Journal of Plant Process and Function

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Salinity is one of the environmental factors that has a critical influence on plant growth and development.  Researchers have shown that some plant growth regulators such as nitric oxide improves the plants resistance to environmental stresses such as salinity, heat, cold and drought. Sodium nitroprusside (SNP) commonly was used as a nitric oxide (NO) donor in plants. The aim of this research was to evaluate the role of SNP on salt tolerance of Zinnia elegans and its effects on some morphological, physiological and biochemical characteristics of this plant. A factorial experiment based on completely randomized design was conducted with five levels of salinity 0 (control), 25, 50, 75 and 100 mM NaCl and four levels of sodium nitroprusside (SNP) (foliar spray) 0.0 (control), 0.25, 0.50 and 0.75 mM with 3 replications. In salinity level of 50 mM, the length of stem and root was reduced 41.22 and 29.63 percent in compared to control. In salinity level of 50 mM, application of 0.5 mM sodium nitroprusside, increased total antioxidant capacity, glycine betain and proline 1.93, 3.98 and 2.12 times respectively compared to control. It also increased ascorbate peroxidase, catalase and guaiacol peroxidase 5.15, 4.69 and 2.78 times respectively compared to control. The application of SNP (especially at salt concentrations lower than 50 mM) ameliorated the adverse effects of salt stress, in Zinnia elegans plant.

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Today, the ornamental plants survival in the green space due to climate change and a sudden increase in temperature in cold seasons has been compromised. In order to evaluate the effect of irrigations and temperatures on viola plants, a factorial experiment was conducted based on completely randomized design with four replications in faculty of agriculture, Ferdowsi University of Mashhad. Experimental factors include levels of irrigation water (80%, 60 % and 40 % FC) and levels of temperatures (20, 0, -3, -6, -9, -12, -15, -18, -21 and -24 °C). After irrigation treatments, some traits including proline, carbohydrate, chlorophyll (a, b and total), carotenoid and relative water content and after temperature treatments activity of superoxide dismutase, ascorbate peroxidase and total phenol were determined. The results showed that carbohydrate and proline significantly increased and chlorophyll and relative water content decreased at 40% irrigation treatment. Interaction effects of irrigation and temperature treatments significantly affected the activity of two enzymes. The maximum activity of superoxide dismutase and ascorbate peroxidase in 40% FC level of irrigation water at 0 °C were seen, but with decreasing temperature, the activity of these enzymes were reduced. In three irrigation levels, the amounts of total phenols were increased from 20 to 0 °C and reached to minimum at -24 °C. After the recovery period, plants treated with 60% FC at 0 °C showed the highest vegetative traits (height, number of nodes, leaves, offshoot and flower diameter).
 

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In order to investigate the effect of drought stress on physiological responses of Alcea rosea plant in greenhouse at two growth stages, a factorial experiment was conducted in a completely randomized design with three replications. The experiment factors included two ecotypes (Mashhad and Tehran), five moisture levels (80 (control), 70, 60, 50 and 40% Field Capacity) at two growth stages (seedling and elongation stem). After applying drought stress at two growth stages, SPAD, electrolyte leakage, relative water content, proline, malondialdehyde, enzymes activity of leaf and total dry weight were measured. The highest relative content of leaf water (88.2%), total dry weight (36 g), and the lowest electrolyte leakage (6.23%) were recorded in Mashhad ecotype under 80% FC treatment at stage of stem elongation. In both ecotype, with increasing drought stress, the amount of proline had a rising trend at two stages. Also, the highest amount was recorded in ecotype Mashhad under 40% FC treatment at stage of stem elongation. In both ecotypes, the highest activity of malondialdehyde was observed in 40% FC treatment at seedling stage (11.9 and 11.4 nmol g-1 FW, respectively). In the ecotype of Mashhad and Tehran, with increasing drought stress from 80 to 40% FC at stage of stem elongation, the activity of the superoxide dismutase enzyme increased, from 49.9 to 1.98, and 1.91 U mg protein, respectively. The activity of ascorbate- peroxidase increased, when plants were under severe drought stress. There was a positive and significant correlation between chlorophyll index and relative water content with total dry weight of the plant. The results of this experiment showed that compared to two ecotypes, Mashhad ecotype compared to Tehran has more tolerance to water shortage.

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Survival of ornamental plants as a vital factor in green spaces has been threatened by climate change and drought stress. An experiment was designed to investigate the effect of soil modifiers on the growth of two plants of the Hollyhock ecotype under drought conditions at Ferdowsi University of Mashhad in 2021. Experimental Treatments included two ecotypes (Mashhad, Tehran), three drought stress levels (80, 60, 40% FC), and four substrates (soil, soil + manure, soil + rice hull, soil + wheat straw). Macroelements (nitrogen, phosphorus, and potassium) of leaves, physiological characteristics of plants, (total chlorophyll, proteins, and enzyme activities), and morphological traits (height, the diameter of the stem, number of leaves, bud, flowers, and leaf area) were measured. The effect of time on the number of Hollyhock leaves under drought stress was also recorded. Treatments affected all physiological and growth parameters of Hollyhock plants, and a significant amount of physiological traits (chlorophyll) and growth parameters were recorded in the Mashhad ecotype below 80% FC in soil + manure. The triple interactions of ecotype, drought stress, and culture medium on protein content, superoxide dismutase activity, and ascorbate peroxidase activity were not significant, but enzyme activity was increased with increasing drought stress. Also, the number of leaves and flowers had a decreasing trend with increasing drought stress. The results showed that applying manure with soil by providing macro elements reduced the adverse effects of drought stress in Hollyhock and increased drought stress resistance in both ecotypes.

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Nowadays, because of making uniform orchards with high yield and desirable product quality the use of dwarf and semi dwarf rootstocks is necessary to reduce fruit production costs in the horticultural industry. Therefore, the appropriate rootstocks and scion is a critical factor to cost savings in fruit production, adaptation to the regional climate, and increasing the shelf life of fruits. In 2019, the quality and storage attributes of ʻBrabernʼ and ʻGolden Deliciousʼ cultivars apple fruits under the influence of vegetative rootstocks MM106 and M9 were investigated at the dense gardens of Astan Quds Razavi. Results showed that traits such as antioxidants, total phenols, total soluble sugar, titratable acidity, pH, fruit firmness, as well as weight loss percentage during storage were significantly affected by the interactions of rootstocks and scion. Total soluble solids (13.9%), pH (15.7%), antioxidant activity (21.6%), and total soluble sugar (3.5%) of apple fruits increased whereas traits such as, titratable acidity (60.8%), phenol content (70%), and fruit firmness (44.5%) decreased during the storage period over time. Fruit weight loss in M9 rootstock started from the second month and in MM106 rootstock from the first month of storage. The highest weight loss (50%) in Golden Delicious cultivar in M9 and the lowest weight loss (64%) in scion Brabern in MM106 was observed in the second month compared to the fifth month. The reduction in tissue firmness during storage was 42% and 38% for Brabern in M9 and Golden Delicious in MM106, respectively.

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Drought stress is one of the most important factors threatening the growth and development of ornamental plants around the world. Clearly, the use of active ingredients that increase drought resistance in plants is very important to reduce the economic losses of ornamental plants in landscapes. For this aim, a study was conducted to evaluate the effects of sodium hydrochulfide on Amaranthus plant (Amaranthus tricolor' early splendor') under deficit irrigation in a factorial design in the form of complete random design. Plants were treated with sodium bisulfide (0, 0.5, 1.5 mM) in the greenhouse for three weeks and then subjected to deficit irrigation (90, 80, 70, and 60% of field capacity). As the drought stress increased, the relative water content decreased, such that deficit irrigation (60% FC) reduced the relative water content by 78.9%. Sodium hydrochulfide reduced the negative effects of deficit irrigation on secondary metabolites (phenol and flavonoid) as well as osmotic regulator (proline), and a concentration of 1 mM increased stress resistance. Ion leakage was reduced by the use of sodium hydrochulfide during high deficit irrigation. 1 mM sodium hydrogen sulfide, with increased antioxidant activity, reduced malondialdehyde by 23.4% and 23% under deficit irrigation conditions 60 and 70% FC, respectively. The application of sodium hydrogen sulfide reduced the negative effects of deficit irrigation on Amaranthus growth traits by increasing secondary metabolites, osmotic adjustment, and antioxidant activity. Overall, our results suggested that the application of sodium hydrosulfide as a producer of hydrogen sulfide could be considered as a strategy to maintain the growth of ornamental plants under deficit irrigation.

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The accumulation of heavy metals throughout the ecosystem is now a major environmental problem that threatens the quality of life of all living organisms. In a factorial experiment based on a completely randomized design, the effect of sodium nitroprusside on the physiological and biochemical responses of tomatoes under nickel stress was investigated. Tomato plants were grown in two concentrations of sodium nitroprusside (zero and 100 µM) and three different nickel concentrations (zero, 25, and 50 µM) with three replications under hydroponic conditions. The results showed that 50 μM nickel sulfate without sodium nitroprusside significantly reduced the relative water content of leaves (43.1%) compared to the same treatment with-sodium nitroprusside. An increase in electrolyte leakage and malondialdehyde were observed as an indicator of oxidative damage in plants under nickel sulfate stress. In response to oxidative stress caused by nickel sulfate, the amount of chlorophyll decreased and carbohydrate and proline concentrations increased compared to the control. Application of sodium nitroprusside resulted in higher concentrations of chlorophyll b (4.54%) and total chlorophyll (3.57%) under non-nickel sulfate stress than the control. Antioxidant, peroxidase, and catalase activity increased by 62, 37, and 38%, respectively, under nickel sulfate stress when treated with 100 µM sodium nitroprusside compared to non-sodium nitroprusside treatment. According to the results, sodium nitroprusside at a concentration of 100 µM can reduce the negative effects of nickel exposure on the growth characteristics of tomato plants such as the number of leaves and dry weight of the plant, by increasing the antioxidant activity (increasing the activity of the enzymes catalase and peroxidase) and also the positive effect of proline accumulation on the RWC, so the use of this substance is recommended for tomato plants growing under nickel conditions.