فصلنامه زیست شناسی گیاهی ایران
سال دهم شماره 3 (پیاپی 37، پاییز 1397)

The survey of the ecological and morphological characteristics of medicinal plants is one of the essential requirements for multipurpose use of rangelands. Accordingly, the ecological and morphological characteristics of Ephedra procera were investigated in the mountain rangelands of Urmia. For this end, regarding to the physical and vegetation characteristics; three habitats representing a wide range of areas of E. procera distribution region were selected. Then, the data inventory was conducted within 30 two square meters plots established on transects along 100-meter with distances of 10 meters apart and the morphological characteristics and amount of forage production were measured. To study the relation between distribution of vegetation and soil characteristics, soil samples were taken with three replications along transects. The results showed that the morphological characteristics of Ephedra and soil physical and chemical properties in study sites; are significantly different among the sites. Analysis of variance linear regression equation between forage production of Ephedra with morphological characteristics indicates a significant relationship between forage production and number of plant shoots. The results of studying the relationships vegetation distribution with environmental factors showed that the influence of environmental variables on vegetation is significant which accordingly the factors such as slope, temperature, aspect, porosity, sand, elevation from sea level, percent of gravel, bulk density and electrical conductivity are of the most important factors affecting the distribution of Ephedra species. The results can be used in planning the protection and restoration practices of Ephedra in natural habitats.

In order to study the effects of nano iron oxide on yield, chlorophyll fluorescence indices and some physiological traits of wheat (Triticum aestivum L.) under rain fed and supplementary irrigation conditions, a factorial experiment was conducted based on randomized complete block design with three replications in Agricultural Research Station of Ardabil in 2016. Factors experiment were included irrigation levels (no irrigation as rain fed, supplementary irrigation at heading and booting stages), foliar application nano iron oxide in four levels (without nano iron oxide as control, application of 0.3, 0.6 and 0.9 g L -1 ). Means comparison showed that 0.9 g L -1 nano iron oxide application and supplementary irrigation at booting stage increased maximum fluorescence (F m ), variable fluorescence (F v ), chlorophyll content, nitrogen percentage, relative water content and grain yield compared to non-application of nano iron oxide under rain fed condition. Rain fed condition increased minimum fluorescence (F 0 ) and electrical conductivity. Foliar application of 0.9 g L -1 nano iron oxide and supplementary irrigation at booting stage increased grain yield 38.43% compared to no foliar application under rain fed condition.

Seed priming often promotes germination and seedling growth under environmental stresses yet as main negative aspect, primed seeds are vulnerable to aging process. In this regard, the current study was carried out to examine the influence of priming treatments (with water and ascorbic acid) on germination of smooth vetch (Vicia dasycarpa) seeds under osmotic stress (-0.9 MPa). In addition, we examined whether or not post priming heat shock treatment may maintain this possible advantage by reducing primed seeds deterioration during artificial aging. Treatments included: hydro priming, hydro priming plus heat shock, priming with ascorbic acid, priming with ascorbic acid plus heat shock, control or non-primed seeds. Primed seeds after partial drying faced heat shock at 40 0 C for 3h. Following heat shock treatment seeds were exposed to accelerated aging for 0, 2, 4, 6 and 8 days. Priming particularly with ascorbic acid substantially increased germination under osmotic stress. Heat shock treatment significantly improved germination ability of both aged-primed seeds with water and ascorbic acid. The difference between HS treated and non-HS treated primed seeds were more considerable following longer terms (6, 8 days) of artificial aging. The results showed that the restoring effect of heat shock was accompanied with lower lipid peroxidation (assayed as malondialdehyde content), electrolyte leakage and enhanced antioxidant activities including catalase, peroxidase and ascorbate peroxidase.

The most important abiotic stresses is salinity and more importantly affect plant growth and limit the plants yield capacity. Silicon is the second most abundant element in the soil and alleviates the biotic and abiotic stresses in plants. The aim of this study is to assess the effects of salt stress and silicon on the some morphological and phytochemical characteristics of purple coneflower (Echinacea purpurea L.). This study was conducted in completely randomized based factorial design with 4 levels of salinty and 4 levels of silicon and 4 replications. Application of stress in hydroponic culture medium (perlite and cocopeat) with Hoagland nutrition solution. The result showed, salinity significantly affected morphophysiological and phytochemical characteristics and silicon affected all characteristics except leaf burn percent. Also, the interactions of these two factors on each trait except shoot wet and dry weight and leaf burn percentage were significant So that the negative effects of salinity stress on growth, morpho-physiological and phytochemical traits of the plant were greatly reduced by silicon and improved the growth and increase of yield. Also, the interaction of these two factors on all traits except the wet and dry weight and leaf burn were affected and the negative effect of salinity stress, especially in the least to medium levels, on growth and morphology, and phytochemical characteristics of the plant were decreased and improved growth. So that the best salinity level in increasing biochemical factors, 25 mM NaCl and the best level for silicon, was 2.25 mM in reducing the negative effects of salinity stress.

An experiment trial run to determine the allelopathic effects of apricot leaves on corn, bean, rye and pigweed. This experiment was done with apricot aqueous leaf extract (75% w/v) and leaf powder (3% w/w) treatments and control (without any treats with leaf extract and powder and irrigated with distilled water) during seedling stage. This experiment was carried out as a factorial experiment in complete randomized design with 3 replicates. According to the results, the lowest and the highest loss percentage of shoot and root dry weight, and stem and root length was observed in corn and pigweed under the treats of apricot leaf extract and powder. Electrolyte leakage increased significantly in bean under leaf extract and powder treats and in rye treated with extract compared to control. Both treats of apricot leaf decreased the content of chlorophyll a and b in bean and pigweed, although these pigments increased in corn and rye under mentioned treatments. Increased soluble sugars of bean and corn under leaf aqueous extract and powder and of rye and pigweed under leaf aqueous extract were significantly more than control. However, treatment with aqueous extract increased proline content in all studied plants, but the content of this amino acid increased only in the bean treated with apricot extract powder. A little changes of superoxide dismutase activity were not significant in corn, bean, rye and pigweed treated with aqueous extract and powder compared to the control.

Potassium has a main effect on plants salinity tolerance through its effect on cells osmoregulation, and the maintenance of cell turgor. The objective of the present study was to investigate the effect of foliar nutrition of potassium sulfate (PS; 0 and 1.5%) on some morphometric and physiological traits of Bidaneh-Sefid grapevine under salinity condition of NaCl (0, 25, 50 and 100 Mm). This experiment was carried out factorially based on completely randomized design in a greenhouse condition. The result showed that salinity decreased plant height, leaves number, leaves area and re-growth, but foliar application of potassium mitigated the negative impacts of salinity on these morphometric indices. Also, application of 1.5% potassium resulted in the stability of photosynthetic pigments compared to non-treated plants under salinity stress. With increasing salinity, the amount of ion leakage increased until salinity of 100 mM without PS treatment and reached to its highest level (64.2%). While 1.5% PS treatment decreased leaf ion leakage significantly (P≤ 0.01) in treated vines in compared to other untreated plants. Unlike insoluble sugar, the content of soluble sugar and proline as two osmoregulant has shown an increasing trend in the response to salinity and the application of potassium and reached to highest in 100 Mm NaCl and 1.5% PS treatments. Also, the PS foliar application use of sulfate-potassium leaf with increasing potassium concentration and then cell Na+ /K+ adjusting, increased the leaf N, K, Mg and Ca concentration in compared to non- PS sprayed plants.