addition, we have observed that chemicals interfering with phospholipase C activity (neomycin) and Ca2+ influx/release (EGTA and loperamide) suppress cochliophilin A or mastoparan induced encystment and germination. These results suggest that G-protein mediated signal transduction mechanism may be involved in the differentiation of the A. cochlioides zoospores. This is the first report on the differentiation of oomycete zoospores initiated by a host-specific plant signal or a G-protein activator. 相似文献
997.
Aguilar E. A. Turner D. W. Gibbs D. J. Armstrong W. Sivasithamparam K. 《Plant and Soil》2003,253(1):91-102
Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O2 in root tissues, the transport of O2 from the shoot to root and the supply of O2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O2 within roots, radial O2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O2 consumption decreased substantially with distance from the root apex and at 300–500 mm it was 80% lower than at the apex. Respiration of lateral roots constituted a sink for O2 supplied via aerenchyma, and reduced O2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60% drop in O2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O2 from cortex to stele in banana, mediated by a convective water flow component. An O2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O2 deficient environments, the stele would be among the first tissues to suffer anoxia and O2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils. 相似文献
998.
Oxidative stress triggered by aluminum in plant roots 总被引:4,自引:0,他引:4
Yoko Yamamoto Yukiko Kobayashi Saddikuti Rama Devi Sanae Rikiishi Hideaki Matsumoto 《Plant and Soil》2003,255(1):239-243
Aluminum (Al) is a major growth-limiting factor for plants in acid soils. The primary site of Al accumulation and toxicity is the root meristem, and the inhibition of root elongation is the most sensitive response to Al. Al cannot catalyze redox reactions but triggers lipid peroxidation and reactive oxygen species (ROS) production in roots. Furthermore, Al causes respiration inhibition and ATP depletion. Comparative studies of Al toxicity in roots with that in cultured plant cells suggest that Al causes dysfunction and ROS production in mitochondria, and that ROS production, but not lipid peroxidation, seems to be a determining factor of root-elongation inhibition by Al. 相似文献
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1000.