فصلنامه گیاه و زیست بوم
پیاپی 49 (زمستان 1395)

Hesare Hosseini-Asadli region, with an area of 26,345 hectares, is located 20 km away from the south of Bojnourd (North Khorasan province). The altitude of the area ranges from 1280 to 3010 m from the sea level. The average annual rainfall and temperature are 385.7 mm 8.9 C, respectively. This study aims at introducing the flora, life forms, and endangered species in this region. On the basis of the results, 56 families, 243 genera, and 408 plant species were identified. The most important families were Compositae and Poaceae with 52 and 47 species, respectively. Hemicryptophyte, with 152 species, is the most frequent life form in the region. The distribution of the 264 species (with 64.70%) belonged to Irano-Turanian region. Of the plants in the region, 47 species were endemic of Iran. Furthermore, according to the criteria of IUCN, 60 vulnerable plant species, species at a lower risk, and those about which a solid database does not exist were identified in the region.

The recognition and analysis of the characteristics of the natural environment in any region is one of the fundamental steps in studying the natural ecosystems. Therefore, the vegetation and its relationship to soil properties is one of the significant elements of natural ecosystems which plays an important role in plant distribution. The study of the life forms and the geographical distribution of plants is also very important as it significantly contributes to the identification of the rare, medicinal, and characteristics plants of the region. This study aims mainly at identifying the characteristic species, chorotype, life form, and plant application and durability by means of Whittaker plot sampling in seven regions (7 hectares) in the North East of Iran. Plant species were identified using various Flora, and the physical and chemical properties of soil were determined after collecting soil samples from a depth of 0 to 30 cm. A total of 121 species belonging to 38 families and 161 genera were identified. Therophyte life form (with about 73%) was dominant. Station 3 showed the lowest pH (6.5). The highest amount of EC belonged to Frizi station. The highest Potassium and Sodium rates belonged to stations 6 and 2, respectively. Stations 6 and 4 had the highest microbial respiration. The maximum amount of organic carbon and total nitrogen belonged to these two stations.

Drought and population growth are the main reasons behind the degredation of natural resources (renglands, forests, & wetlands) and the deflation of water resources. This study was conducted to investigate the effect of recent droughts on reducing the level and changing the use of the lands surrounding Maharlou Lake (in Fars Province) by means of satellite images. For change detection, three Landsat images (belonging to 1987, 2000, & 2009) were used and geometric and atmospheric corrections were applied. Landuse maps were developed for each of the three years using fazzy classification. On the basis of the results, the overall accuracy and Kappa coefficient for all of the maps were more than 83% and 0.78%, respectively. For monitoring the changes, post-classification comparison method was used. The results indicated that rangeland areas, the water level of the lake, and the level of the farmlands had decreased. The area of residential and industrial lands along with the barelands, however, had increased. Monitoring the changes in the three aformentioned periods (during 9, 13, & 22 years) demonestrated that natural resources degradation has been more intense during the recent period (2000-2009). Therfore, to prevent a complete land degradation in the study area, management strategies should be employed.

In an attempt to analyze and compare the density measurement methods, a study site with four replications was selected in the rangelands with Artemisia sieberi-coligonum persicum¬ as the dominant plant species in Mazhanabad of Khaf. In each rangeland site (with an area of 5000 m2 & a dimension of 50×100 m), the real density was calculated by counting all caligonum base species. Samples were taken from each rangeland site following a random-systematic design. Four 100-meter transects were established in each replication. Considering the required sample size for each method, some points were randomly selected and the density measurement methods (i.e., Quarter Methods, Closest Individual Method, Nearest Neighbor Method, Random Pairs Method, Point Centered Quarter Method, & Ordinal Methods including the second & third closest individual) were implemented. The difference between the density measurement methods and the control (base counting) method was analyzed by LSD method. According to the results, the closest estimation to the control belonged to Point Centered Quarter Method¬. Quarter Method showed a significant difference to the control. Point Centered Quarter Method was the most accurate while Random Pairs and Nearest Neighbor Methods were the least accurate.

This experiment explored the impact of seasonal changes on the activity of photosynthetic pigments (i.e., Chlorophyll a, Chlorophyll b, & Carotenoids) and proline on Haloduleuninervis sea grass. The results indicated a decrease in Chlorophyll a during the spring and summer and a decrease in Chlorophyll b and Caroteniods during the fall and winter. Furthermore, proline measurement revealed that its amount in root was less than leaf and that the maximum amount of proline in leaf and root belonged to the spring and summer. The ANOVA results showed a significant difference at p

Air pollution may be natural or synthetic. Synthetic air pollution mainly comes from the vehicles and factories. Using data from Environmental Protection Organization and Air Quality Control Agency, Azadi and Pounak were selected as polluted and clean regions, respectively. The leaves of two plant species i.e., Nerium oleander and Cupressus arizonica, planted in street sides of the polluted and clean regions of Tehran were collected and the activity of antioxidant enzymes catalase, peroxidase, and ascorbate peroxidase was measured. The results showed that air pollution increased the activity of catalase and peroxidase in the polluted area. The ascorbate peroxidase activity decreased in the polluted area in comparison to the clean one.

In this study, three species of algae Chara L. (i.e., Ch.vulgaris, Ch.contraria, & Ch.fragilis) were identified in different suburb areas of Mashhad and were used as natural insecticides to kill Tribolium castaneum and Drosophila melanogaster insects. To investigate the insecticidal properties of the identified species, the alcoholic extract, dried powder, and aqueous extracts of the algae were used. The average mortality rate of the adult insects in the treatment and control groups was counted using the three-factor variance analysis (Univariate), Duncan test of mean pairs comparison, and the bar charts. Based on the obtained results and the impact of Chara algae on the mortality of Tribolium castaneum and Drosophila melanogaster insects, Chara algae can be introduced as a natural insecticide.

Although copper is an essential element for cell-based processes, in high concentrations, it is toxic for plants. Hydrogen sulfide is one of the most important signaling molecules that is involved in many processes of plant stress resistance. In order to investigate the effect of Sodium hydrosulfide pretreatment on mitigating copper damages in soybean, a factorial experiment in a completely randomized design with three replications was conducted in the research laboratory of Kerman University of Shahid Bahonar in 2015. The experiment included two factors: the use of Sodium hydrosulfide (i.e., the presence or absence of sodium hydrosulfide) and different concentrations of CuSO4 (i.e., 0, 100, & 200 μM). The results showed that an increase in copper concentration in the nutrient solution reduced the fresh weight and Chlorophyll content and increased MDA, proline, and hydrogen peroxide in soybean plants. The pretreatment of plants with Sodium hydrosulfide caused an increase in the fresh weight, the amount of Chlorophyll, soluble sugar, and the reduced glutathione and a decrease in the amount of MDA, hydrogen peroxide, and proline in soybean. Probably, hydrogen sulfide protects the plant against the oxidative damage caused by the toxicity of copper by connecting to other signaling molecules such as nitric oxide.

Through obtaining the information necessary for fruit storage, high quality fruits can be offered to the domestic market for a longer time period. This study was carried out following a completely randomized design (CRD) with three replications (20 fruits for each) and several observations. Research treatments included: various concentrations of calcium chloride (0, 250, & 500 ppm) and storage conditions (cold storage 4±2 C & warehouse conventional 15±2 C). After the harvest and washing processes, the fruits were subjected to treatments for two minutes and the treated fruits were kept in conventional and cold storage for 20 days. The percentage of fruit weight loss, firmness, astringency, and calcium was analyzed. The results indicated that the highest degree of firmness and calcium and the lowest percentages of weight loss and astringency belonged to the fruits which were immersed in calcium chloride at a concentration of 500 ppm and were kept in cold storage.