A simple method for formation of CdS nanoparticles on the surface of carbon nanotubes (CNTs) aligned perpendicularly to the silicon substrate has been developed. The size and shape of the CdS nanoparticles were found to depend on the temperature of a solution containing CdCl(2), (NH(2))(2)CS, and NH(3) and the deposition time. Electron microscopy study revealed a direct contact between CdS nanoparticles and CNT surface. X-Ray photoelectron spectroscopy examination of the CdS/CNT hybrid material detected surface oxidation of the grown nanoparticles.

Although salinity is one of the major problems limiting agricultural production around the world, the underlying mechanisms of high NaCl perception and tolerance are still poorly understood. The eects of dierent bathing solutions and fusicoccin (FC), a known activator of plasma membrane ATPase, on plasma membrane potential (E m ) and net¯uxes of Na , K and H were studied in wheat suspension cells (Triticum aestivum) in response to dierent NaCl treatments. E m of cells in Murashige and Skoog (MS) medium was less negative than in cells exposed to a medium containing 10 mM KCl 0 . 1 mM CaCl 2 (KSM) and to a basic salt medium (BSM), containing 1 mM KCl and 0 . 1 mM CaCl 2 . Multiphasic Na accumulation in cells was observed, peaking at 13 min after addition of 120 mM NaCl to MS medium. This time scale was in good agreement with net Na ¯u x changes measured non-invasively by moving ion-selective microelectrodes (the MIFE system). When 120 mM NaCl was added to all media studied, a quick rise of Na in¯ux was reversed within the ®rst 20 min. In both 120 and 20 mM NaCl treatments in MS medium, net Na eux was observed, indicating that active Na transporters function in the plant cell response to salt stress. Lower external K concentrations (KSM and BSM) and FC pre-treatment caused shifts in Na ¯u xes towards net in¯ux at 120 mM NaCl stress.# 2000 Annals of Botany Company

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The effects of fusicoccin (FC) on the early growth processes in sorghum ( Sorghum vulgare M.) seeds germinated in water and in 0.1 M or 0.2 M NaCl solutions were investigated. We studied the rate of seed imbibition, the onset of radicle protrusion, the occurrence of the first mitoses, the mitotic index, the distribution of cells according to the phases of the cell cycle, as well as the length and weight of roots. Seed imbibition was considerably accelerated by treating them with 5 × 10 -6 M FC for 1 h. In these FC-treated seeds placed on NaCl solutions, FC stimulated water influx into seeds, radicle protrusion, and occurrence of the first mitoses. FC pretreatment did not affect substantially the distribution of meristematic cells according to the periods of the cell cycle after 72 h of seed germination on water or 0.1 M NaCl. Root growth was inhibited by 0.1 M NaCl, but it was partially recovered in the presence of FC. 0.2 M NaCl caused a decrease in the mitotic index and in the number of cells in the S phase, an accumulation of cells in the G 2 period and in the prophase, as well as a considerable inhibition of root growth. FC pretreatment of seeds subsequently germinated on 0.2 M NaCl resulted in an increase in the number of cells in the G 1 period, in the mitotic index, and in the root-growth rate. FC virtually did not affect the growth of sorghum in the absence of salt. Pretreatment of seeds with FC followed by salinization resulted in an increase in the water content in seeds. It is suggested that a FC-induced increase in the water content of seeds accelerated metabolic processes in seeds germinating on NaCl solutions, thus regulating ionic homeostasis and thereby stimulating the initial growth processes.