فصلنامه فرآیند و کارکرد گیاهی
سال سوم شماره 2 (پیاپی 8، تابستان 1393)

Serpentine soils contain relatively high and toxic concentrations of heavy metals like nickel, chromium and cobalt. Nevertheless, in the most of these soils some plant species, such as Pistaacia atlantica, are grown which are metal tolerance. In this research, the effect of different concentrations of nickel supplied has been studied on dry biomass, nickel accumulation and the activity of some anti-oxidative enzymes in serpentine species of P. atlantica compared to non-serpentine P. vera and P. khinjuk. The results of dry biomass indicated the serpentine species of P. atlantica is more tolerant to increasing concentration of nickle than non-serpentine species of P. vera and P. khinjuk. It also appears that Pistacia species are some nickel excluders indicated by low nickel content in their shoots with increasing in the medium. The activity of anti-oxidative enzymes of catalase and ascorbate peroxidase increased in Pistacia species with increasing nickel supplied. Their activities were higher in shoots compared to roots, probably to protect photosynthetic systems against oxidative stress of nickel excess. Remarkably, increasing ascorbate peroxidase activity in the shoots of serpentine species, P. atlantica, was higher than non-serpentine species, P. vera and P. khinjuk, in response to increasing nickel concentration in the medium. This characteristic may be involved in the higher tolerance of P. atlantica, compared to P. vera and P. khinjuk, in serpentine soils.

The invention of Light Emitting Diodes (LEDs) has recently provided a new opportunity for the production of medicinal, horticultural and ornamental plants in controlled environments. It is also possible to study the physiological effects of specific light wavelengths on plants. In this study, three genotypes of pepper mint (Mentha piperita) collected from Isfahan, Tabas and Ghazvin were grown in pots inside 5 incubators each containing 100% red LEDs, 100% blue LEDs, 70% red+30% blue LEDs,100% white LEDs or fluorescent, illuminating at 300 μmol m s-1 light intensity. Plants grown in the field were used as control. After two months, the growth of plants as fresh weight per pot, essential oil content and antioxidant activity of catalase, glutathione reductase, ascorbate peroxidase and superoxide dismutase were evaluated. The highest fresh weight was achieved in Isfahan genotype under the combination of red and blue lights compared to the other lights. However, there was no significant difference with plants grown in the field condition. Essential oil content was more than 4-fold higher in Isfahan genotype under red light compared to that grown in the field. The activity of antioxidant enzymes, catalase (CAT), glutathione reductase (GR) and ascorbate peroxidase (APX) were highest in plants under blue light, while the activity of superoxide dismutase (SOD) was maximum under fluorescent light. It is concluded that LEDs through stimulation of growth and accumulation of secondary metabolites could simultaneously increase plant production and quality under environmental controlled conditions compared to natural illuminated environments.

Water deficit is one of the most important environmental stresses limiting plant growth and productivity around the world including Iran. Plants adapted to environmental stress with several strategies such as changes in antioxidant enzyme metabolism. Pennyroyal (Mentha pulegium L.) is an aromatic and medicinal plant of the Labiatae family that is widely used in traditional medicine. In this research, the effects of water deficit stress on growth, photosynthesis and antioxidant enzyme activities in leaf and root organs of M. pulegium plants were studied. Complete randomized block design have been used with four replications. Water deficit was studied at four field capacity levels (100, 75, 50 and 25%). Results showed that the growth, productivity and photosynthesis parameters significantly decreased under water deficit stress. Water deficit significantly increased the activity of antioxidant enzyme such as superoxide dismutase, peroxidase and ascorbate peroxidase in both organs, but the level of increase was more in roots than leaves of plant. Unlike to other enzymes, catalase activity decreased with the increase of water deficit levels, and highest activity was observed in leaves. It seems that pennyroyal plants can tolerate water deficit stress by dedicating less carbon source for growth, increase of antioxidant enzyme activity and regulation of antioxidant enzyme distribution in different organs.

Heavy metal stress in plants may cause oxidative stresses and reactive oxygen species (ROS) production. To reduce this stress, plants use antioxidative defences, such as increasing the activity of antioxidant enzymes. In this study, the role of an arbuscular mycorrhizal (AM) fungi Glomus intraradices as a symbiotic microorganism with plant, was investigated in inducing tolerance to oxidative stress induced by Nickel heavy metal. Tall fescue plants were grown in soils containing 0, 30, 90, 180 ppm of Nickel, in two forms of infected to fungi (M+) and uninfected (M-) for 3 months. Experimental results showed that Nickel treatment caused reduction in growth parameters, where these parameter were higher in M+ plants than M- ones. Membrane electrolyte leakage was increased by the increase of Nickel concentration, and the increase was higher in M+ plants compared to M- plants. Results of measuring the activity of antioxidant enzymes showed that the presence of fungi had increased the activity of catalase (CAT), guaiacol peroxidase (GPX) and glutathione reductase (GR) enzymes against the toxic effect of Nickel, but this had not affected (increasing or decreasing) the activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes. These results demonstrated the negative effect on Glutathione-S-transferase (GST) enzyme. Precense of Glomus intraradices in M+ plants amplified the antioxidant system in Festuca plants and reduced the negative effects of Nickel treatment.

This experiment was conducted to evaluate the relationship between photosynthetic characteristics and grain yield in 30 doubled-haploid (DH) lines of Brassica napus in Agricultural Research Station, Isfahan University of Technology, located at 40 km west Isfahan in 2011-12. A randomized complete block design with two replications was used. The following traits were evaluated transpiration rate, stomatal conductance, mesophylic conductance, the stomata carbon dioxide concentration, photosynthesis, photosynthetic rate, water use efficiency (WUE) and grain yield. Analysis of variance showed that DH lines significantly differed for all the traits associated with photosynthesis and grain yield. Results of correlation coefficients between yield and photosynthetic traits of mesophilic conductance (r=0.29) and conductivity (r = 0.3) were significant at 5% level of probability. There was a highly significant positive correlation between yield and WUE (r = 0.33). Highly significant correlation coefficient obtained between photosynthesis and mesophylic conductance (r = 0.99). Moreover, it was revealed that the highest photosynthesis (27.75), stomatal conductance (0.4), water use efficiency (10.16) mesophilic conductance (0.08) belonged to DH line number 9. On the other hand, DH line number 5 possessed the lowest mesophilic conductance (0.009), water use efficiency (1.18) and photosynthesis (3.08). Overall, it can be concluded that the significant differences in all parameters among the canola DH lines may reflect their high genetic diversity associated with photosynthesis and yield potential.

Jasmonic acid is a plant growth regulator that plays an important role in defense responses to environmental stress specially defense gene expression against diverse pathogen. Changes of key hormones biosynthesis consist salicylic acid, jasmonic acid and ethylene, genes expression related to phytoalexins synthesis, pathogenesis related proteins and ATP binding cassette ABC Transporter are the most important consequences of plant defense, after pathogen attack. Therefore, in this study effect of methyl jasmonate treatment on genes expression of related to defense response, including: PDR8, PDR5, PDR4, PDR3, NPR1, Thionin, PDF1.2 and PR1 using Real Time PCR technique in two cultivars, Hashemi and Khazar in 0, 6, 12, 24 and 48 hours after treatment were studied. Results showed that, methyl jasmonate treatment was increased the expression of all genes. In particular, the increase in 12, 24 and 48 hours were different between the two varieties, but generally the level of expression was significant for Khazar compared to Hashemi.The results suggest that Jasmonic acid treatment increase defense gene expression and probably induce resistance to diseases in rice. In addition genes expression and defense response largely depends on plant genetic background.

Silicon as an essential nutrient in rice plant affects many growth factors including yield. The main object of this study was to evaluate the effects of silicon application on growth, uptake pathways and accumulation of some nutrients and phenolics and lignin contents in rice plant, Oryza sativa cv. Fajr. The plants cultivated in Hydroponic culture medium with Yoshida nutrients in growth chamber under controlled condition. Silicon treatments were included two 0 and 1.5 mM sodium silicate. The plants treated with silicon for 12 days indicated higher fresh and dry weight of shoot, relative growth rate and shoot to root ratio compared to plants devoid of silicon nutrition. In contrast, transpiration was decreased significantly due to silicon application. Also, uptake and accumulation of silicon, iron and potassium were significantly increased and calcium and magnesium uptake and accumulation were markedly decreased following silicon application. Soluble phenolics significantly decreased in roots and shoots of silicon treated plants, while lignin increased in root and decreased in shoot due to silicon application that may related to creation of barrier in apoplastic pathway of nutrients uptake. Measurement of nutrients uptake by reduction of their concentration in nutrient solution following different treatments including 2,4-Dinitrophenol, sodium cyanide and cold in roots environment and saturation of water vapor in shoots indicated that probably silicon deposition in cell wall and vascular space limited apoplastic uptake of calcium. On the other hand, improvement of membranes function increased iron uptake via intracellular pathway.

Diallel crosses of eight cultivars and breeding lines of safflower were conducted. F2 generations were evaluated to estimate genetic parameters for some physiological traits under drought stress with Griffing’s methods 2. Evaluated traits were: Chlorophyll index, Chlorophyll a, Chlorophyll b, carotenoids, relative water content, specific leaf area, leaf nitrogen content and plantlet height. Genotypes of F2 generation (36) were evaluated in a complete randomized block designs with three replication at Research greenhouse of college of Agriculture Shahid Bahonar University of Kerman Analysis of variance based on Griffing’s method revealed significant general combining ability (GCA) and specific combining ability (SCA) mean squares of all studied traits in F2 generations, implementing the importance of additive and non-additive genetic effects. Low narrow-sense heritability estimates and high estimates of dominance effects for all of the studied traits indicated the importance of non-additive genetic efficiency for these traits. Hence the efficiency of hybrid production method would be high for them.

In this study, the effect of jasmonic acid concentrations on secondary metabolites in Thymus vulgaris L. was examined. Second metabolites were analyzed by GC/MS chromatography. The results showed that major compounds were Thymol, Cavacrol, P- cymen, Linalol, γ- terpinen and Borneol. Different levels of jasmonic acid had different effects on content of these metabolites. Results showed that in plants that treated with 200 µM jasmonic acid Thymol increased significantly but decreased in 50 and 400 µM. 200 µM jasmonic acid increased Carvacrol significantly. 50 and 200 µM jasmonic acid didn,t have significant effect on Linalol content but 400 µM jasmonic acid decreased significantly Linalol. γ- terpinon increased significantly in 50 µM but decreased in 200 µM jasmonic acid. P- cymen content increased with 50 and 200 µM jasmonic acid and Borneol content decreased in 50 µM jasmonic acid. Therefore we concluded that different concentration of jasmonic acid had different effect on secondary metabolites in Thymus vulgaris in this research.

In order to evaluate light extinction coefficient and light use efficiency of wheat cultivars in densities of wild mustard, an experiment was conducted in Agricultural Research Station Gorgan during 2010-2012. The experiment design consisted of four randomized complete blocks in a factorial arrangement. The design consisted of two factors, four wheat cultivars and 5 levels of wild mustard densities. The results of means comparison of cultivar×wild mustard density interaction effect showed by increasing wild mustard density, light extinction coefficient increased in wheat different cultivars. In this research, the means of light extinction coefficient in the maximum of wild mustard density in Morvarid, Moghan, Arta and Tajan was 0.23, 0.51, 0.63 and 0.65, respectively. The highest and lowest of light extinction coefficient observed in Tajan and Morvarid, respectively. By comparing the vertical distribution of leaf area in wheat cultivars was distinguished that the highest of gathering amount of leaf area in all of investigated layers observed in Morvarid in competition and pure conditions. The highest of light use efficiency in the maximum of wild mustard density (32 plant/m2) observed in Morvarid (1.85 g/Mj) in the both of years, meanwhile, Tajan (1.21 g/Mj) had the lowest of light use efficiency. Totally, the results of this experiment in two years showed Morvarid had the highest of seed yield for the reason that the most of vertical distribution of leaf area and light use efficiency and too, the lowest of light extinction coefficient in compared to other cultivars, and was the more of succeed in competition with wild mustard.

Salt stress is a major environmental problem in arid and semi-arid agriculture. Kochia is a halophyte, which may provids a good source of forage for livestock by using saline water. In order to investigate the salinity effect on some morphological characteristics of kochia, an experiment was conducted with supply of K+ and Ca+2 in green house and hydroponic condition. Two salinity levels including 20 dSm-1 and 40dSm-1 and control (tap water) and KCl (10mM), CaCl2 (10mM) and KCl with CaCl2 (5 mM) using split plot design, based on RCBD allocated in main and sub plot with six replications respectively. Result showed that increasing salinity decreased shoot and root fresh and dry weight, and reduces the green area index, root volume, shoot and root potassium and calcium concentration. Salinity increased Na and ratio of sodium to potassium in shoots and roots. Use of calcium alone increased calcium of shoot and root. Application of calcium with potassium, showed a positive effect on reducing impacts of salinity. The interaction between calcium and potassium with salinity, the use of calcium alone in salt treatment (40dSm-1) reduced the sodium contents of roots. Application of calcium in salinity treatments (20 and 40dSm-1) showed the greatest impact on shoot and root calcium. Also the use of calcium with potassium improved the traits in this study. Generally, based on this results application of K+ with Ca+2 alleviated effect of salinity and improve dry matter production of kochia.

5-aminolevulinic acid is the key precursor of all tetrapyrrole compounds such as heme, chlorophylls, bacteriochlorophyll, phytochrome and vitamin B12. In this study, the effect of 5-aminolevulinic acid, in reduction of salt stress in Lycopersicun esculentum Mill. var. Falcato were studied. Salinity at three levels (0, 50 and 75 mM NaCl) and ALA treatment at three levels (0, 1 and 2 mM) were investigated in this study. Salinity reduced growth parameters, phenolics content and phenylalanine ammonialyase activity, and increased lipid peroxidation, ion leakage and the activity of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase. 5-aminolevulinic acid application in two levels increased the growth parameters, phenolics content, and the activity of phenylalanine ammonialyase, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase, and decreased lipid peroxidation and ion leakage. These results show that the application of 5-aminolevulinic acid, via enhancing the activity of enzymatic antioxidant system, is effective in salt tolerance of tomato plants.

In order to study the effects of nitrogen rates and seed inoculation with plant growth promoting rhizobacteria (PGPR) on quantitative and qualitative yield, root characterstics, leaf appearance rate and grain filling period of triticale, a factorial experiment was conducted based on randomized complete block design with three replications in research greenhouse of the faculty of Agriculture, University of Mohaghegh Ardabili in 2011. Factors were: nitrogen rates in four levels (0, 80, 160 and 240 kg N ha-1) as urea and seed inoculation with plant growth promoting rhizobacteria in four levels containing, without inoculation as control, seed inoculation with Azospirillum lipoferum strain OF, Psedomunas putida strains 41, and 9. Means comparison showed that maximum of grain yield (1.36 gr/per plant) was obtained at seed inoculation with Azospirillum lipoferum×160 kg N ha-1. Application of PGPR and increasing of nitrogen rates increased leaf appearance rate. Maximum of phyllochron (5.23 days) and the least of leaf appearance rate (0.191/day) was belonged to treatment compound of N0 × without inoculation seed with PGPR and it was vise versa in treatment compound of N240 × inoculation seed with Azospirillum. Rate and effective grain filling period were affected by nitrogen rates and seed inoculation with PGPR. Maximum of grain weight (0.0516 gr) and effective grain filling period (29.6 day) were obtained in seed inoculation with PGPR×160 kg N ha-1. It seems that in order to increasing of grain yield, leaf appearance rate, grain filling period and some traits be applied 160 kg N ha-1 × seed inoculation with Azospirillum lipoferum