فهرست مطالب hajar nemati

Salinity is one of the abiotic stresses that has a major role in limiting the development and cultivation of plants in the green space. One of the most sensitive periods in life cycle of plants is the stage of germination and establishment of the plant in the soil. The application of priming has been effective in improving the germination of many plants. The present study was conducted with the aim of investigating the effect of priming on the germination of the periwinkle seeds under salt stress. The experiment was conducted based on a factorial in a completely randomized design with three replications. The factors include four salinity levels using sodium chloride (0, 4, 8 and 12 dS/m) and five priming levels (potassium nitrate 100 and 200 mg/l and ascorbic acid 100 and 200 mg/l and distilled water). The results showed that salinity reduced all investigated traits, but seed priming was effective in modulating the effect of stress at all salinity levels. Potassium nitrate priming was more effective than ascorbic acid. In treatment without salt stress, the application of priming in some levels, parameters such as seedling length, seedling fresh and dry weight, tissue water content increased compared to the control. According to the results obtained from this experiment, it is suggested that more research be done to reach the appropriate level of potassium nitrate priming for germination of periwinkle plant under salinity stress.

(Festuca ovina) is one of the most important and palatable rangeland species in the rangelands of Mazandaran province and has a wide range of distribution in mountain rangelands that, in addition to nutritional value for livestock, plays a role in the breeding and rehabilitation program of mountain rangelands. Due to the importance of this species, several populations of F. ovina species, whose seeds were collected from different rangelands of the province, were planted in plastic trays. After germination and a short period of operation, in early spring, in the area of Poshtkuh research station in the southeastern heights of Sari, they were planted on two 20-meter-long lines so that 40 bases of each accession were placed on the planting line. Their spacing on rows of 50 m and line spacing of 1 m were considered. The experiment was conducted during 2011-2015. The evaluation began in the spring of 2013. Evaluation criteria for plant selection were phenological stages, plant height at the time of cluster emergence, canopy level, forage production, and seed production. Various phenological stages, including vegetative stage, flowering, seed formation, and fall regrowth, were recorded with weekly reference from the bases that have been nailed for this purpose. The obtained data were statistically analyzed in SPSS16. The results of the combined analysis of variance of the data related to the performance of the evaluated factors showed that there is a significant difference at the level of (p≤0.01) between the six populations of the studied species. The highest amount of canopy cover, plant height, viability, seed production, and forage production is related to the population of Siahsang rangeland, and the lowest values of the mentioned factors are related to the populations of Kangeloo and Doona rangelands. Therefore, to produce and strengthen forage vegetation, the seeds of this population can be used in the mountain rangelands of the central regions of Mazandaran province.

In the program of increasing forage production, it is necessary to collect information about the establishment of forage plants. In this regard, the native population's seeds of sainfoin (Onobrychis altissima.) were collected to study different rangeland cultivation methods from the rangeland areas of Baladeh Noor watershed in Mazandaran province in 2013 and at the research station of Poshtkooh with an average 320 mm of rainfall in a cold semi-arid climate. The cultivation were in two forms: seeding and seed scattering treatments, which were performed on spring and fall sowing in the form of split plots based on the randomized complete block design in three replications. The main treatment of the experiment was date of rangeland cultivation and the sub-plot was (seeding and seed scattering). Factors studied included plant height, canopy cover, seed production, plant production, and establishment percentage. The results show a significant difference between sowing and in spring and fall for the studied factors (plant height, canopy, production, seed and species production. Seeding method in fall had the highest values of the studied factors. Therefore, it is possible to improve the rangelands of similar climatic zones with sainfoin by sowing to increase forage production and direct grazing.

Determining the preference value of rangeland species by grazing livestock is one of the factors in rangeland management. In this study, the preference value of rangeland plants of Polour site in mountainous rangelands of Mazandaran in the months of grazing season (July to September) and different years (2007-2010) was investigated. The species selection index was used to determine the preference value of species. Species Production and consumption inside and outside the exclosure in the months of the grazing season and for four years were collected to calculate the species selection index. Duncan's multiple range test was applied to compare the means of traits. The results show that the species preference index, as well as the species preference index in different months of the grazing season, was significantly different at (p<0.01) Elymus hispidus var hispidus, Arenaria gypsophiloides, Bromus tomentellus, Dactylis glomerata, Festuca ovina, Taraxacum montanum, Tragopogon graminifolius, Falcaria vulgaris were classified in palatable class I. Astragalus aegobromus and Ferula galbaniflua were in palatable class II. Dianthus orientalis, Stipa hohenackeriana, Papaver bracteatum, Thymus pubescens, Verbascum Thapsus, Gagea lutea, Goebelia alopecuroides, and Euphorbia helioscopia were classified in palatable class III. Therefore, in the study of preference value, in addition to the taste of the studied livestock, factors such as the amount of production and the percentage of available plants, the distribution, and the amount of livestock access to them play a role in this area.

Allowable use is one of the most important factors in determining grazing capacity. The present study was carried out to determine the allowable use of Salsola laricina in Khoshkerood site of Saveh. In this research, four treatments including 25%, 50%, 75% harvesting and no harvesting (control) were compared during three years. The results showed that the effect of the year and interaction of different harvesting intensities and year were statistically significant at the level of one percent. In the first year of study, there was no significant difference among treatments; however, in the subsequent years, the effects of treatments were visible. So that the treatments had the most impact on the speciesin the last year. It was clear that there was not significant difference between the 25% harvesting intensity and control treatment. These treatments had the most forage production and also, there was not a significant difference between the other two treatments. The observations showed that the vitality of species in control treatment was less than that of 25% and 50% harvesting intensities, indicating that grazing can increase the plants vitality. Based on the AMMI analysis, the first interaction principal component (IPC1) was significant at the level of 1%, so that 98.2% of the sum of squares of the interaction could be expressed by IPC1. According to the biplot of the IPC1 and mean production, the lowest production rate and stability was recorded for the harvesting intensity of 75%. According to the results, it can be stated thataharvesting intensity of 25% guarantees the survival of S.laricinain this region with no negative effect on the vitality of Salsola laricina.