نشریه فیزیولوژی محیطی گیاهی
پیاپی 57 (بهار 1399)

This study was conducted to investigate antioxidant compounds contents and antioxidant activity of three Amygdalus haussknechtii genotypes in the natural habitat of Ilam Province. Total phenolic content was measured using Folin–Ciocalteu method and antioxidant activity was estimated by two methods, namely DPPH (2,2-diphenyl- 1- picrylhydrazyl) and nitric oxide radical scavenging. High- performance chromatography was used for quantitative estimation of the phenolic compounds. Results showed that antioxidant activity of leaf extract of H3 genotype was significantly higher than that of H1 and H2 genotypes. The high antioxidant activity can be attributed to higher total phenolic and flavonoid contents, so that high correlation coefficient was observed between total phenolic content and DPPH and nitric oxide radical scavenging, R = 0.902 and R= 0.806, respectively. Analyzing the phenolic compounds by HPLC method indicated that catechin, sinapic acid, quercetin, and apigenin were found in H3 genotype. Also, apigenin compound was observe in all three investigated genotypes. Generally, the results suggested that leaf extract of H3 genotype with high phenolic and flavonoid content and antioxidant activity can be presented as a source of natural antioxidant and used in pharmaceutical industries.

Salinity is a major environmental stress, reducing growth and yield of a wide variety of crops all over the world. The present study assessed effects of humic acid and salinity stress on the growth and some physiological responses of wheat in a pot experiment. The layout was 4×4 factorial experiment in RCBD design with salinity stress levels and humic acid concentrations as main factors in Ilam University during 2016. Treatments were the combination of four levels of salinity stress including stress-free conditions (irrigation by distilled water), and 4, 8, and 12 dS/m NaCl and four concentrations of humic acid including 0 (as a control), 50, 100, and 150 mg/l. The statistical analysis showed that salinity stress and humic acid application had significance effects on the morphological, physiological, and biochemical parameters of the wheat plants. Salinity stress imposed negative effects on plant growth and productivity. Under salinity conditions, growth parameters and yield attribute, relative water content, and chlorophyll reduced, but electrolyte leakage and antioxidant enzyme activity increased. Application of humic acid significantly increased plant growth parameters, chlorophyll content, and antioxidant enzyme activity, and decreased electrolyte leakage content. The highest salinity tolerance was obtained with 150 mg/l humic acid application. In general, results showed that the application of humic acid through affecting physiological parameters decreased adverse effects of salinity stress on the wheat plants.

Salinity stress is one of the factors that threatens the growth and yield of corn. The effects of silicon or nanosilicon on salinity alleviation have been reported in some plants. The effects of foliar application of silicon (inorganic and nanopatricle) on mitigation of the effects of salinity stress on some photosynthetic and biochemical parameters were studied in corn. Experiments were conducted in a completely randomized design with factorial arrangement in a pot culture. The first factor was salinity at two levels including 0 and 100 mM NaCl and the second factor was silicon at three levels including control (without silicon) and 2 mM potassium silicate and 2 mM nanosilicon (SiO2). Under salinity stress, the fresh and dry weights of shoots and roots, the chlorophylls and carotenoids contents, and the amount of soluble protein decreased significantly compared to the control. In contrast, the amount of hydrogen peroxide and malondialdehyde increased in these plants. Also, the photosyntheic rate and water use efficiency of plants decreased under salinity. The application of silicon and nanosilicon improved the growth of plants under salinity and increased the photosynthetic rate and the amount of photosynthetic pigments. In addition, severe reduction in transpiration under silicon application compared to nanosilicon resulted in the increased water use efficiency in this treatment. Silicon application also increased the activity of soluble peroxidase enzyme in plants under salinity, a result which was not observed with nanosilicon application. This resulted in a further decrease in hydrogen peroxide and lipid peroxidation of plants under salinity treated with silicon compared to nanosilicon, which showed a further decrease in oxidative stress in this treatment. These findings indicated that stress reduction and growth improvement of the plants under salinity with silicon application were more than the treatment with nanosilicon.

In order to investigate the effect of biopotasse and iron sulfate on antioxidant activity and biochemical characteristics of fenugreek under drought stress conditions, a factorial experiment was conducted as split plot based on randomized complete block design with three replications in 2017. Treatments included drought stress (normal irrigation as non-stress and irrigation in early growth for 14 days as drought stress) as the main factor and biopotasse (0 and 5 kg. ha-1) and iron sulfate (0 and 1.5 per thousand) as sub-factors biofertilizer. Results showed that the effect of drought stress, biopotasse, iron sulfate, and their interaction were significant on anthocyanin and phenolic compounds and flavonoids so that the highest amount of anthocyanin in fenugreek was obtained from 5 kg biopotasse treatment per hectare and 1.5 per thousand iron sulfate in drought stress conditions while the lowest amount was recorded in control treatment under stress conditions. Also, in drought stress, phenolic compounds, and flavonoids increased in fenugreek, as the highest amount of total flavonoid was achieved under drought stress conditions and 5 kg ha-1 biopotasse and 1.5 per thousand iron sulfates. The interaction of drought stress and iron sulfate was significant on the antioxidant activity of the plant, as the highest antioxidant activity (62.8%) was obtained in drought stress and iron sulfate treatment. Also, the highest amount of total carbohydrate in fenugreek was obtained under drought stress conditions and in 5 kg biopotasse treatment, and the lowest trait was obtained under non-stress conditions. Results showed that the highest total chlorophyll content of fenugreek was observed in non-drought stress conditions and 5kg .ha-1 biopotasse and iron sulfate 1.5 per thousand. Based on the findings, drought stress played an important role in increasing phenolic compounds, flavonoids, anthocyanin, and soluble sugar contents of fenugreek and biopotasse biofertilizer and iron sulfate improved biochemical characteristics of the plants.

In order to evaluate the effect of pre-harvest spray with Benzyladenin (BA) on improving flower quality and delaying flower and leaf senescence in Lilium oriental, a study was carried out as a spilt plot factorial experiment where 5 levels of Benzyladenin (0, 25, 50, 75, and 100 ppm) with three replications and two stages of spraying (budding start and before dyeing buds). Assaying the traits were done in seventh and twelfth two-days after harvest. The flowers were sprayed at two stages, budding and before flowering in the bud stage. Distilled water was used as control. Characteristics such as flower shelf life and lipid peroxidation in petals and leaves on seventh and twelfth days after harvest and carotenoids contents of petals on seventh and twelfth days after harvest were measured. Results showed that spraying with 100 ppm BA at the beginning of flower pigmentation was more effective in delaying senescence in flowers and leaves as compared to the control. Lipid peroxidation in leaves and flowers treated with 100 ppm BA application was significantly lower than the control. In contrast, carotenoid content of flowers sprayed with 100 ppm BA was higher and the lowest values were found in the control. In total, it was found that BA maintains stability by improving the quality and prolonging the flowers’ survival.

This experiment was conducted with the aim of evaluating the planting systems of local rice cultivars in the research paddy fields located in Neka, Sari and Babol during 2017 and 2018. Data analysis was done based on a factorial experiment in a complete randomized blocks design where planting systems including conventional, high-input, transition to organic, organic, and low-input were chosen as the first factor and cultivars including ‘Sang Tarom’, ‘Tarom Mahalli’, and ‘Tarom Hashemi’ served as the second factor. Results demonstrated that the highest mean number of panicle per m2 in both years belonged to the high-input system. The highest fourth internode lodging index was obtained at interaction of high-input and conventional system with ‘Sang Tarom’. The maximum paddy yield in both years was produced in high-input and conventional systems. The highest grain phosphorous uptake, nitrogen harvest index, potassium harvest index, and gel consistency were achieved in high-input and conventional systems. The highest grain milling efficiency in the first year belonged to the conventional system (72.83%), but in the second year, it belonged to the transition to organic system (75%). Gelatinization temperature in both years was maximum in the conventional system while it was minimum in the low-input and organic systems. Regarding the findings, it can be stated that high-input and conventional systems resulted in increase of quantitative yield, but organic and transition to organic systems led to an increased NPK uptake and improvement of the grain baking related traits.

Biological fertilizers play a significant role in increasing the quantitative and qualitative yield of medicinal plants. In this research, the effects of vermicompost as well as nitrogen and phosphorous fertilizers were investigated on morphological traits such as height of plant and number of nod and quantitative and qualitative functions of peppermint essential oil. A factorial study was conducted as a pot experiment under the field conditions in a completely randomized design with 4 replications in 2017. Vermicompost treatment levels (consumption and non-consumption according to the manufacturer's recommendation) and nitrogen fertilizers and phosphorus (0, 50, 100, and 150 kg ha-1) were added to the  pot soils early at planting stage. The most essential components in the essential oil (more than 70%) were Alphapinene, Limonene, Izomenton, Menthol, 1, 8 Cineol, and Menton. Analysis of variations showed significant effectiveness of the treatments. Comparison of means suggested that the best treatments were application of vermicompost and nitrogen and phosphorus (100 kg. ha-1) that improved the morphological traits such as plant heights and number of nod and also the quality and quantity of essential oils. It seems that vermicompost increased morphological traits and consequently the amount and components of essential oil of the plant.

Apple (Malus × domestica Borkh.) is one of the most economically important crops which is widely used either as fresh fruit or as processed foods. Apple fruit is usually introduced to the markets after a storage period of several months. This makes it important to protect fruits against the post-harvest diseases specially in organic production. Blue mold (Penicillium expansum) is one of these diseases, which due to spreading very fast in storage and producing a carcinogenic compound, called patulin, is of particular importance. In the present study, the impact of methyl jasmonate, abscisic acid, salicylic acid, beta-aminobutyric acid, and carbocyclic acid sprayed was investigated on blue mold. Apple fruits of 10 cultivars were surface sterilized and inoculated with spores of fungus, and then were treated with the plant growth regulators. The fruit firmness, softening rate and lesion decay were evaluated. Data were analyzed in a factorial design with two factors i.e., cultivar and plant growth regulator in a completely randomized design in R software package. The impact of hormones was significant on controlling the blue mold, and three plant growth regulators, methyl jasmonate, salicylic acid, and beta-amino butyric acid had the greatest inhibitory impact on the disease. Carboxylic acid and abscisic acid had contradictory impacts on different cultivars, and did not result in significant impacts in some cultivars. The results of this study can be used in the breeding programs in order to help better understand plant disease mechanisms. They can also be applied as a practical method to control blue mold in apple.