فیزیولوژی گیاهان
سال:1390 | دوره: | شماره: |تعداد مقالات:10

In this research the role of Salicylic acid (0.1, 0.01 mM) in amelioration of salt stress in species of sweet basil (Ocimum basilicum L.) has been investigated. We studied the effects of salicylic acid on the Na+, K+ content of those plants which were under salt stress for 24, 48 and 72 hours. In stress conditions, while Na+ content of leaf increased compared with those plants pretreated with salicylic acid, there was a reduction in K+ content. Salicylic acid pre-treatment alleviated the adverse effects of salt stress based on Na+, K+ measurement.

A green house experiment was conducted during three consecutive years at Ayub Agricultural Research Institute, Faisalabad (Pakistan) to find out the effect of drought stress on yield parameters of wheat. From the study it was reported that water deficit decreased grains per spike; 1000-grain weight, total biomass, grain yield and harvest index significantly while application of growth substances improved them. Pre-sowing seed soaking in ethephon solution produced the highest 1000-grain weight of 44.39 g, increased per hectare yield by 37 percent and harvest index by 8 percent in comparison with control. Biological yield was significantly decreased by shortage of moisture supply. While number of productive tillers per plant was decreased under moisture stress conditions by 6 percent, this was enhanced by application of growth substances. Growth substances application though was found not to be much beneficial under normal moisture supply, but under moisture stress economic returns were enhanced significantly. Thus, the maximum increase of 36 percent in net income was obtained from ethephon application under drought stress.

The increasing human population demands more food, shelter and resources. However, it is not possible to bring arable lands under cultivation for aromatic and medicinal plants. The demand for medicinal drugs including ispaghol (Plantago ovata) is not only high but is also growing worldwide. The marginal, including salt-affected lands could be successfully utilized for the cultivation of non-conventional crops because these saline soils are not suitable for better vegetation cover due to poor physical properties and excess Na+ concentration. Salinity being a global problem and a major constraint on food production worldwide affects plant growth and crop productivity and contributes to increased poverty in salt-affected areas. Among deleterious effects of high salt concentrations are ionic and osmotic imbalances, oxidative stress and also reduced photosynthetic capacity of plants. Assessing mechanism of salt tolerance in a crop species will ultimately help in devising a strategy to improve crop salt tolerance. The present study was conducted to see how and up to what extent varying degree of salinity stress affects the medicinally important non-conventional crop Plantago ovata (Ispaghol). From the results it is clear that increasing levels of NaCl in the growth medium reduced the growth of P. ovata. However, ANOVA revealed significant growth reduction at the highest salinity level (180 mM). The findings suggest that Plantago ovata might tolerate moderate levels of salinity. It can be tried for cultivation on marginal salted soils.

In the present study we carried out a record of the relative antioxidant activity to secondary metabolites content (phenol, flavonoid and anthocyanin) of Onosma dichroanthum Boiss. in various solvent extracts of plant root. The roots were collected in Kiasar Mountain (1800 m) in Mazandaran province, then dried and different extracts were obtained by acetone, ethanol and methanol (absolute and hydro alcoholic), ethyl acetate, chloroform and n-hexane-dichloromethane. The total phenol varied from 4.5±0.7 to 125.6±3.01 mgGAE g-1 in the extracts. Flavonoid contents were between 9.8±3 to 41±2.3 mgQUE g-1, while anthocyanin contents were 11.5±3.4 to 47.8±6.8 mgECGgr-1. DPPH (1, 1-diphenyl-2-picryl hydrazyl) radical scavenging effect of the extracts was determined spectrophotometrically. The highest radical scavenging effect was observed in acetone extract of plant with EC50 4.06 mg DW. There was a positive correlation between antioxidant activity and total phenolic content for acetone extract. Thus, it was concluded that phenolic compounds were the predominant antioxidant components in the investigated plant species. Therefore, analysis of these results showed acetone was the best solvent to release most secondary metabolites of plant roots, these results will be confirmed the uses of this plant as antiinflammatory to treat of burn and wounds in their traditional medicine.

Heavy metals pollution is a big problem for the large parts of the world. Lead is a heavy metal with high toxicity that inhibition of germination and retardation of plant growth are commonly observed due to its toxicity. The very important role of salicylic acid (SA) in response to different stresses, namely, modifications and decreasing the negative effects of stress has been established in different studies. The objective of this research was to evaluate the effect of different concentrations of salicylic acid to enhance the characteristics of Brassica napus L. under lead stress. Factorial experimental design was arranged in a completely randomized block design with three replications. Treatments were combination of 7 levels application of lead (0, 0.25, 0.5, 0.75, 1, 1.5 & 2 mM) and 2 concentrations of salicylic acid (5 & 10 mM). The results revealed that increasing lead concentration reduced root and shoot length, leaf area, and root and shoot dry weight, root and shoot fresh weight, specific leaf area (SLA) and leaf weight ratio (LWR). Application of salicylic acid on the other hand, significantly increased the studied traits, although specific leaf weight (SLW) and leaf water content area (LWCA) were significantly increased with an increase in the concentration of Pb (NO3)2 (P<0.01). Generally salicylic acid applications improved plant growth parameters ofBrassica napus L.

Hyoscyamus niger L. is an important medicinal plant belonging to Solanaceae family. This plant is a rich source of medicinal substances including tropane alkaloids. In this investigation, we studied effects of different concentrations of nitrogen (0, 12.5, 27.5, 41, 55, 69, 83 mg in each pot) on growth and Tropane production. After the extraction of Tropanes, they were analyzed by TLC and HPLC. The results from TLC showed that roots had the highest content of hyoscyamine and scopolamine. In roots and leaves, scopolamine was the major alkaloid. Control plants had higher contents of hyoscyamine and scopolamine than treated plants. The plants treated with nitrogen had higher fresh weight and dry weight. On the other hand, increased nitrogen concentration increased root and leaf biomass. With HPLC analysis, scopolamine and hyoscyamine retention times obtained 9 and 11 min, respectively.

Salt stress is considered as a restricting factor for plant products. Various species have different levels of tolerance to salt stress. In this research seeds of Millet (Panicum miliaceum L.), cultivars (Talkhonche, Shiraz and Isfahan) were put in Petri dishes under 0, 200, 300 and 400 mg/lit concentrations of NaCl in the same light condition for one week. The seeds of Millet after sterilization were treated by different concentrations of NaCl and after germination some physiological traits were determined in treated 1 week old seedlings. Our results showed that salinity increased fresh and dry weight of shoot, fresh weight of root and chlorophyll content in Talkhonche cultivar, and in Isfahan cultivar these parameters and dry weight of root were decreased. In Shiraz cultivar, fresh and dry weight of shoot and fresh weight of root increased by salinity. Results of this study showed that Talkhonche cultivar was salt resistance; Shiraz cultivar semi-resistance and Isfahan cultivar was salt sensitive in seedling stage.

In order to evaluate the effects of kind of medium and kind of pomegranate cuttings (Malas- Torshe Savah) on rooting ability and growth of cuttings an experiment was done in a green house in research field of Islamic Azad University, Saveh on 2010. Main plots consisted of two medium cultures, (sand+peat and sand) and subplots consisted of three kinds of pomegranate cuttings (one bud, three buds, more than three buds). Cuttings were dipped in NAA solution with 4000 ppm concentration for 5 seconds and planted in different medium, bottom heat system (electric oven) were used to maintain temperature between 23-27°C in the bottom of pots. The cuttings were harvested after 3 months and relevant data were recorded. The results showed that the effect of medium culture on length of roots, number of leaves and number of branches were significant (P>0.05). Interaction of medium culture and kind of cuttings was only significant for root length. Comparison of rooting meanings showed that the effect of medium culture was not significant on any of the parameters. Comparison of means showed that the effects of kinds of cutting were significant on all studied parameters (P<0.05). Cuttings with more than three buds had highest number of leaves, numbers of branches and number of buds, but the highest lengths of roots were observed on cuttings with three buds. Comparison of means also showed that the interaction of medium culture and kind of cuttings had significant effect on number of leaves, number of branches, and number of buds. Medium of sand× more than three buds of cuttings had the highest rooting potential; however, highest length of roots were observed on sand + peat medium × three bud cuttings.

What is PCR purification.PCR Purification Protocol is designed to purify double stranded DNA fragments from PCR and other enzymatic reactions. Fragments from 100bp to 10kb are purified from primers, nucleotides, polymerases and salts using QIAquick spin columns in a microcentrifuge. Even if distinct bands of the expected size are observed, primer dimers should be removed by PCR purification method. In the absence of the purification, the proofreading activity of DNA polymerase will degrade the PCR fragments or remove the 3' terminal deoxyadenosine from the vector during ligation reaction.

How can we clone PCR products.pGEMâ‐T Easy Vector System is a convenient system for the cloning of PCR products.How is the vector prepared?The vector is prepared by cutting the pGEMâ‐T Easy Vector with EcoRV and adding a 3' terminal thymidine to both ends (Fig. I). These single 3' T overhangs at the insertion site greatly improve the efficiency of ligation of a PCR product into the plasmids by preventing recircularization of the vector and providing a compatible overhang for PCR products generated by Taq as a thermostable polymerase. Taq polymerase often adds a single deoxyadenosine, in a template‐independent fashion to the 3' ends of the significant proportion of amplified fragments as shown in the Figure. Using this method, only one insert will be ligated into the vector as opposed to multiple insertions that can occur with blunt ended cloning. In addition, with T vector cloning there is no need to dephosphorylate the vector, and there is a low background of relegated vector.