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Cadmium (Cd) and lead (Pb) are particularly noteworthy metals that can pollute the air, soil and water contributing to serious environmental problems. Tests were done on concentrations of Pb and Cd; treatments tested in the experiment were as follows; Cd concentrations (10, 20, 40, 60, 80, 100 ppm) and concentrations of Pb (100, 300, 600, 900, 1200, 1500 ppm) and control. Tests were done on Mentha piperita L. in a greenhouse, arranged as a randomized complete block design with three replications. Rhizomes with uniform weight were planted in pots 30×50×35 cm. Plants were irrigated with Cd and Pb chloride after germination of all rhizomes. Results demonstrated that with increasing concentrations of Cd and Pb there was a decrease in fresh and dry weights, main stem height, leaf area per plant, leaf number, number of nodes per main stem and essential oil of peppermint compared to the control. Fresh weights were decreased at 100 ppm of Cd and 1500 ppm of Pb, 18.16% and 24.55%, respectively compared to the control at the first harvest. At the second harvest, these decreases were 15.24% and 32.72%, respectively. At the highest concentrations of Cd and Pb, dry weight of peppermint was dropped 22.92% and 39.01% at the first harvest. For the second harvest, decreased dry weights were 25.88% and 26.77% respectively. It seems that peppermint can tolerate waste water or soil polluted with medium range of Cd and Pb concentrations and the essential oil percentage was not affected by these concentrations.

In order to study the effect of seed hydro priming and magnetic field on tomato seed germination an experiment was conducted in laboratory of Ferdowsi University of Mashhad, Iran, in 2010. The experimental treatments were all combinations of two levels of hydro priming (use of dry seed and soaked seed for five h in distilled water) and eight levels of magnetic field treatments (pretreatment of seeds in 15 mT for 5, 15 and 25 minutes, pretreatment of seeds in 25 mT for 5, 15 and 25 minutes, continuous magnetic field with 3 mT and control) with four replications. Results indicated that hydro priming of seeds reduced mean germination time significantly. Root length increased by 14 percent in seed hydro priming treatment in comparison with dry seed treatment. Shoot length, seedling length and vigor index of hydro primed seeds increased by 7, 12 and 13 percent, respectively compared with dry seeds. Exposure of seeds with 3 mT continuous magnetic field and 25 mT for 5 min increased root length by 29 and 25 percents, respectively in comparison with control. The highest shoot length, seedling length and vigor index were obtained in 3 mT continuous magnetic field and 25 mT for 5 min.

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The aim of this research was to test if mean germination time (MGT) can predict seed vigor in 10 seed lots of canola. There was a significant difference between the final germination percentages of the 10 seed lots tested ('Hyola 330' , 'Hyola 401' , 'Okapi' , 'Elite' , 'SLMO 46' , 'Zarfam' , 'RGS 003' , 'Option 500' , 'Echo' , 'Rainbow') and a highly significant correlation between MGT and this value. Of the 10 seed lots, 'Hyola 330' had the lowest final percentage germination (62%) and the highest MGT, 3.64 days. The correlation between MGT and the proportion of "normal" seedlings was also significant. 'Hyola 330' had the lowest percentage of normal seedlings (60%). A tetrazolium test showed that this lot had some dead seeds that could not germinate; some seeds were viable, but they would produce abnormal seedlings. One of the main reasons of low final germination percentage and high MGT in 'Hyola 330' was low viability of this seed lot. Mean germination time is suggested as a good indicator of seed vigor in canola.