جستجوی مقالات مرتبط با کلیدواژه « بنیه بذر » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

The milkweed shrub, in addition to ecological functions, has special industrial and medicinal values. This plant is widely planted for afforestation in arid lands in the south of Iran. Regard to scarcity of fresh water, using of seawater as a vital and alternative source of water for irrigating of halophyte plants was suggested. Thus, the current research was carried out to investigate the efficiency of diluted seawater on seed germination, growth and physiology parameters of milkweed seedling. For this purpose, an experiment was conducted in completely randomized design with three replications in two separate experiments; in vitro and nursery, with different levels of diluted seawater i.e. 0, 12.5, 25 and 50% using saline meter. The results of seed germination test showed that germination parameters and seed vigor index significantly decreased by increasing seawater concentration to more than 12.5%. The results of nursery experiment revealed that concentrations of more than 25% of seawater significantly reduced growth performance and gas exchange of seedling. The survival rate 55%, height 19.9 cm, specific leaf area 190.7 g/cm2 and root length 22.54 cm as well as photosynthesis rate 2.83 µmol, transpiration rate 0.42 mmol, chlorophyll 20.45% and relative water content 43.95% were observed in 25% seawater treatments. It is recommended that researchers conduct a broader study of the salinity-tolerant physiology of this valuable medicinal plant to obtain more comprehensive information for afforestation programs.

Seed germination indices can be affected by drought stress in ripening stage of seeds on mother plant. In this study, four water stress treatments (100, 75, 50 and 25% of field capacity (FC)) were imposed during seed maturation of Satureja hortensis, and subsequently the effects of treatment on seed germination characteristics of S. hortensis were evaluated using a completely randomized design with four replications. The number of germinated seeds was counted each day and sampled after ten days. Then, percentage,rate of germination, vigor, mean daily germination, final germination percentage, daily germination speed, germination index and length of shoot and root were determined. The results indicated that the drought stress had a significant (P

Poa genus has important role for livestock grazing and forage production. To evaluate the effects of both drought and cold treatments on seed germination and seedling growth, 6 genotypes of Poa pratensis and Poa trivialis were examined in laboratory and greenhouse using a factorial experiment based on completely randomized design in three replications. Drought levels (0, -0.3, -0.6, -0.9 and -1.2 MPa), made by PEG 6000 solution, were related to the germinator experiment. For green house experiment, five drought levels of 20, 40, 60, 80, 100% field capacity (FC) were made by weighting of wet and dried soil. Data were collected and analyzed for seed germination percent, speed of germination, root/shoot length ratio, seedling length, vigor index and seedling weight. Results showed significant differences between drought treatments, species, genotypes within species and interaction effects between drought and species for most of traits. No seeds were germinated in -0.9, -1.2Mpa, indicating low to moderate resistance of two species to drought stress. Seed germination traits were decreased by increasing drought stress. In contrast, the shoot/root length ratios (R/S) and dry/fresh seedling weight ratio (D/F) were increased. For -0.3MPa stress, the means of seed germination percent, root and shoot length were 11, 10 and 16% lower than those for control, respectively. In greenhouse, for 20% FC, the average values of root and shoot lengths were decreased by 34 and 23% than those for control. The R/S values were increased to maximum values by increasing drought stress. Therefore, it was suggested as a good indicator for screening of drought resistant genotypes. In comparison between control and cold pre treatment (4°C), results showed significant effects of cold treatments for some of seed germination characteristics in laboratory. It was concluded that genotype Astaneh (24066), belonging to Poa pratensis, had higher values for most of seed characteristics and vigor index than those for other five genotypes in both environments and it was recognized as superior genotype for breeding improved varieties.

Ammoniacum is a medicinal, industrial and forage plants of Apiaceae that has been destroyed due to excessive utilizations. Ammoniacum seeds have a little germination due to seed dormancy. In order to break seed dormancy an experiment with 22 treatments in a completely randomized design with four replications in seed technology laboratories of Birjand University Agricultural Research was carried out. Treatments were consisting of 6 and 12 hours of leaching, chemical scarification with sulfuric acid solution 80% for 5 and 10 min, potassium nitrate 0.3% for 72 hours, hormone treatments, gibberellic acid (250, 500 and 1000 ppm) and benzyl amino porine (0.1 And 0.25 mg per liter), prechilling for 20 and 35 days at +5 °C temperature, and combined prechilling and hormonal treatments. Results showed that the effect of treatments on percentage, rate, mean germination time and seed vigor of ammoniacum was significant (P>%1). prechilling was an essential factor for dormancy breaking of ammoniacum seed and none of the treatments without prechilling had no effect on germination. The best treatment to overcome seed dormancy was the integrated treatment of perchilling for 35 days and gibberellic acid with 250 ppm concentration. however alonely perichilling be able to breaking seed dormancy in this plant.

The genus of Elymus is of important grasses for forage production and soil and water conservation in Iran's rangelands. It has high preference value for livestock grazing because of the high production and high acceptability. Important species of this genus show different tolerances to drought. In order to determine the reactions of 14 accessions of Elymus hispidus and Elymus pertenuis to drought stress, a factorial experiment was conducted using completely randomized design with three replications in a standard germination test in 2008, Shiraz, Iran. Polyethylene glycol 6000 was used at 4 levels (0, -8/0, -9/0- and -1 MPa) as different osmotic potentials. Data were collected and analyzed for germination percentage, speed of germination, root length, shoot length, seedling length, root / shoot length ratio, seedling weight and seed vigor index. The results showed significant differences among accessions, drought effects and interaction effects of accessions* drought for all the traits. However, there were no significant differences between means of two species for all traits except seedling weight. In both species, all traits except root / shoot length ratio were decreased by increasing osmotic potential. In contrast, means of root / shoot length ratio was increased by drought stress. The effect of drought stress was higher on shoot length than those for root length, indicating that the sensitivity to drought stress of shoot length was more than root length. The results showed that some accessions within E. hispidus species as (Yasoj, Eghlid and Brojen) showed the maximum drought resistance in most of the seedling attributes. According to the results of Probit analysis, LD50 were estimated as -0.72 and -0.81 MP for E. hispidus and E. pertenuis, respectively.

Vicia monantha is an important Legume that produces part of required forage for livestock from early spring to summer. Germination is an important stage of plant growth which is often sensitive to environmental stresses including water and salinity stresses. The aim of this study was to assess the effect of salinity and drought stresses on seed germination of Vicia monantha. We applied a factorial trial under completely randomized design using six salinity treatments (0, 50, 100, 150, 200 and 300 mM of NaCl) and six drought treatments (0, -0.2, -0.4, -0.6, -0.8, 1 MP of PEG) separately. Results showed a significant effect of both stresses on seed germination indices. The percentage of germination, seed germination rate and plumule and radicle length, coefficient of alometri, dry weight of plumule, seed vigour, significantly reduced under both stresses. We found seed germination in most of understudy salinity levels whereas few drought treatments showed seed germination. Therefore, it seems this species is more sensitive to drought stress than salinity.

Seed and productivity are two major factors to be considered when exotic species are going to be introduced. In a split plot The effect of seed source was investigated in laboratory on germination and vigour traits of Quercus brantii Lindl. acorn. The acorns were collected from 4 forest habitats (seed sources) in southern Zagros (provinces of Kohkilouyeh-Bouyer Ahmad، and Fars)، located in elevations of 850، 1100، 1500 and 2100 m a. s. l. and examined in incubator (25 c، 8 hours radiation) as completely randomized design with four replications. The results of the 30-day period revealed that seed source significantly affected germination and vigor characteristics of acorns (p > 0. 01)، whereas germination، germination rate، root length، vigor index، dry masses of root، shoot and plant were lower in high elevation seed source than in middle and low elevation ones. Correlation of seed origin with mean time of germination was significantly positive (p> 0. 01)، and with other seed traits was significantly negative (p > 0. 01). Since the germination، germination rate، shoot length and plant dry mass are considered as assessment criteria for seed vigor index، it can be suggested that low and middle elevation seed sources are more proper.