فصلنامه فرآیند و کارکرد گیاهی
سال یازدهم شماره 7 (پیاپی 53، Feb and Mar 2023)

In this study, the reaction of germination and plantlet growth different chickpea cultivars (Arman, Azad, Binalood and Hashem) in relation to osmotic stress due to polyethylene glycol solution (-2, -4, -6 and -8bar) and control (distilled water) using factorial design in completely randomized with four replications was evaluated. In this study, there was a significant difference between the different potentials of drought stress for all measured traits with 99% probability. With the reduction of water potential, the seed germination, germination rate, rootlet length, stemlet length, rootlet wet weight, rootlet dry weight, stemlet wet weight, stemlet dry weight, plantlet wet weight, as well as plantlet dry weight decreased. Also, proline and Fv/Fm (the efficiency quantum of the photosystem II) of cultivars at two levels of control and glycol polyethylene solution at the level of -2bar was different. So that the Hashem cultivar showed the highest amount of proline in the polyethylene glycol solution -2bar. However, the Fv/Fm had a reversed relationship with drought stress. That is, drought stress leads to a reduction in the Fv/Fm. The maximum amount of Fv/Fm was found in the Hashem cultivar under drought stress condition, and the lowest amount in Azad cultivar in stress conditions. The results of activity of antioxidant enzymes in this study showed that drought-resistant cultivars such as Hashem is  to drought stress by increasing the capacity of the antioxidant system to remove reactive oxygen species and prevent membrane peroxidation Overall, the commercial cultivar Hashem showed drought tolerance at high stress levels, indicating their potential for production applications.

To evaluate the biological potential and medicinal properties, the biochemical compositions and quantity and quality of essential oil of Marrubium vulgare L., grown in the natural habitat located in Guynik region, North Khorasan province, were investigated. The content of secondary metabolites including phenol and flavonoids, and antioxidant capacity were measured in laboratory methods. Essential oil of plant was obtained by hydro distillation method and dehydrated with anhydrous sodium sulfate, then it was quantitatively and qualitatively analyzed by gas chromatography (GC) and gas chromatography / mass spectrometry (GC/MS). The results showed that the essential oil yield was 0.24% (w/w), and oxygenated monoterpenes made up 52.40% of essential oil. Also, 18 compounds were identified in the essential oil of M. vulgare plant that the main compounds were dodecanal (23.02%), ß-bisabolene (15.65%) and thymol (9.60%). In this study, the phenol content of extract of M. vulgare was 72.01 (mg Gallic acid/g Dry weight), the flavonoids content was 6.25 (mg Quercetin/g Dry weight) and its antioxidant capacity was 81.12 (μg/ml). Overall, based on the results, it seems that M. vulgare grown in Guinik region can be a potential and rich source of natural antioxidant compounds.

Application of strategies inducing a heavy metal tolerant turfgrass is necessary for cultivation management. Water and soil contamination with heavy metals is an increasing concern for the human and environment health. This study was conducted to evaluate the mitigation of environmental Cd toxicity through landscape turfgrasses as affected by two arbuscular mycorrhizal fungi (AMF) species and to monitor some physiological and biochemical properties of the plants in various Cd concentrations. Plants were inoculated with Rhizophagus intraradices and Glomus mosseae and without AMF, with the addition of different Cd concentration (0, 200, and 300 µg/L). AMF could colonize with the roots of turfgrasses in order as follows: Agropyron elongatum > Festuca aurandinace > F. ovina > Lolium perenne. The highest AMF colonization (~70%), Cd concentration in shoot (250 mg/Kg dry weight) and aerial and underground biomass (about 3 and 1.2 g/pot, respectively) as well as growth rate were displayed in Agropyron elongatum when inoculated with G. mosseae under 200 µg/L Cd solution. Both AMF species reduced H2O2 production and lipid peroxidation and enhanced catalase, peroxidase and superoxide dismutase activity. Lolium perenne accumulated higher Cd in its roots as compared to the other turfgrasses under non-AMF. Although A. elongatum and Festuca aurandinace had a translocation factor (TF)>1, they could produce considerable biomass and grow well through AMF inoculation. It is suggested that the two latter species could be used under highly Cd-contaminated soil/water if AMF is prepared.

Some olive cultivars possess high tendency to alternate bearing, which have a minus economic effect on olive industry. The experiment was performed in an olive orchard located in Shiraz region. Monthly monitoring of concentrations of unstructured carbohydrates (glucose, fructose, sucrose, mannitol and starch), protein, nitrogen, potassium and phosphorus in leaves, branches and roots of olive trees ON and OFF was performed from October 2018 to September 2019. The aim of this study was to evaluate carbohydrate and nutrient reserve changes on flower initiation in ON and OFF olive trees. The results showed that there was a significant difference between carbohydrate concentrations (glucose, fructose, sucrose, mannitol and starch), protein, nitrogen, potassium and phosphorus in the leaves, branches and roots between ON and OFF trees during bearing cycle. During autumn and winter, carbohydrate concentrations showed an upsurge trend in different parts in OFF trees. The content of nitrogen ramped up in the leaves in both ON and OFF trees; whereas, it was declined in the branches as well as roots in both trees during autumn and winter. Furthermore, the content of potassium showed a downward trend in the leaves and branches during autumn and winter. In spring and summer, a better percentage of carbohydrates was recorded in olive organs in OFF trees than in ON trees. In July, the concentration of carbohydrates and amount of nitrogen of OFF trees in all samples was higher than that in ON trees. In July, carbohydrate content and mineral content declined in ON trees. The deficiency of carbohydrate and nutrient reserves during the flowering induction affected vegetative growth strength, fruit size, and flowering in the spring of the subsequent year. Simple correlations were shown for 21 measured traits for ʻFishomiʼ seed olive cultivar in different months, respectively. The correlation coefficient showed that there was the most positive correlation between leaf starch and total leaf carbohydrate. The presence of carbohydrate and nitrogen reserves played a key role in flower induction of olive trees and was expressed as crucial parameters to stimulate alternate bearing.

Allelopathic effect of apricot (Prunus armeniaca L.) root on some crops and weeds was investigated in two independent experiments. First, the effect of concentrations aqueous extract of apricot root (AAR) was assayed on the seed germination of Cicer arietinum L., Phaseolus vulgaris L., Triticum aestivum L., Zea mays L., Amaranthus retroflexus L., Secale cereal L., and Avena ludoviciana Durieu. In the second experiment, two pot trials were carried out to investigate the effect of AAR and apricot root powder (ARP) on the seedlings of P. vulgaris, Z. mays, S. cereal, and A. retroflexus. The results showed that germination was halted in T. aestivum, C. arietinum, A. ludoviciana, and S. cereal under all treatment levels, in A. retroflexus under 75 and 100%, and in P. vulgaris under 100% of AAR. Also, the results showed that effects of AAR and ARP on the biomass, membrane stability index, chlorophylls, carotenoids, proline, and protein content, and antioxidant enzymes activity were not significant, with a few exceptions. It can be concluded that the allelopathic effect of apricot root is mostly exerted by inhibiting the germination of target plants rather than effect on later stage of plant growth and development.

Plants activate antioxidant defense mechanisms under stress, which help maintain the structural integrity of cell components and possibly reduce oxidative damage. Low- temperature stress led to the production of reactive oxygen species and oxidative damage to plants. In this study, the effect of putrescine and proline on reducing the production of reactive oxygen species and increasing the activity of antioxidant enzymes in the peel of three Citrus species were investigated. The results showed that with decreasing temperature, the production of reactive oxygen species and activity of antioxidants increased in three Citrus species. In both C. reticulata and C. sinensis species, the activities of antioxidant enzymes were higher compared with C. paradisi. However, the production of reactive oxygen species in C. paradisi was higher than the other two species. Treatment of fruits with proline and putrescine led to a decrease in the production of reactive oxygen species. The highest amount of glutathione peroxidase and ascorbate peroxidase was observed at -3°C temperature and in fruits treated with proline 20 Mm. Exogenous application proline and putrescine increased the levels of endogenous proline in Citrus species. The levels of endogenous proline under both low temperature and exogenous proline and putrescine were higher in C. reticulata compared with two other species. Overall, the treatment of putrescine and proline has led to the improvement of defense activities in stressed plants and has significantly increased in the C. reticulata species.

Soil and water salinity are the most important problems that limit crop production, especially in the arid and semi-arid regions. This study was conducted to investigate the effect of growth-promoting bacteria and selenium nanoparticle pretreatment on increasing the tolerance of the Chenopodium quinoa plant to salinity. A factorial experiment was conducted in a completely randomized design with three replications. Experimental treatments consisted of selenium nanoparticles at a concentration of 1 mg L-1, Bacillus cereus (BW) and Pseudomonas fluorescens (Ps) and three different levels of saline solution with concentrations of 0, 200 and 400 mM sodium chloride. The results showed that quinoa seeds soaking in selenium nanoparticle solution and PGPRs by increasing photosynthetic pigments (up to about 96% in Se+BW pretreated plants), compatible solutes (approximately 65% increase in prolin content in Se+Bw treatment), reducing oxidative stress (increased the activity of some antioxidant enzyme in about 100%), protecting the cell membrane (decreased the MDA up to 32%) and reducing sodium uptake (in about 23% in Se+Ps pretreated plant) improve plant growth and increase the quinoa resistance at salinity conditions. The results of this study showed that Se, although not essential element for plants, can improve growth and morphological parameters of the plant under salinity stress at low concentrations and it has more effects in the presence of PGPRs. So, it is suggested that these two biostimulators can be used together for protecting plants from salinity damaged and this strategy could be applied for sustainable agriculture. In addition, since most of the positive functions of these bacteria were not affected by salinity stress, so this type of bacteria can be used with selenium in saline soils.

In this study, the effects of peppermint and rose extracts on delaying the aging of Alstroemeria spp. cut flowers were investigated. Peppermint and rose extracts were used in concentrations of 10, 20 and 30%. Quantitative and qualitative traits such as vase life, flower opening index, water uptake, fresh weight, dry weight, population of bacteria in vase solution and stem end, ion leakage, decreasing Brix degree, content of carotenoid and chlorophyll were evaluated. In this study, treatment of 30% rose extract was better than other treatments and the highest vase life, Brix degree, and fresh and dry weights were obtained in this treatment. Treatment of 10% mint extract was also effective in reducing the bacterial population, increasing water absorption and vase life. Treatment of 10% rose extract had the highest efficiency in the process of flower opening and it acted like treatment of 30% rose extract in fresh weight and Brix degree. The highest amount of chlorophyll was related to 20% rose treatment and the highest amount of carotenoid was related to 30% mint extract treatment.

Since the use of seed priming agents to reduce the potential toxicity of AgNPs has not been explored, we evaluated the combined effects of 0.1 mM salicylic acid (SA) and 0.1 mM nitric oxide (NO) on responses of Hypericum perforatum plants to Ag-induced stress. The results of growth parameters together with measurement of malondialdehyde (MDA) revealed that exposure to AgNPs or AgNO3 caused more toxicity, which was closely associated with the over–accumulation of ROS. However, SNP (NO) and SA addition successfully mitigated adverse impact of AgNPs on H. perforatum seedlings, which was associated with the higher synthesis of chlorophyll b pigments and proline. In addition, a further increase in antioxidants (phenolic compounds) was observed in NO-primed plants under AgNPs-induced stress, which was concomitant with the high level of SOD activity. We concluded that NO minimized the inhibitory effects of AgNPs stress by increasing the phenolic compounds as well as by regulating accumulation of Ag, ROS and antioxidants. To sum up, exogenous NO plays a key role in enhancing its resistance to Ag stress in physiological base, thereby improving the growth and phenolic compounds production (chlorogenic acid, quercetin and rutin) of H. perforatum plant.