Journal of Plant Biological Sciences
Year:2012 | Volume:4 | Issue:13|Papers Count:9

The present study is a floristic inventory of the north of Badrud region which investigated species composition, plant life spectra as well as chrological analysis of the region. This desert is located 30 km north of Natanz, with the elevation ranging from 946 m to 1021 m. It has two major land forms including a sand and gravel plain which is partly covered with sand dunes. A total of 63 species representing 49 genera and 15 families were recorded among which 11 belonged to monocotyledons and 52 to dicotyledones. They mostly belonged to the Asteraceae (22.2%), Chenopodiaceae (19.0%), Poaceae (15.9%), Brassicaceae (14.3%) and Boraginaceae (9.5%) families. The largest genera wereAstragalus, Salsola, Seidlitzia and Stipagrostis, each one representing 3 species. Therophytes (63%) were the dominant life-form followed by hemicryptophytes (14%). Chamaephytes (9.52%) and phanerophytes (7.93%). Chrological analysis showed 60.32% uniregional elements (57.14% of which were Irano-Turanian), 25.5% bi-regional, 11.11% tri-regional and 3.17% cosmopolitan elements. Three species including Pterochaenia stewartii, Reicharidia orientalis and Silene arenosa were identified in this region which were recorded for the first time in Isfahan province.

In this research, physiological and molecular response of diploid (Gossypium herbaceum: Ghozedorosht Mahriz) and tetraploid (Gossypium hyrsutum: Sahel) cotton cultivars were investigated under salt stress. After germination, seedlings were treated by different concentrations (0, 50, 75, 100 and 150 mM) of NaCl under greenhouse conditions. This experiment was implemented applying randomized complete block design in three replicates. The results indicated that the height of Ghozedorosht and Sahel cultivars were decreased by salt treatment. The amount of Chla, Chlb and total chlorophyll showed more reduction in Ghozehdorosht cultivar compared to Sahel cultivar under salinity. After NaCl treatment, Ghozedorosht cultivar showed higher leaf Na concentration compared to Sahel cultivar. The study of antioxidant enzyme activity showed that the peroxidase and polyphenol oxidase activity was reduced by salt treatment. But, peroxidase enzyme activity was significantly induced in Sahel cultivar by treating with NaCl. Gene expression analysis showed that salt treatment can induce TPS1 expression in leaf and root organs. The results indicated that Sahel cultivar had higher TPS1 gene expression than that of Ghozedorosht cultivar under salt stress. These results also suggested that increasing of peroxidase enzyme activity and TPS1 gene expression had important roles in Sahel cultivar to be resistant to salt stress compared to Ghozedorosht cultivar.

The objective of the present study was to investigate the effect of static magnetic field (0, 25 and 50 mT) and the exposure time (0, 30, 60 and 120 minutes) in Nigella sativa L. seeds germination. The results showed that magnetic field application enhanced seed performance under laboratory germination tests. In these magnetic fields, treatment of N. sativa L. seeds increased significantly the germination, speed of germination, root length, seedling length, seedling fresh and dry weight and vigor index I and II compared to control. Among the various combinations of field strength and duration, 25 mT for 60 minute showed the best results. In germinating seeds, enzyme activities of α-amylase, dehydrogenase and protease were significantly higher in treated seeds to compared to the controls. The higher enzyme activity in magnetic-field-treated N. sativa seeds could trigger the fast germination and early vigor of seedlings.

The purpose of this study was to classify ecological groups and their gradient analysis according to soil physio-chemical properties in the forest reserve park of Sisangan under the Buxus hyrcana Pojark. For this purpose, 46 systematic sample plots of 400 m2 (20×20 m) were selected. In each sample plot, canopy cover values by species abundance-dominance coefficients based on Brown-Blanquet's method were measured and then soil samples were taken in the both depth of 0-15 and 15-30 cm to analyze some properties such as OC, N, P, K, C/N, pH and EC, texture, lime and moisture content. Using TWINSPAN analysis of species cover percentages, three ecological groups determined in the area and using methods of Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to explain relationships between ecological groups and soil properties. The results showed that the shape of the ecological groups in the area and soil factors including: silt and clay, organic carbon, nitrogen and C/N in the first depth, moisture content and available phosphorus in non-Buxus type and percentage of sand, acidity, electrical conductivity, lime, available potassium, organic carbon, total nitrogen and C/N in second depth in Buxus type were relatively correlated to each other. The results of ecological groups' classification into species-environmrntal factors and releve-environmental CCA biplot showed that sample plots and indicator species of each unit from each other in ordination diagrams were separated.

In this research, anatomical structure of leaf in Artemisia sieberi Besser was studied. Specimens of leaves were harvested from 34 stands in the spring. Also, seeds of plants collected and were planted in the farm. Leaves of farm plants harvested after complete growth. All specimens were studied from anatomic viewpoint in the laboratory. For comparison between nature stands and farm stands, normal curves were drawn by Minitab software. Anatomical characters of natural and cultivated plants were compared by T-student analysis. Averages of anatomical characters were analyzed by PCA in according to semi-arid, arid and hyper-arid zones. Also, averages of climatic parameters in the zones were analyzed by PCA. Some of anatomical characters increased in farm, because of adequate moisture.Thickness of cuticle decreased in farm accessions. Length of stomata increased but density of them decreased in farm. Climatical groups completely coincided with anatomical groups. Comparison of anatomical characters in nature and farm showed the effect of climatic parameters on anatomical features.

An efficient maize regeneration system was developed using mature embryos. The use of mature embryos from dry seeds possesses several advantages: mature embryos are easy to handle and available throughout the year and in bulk quantities. In this study, mature dry seeds of five maize inbred lines (K126, L105, B73, Mo17 and S61) were used. Embryos were removed from surface-sterilized mature seeds and sliced into halves. They were used as explants to initiate callus on induction medium containing 4 mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D). Mature embryos were incubated at 27 oC in darkness. The induction frequency of primary calli was over 90% for all tested inbred lines. Then, the primary calli were transferred onto subculture medium supplemented with 2.0 mg/l 2, 4-D concentrations 0.2 or 0.5 mg/l of 6-benzylaminopurine (BA) or Thidiazuron (TDZ) and 10 mg/l AgNO3.Embryogenic callus readily formed plantlets on regeneration medium supplemented with 0.2 or 0.5 mg/l BA or TDZ. The regenerated plantlets were transferred to half-strength Murashige and Skoog (MS) medium supplemented with 0.6 mg/l indole-3-butyric acid (IBA) to develop roots. The frequency of green shoot formation ranged from 18.3-40.25%. The highest mean percent (40.25%) was observed for S61 genotype on medium containing 0.2 mg/l TDZ and 10 mg/l AgNO3. This efficient regeneration system provided a solid basis for genetic transformation of maize.

Salt stress is considered as one of the major limitations for food production especially in irrigated regions. The rice as a major food is very sensitive to salt stress. The comparison of physiological responses to salt in rice can be useful to improve resistance to this stress. For this purpose, in this study two Iranian rice cultivars with different resistances to salt stress namely, Khazar (salt sensitive) and Zayandehrood (salt tolerant) were examined. The seeds after sterilization were treated with different NaCl concentrations (0, 50, 100 and 200 mM) in Hoagland medium and germination percentage was determined. Then, the growth factors in 15 days-old seedlings and proline content, catalase activity and Photosynthetic parameters were determined in 25 days old plantlets under 100 mM NaCl. The results showed that with increasing of salt concentration, germination percentage was significantly decreased in both cultivars but this effect was more drastic in Khazar. Salt stress (100 mM) reduced length, fresh and dry matter and also the relative water content of shoot in both cultivars. The results showed more accumulation of proline in Zayandehrood than Khazar. The catalase activity was significantly increased in Zayandehrood by salinity but not in Khazar. Salt stress significantly decreased chlorophyll content in Zayandehrood but not in Khazar. Maximal quantum yield of PS II of rice leaves showed no significant difference for Zayandehrood but in Khazar, salt stress significantly decreased the ratio of Fv/Fm. It seemed that prolin content, catalase activity and Fv/Fm ratio playes essential roles in salt tolerance in rice.

Chromium (Cr) as the seventh most abundant element in the Earth crust can enhance growth of plants in low concentrations. However, excess Cr is highly toxic to animals and plants. Chromium also can cause oxidative stress in plants by producing free radicals. In this research, effects of various concentrations of Cr on some growth parameters of sunflower (Helianthus annuus)’s shoot were studied. Also, the effect of Chromium in inducing oxidative stress on the sunflower's shoot investigated, as well. Cr treatments applied in six concentrations 0, 0.001, 0.01, 0.1, 1, 5 and 10 mM on 4-week sunflower plants and one control group. Plants were allowed to grow under Cr treatments for three weeks before they were harvested. The results demonstrated that the 5 and 10 mM concentrations of Cr decreased the growth parameters of shoot (such as: fresh and dry weight, leaf area and also the length of stems), whereas, the lower concentrations, no significant differences were shown compared to the control. MDA content of plants' shoots significantly increased in 1, 5 and 10 mM concentrations of Cr. Shoot proline concentration was built up as Cr concentration increased in the treated plants, whereas, protein content decreased. Ascorbate content of plants decreased in 0.1, 1, 5 and 10 mM concentrations of Cr, but, dehydroascorbate and total ascorbate increased. It was concluded that ascorbic acid can play a key role in the tolerance of sunflower against oxidative stress induced by chromium. Chromium accumulation in seeds, showed increase in 5 and 10 mM concentrations. Thus, it is so important to pay more attention to use safe edible plants for both humans and animals, as well.