فصلنامه فرآیند و کارکرد گیاهی
پیاپی 2 (پاییز و زمستان 1391)

Olive (Olea europaea L.) is an evergreen tree traditionally cultivated in the Mediterranean area, resistant to some degree to salinity and drought conditions. However, olive trees are not so resistant to low temperatures. In recent years, because of high demands for olive oil and fruit, the cultivation of olive trees has been increased in Iran. Different cultivars of olives have diverse reactions to cold stress and so, the selection of cold resistant cultivars is the most effective method to avoid frost damages. In order to compare the impact of cold stress on the content of total protein, lipid peroxidation and photosynthetic pigments, 1-years old olive cultivars of Sevillana and Frantoio, were exposed to low temperatures of 10, 5, 0, -5, -10, -15, -20 and control 20 °C for 12 h. The results indicated that the both examined cultivars were resistant to 0 °C temperature with no significant damages. The photosynthetic pigments of Frantoio did not change even in -15 °C and malondialdehyde levels slightly increased compared with the control (20 °C). Total protein content in Frantoio showed significant decrease from -10 °C, while in Sevillana cultivar there was significant decline of total protein content from -5 °C. Therefore, it can be concluded that Frantoio is more resistant to cold stress than Sevillana.

Enhanced leaf proline, soluble sugar and soluble protein contents with sever salinity stress can improve stomatal conductance and Relative water content. This can inhibit dry matter depletion due to salinity stress, so can be used for screening of safflower cultivars under salinity stress. To evaluate the changes in leaf proline, soluble sugars, glycinebetaine and protein content of six spring safflower under salinity stress, a pot experiment was conducted as factorial base on completely randomized design with three replications in summer 2011 in Yasouj University. The first factor included of four salinity levels as zero, 75, 150 and 225 mM. Second factor included of six safflower cultivars, as Local Isfahan, Spinned Sina, Isfahan 14, Goldasht, Padideh and Sina 411. Traits such as leaf Proline, glycinebetaine, soluble sugars and soluble protein content and leaf relative water content were measured. Interaction of salinity and cultivar was significant for all measured traits. Salinity stress significantly increased leaf proline and soluble sugar content. Relative water content decreased significantly by salinity, so that maximum of it (91.03%) was seen in Padide at control. Sina 411 due to having more leaf soluble sugar and RWC at 225 mM salinity level and Goldasht due to having more proline and glycinebetaine content was more tolerance cultivars than the others, and Esfahan14 that had the least soluble sugar, Relative water content and glycinebetaine content introduced as less tolerant cultivar.

Regarding to excess entry of heavy metals to the natural resources and the importance of heavy metals removal from the environment, in this investigation, the effect of some organic acid treatment on cadmium and lead absorption was studied on one week Brassica napus seedlings. Canola seeds were cultured in Petri dishes containing 10 mL of 100 μM CdCl2 or 100 μM PbCl2 and some organic carboxylic acids including 50 μM citrate, 1 μM oxalate, 50 μM fumarate or 300 μM histidine. To study the role of these organic acids on abbreviation of heavy metal stress, some biochemical and growth parameters including the content of total chlorophyll, carotenoids, hydrogen peroxide, malondialdehyde and dry weight, was also investigated in 7 days canola seedlings under Cd and Pb stress. Although organic carboxylic acid treatment increased Cd and Pb absorption by canola seedlings, there was also an increase in content of total chlorophyll, carotenoids and dry weigh in seedlings treated by carboxylic acids. Cadmium and lead stress caused the higher content of hydrogen peroxide but carboxylic acid application decreased the content of malondialdehyde and hydrogen peroxide in seedlings under heavy metals stress. Based on the results, it seems that the application of some organic carboxylic acids not only improve remediation capability of Cd and Pb by canola seedlings, but also has positive effects on abbreviation of Cd and Pb toxicity in canola seedlings.

The effects of salt stress on the activity of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD) enzymes, carotenoid content, the rate of lipid peroxidation (LP) in term of thiobarbituric acid-reactive substances (TBARS) content and grain yield were investigated. Eighteen triticale lines comprising 9 doubled haploid (DH) lines and 9 their corresponding F8 lines as well as two bread wheat cultivars ('Roshan' as a drought tolerant and 'Kavir' as a salt tolerant cultivar), were used. A randomized complete block design with three replications was used for each environmental condition (non-stressed and salt-stressed conditions) at the Research Farm of College of Agriculture, Isfahan University of Technology in a silty clay loam soil in 2008-2009. Both salt stressed and non-stressed experiments were irrigated with water having EC of 1 dS m-1 until mid-jointing stage (43 growth stage of Zadoks scale), and afterward salt-stressed experiment was irrigated with saline water containing 175 mM NaCl and EC= 16 dS m-1. Salinity led to an increase in the enzymes activities and LP and decrease in carotenoid content in the leaves of both triticale and wheat genotypes. An inverse and significant relationship between grain yield loss due to salinity stress with carotenoid content was observed under salinity stress (r = -0.54*). Under both conditions, negative and significant correlations (r = -0.61**) were observed between grain yield and LP. The orthogonal comparison between triticale line and wheat cultivars revealed the superiority of triticale lines for the production of antioxidants and less LP in triticale than wheat under both environmental conditions, which may be related to the development of relatively higher salt tolerant in triticale.

We investigated the effect of jasmonate on plastidial terpenoids on Cannabis sativa at vegetative stage. We used jasmonate solutions with 0, 1, 5, 10 and 100 µM concentration for treating of plants. Plant treated with Jasmonate showed an increase in chlorophyll a content in comparison with control plants. However chlorophyll b content only increased in 5 µM jasmonate treatment. Also carotenoid content increased in all treated plants but there was no significant difference between various concentrations of jasmonate. The amount of α-tocopherol enhanced in plants treated with 10 and 100 µM jasmonate. Treatment with 1 and 5 µM jasmonate caused a considerable increase in tetrahydrocannabinol. 5 µM jasmonate solutions were more effective in this regards. Cannabidiol content decreased in all plants treated with jasmonate. These results showed that jasmonate encourage the accumulation of primary and secondary isoprenoids in chloroplasts.

Salinity is one of the most important factors that limit plant growth and production in the whole word. Compounds, which are able to reduce the damaging effects of various stresses such as salinity, should be of great important. In this investigation, the effects of spermidine on salt tolerance of Matricaria recutitaa were investigated. The results showed that, salt stress in chamomile plants caused the reduction of growth and increased the amounts of hydrogen peroxide, malondialdehyde and the activity of ascorbate peroxidase and guaiacol peroxidase. Pre-treatment of chamomile plants with spermimdine had no significant effect on shoot growth and the activity of ascorbate peroxidase enzyme, while reduced the content of hydrogen peroxide and malondialdehyde obviously, and increased the root growth and activity of guaiacol peroxidase significantly. Application of spermidine with methylene blue reduced the effect of spermidine on the increment of root growth, decrease of hydrogen peroxide, malondialdehyd and ascorbate peroxidase activity while had no significant effect on shoot growth and guaiacol peroxidase activity. Therefore, it seems that Spd effects on these physiological parameters are through nitric oxide and guanylate cyclase pathway however, more studies required for detail investigations.

In order to evaluate the effect of Pseuodomonas different strains on nutrients uptake efficacy and rice yield, an experiment was arranged in Rice Researches Institute of Guilan Province (Rasht) during 2009. The experiment design consisted of four randomized complete blocks in a factorial arrangement. In this research, two factors were evaluated: first, two cultivars (Khazar and Hashemi) and second, eight levels of seed inoculation with PGPB strains (168, 93, 177, 136, 103, 169, 4 and control (without inoculation)). Investigated characteristics consisted of: nitrogen consumption efficacy, phosphorus consumption efficacy, potassium consumption efficacy, phosphorus harvest index, apparent recovery efficacy of nitrogen and phosphorus, physiological efficavy of nitrogen and phosphorus, agronomic efficacy of nitrogen and phosphorus, yield and yield components (number of seed per panicle, number of panicle per panicle and 1000-seed weight). In this experiment, effect of bacteria were significant in the most of studied characteristics. The results of experiment showed that inoculation with bacterial strains had a significant effect on rice cultivars, so Khazar had better response on the most of studied characteristics in compared with Hashemi. Between bacterial different strains, seed inoculation with 168 strain in compared with other strains increased evaluated characteristics significantly. The findings of this research showed that PGPB can interact positively in promoting plant growth, As well as nutrients uptake of rice plants in soil especially P and too, increase the solubility of ions through increased enzymes activity and production of growth hormones that consequently, leading to improved yield.