فصلنامه زیست شناسی گیاهی ایران
سال نهم شماره 2 (پیاپی 32، تابستان 1396)

In order to evaluate the effect of Piriformospora indica fungi inoculation on some physiological parameters of peppermint medicinal plant under salt stresses, a field experiment was arranged in a factorial experiment based on completely randomized design with three replications. Treatments including P.indica symbiosis and four salinity levels (irrigation with distilled water and the Caspian Sea water mixture at of 0, 3, 6 and 9 dS m-1). The measured parameters were leaf dry weight, leaf total phenolics, flavonoids, anthocyanins, radical scavenging, essential oil yield and the content of Na, P and K and stomatal conductance. Results showed that with increasing of salinity, the anthocyanins, flavonoids and Na content were increased, while P and K content, leaf dry weight and essential oil yield were decreased. The symbiotic fungi increased anthocyanins and flavonoids content by 17 and 31%, respectively as compared to the uninoculated control plants. Fungal treatment, reduced the negative effects of salinity on stomatal conductance, P and K content, leaf dry weight, essential oil yield and also decreased Na content in saline conditions. In 9 dS m-1 of salinity, fungi inoculation could increase total phenol content and essential oil yield up to 37 and 76%, respectively. It seems, the root inoculation of the peppermint medicinal plants with P. indica, stimulates the synthesis of phenolic compounds and essential oils, also increases the nutrient uptake which ameliorate the negative effects of salinity in the plant.

Salicylic acid (SA) is one of the important signal molecules, which modulates plant responses to environmental stress. In the present work, impact of exogenous SA on some physiological and biochemical traits of Hibiscus sabdariffa in response to drought stress was studied. Hibiscus sabdariffa seedlings were exposed to six drought levels (0, -0.05, -0.1, -0.5, -0.75, and 1 MPa) with two SA concentrations (0 and 500 µM) in 5 days intervals up to 20 days in a factorial design. During drought stress period, the root and shoot growth, relative water content, pigments content, non-reducing sugar and starch content was significantly decreased. SA treatment cause prevention of the growth reduction and improvement of relative water content. Protein concentration was roughly unchanged during drought stress with SA, while, reducing sugars accumulates and non-reducing sugars and starch significantly decreases. The results show that exogenous SA application on leaves during drought stress can ameliorate detrimental effects of stress through reducing water loss and accumulating reducing sugars, which cause preserving turgor pressure of the cells.

Salicylic acid is an antioxidant which has been used in recent years to increases the resistance of plants to deal with stresses. In this study different concentrations (0.1, 1.5, 3, 6 and 9 mM) of salicylic acid were investigated on the quantity of fresh and dry weight, chlorophyll, carotenoid, malon di aldehyde, flavonoids, rutin and quercetin in pepper (Capsicum annuum). After 5 weeks, plants were treated with different concentrations (zero, 0.1, 1.5, 3, 6 and 9 mM) of salicylic acid. The results showed that concentrations of 0.7, 1.5 and 3 mM of SA increased fresh and dry weight, chlorophyll a, b, total and carotenoid content, but concentrations 6 and 9 mM of SA decreased fresh and dry weight, chlorophyll a, b, total and carotenoid content. Concentrations of 1.5 and 3 mM of SA decreased malon dialdehyd and other aldehyde content, but concentrations 6 and 9 mM of SA increased malon dialdehyd and other aldehyde content. Concentrations of 0.1, 0.7, 1.5 and 3 mM SA caused significant increase in total flavonoids in treated leaf. The results showed that under our experimental conditions different concentrations (0.7, 1.5 and 3mM) of salicylic acid increased rutin and quercetin content. In general, according to the results, treatment of salicylic acid in low concentrations has positive effects and high concentrations has negative effects on the growth of the pepper plant.

Soybean (Glycin max L.) is one of the most important oily seeds in the world. This plant is rich in protein and unsaturated fats, and plays a significant role in human health with phenolic compounds and flavonoids. Indole Butyric Acid (IBA) is a plant growth regulator that plays a key role in producing phenolic compounds and increasing the antioxidant capacity of the plant. Thiamine is one of the important vitamins in strengthening the immune system and increasing the resistance to environmental stresses in the plant's growth stages. Regarding the effect of hormone auxin and thiamine on the production of phenolic compounds as one of the antioxidant compounds in growth stages, the aim of this study was to investigate the effect of the two compounds in two stages of soybean growth and compare their effect on phenolic compounds changes in order to Detecting higher antioxidant capacity in environmental stress tolerance. For this purpose, the DPX cultivar of soybean seeds were prepared from Dezful Agriculture Research Center and planted in perlite containing flowers. The plants were planted under factorial design under IBA treatments with three concentrations of 0, 10 and 50 and thiamine with three concentrations of 0, 50 and 200. Extraction and evaluation of phenolic compounds, anthocyanins and pigments in leaves were performed. Data were analyzed using Duncan's test at a significant level of 5%. The results showed that the combined use of auxin and thiamine increased the carotenoid content in both phases and caused a significant increase in phenolic content. Application of auxin alone reduced auxin and thiamine the anthocyanin content significantly in both phases, but did not have a significant effect on phenolic content. The results showed that the PAL activity of the phenolic and anthocyanin content increased significantly in the 9-leaf stage compared to 3-leaf. Generally, the results showed that interaction effect between auxin and thiamine on phenolic compounds in different stages of vegetative growth significantly improved and increased plant defense.

Floristic study of a region is of great importance as the list of plants represents the genetic resources of the area. The intended region (Jozak-Chaminbid) with an area of ca. 3637.81 ha. is located in the western part of North Khorassan Province in the Maneh and Semelghan counties. Phytogeographically, this region is located in Khorassan-Kopet Dagh floristic province of the Irano-Turanian region. The mean altitude is 1415 meter and mean annual precipitation of the area is 559 mm. The plant species of the area were collected and identified according to the Floras. The floristic list of the area and its life forms and endemic species were presented. The results showed the presence of 53 families, 205 genera and 308 species. Among them 13 species were endemic to Khorassan-Kopet Dagh Province. The largest plant family was Asteraceae with 28 genera and 40 species. According to Raunkiaer’s life form categories, the identified species are categorized as hemicryptophytes 35.38%, therophytes 34.74%, cryptophytes (geophytes) 12.33%, chamaephytes 11.03% and phanerophytes 6.49%. The high percentage of hemicryptophytes indicated that the area had a cold mountain climate. The chorotype of species was obtained on the basis of the available sources. Irano-Turanian plants were the most frequent chorotype of the area with 59%.