IRANIAN JOURNAL OF SEED RESEARCH
Year:2018 | Volume:4 | Issue:2 |Papers Count:9

In order to study the effects of different levels of salinity on germination components of wheat cultivars, a factorial experiment was conducted based on a completely randomized design with three replications. Experimental factors were wheat cultivars at eight levels (Saysons, Gaspard, Finkan, MV-17, Chamran, Sardari, Atila-4 and Azar-2) and six levels of salinity (0, 25, 50, 100, 150 and 200 mM NaCl). The results indicated that salinity had significant effects on all of the traits studied (i.e., radicle length and dry weight, plumule length and dry weight, remaining seed weight after germination, seedling weight, the longest radicle and plumule, number of radicle per seed, ratio of radicle weight to plumule weight and rate, and uniformity and percentage of germination). All of these traits declined with an increase in the salinity (except the ratio of radicle weight to plumule weight, remaining seed weight after germination and seedling weight). The highest ratio of radicle weight to plumule weight, remaining seed weight after germination and seedling weight were recorded in the salinity of 200 mM NaCl. The cultivars showed significant effects on all of the traits studied (except remaining seed weight after germination and seedling weight). Chamran cultivar showed the highest number of radicle per seed, the ratio of radicle weight to plumule weight, rate and percentage of germination. The highest radicle length and the longest radicle were obtained from the Sardari cultivar while in Azar-2 cultivar it was vice versa in plumule. Atila-4 cultivar showed the highest radicle and plumule weight. It seems that compared with other cultivars, out of the cultivars studied, Chamran, Azar-2, Sardari and Atila-4 were more resistant to salinity stress.

 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.

Salt and drought are two major environmental stresses that affect growth and development of plants. In order to study the effects of sodium chloride and polyethylene glycol (6000) on germination characteristics and early seedling growth of redroot pigweed (Amaranthus retroflexus), two completely randomized designs with 4 replications were conducted at Weed Research Laboratory of Bu-Ali Sina University, Hamedan in 2015. The treatments were salt and drought stress as osmotic potential at six levels (zero (control), -2, -4, -6, -8 and -10 bar). The results showed that when stress increased, germination percentage, germination speed, radicle and plumule length, seedling length and seedling vigor index decreased significantly (p 0.05). With an increase in the intensity of salt and drought stress from zero to -10 bars, redroot pigweed seed germination reduced about 96 and 100 percent, respectively, compared with the control. The highest seedling length in both stresses was observed in the control (7.71 cm) and by increasing stress intensity to - 10 bars in both salinity and drought stresses, seedling length was reduced to 1.52 cm and 0 cm, respectively. Fitting of the three-parameter logistic model provided a successful estimation of the relationship between salt and drought stress levels and germination percentage of redroot pigweed as well as germination speed. This model showed that salinity and drought stress at -3.58 and -3.75 bars caused a 50% reduction in maximum germination percentage of redroot pigweed. In addition, 50% decrease in germination speed caused by salinity and drought stress was observed in -2.58 and -2.88 bars, respectively.

This study was conducted to evaluate the effect of hydropriming and seed aging on germination and enzymatic properties of pinto bean under salinity stress as factorial based on a completely randomized design with four replications. Two groups of seeds (i.e., non-aged and aged seeds), two hydropriming treatments (i.e., hydro primed and unprimed seeds) and six salinity treatments (i.e., 0, 2, 4, 6, 8 and 10 dS/m) were the experimental factors. The results showed that the highest mean time and percentage of germination, plumule length and vigor were observed in the control (i.e., distilled water) and hydropriming treatments. Maximum root length and percentage of seedling water were obtained in the control (i.e., distilled water) and aged seed treatments. In addition, in terms of radicle dry weight, the highest amount was observed in salinity of 4 dS/m and non-aged hydro primed seeds. The highest plumule dry weight was observed in salinity of 6 dS/m and allometric index in salinity of 8 dS/m for non-aged seed and aged seed without hydropriming, respectively. An increase in the levels of salinity stress and aging the seeds increased the malondialdehyde and reduced the activity of germination, mean time and germination percentage, and seedling growth. Seed hydropriming reduced the peroxidation of the cell membrane and generally improved the speed and uniformity of germination, aged and natural seeds vigor under both salinity and optimum conditions. As a result, hydropriming can increase the tolerance of bean seeds to salinity at the germination stage and increase the germination capacity of stored seeds for cultivation.

To study the effect of production region and seed size on germination indices and heterotrophic growth components of peanut seedling, a study was performed in three peanut fields in Astaneh Ashrafieh and Agronomy Laboratory of Rasht Islamic Azad University from 2010 to 2012. This research was carried out using the standard germination, cold and accelerated aging tests. Tests were performed using factorial experiment with a completely randomized block design in 3 replications. The first factor was seed production region in 3 levels (Noghredeh, Amshal and Bandar-Kiyashahr) and the second factor was seed weight in 3 levels [large, medium and small]. The results indicated that the effect of production region on the germination speed (p<0.01) and coefficient of uniformity of germination (p<0.05) was significant so that the maximum means (6.17 and 18.11 day-1, respectively) were achieved in seeds produced in Amshal. The effect of the interaction of the region and seed size on the mean germination speed was significant so that the maximum mean (282.22) was achieved in large seeds produced in Amshal. The effect of production region on the seed reserve use rate was significant in standard germination (p<0.01) and cold tests (p<0.05). The effect of seed size on the seed reserve use rate and seed use reserve fraction were significant (P<0.01) in all the three germination tests. The maximum amount of seed reserve use rate was achieved in seeds produced in the Amshal region (in standard and cold tests with averages of 0.562 and 0.440, respectively). In addition, the maximum amount of seed reserve use rate was achieved in large seeds (with averages of 0.541, 0.470 and 0.277 mg per seed in standard, cold and aging tests, respectively). The maximum seed use reserve fraction was achieved in small seeds (with averages of 1.371, 1.310 and 1.664 in standard, cold and aging tests, respectively).

This study was conducted to study the effects of different priming methods on germination rate and percentage under salinity stress and to determine the stability of primed seeds. In order to accomplish this, three different experiments were conducted separately, including the experiment of water uptake, the experiment of salinity stress, and the experiment of storability of primed seeds. Priming treatments were five levels of control (unprimed), hydropriming (Hyd), priming with humic acid (HA), priming with salicylic acid (SA) and priming with gibberellic acid (GA). Salinity stresses were four levels of 0, 4, 8 and 12 ds/m of NaCl. The stability of prime seeds was investigated over a period of 226 days after priming. The results of water uptake showed that rapeseeds entered into the third phase of water uptake after 18 hours of hydration. The results of the salinity experiment showed that salinity levels of 12 and 0 ds/m had the lowest (74.3 %) and highest (83 %) germination percentage, respectively. In terms of germination rate, there were significant differences between GA (0.034 h-1), HA (0.036 h-1) and Hyd (0.036 h-1) with C (0.019 h-1) and SA (0.027 h-1). Generally speaking, primed seeds germinated better than control seeds at all levels of salinity. The storability of primed seeds and control seeds had no significant decrease during storage. Finally, it was concluded that seed priming increased the tolerance to salinity stress; in terms of storability, there was no significant difference between primed seeds and primed seeds could be stored in the same way as control seeds.

Salinity is one of the most important factors limiting agricultural production. Cotton, as an oilfiber plant, is one of the most important industrial plants and is sensitive to salinity, especially at germination and seedling stages. Therefore, in this study, 14 allotetraploid varieties of commercial and local cotton were selected. The study was carried out as factorial with a completely randomized design and three three replications, using the sandwich method. Germination tests were performed at three salinity levels of 0, 8 and 16 ds.m-1. Afterwards, root and shoot length, fresh and dry weight of root and shoot, germination percentage, allometric coefficient, seedling water percentage and seed vigor index were measured and stress tolerance indices were calculated based on yield (seedling dry weight) in stress and non-stress conditions. Given these indices, all cultivars were aalyzed at two levels of 8 and 16ds.m-1, using principal component analysis and biplot diagrams were drawn. Finally, the dendrogram classification of genotypes was plotted based on STI indices (stress tolerance index), SSI (stress susceptibility index), and the performance (dry weight plantlet) in stress and non-stress conditions. The result of variance analysis for genotype, salinity and salinity×genotype demonstrated that dry weight root, dry weight shoot, fresh weight root, stem length, vigor index seedling, allometric coefficient, dry weight seedling, and length seedling were significant in p-value 0.01, and fresh weight shoot, length root were significant in p-value 0.05. Clustering and the biplot of the genotypes based on STI and SSI indices at salinity levels of 8 and 16 ds.m-1 indicated that the Sepid and Giza genotypes were tolerant and that the Kashmar genotype was sensitive to salt levels at germination stage.

In order to investigate the effect of different levels of temperature and drought stress on seed germination parameters of nettle roman (Urtica pilulifera L.), an experiment was conducted as factorial in a completely randomized design with three replications at the Department of Agronomy, College of Agriculture, University of Guilan, in 2014. Treatments included different temperature levels (5, 10, 15, 20 and 25oC) and drought stress levels (0 (control), -2, -4,-6 and -8 bars). The results showed that treatments and their interactions had a significant effect on germination percentage (GP), germination rate (GR), root length and root dry weight. The highest GP (88%), GR (1.8 seed/day) and root dry weight (0.06 g) were obtained as the result of the interaction between the temperature of 25oC and no-stress condition. In this study, with an increase in drought stress and a decrease in temperature, GP, GR, root dry weight, root length and shoot length decreased. The impact of drought stress on GR and GP was lower at 20oC, compared with the temperature of 25oC. A decrease in water potential from -4 to -6 bars at 20oC caused a reduction of 50% and 30% in GP and GR, respectively. However, these reductions at 25oC were 75% and 70%, respectively. According to the results, it could be stated that the significant reduction threshold of seed germination parameters was -2 bars.

The present study sought to compare the effect of seed priming by hydropriming, ascorbate and calcium chloride (CaCl2) versus different concentrations of silver nanoparticles on two Iranian rice cultivars (Hashemi and Shiroodi) under drought stress. The experimental design, which was factorial, was completely randomized. The first factor was control (without priming), hydropriming, 20 mg.L-1 calcium chloride, 20 mg.L-1 ascorbates and 20, 40 and 80 mg.L-1 of silver nanoparticles. The second factor was the drought stress, including control, -1.48 and -4.91 bars created by polyethylene glycol 6000 solutions. In plants without drought stress, the time required to reach 50% germination (T50) reduced to 34 and 54 percent under ascorbate and CaCl2 priming in the Hashemi and Shiroodi cultivars, respectively. In the drought stress condition, ascorbate and hydropriming pretreatments decreased T50 and the time required to reach 90% germination (T90) more than silver nanoparticles, especially in the Shiroodi cultivar. On the other hand, in comparison with other pretreatments, CaCl2 had an important role in increasing the growth factors in all of the drought stress treatments. Although 40 mg.L-1 silver nanoparticles increased the growth factors to some extent, it seems that higher levels of silver nanoparticles cause stress in seeds and therefore decrease the seed germination and growth of seedlings. By decreasing reactive oxygen species, Ascorbate improves the germination and by increasing plasma membrane efficiency, CaCl2 enhances the seedling growth under drought stress.