Medicinal Plants
S. Sadeqifard; M. Azizi; S. Karimi Zinkanlu
Abstract
IntroductionGrowth regulators play a vital role in developmental stages of plants and their use can be improved the yield of crops. One of the most important compounds that used as growth regulators in recent years is salicylic acid. The application of salicylic acid in the activation of systemic acquired ...
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IntroductionGrowth regulators play a vital role in developmental stages of plants and their use can be improved the yield of crops. One of the most important compounds that used as growth regulators in recent years is salicylic acid. The application of salicylic acid in the activation of systemic acquired resistance, and metabolite synthesis and antioxidant enzymes has been proved. Also, salicylic acid as a natural compound has potential to prevent ethylene production and its effect. In order to evaluate the effect of salicylic acid in different concentration on yield and oils content of Ziziphora, a split plot experiment with three replications during 2014-2015 in the field of Agricultural Faculty of Shirvan and Ferdowsi University of Mashhad laboratories was conducted. Materials and MethodsThis research was conducted during 2014-2015 under field conditions in a split plot design in time, at Shirvan Agricultural Research Station (latitude 40 º / 37, longitude 93 º / 57 and with a height of 1097 m above sea level) and in laboratory Department of Horticultural Sciences, Ferdowsi University of Mashhad. Each plot had an area of 4 square meters in furrow planting way which the distance between rows were 50 cm and on rows 15 cm and were carried out on 25 March 2014. Irrigation was carried out immediately after planting, and a second irrigation was done 20 days later, once the seeds had germinated. Irrigation and weed control are also done manually once a week. Salicylic acid (Sigma Aldrich, 99.5%) in the three phases of plant growth (The onset of vegetative growth, throughout vegetative growth, and at the flowering stage), at concentrations (0, 10-2, 10-4 and 10-6 M) in three repeats were sprayed. The first spraying (The onset of vegetative growth) was done on April 3, 2014, the second spraying (throughout vegetative growth) on May 4, and the third (at the flowering stage) in early June 2014. The plants were harvested on July 20. To measure the dry weight of the plants, the samples were dried in the shade for a week. Essential oil content was determined using a 30-gram dry sample in 500 ml of water through hydro-distillation with a Clevenger apparatus for 4 hours. For biochemical characteristics first samples extract were obtained. To prepare extracts, dry samples were milled then one gram of each sample was transferred to the 50 ml Erlen and 10 ml of 80% methanol was added and shaken for 24 hours. After 24 hours the extract was filtered using filter paper then used for measuring phenols, flavonoids and antioxidant activity. Phenol measurement: phenolic content was measured using the Folin reagent. In 5.0 mL of each extract (10 milligrams per ml) 5.2 ml Folin reagent was added. After five minutes, 300 ml of a molar sodium carbonate solution is added and maintained in a 40 °C bath for 30 minutes. The sample absorbance at 760 nm was measured by a spectrophotometer against the blank. Gallic acid was used as the standard for calibration curve. Flavonoids measurement: Flavonoid content of the samples were measured using aluminum chloride reagent. In 5.0 ml of methanol extract (10 milligrams per ml), 5.1 ml of methanol, 1.0 ml of 10% aluminum chloride, 1.0 ml of a molar potassium acetate and 8.2 ml of distilled water was added. The mixture kept in dark for 30 minutes and absorbance at a wavelength of 415 nm was read against the blank. Quercetin was used as the standard for calibration curve evaluation. JMP statistical software was used to analyze the data. Results and DiscussionBased on the results, the application of salicylic acid significantly affected fresh and dry weight, plant height, and phenol and flavonoid content (P < 0.01), but had no significant effect on essential oil percentage or yield. The highest fresh weight (264.763 grams per square meter) and dry weight (93.11 grams per square meter) were obtained with the application of 10⁻² molar salicylic acid during vegetative growth, while the lowest fresh and dry herb yields were observed in the control group. Maximum height of plants (29.01 cm) was related to 10-2 M salicylic acid during vegetative growth and the lowest of plant height (23/24 cm) was related to control treatment at the time of flowering. The highest amount of phenols (0.504 mg equivalents gallic acid per gram of dry weight) was detected in plants treated with 10-2 M salicylic acid during vegetative growth and the lowest phenols (0.248 mg equivalents gallic acid per gram of dry weight) was reported in 10-2M salicylic acid and during vegetative growth. The highest amount of flavonoids (0.31 mg equivalent Quercetin per gram of dry weight) was obtained in 10-4 M salicylic acid treatments during vegetative growth and the lowest of them (0.176 mg equivalent Quercetin per gram of dry weight) was in 10-6 M salicylic acid treatment at the beginning of vegetative growth. ConclusionsIn conclusion the results showed that the highest amount of fresh and dry weight and plant height was under the conditions of 10-2 M salicylic acid concentration and during vegetative growth and the best yield of essential oils, phenols and flavonoids in during vegetative growth and 10-4M salicylic acid concentration was obtained.
