جستجوی مقالات مرتبط با کلیدواژه « free radicals » در نشریات گروه « زراعت »

Abstract
In this research, the effect of humic acid fertigation in two levels (0 and 20 kg.ha-1) and salicylic acid spray in four levels (0, 0.5, 1 and 1.5 mM) on the yield, yield component, and antioxidant activity of garlic was evaluated. Based on obtained results, all salicylic acid treatments caused higher yield in comparison with control significantly, so that treatment of 1 mM salicylic acid elevated the yield more than 2 tons per hectare by comparison with control. Also humic acid led to yield increment of garlic around 5 tons per hectare by comparison with control. The highest weight of garlic was obtained in humic acid + salicylic acid 1 and 1.5 mM treatments which produced 105 and 106.66 g respectively, around 2.5 times more than control. Single treatment of salicylic acid in low and middle concentrations (0.5 and 1 mM), and high concentration of salicylic acid (1.5 mM) alongside with humic acid contributed to antioxidant capacity improvement around 20 percent more than control. Finally, it can be concluded that humic acid 20 kg.ha-1 + salicylic acid 1.5 mM for increasing garlic yield in the open field culture is recommended.
Garlic (Allium sativum L.) is the second most important crop among Allium species. This plant has important medicinal properties such as lowering blood cholesterol, lowering blood pressure, preventing the formation of blood platelet masses, antimicrobial, antifungal, anticancer effects, stimulating the immune system, anti-inflammatory effects, and high antioxidant properties. Many efforts have been made to increase the quantitative and qualitative properties of garlic. Among the effective treatments on plants, the role of humic substances in increasing plant growth and plant biomass has been reported frequently. Although this positive impact can be affected by the concentration, source, plant species, plant age and cultivation conditions, the direct role of humic acid in increasing the photosynthesis rate and plant growth has been well documented. Also, many studies have reported the effect of humic acid on reducing the damage caused by environmental stress, but the exact mechanism of this effect is not yet known. On the other hand, salicylic acid is another substance which is a phenolic compound in plants and acts as a hormone. Salicylic acid plays an important role in regulating plant growth and development. Also, the role of salicylic acid in the absorption of nutrients, membrane stability, water relations, stomatal function, inhibition of ethylene synthesis, and growth enhancement has been reported. Considering the positive role of humic acid and salicylic acid on the performance and physiology of plants, in this work, the simultaneous application of these two substances was investigated in garlic.
This research was carried out in factorial format based on randomized complete block design (RCBD) with two factors and three replications. The first factor was humic acid fertigation in two levels (0 and 20 kg.ha-1) and the second factor was salicylic acid spray in four levels (0, 0.5, 1 and 1.5 mM). Each of the mentioned treatments were applied in four times in May when the bulbs were grown. Evaluated parameters included yield, yield component, and antioxidant activity. Traits related to yield and its components, including yield of the whole plant (edible part with aerial part), weight of single bulb, weight of clove, length and width of clove and number of cloves were calculated at the end of the experiment. Diphenylpicrylhydrazyl stable radical or DPPH was used to measure total antioxidant activity. Total phenol and total flavonoid contents were measured as antioxidant substances and dietary value properties. The comparison of means was done using Duncan's multiple range test at the probability level of one and five percent.
Based on obtained results, all salicylic acid treatments caused higher yield in comparison with control significantly, so that treatment of 1 mM salicylic acid elevated the yield more than 2 tons per hectare by comparison with control. Also, humic acid led to yield increment of garlic around 5 tons per hectare by comparison with control. The highest weight of garlic was obtained in humic acid + salicylic acid 1 and 1.5 mM treatments which produced 105 and 106.66 g respectively, around 2.5 times more than control. Single treatment of salicylic acid in low and middle concentrations (0.5 and 1 mM), and high concentration of salicylic acid (1.5 mM) alongside with humic acid contributed to antioxidant capacity improvement around 20 percent more than control. In general, it can be concluded that the optimal doses of salicylic acid can have a positive effect on photosynthesis and ultimately on growth. Because of its water retention properties, humic acid can help the movement of elements in the soil, increase soil microbial population, release some nutrients, improve soil properties, increase soil organic matter, and can be used to increase crop yield. Because of this, the combination of these two factors (salicylic acid and humic acid) could lay positive effects on different aspects of garlic growth and development. It seems that the increase in antioxidant capacity following the treatment of high concentration of salicylic acid occurs when some substances, including nutritional elements, are also available, and the presence of humic acid can respond to this need.
It can be concluded that humic acid 20 kg.ha-1 + salicylic acid 1.5 mM for increasing garlic yield in the open field cultivation can be recommended. This combined treatment showed a high antioxidant activity as well, so humic acid 20 kg.ha-1 + salicylic acid 1.5 mM was the best treatment both in quantitative and qualitative aspects.

Ocimum basilicum L. (O. basilicum) or sweet basil belongs to the family Lamiaceae which has been used as a medicinal plant and its essential oils are used to flavor foods, in dental and oral products and in fragrances. One of the methods to increase yield and availability of minerals in the soil, with the decreased use of inorganic fertilizers, is to apply biological fertilization, which also affects the essential oil of aromatic plants. Hence, this study was carried out to describe detailed growth and chemical investigation of basil essential oil affected by chemical and biological fertilization.

This study was carried out as factorial based on completely randomized design with three replications. The first factor involved plant (O. basilicum var. Thyrsiflora and O. sanctum.L ) and the second factor was fertilizer types (0%, 50% and 100% of the plant phosphorus requirement, only bacteria, bacteria with 50% of plant phosphorus requirement, bacteria with 100% of plant phosphorus requirement). The pots filled with five kilograms of soil. Phosphorus fertilizer was added to the pots from the triple super phosphate source based on the experimental treatments. Overnight culture of Pseudomonas putida in nutrient broth was prepared and applied under each seed. At full bloom stage, the leaves and inflorescences of each plant were completely separated and their number counted. Extraction of leaf samples was performed using 70% methanol solvent to measure phenolic compounds and the flavon and flavonol content of the extract was read by measuring the absorbance at 425 nm. The amount of phosphorus content of plant leave was also determined.

Shoot dry weight, number and length of inflorescence were significantly (p<0.01) affected by the interaction effect of fertilizers and plant species. The highest shoot dry weight, number and length of inflorescence were recoded with only bacteria without the use of phosphate fertilizer treatment and followed with samples treated with bacterial + 50% chemical fertilizer. The maximum phosphorus concentration in both basilicum and sanctum leaves (4.92 and 4.82 mg g-1 dry weight, respectively) and phenols, flavonoids and flavonoid compounds were obtained in treatments containing only bacteria without using phosphate fertilizer and followed with samples treated with bacterial + 50% chemical fertilizer, as well. The highest percentage inhibition of free radicals was recorded in basilicum and sanctum (67 and 75 percent respectively), in the presence of the bacteria without using phosphorus fertilizer. Applied bacterium in this research improved the quantity and quality of basil, thus to recommend it as a biological fertilizer considering its potential needs to be examined at farm conditions.

According to the results, using biofertilizer in this research reduced the demand for phosphorous fertilizer and improved the quantity and quality of basil; so as a result to recommend it as a biological fertilizer considering its potential needs to be examined at farm conditions.

Chickpea is one of the pulse crops and its protein percent is about 22 to 24 percent. Therefore it plays an important nutritional role in human being diet. All plants, including chickpea, experience physiological changes and decreased growth while facing water deficit. Change in photosynthetic electron transport under low-irrigation conditions is one of the factors causing formation of reactive oxygen species (free radicals) including oxygen peroxide, super oxide and hydroxyl (oxidative stress). These free radicals are mainly produced in chloroplast, mitochondrion, and peroxisomes which could inflict destructive and harmful effects on plant cells. In stressed plants, the endogenous polyamine compounds are increased which is mainly a defensive response of plant to oxidative stress. Polyamines are aliphatic hydrocarbons with low molecular weight, straight chain of 3 to 15 carbons, which arginine and ornithine amino acids are their precursor. There are two major biosynthetic pathways for putrescine including ornithine decarboxylase and arginine decarboxylase. After putrescine synthesis, the larger polyamines (spermidine) are synthesized. This process is catalyzed by spermidine synthase through consecutively adding aminopropyl groups to putrescine. This experiment aimed to study the possibility of decreasing harmful effects of low-irrigation on growth and yield of chickpea through spermidine spraying.

This study was carried out as split plot based on complete blocks design with three replications in research farm of Shahrood University of Technology in 2016 in which the chickpea was sown in June as a secondary planting. The experimental treatments were irrigation regimes (distributed in main plots) in three levels (control (the conventional irrigation; 7-day interval irrigation), 10-day interval irrigation, and 13-day interval irrigation) and spermidine spraying in three levels (control (spraying of water on plant), concentration of 0.3 and 0.6 mM) at 4-leaf, flowering and milky stages. The studied traits were biomass, grain yield, number of pods per plant, grain protein percent, chlorophyll content and activities of catalase and guaiacol peroxidase enzymes.

The results indicated that under 13-day interval irrigation conditions, the activity of guaiacol peroxidase decreased with increasing concentration of spermidine (About 0.07 µM/min.g fw for 0.1 mM increase in spermidine concentration). No significant difference was found between zero (control) and 0.6 mM in terms of catalase enzyme; these spermidine levels appeared to have the highest activity of catalase enzyme. Under 10-day interval irrigation conditions, the catalase activity amount was statistically similar to its activity under control conditions. However, under 13-day interval irrigation conditions, the activity of mentioned enzyme was almost 80% higher than control. The linear decrease of guaiacol peroxidase activity with increasing spermidine concentration under 13-day interval irrigation conditions and also decrease in catalase enzyme activity under spraying plant with 0.3 mM spermidine may confirms the previous reports regarding the capability of polyamine compounds in direct elimination of free radicals and promoting stability and conserving the membrane. The experimental evidences have indicated that the application of exogenous potrisine has increased the polyamines amount in thylakoid membranes; these results have also been repeated by application of exogenous spermidine. Under 13-day interval irrigation conditions, the relative leaf chlorophyll content appeared to be linearly increased with enhancing the spermidine concentration (One Spad value for 0.1 mM increase in spermidine concentration). In each irrigation regimes, the number of pod per plant was proportionally increased with increasing spermidine concentration (Averagely, about one pod per plant for 0.1 mM increase in spermidine concentration). In each irrigation regimes, the biomass and grain yield were proportionally increased with increasing spermidine concentration (For 0.1 mM increase in spermidine concentration, the average increase in biomas and grain yield was about 72 and 31 Kg/ha, respectively), which proves that spermidine alleviates the harmful effects of low-irrigation. The 0.6 mM spermidine could alleviate the harmful impacts of 10- and 13-day irrigation regimes on grain yield by 20% and 34%, respectively. Proportional to spermidine concentration, grain protein content got increased (About one percent for 0.1 mM increase in spermidine concentration). So that for 0.3 and 0.6 mM spermidine concentrations, the grain protein content was higher than control by 3% and 6%, respectively.

The results indicated that imposing low-irrigation stress affected all measured traits. The application of spermidine polyamine at three stages of 4-loaf, flowering and milky stages caused some changes in activity of antioxidant enzymes catalase and guaiacol peroxidase. These changes took place along with increasing chlorophyll content and number of pod per plant (decreasing flower abortion and enhancing fertile flowers). The changes in the mentioned traits were some of the reasons for spermidine-resulted alleviating the negative effects of low-irrigation on growth and grain yield of chickpea. The 0.6 mM spermidine was found to be the best treatment level for both drought stress and no drought stress conditions.

Saffron is one of the most valuable food and medicine products that has a high economic importance in Iran and other countries. Harmful environmental factors prohibit the human body from collating the free radicals that are produced during breathing resulting in problems such as premature aging, atherosclerosis and cancer. There has been only a few reported research studies on the antioxidant properties of Saffron petals in world. This research was carried out in order to survey the antioxidant compound that may be extracted from Saffron petals and indicate the total phenol content (TPC) and total flavonoid content (TFC) in the cultivated Saffron farms of the Lorestan province. After specifying the Saffron farms by the Random systematic method, the compound sampling was carried out (Saffron petals amount 2 kg). Then, the antioxidant activity, total amount of phenols and flavonoids in the extracts were measured by methods of DPPH, Folinciocalteau and Colorimetric assay, respectively. The results showed that the amount of IC50 was the lowest and highestin Noorabad and Vician farms with amounts of 1.66 and 156.4μg/ml, respectively by the Duncan test. The results of mean comparison showed that the total phenol content and total flavonoid content of 1098.8 mg Gallic acid/g extract and 41.39 mg cou/g extract, respectively that belonged to the Noorabad and the Chaghalvandi farms had the highest amounts among all of the saffron cultivation in the farms.