فصلنامه فرآیند و کارکرد گیاهی
سال چهارم شماره 2 (پیاپی 12، تابستان 1394)

Nitric oxide (NO) as a gaseous molecule has a central role in plant responses to biotic and abiotic stresses. Low temperature is an important factor that limits the survival، productivity and geographical distribution of plants in large areas of the world. Low temperatures by a variety of biochemical، physiological and molecular changes are leading to oxidative stress. In this experiment، the effects of 0. 1 mM nitric oxide pretreatment were studied on pea plant (Cicer arietinum) during low night temperatures (5، 15، 25℃). The experimental design was completely randomized factorial with four replications for evaluate the amounts of hydrogen peroxide، lipid peroxidation، soluble and insoluble phenolic compounds، total antioxidant capacity، peroxidase and superoxide dismutase enzyme activities. The results showed that nitric oxide pretreatment was effective on the content of hydrogen peroxide، soluble and insoluble phenolic compounds، total antioxidant capacity، but it was effective on the content of lipid peroxidation، peroxidase and superoxide dismutase enzymes activity. Night temperatures were effective on all of them. Interaction between nitric oxide and temperature has significant effect on the content of total antioxidant capacity and superoxide dismutase enzyme activity. The hydrogen peroxide content، lipid peroxidation، soluble and insoluble phenolic compounds amount and peroxidase enzyme activity was not affected by interaction between nitric oxide and temperature.

To find out the biochemical and physiological responses of purple coneflower (Echinacea purpurea L.) medicinal plant to low temperature stress، a compeletly randomized design with three replications was conducted at Sari Agricultural Sciences and Natural Resources University in 2013. Five months old of coneflower seedlings exposure to three temperature levels of 23 ºC (control)، 4 and 4 ºC for 6 h and then electrolyte leakage and malondialdehyde (MDA)، enzyme activities of superoxide dismutase (SOD)، peroxidase (POD)، catalase (CAT)، ascorbate peroxidase (APX) and polyphenol oxidase (PPO)، protein oxidation of the leaves، total phenols and flavonoids contents، percentage of DPPH free radical inhibition، as well as chlorophyll fluorescence parameters included F''m، F''v/F''m، qp، NPQ and ФPSII were determined. Results of experiment showed a significant increment of electrolyte leakage and malondialdehyde (MDA) content in leaves where the highest electrolyte leakage (55. 7%) and MDA (12. 3 nanomol/ g FW) were obtained at 4 ºC. In this study، the maximun activity of antioxidant enzymes (SOD، CAT and APX) were recorded when coneflower seedlings exposure to temperature lower than 4 ºC. Activity of POD and PPO enzymes، however، were decreased when temperature reduced to 4 ºC. The highest total protein content was calculated at 4 ºC that showes about 65% increment than control. Low temperature stress reduced total phenolic and flavonoid content of seedlings. Also، the highest antioxidant capacity of leaves (0. 93%) were measures in control seedlings. No significant differences were observed between the fluorescence parameters in dark-adapted leaves. In light-adapted leaves، F''m and F''v/F''m content decreased with increasing stress and the highest content of the NPQ and qP were recorded at 4 ºC. Meanwhile، the lowest ФPSII was obtained at 4 ºC. In conclusion، it seems that the coneflower plant relatively had good tolerance to low temperature stress to 4 ºC.

Basil (Ocimum basilicum) is a medicinal plant of the family of Lamiaceae. It contains phenylpropanoid and terpenoid componds. Chitosan with elicitor action induce defence mechanisms of plant. In the present study، the effect of chitosan on malondialdehyde (MDA)، hydrogen peroxide (H2O2)، gayacol peroxidase (GPX)، peroxidase (POD) and poly phenol oxidase (PPO) antioxidant enzymes activity، phenol compounds، flavonoids، antosyanin، chlorophyl a، b and carotenoid، soluble sugars and proline was evaluated. The plants were treated at pre flowering stage with 2 g/L chitosan and harvested after 1، 2، 3، and 5 days after chitosan. Comparing with control، the results showed that MDA and H2O2 increase in shoot in different harvest stages under treatment with chitosan. Also antioxidant enzymes activity، phenol compounds، flavonoids، antocyanin، chlorophyll a، b and carotenoid، soluble sugars and proline، in comparison with control، increased in many cases in different harvest steges. So it seems that chitosan، as a biotic elicitor، enhanced antioxidant enzymes activity and secondary metabolites production.

Heavy metals are normally found in soils. Industrialization and urbanization have increased the anthropogenic contribution of heavy metals in biosphere. Phytoremediation is an important technology for remedying contaminated sites. In this work، we studied the capability of stability، growth، and uptake of heavy metals by means of Thlaspi caerulescen، Zea mays، Helianthus annuus، Eruca sativa، Brassica napus، Solanum nigrum and Alyssum bracteatum on Irankooh soil، containing high concentrations of Zn، Pb and Cd. S. nigrum were able to uptake Zn and Pb to a large extent (1716. 8 and 724 mg kg-1، respectively). Among eight species planted on Irankooh soil، T. caerulescen could accumulate Cd to a large extent (35. 3 mg kg-1). E. sativa and B. napus were another species for phytoremediation because they absorbed Zn، Pb، and Cd (specially Zn) more and produced high biomass yield. Z. mays and H. annuss could not accumulate high amount of heavy metals. These two species are not suitable plants for phytoremediation of heavy metals from contaminated soils of Irankooh.

Low quality of irrigation water along with increasing salinity level has reduced the olive yield over recent years in Iran. Screening of salinity tolerance in olive cultivars using gas-exchange parameters، water use efficiency، and relative leaf chlorophyll content are important in olive development programs. This study was carried out to assess the salinity tolerance of four olive cultivars (Amygdala، Dakal، Shiraz and Zard) under greenhouse condition. A factorial experiment through completely randomized design with four replications and four levels of salinity including 0، 100، 150، and 200 mM NaCl were used. The results showed that with increasing salinity levels CO2 assimilation rate، stomatal conductance، transpiration rate، water use efficiency، and relative chlorophyll content decreased and internal CO2 concentration increased. The results also indicated that there were significant differences among the examined olive cultivars. In overall، the results showed that “Zard” and “Shiraz’ cultivars were the most tolerant cultivars to salt stress.

In order to evaluate the effect of urban wastewater and different fertilizer treatments on growth and some physiological traits of sugar beet، a field experiment arranged as split plot in RCBD design with three replications at Research Station of Shahrekord University in 2013. The main factor including: irrigation with urban wastewater at 2-4 leaf stage، 8-12 leaf stage and irrigation with tap water (control) and four types of fertilizer including sheep manure، spent mushroom compost، chemical fertilizer and no fertilizer (control) in sub-plot. The results showed that the highest leaf area index with 4. 84 was obtained from sheep manure at 84 days after planting. Also، crop growth rate، dry shoot weigh to dry root weight ratio and biomass weight were higher in sheep manure than other fertilizer treatments. Under application of urban wastewater treatment، the amount of leaf area index، crop growth rate and net assimilation rate significantly were higher compared to tap water treatment. In this experiment the highest harvest index and extractable sugar percent belonged to tap water treatment.

Physiological and biochemical changes during sunflower seed deterioration were studied during incubation for 2، 4، 6 and 8 days at 43 °C and a relative humidity of 100%. Parameters such as germination percentage، germination rate، seedling length، seedling vigor and protein decreased whereas electrical conductivity، fatty acids and lipid hydroperoxides increased during seed deterioration. Increased levels of fatty acids and lipid hydroperoxides during seed deterioration indicated damage to cellular membranes witnessed by increased electrical conductivity. These changes implied increase in reactive oxygen species and decreased antioxidant enzyme activity. Reactive oxygen species alter protein structure and as a result the de-natured proteins will degrade during seed aging. Finally it can be concluded that seed germination percentage and seed vigor decrease during seed deterioration. Thorough increase in Lipid peroxidation can be one of the physiological mechanisms in deterioration of sunflower seeds.

Dunaliella salina، a unicellular green microalga with ability of large quantity β-carotene accumulation، was used as a proper model for analysis of expression of the pds and lyc genes، involved in β-carotene biosynthesis pathway، under different light intensities and salinity concentrations. For this purpose، an experiment with two factors، light intensities (200 and 1000 µmol m-2s-1) and salinity (2 and 4 M NaCl) were performed in completely randomized factorial design. During 4 days، the steady-state levels of transcripts encoding phytoen desaturase increased substantially in 200-4 and 1000-2 treatments، while lycopene beta cyclase transcripts increased in 200-2، 1000-2 and 1000-4 treatments. As an enhancement effect of increased expression of both genes، the β-carotene reached to its maximum amount in 1000-2 treatment. These results indicated that light intensity induced the expression of the above indicated β-carotene biosynthesis pathway genes. The accumulation of β-carotene could be considered as a protection mechanism of the algae against oxidative stress originated from primary light stress.

Construction and function of active substances of medicinal plants is influenced by environmental factors such as deficiency or increasing of nutrients in the soil and substrates type. Thus، an experiment was carried out in factorial experiment in the base of randomized complete with 16 treatments and 3 replications. The aim of this research was Influence of vermicompost and nano potassium fertilizer on morphological and phytochemical characteristics in Aloe vera. The treatments were four levels of vermicompost (0،15، 30 and 45)، in the Volume percents with soil of culture and Nano potassium in 3 levels 2، 4، 6 gr/l and 0 as control. The results showed that the maximum amount of gel weight، gel moisture content، gel glucomannan and anthocyanin of cortex was obtained in 30% of vermicompost and 4 g/l of nano potassium. The interaction of these two factors was increased the gel antioxidant capacity and moisture content and showed maximum amount in 30% vermicompost and 2g/l nano potassium. The maximum of weight leaf was belonged in 30% of vermicompost and 6g/l nano potassium and maximum amount of gel flavonoid showed in 15 % of vermicompost and 4g/l nano potassium. Thus، using of combination substrateand of vermicompost ana foliar application of nano potassium fertilizer in aloe vera cultivation. has an effective role in the production leaves and gel high quality and the way influence it depending on characteristics is function of combination vermicompost substrate and nano-potassium fertilizer concentration.

Drought is a major factor that limiting plant growth. Mycorrhizal fungi can modified and improved water relation and drought stress with phosphorus and water absorption. In the other hand،Silicon is known as a positive factor that improved water and soil relation and reducing biotic and abiotic stress in some plants and resistant them against stress. Since the cucumber plants in early phase of growth need high water and dehydration can seriously reduce the performance of the excessive use of water in greenhouse cultures and fungal diseases. Therefore، the purpose of this research is investigation of mycorrhizal fungi and silicon in cucumber culture and water deficit. Thus، a factorial experiment based on completely randomized design with four replicates and 3 treatments (silicon 2/0 mM، arbuscular mycorrhizal fungi (Glomus intraradices) and dry growing conditions) in the greenhouse were conducted on cucumber plant. The results showed that mycorrhizal fungi alone and with dry stress significantly increased phosphorus content in fruits، roots and leaves of the plant in. The content of proline، soluble sugar and reduced sugar increased in dry treatments. In plants that treated with silicon and dry the amount of sugar in fruits، leaves and roots increased significantly at 5% level. In mycorrhizal plant soluble sugar content in leaf and root increased significantly. Generally in this study we concluded that silicon and mycorrhizal treatment able to increase the amount sugar and proline content in cucumber plants and resistant this plant against water stress.

In order to study the effect of chitosan on growth and some biochemical characteristics of chickpea under salinity stress condition a greenhouse experiment was conducted in Vali-e-Asr University of Rafsanjan in 1392، as factorial arrangement in completely randomized design with three replications. Experimental factors included salinity (0، 4، 6 and 8 dS/m) and level of chitosan (0، 0. 1، 0. 2%، all dissolved in 1% acetic acid) along with an additional treatment of distilled water. Results indicated that with increasing salinity malondialdehyde content (0. 834 mM g-1)، proline (0. 254 mg. g-1 FW)، total carbohydrate (10. 48 mg. g-1 FW)، Na+ concentration of shoot (1. 87%)، Na+ concentration of root (2. 05%) were increased while other traits under study were decreased. Chitosan treatment increased shoot height، shoot dry weight and relative water content and decreased malondialdehyde content. Under salinity conditions، chitosan treatment root height، root dry weight، proline and total carbohydrate were increased. Also، chitosan increased K+ concentration and decreased Na+ concentration of shoot under both unstressed and stressed condition. In plants treated with chitosan، K+ concentration of root increased compared with control plants، but the Na+ concentration of root decreased by 7. 14 %. The results of the study indicate that priming the chickpea seeds with chitosan reduce the harmful effects of salinity via either reduction in Na+ absorption or by accumulation of proline، total carbohydrate and K+.

Tropical plant، Catharanthus roseus contains worthy alkaloids such as vinblastine and ajmalicine. Since amount and pattern of alkaloid production could be affected by different environmental conditions، the effect of two elements of cadmium and nickel were investigated. Plants in the greenhouse conditions using a chemically inert substrate were cultivated and in a complete randomized block design were treated by different concentrations of cadmium and nickel until appearance of toxicity symptoms. The concentrations of cadmium and nickel، chlorophyll and total alkaloids of the leaves were measured. The patterns of alkaloids were determined by thin layer chromatography using of UV light and specific reagents of ceric ammonium sulfate and dragendorff. The results showed that toxicity symptoms of cadmium occurred at 10 µM or more and 50 µM or more for nickel which was accompanied with a decrease in chlorophyllconcentration and intervein chlorosis. By increase the concentration of metals، both the concentrations of metals and alkaloids increased in leaves but the concentrations of alkaloids decreased at very high concentration of cadmium. The chromatographic pattern of alkaloids was changed too. Treatment by cadmium and nickel caused appearance or intensified the bands of alkaloids with medium RF such as vincolidine or low RF such as serpentine. Indeed، cadmium and nickel by increase of the ample alkaloids، increase of the accumulation of rare alkaloids and increase in the ratio of alkaloid content to biomass، caused an increase to the total alkaloids.

In order to evaluate the effects of both cold and light stresses on chlorophyll fluorescence and feasibility of using chlorophyll florescence technique to evaluate effect of light intensity on cold tolerance in soybean، an experiment was done in a factorial arrangement based on a completely randomized design with three replicates. Two soybean cultivars consisted of 032 and BP grown under greenhouse conditions. After three weeks، plants were kept in either 5 or 28 °C and either 2000 or 8000 lux of light intensity then chlorophyll fluorescence parameters was measured. Results showed that cold stress in both light intensities significantly decreased variable fluorescence (Fv)، maximum photochemical quantum yield of photosystem II (Fv/Fm) and effective photochemical quantum yield of photosystem II [Y (II)] while increased quantum yield of regulated non-photochemical [Y (NPQ)]، quantum yield of non-regulated non-photochemical [Y (NO)] and non-photochemical quenching (NPQ). These parameters، however، generally more changed in 8000 than in 2000 lux. Under cold stress، reducing in Fv/Fm and increasing in NPQ was greater in 032 than BP cultivar. Also، in 032 cultivar، greater ratio of reduced Y (II) replaced by Y (NPQ) to avoid greater increase in Y (NO). Cold stress in two light intensities (2000 and 8000 lux) could damage to photochemical and photosynthetic systems in soybean plants، however، damage rate increased when light intensity increased from 2000 to 8000 lux. In cold stress conditions، cultivar 032 showed more tolerance than BP since it could dissipate more excessive energy through non-photochemical quenching and xanthophylls. Therefore، 032 cultivar showed more tolerance to cold stress and could be recommended particularly for regions with cold temperature along with higher light intensity.