Effect of Plant Preservative Mixture Ppmtm on the Shoot Regeneration of Watercress (Nasturtium Officinale)

Plant Preservative Mixture™ (PPM), a relatively new broad-spectrum preservative and biocide for use in plant tissue culture, was evaluated as an alternative to the use of conventional antibiotics and fungicides in plant tissue culture. Culture inoculated in MS media supplemented with PPM (1.5 ml/l) was the effective concentration which gave the best values. The top values were recorded for all studied characters using apical buds compared with lateral buds. The combination between apical buds and (1.5 ml/l ) PPM concentration showed the superior values of all studied parameters( 33.25%,19.40%, 14.46%,20.53% and 79.46%)(60.55%,39.80%,20.97%,45.33% and 54.44%) and (31.20%, 20. 06%, 12.33%, 35.13% and 81.06 %) for contamination, %bacterial contamination, % offungi contamination, dead explants% and survival explants% respectively.  Different concentrations of PPM (0, 0.5, 1.0, 1.5, 2.0 and 2.5 ml/l) were tested using single node and apex explants of watercress (Nasturtium officinale). PPM at (1.5ml/l)  had significant effect on the studied characters; shoots height, shoots number, leaf pairs number, fresh and dry weight which they reaches (4.16, 4.62, 42.00,0.524 and 0.063 g, respectively ). Apex bud explants showed the greatest effect on shoots height shoots number, leaf pairs number, fresh and dry weight and their values were 3.52, 32.02, 3.38, 0.405 and 0.036 g, respectively. The best parameter were recorded on MS media supplemented with PPM at (1.5ml/l) with apex buds explant  (4.55, 5.34, 46.28, 0.570 and 0.085, respectively) for shoots height, shoots  number, leaf pair number, fresh and dry weight. Current study aimed to determine the best concentration of PPM for limiting the contamination of watercress and micro shoot regeneration

Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg

© 2018, The Author(s). High-pressure torsion (HPT) processing was applied to cast pure magnesium, and the effects of the deformation on the microstructure, hardness, tensile properties and corrosion resistance were evaluated. The microstructures of the processed samples were examined by electron backscatter diffraction, and the mechanical properties were determined by Vickers hardness and tensile testing. The corrosion resistance was studied using electrochemical impedance spectroscopy in a 3.5% NaCl solution. The results show that HPT processing effectively refines the grain size of Mg from millimeters in the cast structure to a few micrometers after processing and also creates a basal texture on the surface. It was found that one or five turns of HPT produced no significant difference in the grain size of the processed Mg and the hardness was a maximum after one turn due to recovery in some grains. Measurements showed that the yield strength of the cast Mg increased by about seven times whereas the corrosion resistance was not significantly affected by the HPT processing