modern research physics

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Maize (Zea mays L.) plants grown in hydroponic culture were treated with 50 &thinsp&mum CdCl2. Growth and metabolic parameters indicative of oxidative stress and antioxidant responses were studied in leaves and roots of plants. Apart from increasing lipid peroxidation, death cells and H2O2 accumulation, supply of Cd suppressed growth, fresh and dry mass of plants. The activities of catalase (CAT), ascorbate peroxidase, guaiacol peroxidase (GPX) and gutathione reductase (GR) however increased in plants supplied with 50&thinsp&mumCd. Therefore, it can be concluded that a supply of 50&thinsp&mumCd induced oxidative stress by increasing production of ROS despite increased antioxidant protection in maize plants.

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The effects of cadmium and iron interaction on some physiological parameters in rice (Oryza sativa L.cv.fajr) plant were studied. The four days old seedlings were transferred to pots containing sand, irrigated with Hoagland solution in growth chamber. The 15 days old plants were treated with 0, 50 and 100 &muM  CdCl2 supplemented with 5, 10 and 20 ppm Fe as Fe-EDTA. Plants were grown under controlled condition and harvested after 30 days for measurements of some biochemical and physiological parameters. Treatments were conducted with four replications. Under Cd stress, growth of plant decreased. In plants treated with CdCl2, relative growth rate, net assimilation rate and photosynthetic rate were decreased. Addition of Fe-EDTA (10 and 20 ppm) moderated cadmium effects. Under Cd stress without Fe, respiration rate and CO2  compenstation point increased, however, in solutions containing both CdCl2 and Fe-EDTA, respirations rate and CO2  compenstation point decreased. In plants treated with CdCl2, catalase activity increased. However, after increasing Fe in solution containing CdCl2, catalase activity decreased. Therefor, the results indicated that in CdCl2 treated plants with increasing Fe-EDTA, the toxic effects of Cd decreased.

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Salvia L. is one of the important genera of the Lamiaceae family, that most of its species have nutritious and medicinal values. This study aimed to examine the total phenol and flavonoid contents and the antioxidant activities of S. aethiopis using spectrophotometric method. The essential oil of this species was analyzed using GC and GC/MS methods. In addition, antibacterial activities of the essential oil and methanolic extract were evaluated against six gram positive and negative bacteria, respectively. Results showed that the extract has high content of phenolic compounds with high antioxidant activity. From GC analysis, 11 different compounds were indentified in which &alpha-copaene was the most abundant compound with 33.48%. The extract of the species showed a high antibacterial activity against Proteus vulgaris. However, the essential oil of S. aethiopis had no effect on examined bacteria.

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Copper and nickel are an essential micronutrient for plants, playing an important role in maintaining plants' natural metabolism and growth, but in excess both heavy metal are also a proven inhibitor of various physiological functions. In this study maize (Zea mays L.) plants grown in hydroponic culture were treated with CuSO₄ (0, and 100 &mum),NiSO₄ (0,100 and 200&mum)and interaction of CuSO₄ (100 &mum)and  NiSO₄ (100 and 200 &mum). After 1 mounth of treatment, growth parameters and some biochemical changes were studied in roots and shoots of plants. The results showed that with increasing Cu and Ni concentration, pigment contents (chlorophyll a, b and total carotenoids), root and shoot length and dry weight were decreased, while k⁺ leakage, malondealdyde as indicator lipid of peroxidation and some antioxidant enzyme activity were increased. Also result showed that interaction of Cu and Ni has been cooperation effects on together and intensify each other's work

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    The methanol extracts of leaves and bulbs of Allium ampeloprasum L. (Alliaceae) were analyzed for their phenolic profiles and screened for their antioxidant and antibacterial activities. Two biochemical assays, namely DPPH free radical scavenging and &beta-caroten/linoleic acid activity systems, were used to evaluate antioxidant activity. Total phenol and flavonoid contents of the species were determined by Folin-Ciocalteu and AlCl₃ assays, respectively. Results indicated that the extracts are different in total phenolic content. Results from antioxidant activity showed that the extracts studied in DPPH radical scavenging assay are lower active than ascorbic acid and BHT as synthetic antioxidants. Antibacterial assay showed that the bulbs extract is more effective in inactivation of Haemophilus influenzae and Bacillus cereus and the leaves extract is more effective in inactivation of Bacillus cereus at 100 mg ml^-1 than others. Then, the extracts of Allium ampeloprasum possess strong antioxidant activity and may be used as new drug supplements in the future.

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Salicylic acid (SA) is a compound that has a basic role in increasing cold tolerance in plants. When two-days old radish seedlings were pretreated with different concentra-tions of SA (0, 0.5, 1, 1.5 and 2 mM) for 24 hours and then imposed to cold stress at 2.5 ˚C for 48 hours, cold resistance is increased in them. This phenomenon is shown by reduced efflux of K+ ions and soluble sugars and increased root length of seedlings especially at 0.5 mM, SA concentration. This finding shows that there is a straight correlation between SA concentration and reduced cold injury. Measuring the activity of three antioxidant enzymes, ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) in shoot and roots of radish seedlings, revealed that SA induced cold resistance is accompanied by increased activity of these antioxidant enzymes.