فصلنامه زیست شناسی گیاهی ایران
سال دوازدهم شماره 2 (پیاپی 44، تابستان 1399)

Soil contamination with heavy metals is one of the most important environmental problems in many parts of the world. Nickel (Ni) and lead (Pb) are heavy metals that are major contributors to environmental pollution. Since dill (Anethum graveolens L.) is cultivated as a leafy vegetable in various places, even in heavy metal-contaminated areas, this study was conducted to investigate the effects of lead and nickel on the activity of dill antioxidant enzymes and antioxidant compounds. In this study, dill seeds were planted into pots containing coco peat and perlite and treated with lead nitrate (0, 500 and 1000 μM) and nickel nitrate concentrations (0, 100 and 200 μM) in three replications. After the treatments, the length, fresh weight and dry weight of root and shoot, photosynthetic pigments content, the amount of phenolic compounds, flavonoids, anthocyanins, catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), superoxide dismutase (SOD) activity and the concentration of Pb and Ni in the shoot and root were evaluated. Use together of lead with nickel on the plant showed that plant length, Chlorophyll a, chlorophyll b, and total chlorophyll decreased respectively to 1.32, 1.02, and 2.03 compared to the control with values of 6.26, 4.54, and 10.32 mg / g under lead and nickel treatments. The anthocyanins, total phenols and flavonoid contents were respectively 4.7, 0.69 and 0.51 mg/g which increased by 23.5, 8.6 and 6.37 compared to the control. CAT, APX and SOD activities increased. Whereas, carotenoid content, fresh and dry weight of roots and shoots, guaiacol peroxidase activity were not affected. Simultaneous use of lead and nickel led to an increase in the amount of lead and nickel in shoot and root. The presence of lead reduces the uptake of nickel by the plant. Accordingly, it seems the plant uses antioxidant compounds such as phenols and some antioxidant enzymes to counter lead and nickel oxidative stress from. On the one hand, the treatment had no effect on fresh and dry weight and also roots and stem length decreased slightly. A number of antioxidant enzymes were activated and the antioxidant compounds increased and the more accumulation of elements in the root, it is possible that even if the plant is not resistant to these stresses, it can grow in the Pb and Ni contaminated soil without serious damage.

Boron is an essential micronutrient for plants and boron deficiency is a common nutritional disorder in crop species. In this research work, the effect of boron deficiency on the amount of pigments, phenols, soluble sugars, starch, chlorophyll fluorescence parameters and enzyme activity in oilseed rape (Brassica napus L. cv. RGS) plants during vegetative and reproductive period were studied. Boron deficiency caused reduction of plants dry matter production and impaired development of the young leaves. The leaf concentrations of chlorophyll, carotenoids and anthocyanin were decreased and the net assimilation rate was diminished following reduction of stomatal conductance and consequently, non-structural carbohydrates were decreased in the leaves of boron-deficient plants. In contrast, the leaf concentration of cytosolic phenolics compounds increased in boron-deficient plants associated with a rise in the leaf activity of phenylalanine ammonia lyase while polyphenol oxidase was not influenced by boron deficiency. Boron-deficient plants formed distorted inflorescences with higher rate of flower drop. Pollen tube showed apical swelling with lower germination percentage in boron-deficient plants. During the anther development, differentiation of the layers of pollen sac wall impaired by boron deficiency accompanied by an earlier disintegration of the nutritive cell layer. Boron-deficient plants had less fruits with lower growth rates and smaller seeds. Our results demonstrated that during vegetative growth, boron deficiency influences mainly carbon metabolism but during reproductive growth it affects several developmental processes including germination of pollen grains, development of the siliques and filling of the seeds.

The use of crop residues grown in contaminated soils such as iron mine soils can to some extent improves soil properties such as soil fertility, soil organic matter and soil microbial activity. Therefore, this type of soil can be used to supplying the plant's need for copper and iron elements. For this purpose impact of safflower, clover, corn, canola, amaranth and sorghum residues contains iron and copper (25 mg/kg) on growth of tomato and compensation of iron and copper deficiency (1/7 and 1 mg /kg) were investigated in soil with intense deficiency of microelements. This research was done in a completely randomized design with 3 replications. The results showed that use of plant residues especially clover and corn Compared with control treatment improved optimum growth of tomato. Also the addition of rapeseed and clover residues increased the concentration of copper in the roots and shoots of tomato plant, respectively. Also greatest increase of iron concentration was observed in roots and shoots of sorghum. Therefore, application of plant residues containing nutrients as green manure while saving chemical fertilizers, will resolved the shortage of these elements (iron and copper) in agricultural soils and Due effect of plant residues on soil chemical and physical characteristics and their role in plant nutrition managing, plant residues can play an important role in providing organic matter, especially in arid areas.

Teucrium polium, from Lamiaceae family, is a medicinal plant. Due to overexploitation, low distribution and habitat destruction, this plant, is facing extinction. Plant biotechnology and tissue culture is an alternative method for plant secondary metabolites production. The present study aimed to enhance the production of secondary metabolites and antioxidant capacity of Teucrium polium L. using methyl jasmonate and salicylic acid elicitors. Leaf explants from hydroponically cultured 4-month-old plants were inoculated on Murashige and Skoog medium (MS) containing 2, 4-dichlorofenoxy acetic acid (2, 4-D) in concentrations of 0, 0.5, 1, 1.5 mg/L alone or in combination with benzyl aminopurin (BAP) at, 0.5, 1, 1.5, 2 mg/L concentrations. According to the results, the best callus induction (100%) was achieved at MS medium containing 1.5 and 2 mg/L BAP. Calli obtained from this treatment were subsequently treated with Methyl Jasmonate or Salicylic Acid at 0, 50 and 100 μg/L concentrations. After 40 days, the content of phenolics, flavonoid compounds and total antioxidant capacity were evaluated in a completely randomized design with three replications. Based on biochemical assays, the greatest total phenol content, flavonoids and total antioxidant capacity belong to calli treated with 100 μg/L acid salicylic (SA) and after that to cali treated with 50 μg/L methyl jasmonate(MeJa), while the difference between them was significant. The results of means comparison showed applying 100 μg/L SA on calli in medium with 1.5 mg/L BAP had the greatest effect on total flavonoid content. Therefore, the use of appropriate concentrations of these elicitors can play an effective role in enhancing the medicinal compounds in Teucrium polium.

In this study, the flora of the Drakhtak Frieden area was investigated. A total of 265 species belonging to 184 genera and 42 plant families were identified in the area. Of these, 35 belong to dicots and seven to monocots. The most important plant families include Asteraceae (32 genera and 48 species), Brassicaceae (24 genera and 32 species), Poaceae (20 genera and 25 species). The genus Astragalus with 11 species and the genera Cousinia and Centaurea each with five species accounted for the largest share in the plant composition of the region. The geographical distribution of plant species showed that 52% of the plants belong to the Irano-Turanian regions. Subsequently, by and large, elements from the Irano-Turanian / Europe-Siberia / Mediterranean area are most present. Hemicryptophytes and trophytes accounted for the most (40.75%), with camphores, geophytes, and phanerophytes being the next levels. The vegetation of the area based on the physionomy is shrublands, that dominant species including Astragalus verus and Astragalus gossypinus. Of the identified plants in the region, 42 are endemic species and 82 species have medicinal value.

Jujube (Ziziphus jujuba Miller) is one of the valuable medicinal plants that is widely used in traditional medicine and pharmaceutical industries. This species is native to Iran and due to the wide range of ecological tolerance in different parts of the country with different climatic conditions is naturally distributed and planted. The aim of this study was to investigate the effect of ecological factors on morphological, anatomical and phytochemical traits of jujube natural populations in three regions of South Khorasan province. The highest values of morphological traits including height, diameter of breast-height, canopy diameter and canopy cover, length, width and weight of fruit are related to Shahrakht habitat, and leaf length and width to Alghor habitat. The highest values of anatomical traits including number of layers and thickness of spongy parenchyma, thickness of epidermis, midrib and bundle sheath and stomata length were observed in Bijar habitat. Also, the highest values of thickness of lamina, mesophyll and cuticle as well as number of layers and thickness of collenchyma and palisade and number of stomata are related to Shahrakht habitat. In addition, the highest amount of phytochemical traits including extract and antioxidant activity belong to Bijar habitat and the amounts of total phenol and flavonoids belong to Shahrakht habitat. Analysis of variance showed that there was a significant difference between all these traits in the three populations. The results of Pearson correlation showed that among environmental factors, rainfall, annual temperature and altitude had the highest significant correlation with the studied traits, respectively.