Iranian Journal of Seed Research

The effect of seed rate of alfalfa (Medicago sativa L.) and efficiency of plant growth promoting bacteria (PGPR) that facilitates phosphorus uptake with different doses of phosphate fertilizer was evaluated on seed quality. For this purpose, the germination and seed vigor tests before and after accelerated aging were performed in a split split plot experiment based on randomized complete block design with three replications in 2010 in the field of education and research in the College of Agriculture and Natural Resources, Tehran University, Karaj. Phosphorus factor at 4 levels (0, 30, 60 and 90 kg Phosphorus.ha-1) in main plots, PGPR (Pseudomonas) in three levels (no bacteria, bacterial strains, No. 9 and bacterial strains No. 41) in subplots and rate of seed factors on three levels (2, 6, and 10 kg of seed per hectare) were the sub-subplots. The results showed the highest rate of germination and seed vigor obtained by use of 6 kg seeds per hectare, PGPR No.41 strains with 30 kg Phosphorus per hectare and after accelerated aging. The highest rate of germination and seed vigor at 10 kg of seed per hectare were found for PGPR No.41 strains, with 60 kg Phosphorus ha-1 treatments. After accelerated aging practices to achieve maximum germination index and vigor, seed rates and phosphorus requirement were more than standard conditions. Based on obtained results for the storage conditions, bacterial strains No. 41 had a better effect on increasing seed vigor than bacterial strains No. 9. To produce alfalfa seed with high vigor and obtain better results, use of optimum seed rates and phosphorus (6 and 30 kg.ha-1, respectively) along with PGPR (strain No. 41) could be considered in crop plants.

Osmotic stress is the most important of the abiotic stresses that lead to limitation of growth and yield in rapeseed. This study was conducted to examine the effect of cycocel seed priming on osmotic stress tolerance in germination and early growth stages of rapeseed, as a factorial experiment based on completely randomized design at Agriculture College of Shiraz University in 2012. The treatments included seed priming in three cycocel concentrations: 0 (without priming as control), 2.5 and 3.5 g L-1 and osmotic stress in five levels: 0 (as control), -0.3, -0.6, -0.9 and -1.2 MPa using polyethylene glycol. The results showed that osmotic stress was significantly reduced germination percentage (15.1%), germination rate (15.3%), radicle length (29.5%), plumule length (31.6%), radicle fresh weight (22.4%), plumule fresh weight (37.6%) and vigor index (39.9%). Furthermore, osmotic stress leads to increase radicle to plumule fresh weight and radicle to plumule length ratio as 6.8 and 24.3 percent, respectively. Seed priming with cycocel reduced the adverse effects of osmotic stress on measured parameters. Although, there was no positive effect on germination percentage and rate under osmotic and nonosmotic conditions for cycocel in both concentrations, but cycocel at 3.5 g L-1 appeared to have a greater positive effect than 2.5 g L-1. Considering positive impact of cycocel seed priming on the reduction adverse effects of osmotic stress further research on cycocel seed priming and osmotic stress tolerance is recommended under field conditions.

Due to the importance of medicinal plants, understanding the seed germination response to temperature is agronomically important. A laboratory study was conducted to investigate the effect of different temperatures on seed germination of fennel, cannabis and sesame in a completely randomized design with four replications. Various constant temperatures (5, 10, 15, 20, 25, 30, 35 and 40°C) were considered. According to the results, the effect of temperature on germination rate and percentage in all species was significant. The seeds of fennel were not germinated in 5, 35 and 40 ⁰C and seeds of sesame germinated only in 5 ⁰C. The maximum rate of germination obtained in 30 °C for fennel and 25 °C for sesame and cannabis. The highest germination percentage of fennel and cannabis and sesame were in 20, 25 and 30 0C respectively. The lowest of germination uniformity (GU) were observed in 20 ⁰C for fennel and in 15 ⁰C for cannabis and sesame. Amount of seedling vigor maximized for fennel and cannabis in 25⁰C and for sesame in the 300C. The values of length and weight of radical and plumule were enhanced with the increase of temperature and record on maximum in special temperature and then reduced slowly. The quantitative information provided by this study can be used in prediction of emergence under diverse temperature conditions. Germination of cannabis seeds occurred in a wide range of temperatures and this seed are less sensitive to temperature compared to the other two plants. Germination of fennel seeds was less, except at 200C. The sesame seeds had good germination at 15-35 ⁰C.

To evaluate the interaction of Cd and SA on seed germination of Safflower (Carthamus tinctorius L. cv. Soffe), this experiment was carried out as a factorial based on CRD with four replications in 2012, in Yasouj University seed lab. Factors included of four levels of seed priming with SA (0, 0.3, 0.6, and 0.9 mM) and eight levels of cadmium nitrate (0, 5, 10, 15, 20, 25, 30 and 35 mM). In all Cd treatments, SA 0.9 mM had maximum germination percentage (84% in 0 mM Cd) and rate (6.58 seed day^-1 in 5 mM Cd), radical length (4.21 cm in 0 mM Cd) and stem (3.29 cm in 0 mM Cd), radical dry mater (2.25 mg in 0 mM Cd), shoot dry matter (0.94 mg in 0 mM Cd) and seed vigor index (6.30 in 0 mM Cd). Generally, seed priming with SA decreased the impact of Cd on seed germination and SA 0.9 mM was the best treatment.

In order to determinate the cardinal temperatures and investigate the effect of temperature on seed germination and seedling growth of Securigera securidaca, a study was conducted in a completely randomized design with 8 temperature treatments (5, 10, 15, 20, 25, 30, 35 and 40^oC) and four replications in research laboratory of faculty of agriculture at the Birjand University in 2013. A two-segmented linear regression model was fitted between germination rate and temperatures to determine cardinal temperatures for germination. Cardinal (minimum, optimum and maximum) temperatures of germination were determined as -1, 22.5 and 40.2^oC respectively. Maximum rate and percentage of germination obtained in the range of 20-25^oC. Maximum of radicle length and dry weight, maximum of caulicle length and dry weight and maximum of vigor seedling were obtained in 20^oC,10-20^oC and 5-30^oC respectively. Maximum and minimum germination uniformity (GU) was obtained in 25 and 5^oC. 

Seed priming is a method which is a quite effective method for improving germination and seedling establishment. Two separate experiments were performed to determine the best hydro and osmopriming treatments effects on canola‘s seed germination. The experiments were performed in seed technology laboratory of Islamic Azad University, Karaj, Iran, 2014. The first experiment contained three canola varieties seeds hydropriming (Okapi, Zarfam and Talayeh) using tap water over time interval 0. 2, 6, 10, 14, 18, 20 and 24 hours. The second experiment included, tree canola cultivars in accompany with six concentrations of ZnS04 (0, 0.035, 0.1, 0.4, 1 and 4 gr.Lit^-1) over priming time interval of 0, 6, 10 14 and 18 hours. Both experiments were conducted as a factorial experiment in the context of completely randomized design (CRD) with four replications. The results revealed that the maximum germination percentage across all cultivars e.g. Okapi (99%), Zarfam (95%) and Talayeh (80%) is achieved at 10 hours hydropriming interval. Also concerning to germination rate, the best performance was observed for Talayeh cultivar at 10 hydropriming hour’s interval. The most vigor longitudinal and vigor weighted indices (1050.55 and 4.56) were observed in the Okapi cultivar in the fourth hydropriming level. The interaction between the cultivars, the concentration of ZnS04 and osmopriming time was significant for all characters except for shoot dry weight and vigor weighted Index. The three-way interaction showed that the highest shoots dry weight (0.11, 0.057 and 0.055) and also vigor weighted index observed in Okapi, Zarfam and Talayeh cultivar in 0.035 concentration of ZnS04 (gr.lit^-1) at the time was 10 hours, respectively. The results of this study showed that hydropriming and ZnS04 might improve the performance of rapeseed Cultivars seed.

Gaining insights into the germination and emergence patterns of weeds as well as the factors which have an impact on these patterns is beneficial for weeds management programs. In order to investigate the effect of temperature, waterlogging and salinity on germination and emergence of common lambsquarters, three separate experiments were conducted, adopting a completely randomized design with four replications. The results of the temperature experiment showed that the highest germination percentages, which were 87, 93 and 88%, were obtained in the temperature range of 15, 20 and 25°C, respectively. Maximum values of germination rate, radicle length, plumule length, and seedling dry weight were obtained at 20°C. In addition, optimum seed vigor index of 796.29 was observed at 20°C. The results of the Regression Model showed that germination percentage decreased with an increase in waterlogging duration and halted after 8 and 10 days of consecutive waterlogging. Mean comparisons revealed that radicle and plumule length, seedling dry weight and vigor index decreased significantly by increasing the period of waterlogging. Salinity adversely affected germination percentage, germination rate and seedling dry weight of common lambsquarters. These factors were at their highest amounts in the control and 50 mM NaCl treatments. A downward trend was observed in these factors as NaCl concentrations increased and finally the germination process stopped in concentrations ranging from 300 to 400 mM NaCl. Radicle and plumule length also decreased from 10.51 and 9.23 cm in the control treatment to 3.57 and 2.47 cm at 250 mM NaCl. Overall, the results revealed that the maximum seed vigor index of 851.84 was obtained in the control treatment and seed vigor halted when the salinity level increased to more than 250 mM NaCl. Finally, the results showed that optimum temperature for germination of common lamsquarters was 20 °C and the existence of salinity and waterlogging stress can decrease growth indices of this weed at germination and seedling stages.

Given the medicinal and ornamental properties of Hawthorn (Crataegus spp.), and given that there are some problems in its propagation, which is due to the hard cover of the seeds and immature embryo, working out techniques that can facilitate the process of seeds’ germination is of great import. Thus, the present study sought to identify the best method for the purpose of breaking the seed dormancy of 8 species of native hawthorn of Iran. The study was carried out as factorial with a completely randomized design and had three replications. The first, second and third factors were, respectively species of Hawthorn in eight levels, sulfuric acid in three levels (half and an hour versus non-treated (control) and chilling treatment in three levels (90, 105 and 120 days, respectively). The results showed that the highest percentage of germination (32%) and germination rate (9.1 day^-1) were obtained under the interaction of sulfuric acid treatment for one hour, followed by a 120-day chilling period in C.turkestanica, which had a significant difference with other treatments. It is concluded that hawthorn seeds have deep endocarp and physiological dormancy. The interaction of Sulfuric acid treatment and moist chilling play an important role in increasing the percentage and speed of germination of Hawthorn seeds.

Highlights:

1.  Achieving the best way to break the dormancy of Hawthorn seeds in different species and genotypes.
2. Shortening the seeds’ germination time.

1. Cold stratification and hydrochloric acid treatments increase the efficiency of sugar beet seeds under drought stress conditions.
2. Cold stratification and Hydrochloric acid treatment have a synergistic effect on sugar beet seeds.

1. Chitosan nano particle and potassium nitrate increase quinoa germination.
2. Chitosan nano particle and potassium nitrate increase the content of chlorophyll a and b.

1. The effect of magnetic field on germination of multipurpose seed of Niger plant.
2. The effect of drought stress on germination of multipurpose seed of Niger plant, given Iran’s being located in dry belt.
3. The positive effect of magnetic field on germination of Niger seed to improve the negative effects of drought stress.

Extended abstract
Introduction: Crop rotations are practiced to eliminate the effect of monoculture, but the succeeding crop may be influenced by the phytotoxins released by the preceding crop. Among plants, Brassica species contain allelochemical compounds as glucosinolate that is, under special conditions, released to environment and affects seed germination and plant growth. Wild mustard (Sinapis arvensis L.) as a weed of 30 crops in 52 countries which has a series of allelopathic effects that prevent germination of other plants. Products of glucosinolate- like ionic thiocyanate (SCN-) inhibited the root or shoot growth of many crop species. Also volatile compounds like isoprenoid and benzenoid released from Brassica tissue degradation may suppress many crops growth. It was also found in many studies that allelochemicals, which inhibited the growth of some species at certain concentrations, might stimulate the growth of same or different species at lower concentrations. The present research was conducted to evaluate the effects of aqueous extract concentration of various mustard parts on barley seed germination and seedling growth.
Materials and Methods: In order to evaluate the allelopathic effect of mustard in agro ecosystems, a factorial experiment based on completely randomized design with three replications was carried out in botany laboratory of agriculture faculty, Illam University in 2014. Experimental treatments included five concentrations of mustards foliage and root aqueous extract (0, 10, 30, 50, and 70 percent) that were studied at germination and early growth stage of barley (cv. Abidar) in two separate experiments. In the seed germination section, the effects of aqueous extract of mustard on germination rate and germination percentage of barley seed were measured. In the study of the effect of aqueous extract of mustard on barley seedlings, weight and length of root and shoot, leaf chlorophyll content, proline and soluble sugars content were measured.
Results: Results showed that the highest amount of barley seed germination percentage and germination rate (100 and 19.5, respectively) were observed in control and the lowest amount (40 and 9.5, respectively) belonged to mustard root aqueous treatment with 70 percent concentration. The most decrease in barley seedlings length and weight were observed at the highest concentration of aqueous extract. The amount of chlorophyll a decreased from 2.39 in control to 1.66 mg per fresh weight in 70 percent concentration of aqueous extract treatment. The highest amount of proline (66.8 μM per fresh weight) in barley foliage was observed in 70 percent aqueous extract treatment. The results from this study showed that mustard allelopathic effect may be a possible mechanism controlling the barley germination and early growth stage in agro ecosystems.
Conclusion: Generally, we were able to demonstrate short term auto toxicity and possible short-term allelopathy due to mustard has harmful effects on barley including reduced seed germination and emergence of barley seedling. Depending on the concentrations of Mustard extract, allelopathic activity will vary Mustard. Further investigations are also needed to determine the influence of cultivar variations, and to identify the active compounds involved in mustard auto toxicity and Allelopathy.
  
Highlights:
1-Mustards aqueous extract reduced seed germination percentage and plant growth in barley.
2-Mustards aqueous extract increased proline and soluble sugars in barley, but it reduced amount of chlorophyll in this plant.

1. Study of germination and biochemical properties of fenugreek seed aged under different level of osmotic potantials and temperatures.
2. In areas with a lower osmotic potential it is better to cultivate Fenugreek seed at temperatures below 20 °C.

1. Introduction of clover species with more tolerance to drought and salinity in germination stage.
2. Evaluation of germination indices of clover species under drought and salinity iso-osmotic conditions.

Extended abstract
Introduction: Due to their aggressive and competitive habits, weeds inhibit the growth of valuable plants. Interference in plants includes environmental competition and allelopathy (Autotoxicity and hetrotoxicity). In hetrotoxicity, chemical compounds released from plants are able to effect the neighboring plants. Proper management of weeds and the exploitation of their hetrotoxicity potential can reduce losses caused by weeds. This could also represent an effective step towards the reduction of the use of herbicides. Therefore, the purpose of this study was to evaluate the effect of hetrotoxicity potential of aqueous extract of various organs of Malva sylvestris L. weed on traits of germination and photosynthetic pigments of Echinochloa crus-galli L.
Material and Methods: An experiment was conducted to evaluate the effect of hetrotoxicity potential of aqueous extract of Malva sylvestris  L. weed including the stem, leaf and flower as well as their mixture on traits of germination and photosynthetic pigments of Echinochloa crus-galli L. as a completely randomized design in three replications in Weeds Science Laboratory of Gonbad Kavous University in 2017. For this experiment, aerial parts of M. sylvestris were first collected at the flowering stage from Ramian field. They were subsequently separated with great care and were powdered. Then from them, 5% suspensions (weight/volume) were prepared, using distilled water. Finally, the extract of each organ of M. sylvestris was added to Petri dishes containing E. crus-galli seeds. After the 7^th day, traits such as rate and percentage of germination, radical and shoot elongation, vigor index, total content of chlorophyll a and b and carotenoids were measured.

Results: The results showed that various organs of M. sylvestris and their mixture had different inhibitory effects on traits of germination and seedling length of E. crus-galli weed. The highest inhibition effects on rate and germination percentage and elongation of radical and shoot of E. crus-galli were obtained using leaf extract of M. sylvestris about 64.04, 64.37, 87.69, 62.81%. In this study, radical length is more affected under hetrotoxic compounds of various organs of M. sylvestris, as compared with shoot length. Based on the results, various organs of M. sylvestris and their mixture also have different inhibitory effects on chlorophyll and carotenoid content of E. crus-galli weed. It seems that the differential effects among different organs of M. sylvestris are a function of the threshold concentration of allelochemicals to hetrotoxic compounds of the organs, which causes various response by E. crus-galli.
Conclusion: Given the evidence for the effect of hetrotoxicity potential of various organs of M. sylvestris on traits of germination and pigments of chlorophyll and carotenoid of E. crus-galli and huge biomass generated, it is advisable to exploit allelochemical compounds of this plant as bio-herbicides.
 

 
Highlights:
1- Study of the the effect of hetrotoxic potential of Malva sylvestris weed on germination characteristics and photosynthetic pigments of Echinochloa crus-galli in Ramian field.
2- E. crus-galli weed exhibits great sensitivity to hetrotoxic compounds of various organs of M. sylvestris,  especially the leaves.
3- Allelopathic characteristics of M. sylvestris weed have huge potentials for the production of bio-herbicides.