نشریه تحقیقات بذر
پیاپی 27 (تابستان 1397)

In order to study the effect of nickel and lead metals on germination characteristics and flax seedling growth, a factorial experiment in a completely randomized design (CRD) with three replicates was conducted in Laboratory of Seed Science and Technology, College of Agriculture, Shahed University in 2016. The factors were heavy metals treatment including lead )control, 250, 500 and 750 μm), and nickel (200, 400 and 600 μm). The results of analysis of variance showed that the effect of heavy metals on germination percentage, germination rate, root length, shoot length and seedlings length, seedling fresh and dry weight, viguor of seedling length index and relative water content was significant at one percent probability level. The highest germination percentage (98.66 percent) and germination rate (11.86 1.day) were related to control treatment. Also, using lead metal reduced germination characteristics and flax seedling growth compare to controls. But, the inhibitory effect of lead metal on germination characteristics and flax seedling growth was less compared to all of nickel concentrations. With increasing nickel concentrations the inhibitory effect were increased, therefore the lowest germination characteristics and flax seedling growth were observed in 600 μm nickel concentrations. In general, results showed that nickel and lead metals lead to reduce germination seed and growth of flax.

Biological soil crusts greatly affect the surface properties of the soil, which in turn may also alter the germination of the seeds of vascular plants. The aim of this study was to investigate the effect of moss on germination of five dominant species of Golestan National Park. At the beginning of the experiment, the seeds of five dominant plant species: Avena barbata, Bromus tectorum, Melica ciliata, Stipa caucasica and Taeniatherum caput-medusae were collected in the field and three different treatments: live moss, dead moss and control on percentage and germination rate of these seeds were investigated in five replications. In order to determine the most important factor affecting the percentage and speed of germination, the General linear mixed model and comparison of the mean were done using Tukey test. The results showed that germination percentage of B.tectorum and M.ciliata were not significantly different between different treatments but germination percentage of S.caucasica, A.barbata and T.caput-medusa among different treatments have significant differences. In all three species, the percentage of germination on the moss treatment was significantly increased. The mean germination speed of A.barbata, B.tectorum, M.ciliata, S.caucasica and T caput-medusa species were 5.87, 3.38, 2.16, 22.01 and 6.20 respectively, and only S.caucasica species among different treatments was a significant difference.

Osmopriming is a technique for soaking seeds in an osmotic solution with a low water potential to control the amount of water absorbed by the seeds. In order to investigate the effect of green Basil seeds priming with potassium nitrate in drought stress conditions, a factorial experiment was conducted in a completely randomized design with three replications in Laboratory of Seed Science and Technology, Faculty of Agricultural Sciences, Shahed University, Tehran, in 2016. Treatments consisted of seed priming in three levels: control (no priming), 0.2% and 0.5% potassium nitrate concentrations and drought stress induced by polyethylene glycol 6000 (PEG 6000) at four levels (0, -0.3, -0.6, -0.9 MPa). Traits included germination percentage, germination speed, average germination time, germination time variance, germination time homogeneity, seedling length and root length. The results showed that priming of seeds with potassium nitrate had a significant effect on germination percentage, germination speed, seedling length and root length, and increased these traits. Drought stress had a significant effect on all traits at 1% probability level. The interaction of potassium nitrate and water deficit had a significant effect on seedling length of grass basil. According to the results of this study, it can be concluded that potassium nitrate had positive effects on germination and seedling growth of green basil. However, can not definitely say abou the positive effects of potassium nitrate in drought stress conditions.

The influence of salicylic acid pre-treatment on correlation and germination traits of different rice genotypes are examined using a factorial experiment based on completely randomized design with three replications at Cytogenetic and Molecular Genetics Laboratory of Sari Agricultural Sciences and Natural Resources University (SANRU) in 2016. Factors included seven genotypes (M185, M181, M436, M618, L59, Nonabokra and shastak mohammadi) and three levels of salicylic acid (0, 0.5 and 1 mM). Results indicate that germination percentage, shoot length, root length, root fresh weight and root dry weight increased under salicylic acid pretreatment. However, shoot dry weight significantly decreased when salicylic acid dosage increased. Among all examined traits, shoot fresh weight had the highest positive and significant correlation with shoot dry weight (0.82), however, the highest negative correlation was obtained between shoot length and shoot dry weight (-0.61).In general, three components have been identified for these eight traits which explain the total of 89.46% of observed variance.

Drought stress is the most important factors in disruption of growth and development plants especially in germination stage in arid and semi-arid regions. An experiment was conducted to investigate the seed priming with salicylic acid on the germination properties of the Lallemantia royleana medicinal plant under drought stress (PEG 6000) at the Agricultural Laboratory of Shahed University in 2016. This experiment was conducted as factorial in a completely randomized design with three replications. Factors of experiment include of salicylic acid in three levels (0, 0.5, 1 mM) and drought stress (0, -3, -6 and -9 bar). The studies traits were measured include percentage and germination speed, average time and germination rate, daily germination mean, seedling vigor index, root length, shoot length and ratio, root fresh weight, fresh weight and dry weight seedling. The results of analysis of variance were showed that salicylic acid priming, drought stress and interaction of traits a significant effect (P <0.01). In addition to, the results showed that with increasing drought stress were reduced germination characteristics and growth parameters of L. royleana plant and the use of salicylic acid improved and increasing of seed germination and seedling growth. Also, the results of the research indicated that the L. royleana could germinate and survive in response to -9 bar stress, but seedling germination and seedling growth reduced significantly the control conditions. Among salicylic acid pre-treatment levels, 1 mM level has the highest germination percentage in the 9-bar stresses.

Salinity is an environmental factor that affects all stages of plant development from germination to fruit and grain production more or less. Germination is one of the most critical stages in plant growth under salt stress conditions. In order to investigate the effect of salicylic acid on germination and growth characteristics of Fenugreek seedlings seedlings under salinity stress, an experiment was carried out in a factorial experiment in a completely randomized design with three replications in 2017 in Agriculture and Technology Laboratory, University of Mohaghegh Ardebili. Experimental factors included concentrations (0, 0.5 and 1 mM) of salicylic acid and salinity levels including zero (control), 50, 100 and 200 mM sodium chloride. The results showed that with increasing salinity percent and germination rate, seedling length, seedling dry weight and Fenugreek weight decreased. Germination percentage (50%), germination speed (35%), seedling length (40%) and seedling dry weight (45%) were obtained at 200 μm salinity (without salinity). Application of 1 mM salicylic acid could significantly improve the traits compared to the control. The results of this study showed that the use of salicylic acid could greatly endure fungal strain under stress conditions.

Selenium (Se) is a beneficial element with anti-oxidant and anti-viral properties that strengthens the defense system and increases plant adaptability under environmental stress conditions. In present study we examined the effect of Se on alleviating adverse effect of Cd, Pb and Ni alone and in combination together in cucumber (Cucumis sativus cv. Super Dominus). The research was conducted using a completely randomized design with factorial arrangement in three replications for two germination tests. The first experiment was carried out to determine the optimal effectiveness of Se and heavy metal toxicity threshold levels, which contain levels of Se (0, 4, 6, 8, 10 mg.L -1 ), cadmium (0, 10, 15, 20, 25 µM), nickel (0, 50, 100, 150, 200 µM) e and lead (0, 20, 40, 60, 100 µM). The second experiment were consisted of two levels of Se (0 and 8 mgL-1) and toxicity threshold levels of heavy metals, including cadmium (0, 25 µM), nickel (0, 200 µM) and lead (0, 100 µM) treatments. The result showed that the germination percentage and germination rate significantly reduced at all heavy metal stress and Se has beneficial effect in alleviation of toxicity of heavy metal. Heavy metals stress increased electron leakage (EL) malondialdehyde (MDA) and Se supplementation enhance EL and MDA under heavy metal stress. Cd, Pb and Ni alone or in combination together significantly reduced enzyme activity such as catalase (CAT), glutathione peroxidase (GPX) and ascorbate peroxidases (APX) in cucumber leaves and Se increased enzyme activity in stress condition in comparison with non-Se application. In general, Se has beneficial effect in alleviation of heavy metals stress in cucumber during germination by preventing oxidative damages.

Seed vigor is an index of its quality. Seed vigor tests are designed to predict more accurately of seedling emergence in the field In order to predict seedling emergence more accurately, seed vigor tests are designed, depending on their prediction accuracy, each is used for different plants. This study was conducted at the seed technology laboratory in Ramin University of Agricultural Sciences and Natural Resources and field Research in 2016. In order to laboratory evaluation of seed vigor tests for predicting seedling emergence in the field, 5 safflower seed lots was used. In this study seed vigor tests include seedling establishment percent in field, standard germination test, seedling growth test, seed germination rate test and salinity test (0, 100, 200, 300 and 400 mM) The results showed that the standard germination test, seedling growth, germination rate and salinity were not significant correlated with seedling establishment percent for seed lots in the field. Therefore, these tests can not confidently used to separate the weak and strong safflower seed lots. However, the results of the comparison of the two-fold model did not succeed in distinguishing between strong and weak masses The analysis of the same data using the HydroTime model yielded results that could be separated by strong and weak safflower masses these tests can be used to separate the weak and strong safflower seed lots and used for predicting emergence in the field.