نشریه فیزیولوژی محیطی گیاهی
پیاپی 75 (پاییز 1403)

Silicon, being the second most abundant element in the soil and the earth's crust, has been shown to possess the ability to promote plant growth and enhance plant response to stress factors such as heavy metals. To investigate the impact of silicon on various growth and physiological parameters of rapeseed (Brassica napus) under arsenic and cadmium stress, a factorial experiment was conducted in the form of a completely randomized design with three replications. After reaching the four-leaf stage, plants were treated with 600 µM arsenic and cadmium and 0, 0.5, 1 and 2 mM silicon for 14 days. The results showed that cadmium was more accumulated than arsenic in the aerial part of rapeseed, so it had significant toxic effects on plant growth parameters. Compared to the single treatment of arsenic or cadmium, silicon supplementation, especially in the 2 mM treatment, decreased hydrogen peroxide content and, on the contrary, increased the activity of glutathione S-transferase. In general, silicon improves the plant healing potential and resistance of rapeseed by improving growth factors, reducing heavy metal uptake, and oxidative stress damage. Therefore, silicon can enhance crop production and increase plants' resistance to heavy metal stress.

Biological and chemical fertilizers have important effectiveness in growth and development of plants, and consumption of this fertilizers made increasing in quantitative and qualitative production in plants. In this study, the effects of biological fertilizers such as Botamisol, Humic acid,  horse manure, sheep manure, cow manure, poultry manure, vermicompost and complete chemical NPK with two control (water foliar application and without any foliar application) and three levels of drought stress (Field Capacity, 50% and 75% loss of gravitational water) on morpho-physiological characters and content/composition of essential oil of Salvia syriaca L. were investigated. This research was performed in randomized complete block design in factorial layout with 3 replication. From fifteen essential oil components, the most components were 1, 8 cineole, cis-thujone, trans- thujone, camphor (oxygenated monoterpenoides). Cis-thujone (30.3-29.5 %) had the most amount in essential oil components. Treatments of vermicompost, poultry manure and complete chemical NPK in Field Capacity made the most height of plant (48.8-49.4 cm), number of stem (20.1-19.5), total chlorophyll (2.42-2.55 mg.g FW-1), RWC (69.2-67.8) and content of essential oil (1.4-1.55%). Compositions of sesquiterpene hydrocarbons such as caryophyllene, alpha humulene and manool increased in drought stress. Suggest to obtain the most quality of essential oil in Salvia such as important components (cis-thujone and camphor) in same condition, use the poultry manure and complete chemical fertilizers.

Drought, one of the major ecological limiting factors, has a significant effect on the growth and secondary metabolic process of medicinal plants. Water stress reduces the size, density, leaf surface of the plant and reduces the biomass, and not only changes the plant structurally, but also leads to fluctuations in their secondary chemical compounds. The present study was carried out to investigate the effect of using brassinolides and surfactant on drought stress tolerance on Sarkhargol medicinal plant at Islamic Azad University of Mahabad during 2016 - 2017. The studied factors include dryness at three irrigation levels of 70, 120 and 170 mm, evaporation from class A pan as the main factor, surfactant consumption at two levels (0 and 0.5 liters per hectare) and 24-epibrassinolide at three levels (0, 0.01 and 0.1 μmol) were as secondary factors. According to the results of the present study, drought stress had a decisive role in reducing the properties of Sarhargol medicinal plant, as well as the main effects of brassinolide, surfactant solution and drought stress according to the content of soluble sugars, proline, glycine betaine, amino acids, lysine and methionine. They had Due to the limitation of water resources, irrigation after 120 mm, use of brassinolide and surfactant can have a positive role in removing the damages of drought stress. In addition, brassinolide and surfactant led to increased tolerance to drought stress in Sarhargol medicinal plant, which led to relative resistance to drought and stability of the yield of dry matter of the plant and its essential oil.

Improper use of chemical fertilizers to increase the yield of various crops has caused numerous damages in various fields .The international community is moving towards the use of fertilizers and bio stimulants in the form of organic agriculture in order to reduce the risks and harms caused by the use of chemical fertilizers and at the same time maintain crop yields. In order to investigate the effect of urea chemical fertilizer and foliar application of Ulva fasciata Delile seaweed extract on growth factors of alfalfa (Medicago sativa L.), A Split plot study was conducted in the form of a randomized complete block design with 3 replications in Shavour Agricultural Research Station and Plant Physiology Laboratory of Shahid Chamran University of Ahvaz in 1399-1400. The treatments for this experiment included different concentrations of 4 levels urea fertilizer (0, 40, 70 and 100% of the usual amount of urea fertilizer) and different concentrations of 4 levels ulva seaweed extract (0, 5, 10 and 15%). Different concentrations of urea chemical fertilizer were used as soil application and different concentrations of ulva seaweed extract were used as foliar application. The treated plants were examined in the beginning of reproductive phase. The results were statistically analyzed by MSTAT-C software. Comparison of the mean interaction of urea fertilizer and seaweed extract showed that the application of 15% ulva seaweed extract along with 70% of the usual amount of urea chemical fertilizer leads to an increase in the desired factors compared to other treatments. In addition, malondialdehyde a level in plants treated with ulva seaweed extract were decreased. Based on this, it can be said that foliar application of 15% seaweed extract has an effect almost similar to half of the usual application of urea chemical fertilizer.

This research was carried out with the aim of introducing the most suitable accession in Thymus kotschynus species for the development of cultivation in saline conditions at Pardisan Qom Medicinal Plant Research Station. The seeds of the top 4 accessions along with the control (T.vulgaris) were planted in January 2016 in JF pots, and in April of the following year, potted seedlings were planted in the main field in the form of a randomized complete block design in three replications. Essential oil extraction was done by water distillation method and essential oil analysis was done by gas chromatography method. The results of composite variance analysis of traits showed that the effect of population, year and the interaction of year in the population on aerial organ performance, essential oil percentage and essential oil performance were significant at the error probability level of 1 or 5%. Comparison of the average interaction effect of year and population revealed that the highest yield of aerial parts was in the control with 3496 and population 5 at the rate of 3405 tons per hectare (in the second year of the experiment). After the control population in the first year, the highest percentage of essential oil was recorded in the populations of 70 and 54 and in the second year of the experiment. Also, the highest yield of essential oil with 30 kg per hectare was observed in populations 5 and 54. Although the performance of both essential oils was significantly lower than the control. Carvacrol chemotypes were identified in accessions 5 and 22, thymol in accession 54 and geraniol in accession 5. In total, accessions 5 (Qazvin 1) and 54 (Naqadeh) can be considered for the development of cultivation in saline water and soil conditions.

Heavy metals are the first pollutant in water. Lead is one of the most dangerous heavy metals in the environment, which is known as one of the most toxic heavy metals due to its harmful effects on the human nervous system, circulatory system, kidney, and reproductive system. Among the various methods of removing heavy metals, we can mention biological absorbents such as microalgae. In this research, the bioabsorption capability of lead metal was measured by two microalgae, Scenedesmus obliquus, and Chlorella vulgaris, and the effect of parameters such as acidity, light intensity, temperature, density, and culture method on the amount of heavy metal absorption was investigated. Also, the ability of two microalgae production methods, biofilm, and suspension, were compared. The results showed that Sandesmus algae were a better absorbent than Chlorella vulgaris algae. Also, the biofilm production method had higher lead absorption compared to the suspension method in both Sandesmus and Chlorella vulgaris algae. As the temperature increased, the absorption of lead in microalgae increased. In both production methods, lead absorption had a uniform trend with increasing pH. At a density of 20 to 60 in both algae, a decreasing trend in lead absorption was observed, but from a density of 60 onwards in the suspension method and 80 onwards in the biofilm method, an increasing trend in lead absorption was observed in microalgae. With the increase of contact time from 60 to 110 minutes in both suspension and biofilm methods and in Chlorella and Sandesmus algae, the amount of lead absorption increased. In the end, the method of biofilm and Scenedesmus obliquus algae was suggested for lead absorption

In order to investigate the effect of nitrogen fertilizer and foliar spraying of humic acid and Vita free on phenological stages, remobilization indices and yield of sunflower in the second experimental planting in a factorial manner based on a randomized complete block design with with three replications in summer 2018 at Gonbad Kavous University farm research. Cultivar factor was included Haysan 25 and Oscar and combination of fertilizer factor was included no fertilizer application, 100 kg N/ha, 50 kg N/ha, 50 kg N/ha + 1.5 kg humic acid/ha, 50 kg N/ha + 0.5 kg Vita free/ha and 50 kg N/ha + 1.5 kg humic acid + 0.5 kg Vita free/ha. The results showed that the effect of cultivar and fertilizer on most of the measured traits was significant. The results showed that cultivar and fertilizer were significant on most of the studied traits. The maximum days from planting to 50% Flowering, the dry matter of vegetative organs in the flowering stage, the remobilization, current photosynthesis and seed yield were obtained from Oscar cultivar. The maximum remobilization and remobilization efficiency were obtained in the treatment of no fertilizer use. Days from planting to 50% flowering, days from planting to 50% maturity, current photosynthesis and seed yield in 100 kg N/ha treatment and 50 kg N/ha + 1.5 kg humic acid/ha + 0.5 kg Vitafree/h was higher than other fertilizer treatments. Based on results, in order to achieve the maximum seed yield of sunflower and to prevent excessive use of chemical fertilizers, the combined use of Nitrogen fertilizer, humic acid and vita free is necessary.

Salinity is one of the major factors that adversely affect the performance and growth parameters of most agricultural crops worldwide. Plant growth and the levels of secondary metabolites are influenced by salt stress. The aim of this study was to investigate the effect of soil organic amendments on some physicochemical traits of Salvia viridis L. plants under salt stress. The present study was conducted in a factorial design in a completely randomized manner. The treatments included five levels of organic amendments (control without any amendment, half and one gram of seaweed extract per liter of water, 20% volume of pot cow manure compost, and 20% volume of pot vermicompost) and three levels of soil salinity (3, 6, and 9 deci-Siemens per meter) with three replications in a greenhouse. The control treatment had no fertilizer. The findings indicated that as the salinity level increased, growth parameters (fresh weight, dry weight of stem and leaf, leaf area), chlorophyll content, and proline decreased, while malondialdehyde increased. The highest fresh and dry weight of stem and leaf, proline content, and essential oil percentage were obtained in plants treated with seaweed extract, while all amendments showed higher chlorophyll content compared to the control. Furthermore, among the investigated treatments, seaweed extract at a concentration of 1 milligram per liter proved to be more effective in preserving the plant from the adverse effects of salt stress and improving its growth characteristics.