The development of crops with suitable root traits, enable them to have higher yields in soils with higher salt and limited water. The aims of this study were to determine soil water potential levels to obtain a significant root growth response and identify genotypic differences in seminal root length and root branches in response to drought stress. Three separate factorial greenhouse experiments at vegetative stage of wheat were carried out based on completely randomized design with three replications. The optimum water potential level needed to obtain a significant root growth response ranged from − 7 to − 8 bar. The results showed the genotypic diversity in root growth response to drought stress. Drought stress reduced root system growth such as seminal axile root length, two longest seminal axile roots, number of seminal roots and distance between the root tip and the first branch root by 19, 21, 37 and 46 % respectively, compared to control. The reduction of root growth traits of tolerant drought stress cultivars was less than sensitive ones. Genotypic variation in root growth response to drought stress indicates the suitable opportunities to improve drought tolerance through plant breeding.

Drought is one of the most important abiotic stresses limiting the survival, growth, and production of plants in many regions of the world including Iran. Genetically, different species adopt different strategies to confront with drought. One of the mechanisms that plants have evolved to adapt to the environmental changes is stress memory. In this study, different genotypes of smooth bromegrass were evaluated to investigate the drought stress memory and drought stress tolerance based on a greenhouse pot experiment. Thirty three genotypes of smooth bromegrass were evaluated in three moisture environments: control (C), once drought-stressed (D2), and twice drought-stressed (D1D2) in a factorial arrangement according to the randomized complete blocks design with two replications. The dry matter yield decreased by 45 and 36% in the one-stress and two-stress treatments compared to the control, respectively. These results indicated the role of drought stress memory in modulating drought stress through the influence on forage dry yield and root dry weight. The root dry weight reduced in the once stress and twice stress conditions by 32 and 19%, respectively, compared to the control environment. This finding shows the significant effect of stress memory on the root growth. Based on the principal component analysis, superior genotypes were identified for future researches. Overall, the results suggested that smooth bromegrass is capable to activate some drought stress memory mechanisms related to morphological and root traits. Background and Objective: Smooth bromegrass is particularly adapted to areas with medium and low annual precipitations and has a high drought tolerance when compared with the other grasses. Drought is one of the most important environmental factors with adverse effects on plant growth and development and affects all morphological, physiological, biochemical and metabolic aspects of plants (Farooq et al., 2009). Therefore, it is necessary to identify drought-tolerant genotypes (Saeidnia et al., 2017b). The term stress memory was first proposed by Trewavas (2003), as the plant's ability to access past experiences to better respond to future stresses. In open-pollinated species that are difficult to develop inbred lines, such as smooth bromegrass, the main breeding method is to create synthetic varieties that are obtained through the crossing of suitable parents. Besides, half-sib matting is one of the most common methods for obtaining genetic information such as estimating the additive effects and dominance of genes (Nguyen and Sleper,  1983). Saidnia et al. (2017a) in a study on the genotypes of orchardgrass species found superior genotypes for hay production. They also examined the genetic parameters and heritability of dry matter yield and introduced the superior genotypes for the further researches. Hence, this study was designed to investigate stress memory and its effect on improving drought tolerance in a smooth bromegrass germplasm. Methods: This research was carried out from February 2017 to June 2018 in the research greenhouse located at the Isfahan University of Technology as a pot experiment. A sandy loam soil with bulk density, field capacity, and wilting point of 1. 57 g cm-3, and 12. 5 and 7. 4 %w/w, respectively, was used for filling the pots. The genetic materials included 33 genotypes of smooth bromegrass that were collected from different regions of the country and some foreign gene banks. The genotypes were investigated in three moisture environments including control (C), once drought-stressed (D2) and twice drought-stressed (D1D2) as a factorial experiment in the form of a randomized complete blocks design with two replications. Results: The analysis of variance showed that drought treatments had a significant effect on most of the traits. A significant difference was observed between the genotypes regarding the measured traits indicating high genetic diversity among the genotypes. The secondary drought stress significantly reduced most of the traits. The dry matter yield decreased by 45 and 36% in the once-stress and twice-stress treatments compared to the control, respectively. These results indicated the role of drought stress memory through the effect on dry yield of forage and root dry weight. Also, the root dry weight was reduced by 32 and 19% in the conditions of one stress and two stress compared to the control environment, respectively, which shows the significant effect of stress memory on the root system. Multivariate analysis showed that under the twice stress condition compared to the other two moisture environments, the relationships of the traits have undergone severe changes, which is a confirmation of the effect of initial stress and stress memory. Conclusions: This research indicated a high genetic diversity among the smooth bromegrass genotypes in terms of stress memory responses, which can be used in the selection methods. For example, the means of dry matter yield and root dry weight decreased to a lesser extent when grown in the presence of twice drought stress, than once drought stress. This finding shows that the mechanisms of the stress memory related to morphological and root traits in this plant are activated by applying preliminary mild drought stress and help the plant to have a smaller decrease in growth. Based on the principal component analysis, superior genotypes were identified for future research. The results of this research can be used in breeding programs and future genetic research. It is also suggested that suitable genotypes be studied more in field conditions over several years. References: 1. Farooq, M., Wahid, A., Kobayashi, N., Fujita, D., Basra, S. M. A., 2009. Plant drought stress: effects, mechanisms and management. In: Alberola, C., Debaeke, P., Lichtfouse, E., Navarrete, M., Véronique, S. (Eds. ), Sustainable Agriculture. Springer Dordrecht. pp. 153–188. 2. Nguyen, H. T., Sleper, D. A., 1983. Theory and application of half-sib matting in forage grass breeding. Theor. Appl. Genet. 64, 187–96. 3. Saeidnia, F., Majidi, M. M., Mirlohi, A., 2017a. Genetic analysis of stability in poly­crossed populations of orchardgrass. Crop Sci. 57, 2828–2836. 4. Saeidnia, F., Majidi, M. M., Mirlohi, A., Manafi, M., 2017b. Productivity, persistence and traits related to drought tolerance in Smooth Bromegrass. Plant Breeding. 136, 270–278. 5. Trewavas, A., 2003. Aspects of plant intelligence. Ann. Bot. London. 92, 1–20.

Salinity is one of the limiting factors in many crops including rice production. The objective of this study was to investigate the response of 89 recombinant inbred lines derived from a cross between two Iranian rice cultivars, Tarom-Mahalli (indica) and Khazar (indica), under non-stress and 8 dS. m-1 salinity stress at vegetative stage conditions. The experiment was carried out as pod experiment under open air conditions in a completely randomized design with four replications. The results of combined analysis of variance under non-stress and salinity stress conditions showed that the the effect of line and line×stress interaction for all the studied traits was significant, indicating different reaction of the lines under two conditions. The results of simple analysis of variance also showed that the difference between lines in both conditions was significant for all traits at 1% probability level. Correlation coefficients among traits indicated that the highest correlation coefficient was observed between biomass and stem dry weight under both conditions. Stepwise regression analysis for biomass under non-stress conditions showed that root length, root to shoot dry weight ratio, number of tillers per plant at 120th day and plant height at 120th day were the most important traits influencing biomass, respectively, while under salinity stress conditions, root area and root volume in addition to these four traits, were also identified as effective traits on biomass. Factor analysis also showed that three and five independent factors explained the correlation between biomass and the other traits in the studied lines under non-stress and salinity stress conditions, respectively. Cluster analysis using Ward’ s minimum variance method under non-stress conditions divided the lines into four groups which the fourth group was consisted the lines with higher values than total average for most traits. Under salinity conditions, the lines were divided into three groups and the lines into first group had the highest biomass and the lowest genotypic score and were tolerant to salinity stress. In total, the results of current study showed that the lines 6, 9, 13, 14, 17, 18, 23, 24, 34, 39, 44, 45, 68, 79 and 80 had the higher values for most the studied traits than the other lines, in addition to higher biomass, and could therefore be considered as salinity tolerant lines in future researchs.

Environmental stresses such as salinity have a great impact on the amount and quality of secondary metabolites of medicinal plants. To investigate the effect of salinity on phytochemical attributes of cannabis (Cannabis Sativa L. ), an experiment in the form of a randomized complete block design with three replications and 5 salinity treatments (0, 2, 4, 6 and 8 dS/m) was conducted in 2019 in medicinal plants research center, Karaj, Iran. In this study, the amount of potassium (K) and sodium (Na) elements and chlorine (Cl) in leaf and root organs of the plant were measured by a flame photometer and colorimetric method, respectively. The content of cannabinoids compounds in leaves including tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabichromene (CBC) were measured by GC/MS. The results showed that there was a significant difference (P≤0. 01) among different salinity treatments in terms of Na, K, Cl and cannabinoids THC, CBD and CBC. With increasing salinity level, the amount of Na and Cl ions in leaves and roots increased compared to the control treatment and the highest amount of leaf and root Na (15. 81, 14. 06 mg/g, respectively) was observed in salinity treatment of 8 dS/m. Also, increasing the salinity concentration caused a decrease in leaf and root K of the plant and the highest amount of leaf and root K (34. 83, 34. 46 mg / g, respectively) was related to the control treatment. The highest amount of THC and CBD (7. 94 and 1. 45 mg / g of dried plant, respectively) at salinity concentration of 4 dS / m and the highest amount of CBC at salinity of 2 dS / m (0. 012 mg / g dry leaf) were obtained. Therefore, salinity changes the amount of cannabinoids in cannabis and the highest levels of THC, CBD and CBC are obtained at low salinity levels.

In order to assess the protein pattern changes in tolerant and susceptible cultivars of wheat under drought stress in seedling stage and for understanding their mechanism of stress tolerance, two cultivars of spring wheat, including Kavir (as tolerant) and Bahar (as susceptible) were cultured in the growth chamber. Proteome analysis by 2D electrophoresis and staining of gels by Commassie brilliant blue for two cultivars was performed and 20 and 86 protein spots with significant difference between control and drought condition in the Kavir and Bahar cultivars were identified, respectively. Using MALDI-TOF/TOF, 18 and 84 protein spots of them in the Kavir and Bahar was identified. Total of proteins with significant expression changes related to the Kavir were divided into six functional groups, including Calvin cycle (seven protein spots), light reaction of photosynthesis (four spots), nitrogen assimilation and proton transfer (each two spots), the biosynthesis of starch and glycolysis (each one spot) and the unknown proteins (three spots). The number of protein functional groups in the Bahar was more diversity and these proteins were divided into 11 functional groups, while in Bahar as well as Kavir the highest numbers of proteins was related to the Calvin cycle (35 protein spots), light reaction of photosynthesis (22 spots), assimilation of nitrogen (eight spots) and proton transfer (five spots). Generally, the most protein amounts in the Kavir were related to Calvin cycle such as Fructose-bisphosphate aldolase (three spots) and RuBisCO small subunit precursor (two spots), respectively. While more of proteins involved in the Calvin cycle of Bahar cultivar such as RuBisCO activase A proteins (seven spots), fructose 1, 6-biphosphate aldolase (six spots) and catalytic large subunit of RuBisCO (five spots) were. On the other hand, in Bahar, proteins of OEC (12 spots) were the largest of protein groups involved in light reaction of photosynthesis. While in the Kavir, Cytochrome b6-f complex, Chlorophyll a-b binding protein, CYP38 and HCF136 protein under drought stress just one of each apiece were induced. Also in the Kavir and Bahar, the largest of protein groups related to nitrogen assimilation were Glutamine synthetase (GS) enzyme. Generally, these results to identify and better understand of the metabolic pathways, effective proteins and important proteins involved in tolerance and sensitivity of wheat will help.

The aim of this was to investigate the effect of high and low temperature stress on growth, photosynthesis and antioxidant changes in vegetative growth stage of tomato. Tomato plants which were grown in hydroponics system exposed to temperature stress at 40 º C and 10 º C compared with plants grown in the greenhouse at optimum temperature of 25± 2 as control. All plants were transfer to optimum condition in the greenhouse after stress treatments and growth parameters were measured after 10 days. The results of the comparison between these three temperatures showed that the highest fresh weight of shoot was observed at control treatment. In high temperature stress conditions observed 56. 7% decrease fresh weight compared to control treatment and in low temperature stress conditions observed 65. 3 decrease. Similarly, fresh weight of root was highest in control treatment and heat stress 45% and low temperature stress 64. 6% showed decrease compared to optimum temperature conditions. Root volume was reduced by temperature stress significantly and photosynthesis rate was the highest in control treatment and lowest under high temperature stress. In general, it can be stated that temperature stress in this study affected growth and photosynthetic traits more than antioxidant traits.

The objective of this work was to evaluate the effects of periodic water stress on yield and yield components of Quinoa in the experimental research under greenhouse conditions. This research was conducted to study the effect of water stress on yield and yield components of Quinoa in the experimental research greenhouse of Ferdowsi university of Mashhad during 2018-19. NSRQC cultivar of Quinoa was planted and experimental design was completely randomized with five treatments and four replications. Treatments were full irrigation in all growth stages, water stress in vegetative stage, water stress in flowering stages, water stress in grain filling stage and deficit irrigation in all growth stage treatment with supplemental irrigation in time of planting. Results showed that the effect of periodic water stress on leaf number, leaf panicle, panicle length, stem diameter, plant height, SPAD index, 1000 kernel weight, grain yield and water productivity were highly significant (P>0. 01), but different irrigation regimes on branches number and panicle width were significant at 5 % levels. Results showed that the highest 1000 kernel weight (3. 99 g), grain yield (21. 2 g) and plant height (67. 9 cm) were in full irrigation in all growth stage treatment and the highest water productivity (2. 14 kgm-3) was in deficit irrigation in all growth stage treatment. With 50% reduction of water in vegetative stage, flowering stage, grain filling staged and deficit irrigation in all growth stage compared to full irrigation in all growth stage treatment, 1000 kernel weights were decreased by 19. 0, 9. 0, 4. 5, and 26. 6 % and Grain yield was decreased by 19. 3, 11. 8, 7. 5 and 21. 2% respectively. Due to the problems same as water shortage in most parts of the country, use of deficit irrigation (50% of FC. ) at grain filling stages for Quinoa cultivation is applicable.

In this research, the effects of cysteine on alleviation of heavy metal stress in purple basil plants were studied and some parameters such as fresh weight of shoot and root, chlorophyll a and b content, carotenoids, anthocyanin, and total phenolic compounds and reducing sugar was measured. Research was conducted in two separate trials for the two group pre-treated cysteine and cysteine -cobalt combined treatments. The treatments containing of 0, 500 and 2500 mM cysteine and 0, 100 and 500 mM cobalt was used. Higher concentrations of cobalt decreased photosynthetic pigments, leaf, root and shoot length, fresh weight of roots and shoots while cobalt stress increased, caused reducing sugars, anthocyanins and total phenolics content. Cysteine reduced the fresh weight of roots, reduction sugar, anthocyanins, and total phenolics of plants compared to plant treated with cobalt treatments without cysteine. Thus, this amino acid improved leaf area, root and shoot length, shoot fresh weight and photosynthetic pigments in stress conditions. Generally, the results showed that pre-treatment of cysteine could alleviate low concentrations of cobalt stress effects than higher amounts application of this heavy metal, while combined treatments containing cysteine was more effective at higher concentrations of cobalt. Based on these results probably cysteine with chelating of cobalt and biosynthesis of phytochelatins reduced the stress.