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.
Seed priming is one of the most important techniques used to improve seed germination under biotic and abiotic stresses. For this purpose, germination and seedling growth characteristics of primed seeds of Tall wheatgrass (Agropyron elongatum (Host.) P. Beauv) were evaluated under drought and low-temperature condition. A factorial experiment was conducted on the basis of randomized completely block design with three factors with four replications. The experimental factors were priming with two levels including urea primed (using urea -4 bar at 10 °C for 36 h) and non-primed seeds germination temperatures, including 3, 6, 9, 12, 15, 20 and 25 °C and osmotic potential including zero (distilled water), -3, -6, -9, and -12 bars (applied by polyethylene glycol 6000). Increasing trend has been observed for all germination indices, except mean germination time, with increasing temperature from 3 to 25 °C and seeds revealed the greatest sensitivity to temperatures below 9 °C. However, this trend was reversed with increasing drought stress, the seeds sensitivity to drought stress started from the potential of -6 bar and reached the maximum in -12 bar. However, primed seeds compared to non-primed seeds have demonstrated better germination under both drought and low-temperature stresses. The results of this study showed that the highest seedling vigor index and germination rates achieved in the temperature range of 20-25 °C and water potential of zero to -3 bar.
In order to study, the effects of hydropriming and osmopriming on germination characteristics of Nigella sativa L. under salt stress an experiment was conducted in factorial laid out in completely randomized design with four replications at Research Laboratory, Faculty of Agriculture, Mashhad Branch, Islamic Azad University-Mashhad Iran, in 2014. Factors were included of priming treatment in six levels [control (Non-priming), hydropriming with distilled water, osmopriming with KNO3, KCl, CaCl2 and NaCl] and salinity treatment in four levels [0, 50, 100 and 150 Mmol]. Analysis of variance showed that the effects of salinity and seed priming on all measured indices and interaction between two factors on germination percentage and rate, radicle and plumule length and seed vigor were significant at the probability level of 1%. The results showed that with increasing salt concentration all measured traits were decreased. This decreasing started from the 50 Mmol concentration. Under salt stress condition, osmopriming with KNO3 and then hydropriming and osmopriming with KCl improved all germination indices compared with control.
In order to evaluate the effect of priming on some germination and seedling growth characteristics of safflower (Carthamus tinctorius L.) under drought stress, an experiment was conducted base on completely randomized design with four replications at the Seed Technology Laboratory of Yasouj University, in 2011. Treatments were included of five priming levels (control or no prime, hydro priming, potassium nitrate 3% (KNO3), PEG and Urea -4 bar) as the first factor and three levels of drought stress (0, -4 and -8 bar) as the second factor. The results showed that the interactions of drought stress and seed priming on germination percentage and the germination rate was not significant. But the main impact of priming and drought stress on them was so significant at 1% probability. The highest germination percentage and germination rate (75.66% and 3.62 seed.day-1, respectively) were shown in urea priming and the lowest (52% and 2.31 seed.day-1 respectively) in the control treatment (no prime). Drought stress was caused a significant decrease in germination traits. In general, the results obtained in this study showed that treatment with urea and potassium nitrate compared with PEG improved germination and seedling growth of safflower.
In order to evaluate the effect of hydropriming on seed germination of Vigna radiata under salinity stress, an experiment was arranged in a factorial based on a completely randomized design with three replications in the laboratory of the Agricultural College of the University of Ramin Khuzestan. Treatments were salinity stress at 4 levels (0, 3, 6 and 9 Mmhos) and hydro priming at 3 levels (1, 1.5 and 3 h) and two sizes of seed (small and large seeds) that was carried out by NaCl. Results showed that all of the germination characteristics decreased with increased salinity, but this decrement for seeds that primed at a long time, was less. Also at all characteristics, small seeds, showed better reactions than large seeds. Generally, hydropriming was improved germination characteristics of Vigna radiata under saline conditions. According to this experiment, hydropriming improved germination and establishment.
Priming of seeds by magnetic fields (magneto priming) is proposed as an ecological, useful and low-priced method for improvement of seed germination and plant emergence. In order to evaluate the germination behavior of sesame seeds affected by magnetic fields, an experiment was conducted as a completely randomized design with 22 treatments (non-exposure to magnetic fields (control) and 21 magneto priming treatments) with three replications at the college of agriculture, the Ferdowsi University of Mashhad in 2014. the seed of sesame put into a plastic bag bulky and was treated with different intensity of magnetic fields (25, 50, 75 and 100 mT) for several times (10, 20, 30, 60 and 120 minutes). For assessment of germination traits of sesame under constant magnetic field conditions, magnetic tapes with three mT strength were used in each Petri dish throughout the experiment. Results showed that magnetic fields had no significant effects on final germination percentage and mean germination time and all magnetic treatments except for 75 mT at 60 minutes indicated reducing effects on germination percentage in comparison to control. Priming of seeds with magnetic fields in 50 mT strength for 20 minutes led to the increment of germination rate compared to control treatment but all levels of 100mT treatment caused a reduction in germination rate than control. The most radicle length, seedling length and seedling vigor length index belong to 75 mT at 60 minutes treatment and the most seedling dry weight and seedling vigor weight index related to 100 mT for 20 minutes treatment. Ranking of treatments showed that exposure of seeds for one hour in 75 mT and 10 minutes in 25 mT magnetic fields strength had the best outcomes.
Germination is the first and the most stages for sainfoin (Onobrychis viciifolia) growth; which it has especially sensitivity to environmental stresses such as alkalinity. The current study was conducted to evaluate the effectiveness of seed pre-treatment methods on improving sainfoin tolerance to alkali stress in germination, early growth and its recovery as a factorial experiment based on a completely randomized design in College of Agriculture, Shiraz University in 2013. The first factor was four seed pre-treatment methods (seed with the pod, seed without the pod, pre-chilling of seed without pod and hydro-priming of seed without pod) and the second factor was five alkali stress levels (pH= 6.7, 7.9, 8.9, 9.8 and 10.7). Alkali stress levels were prepared using two neutral salts (Na₂SO4 and NaCl) and two alkaline salts (NaHCO3 and Na2CO3). The results showed that germination percentage was decreased as alkalinity (pH) levels were enhanced; so that, there were no germinated seeds in 9.8 and 10.7 treatments. Alkali stress reduced initial germination percentage (51.9%), final germination percentage (51.8%), plumule length (55.7%) and radicle length (72.2%). Under all alkalinity conditions, the lowest seed germination and seedling growth were observed in with pod seed, followed by pre-chilling treatments; while their highest were achieved in without pod seeds and hydro-priming treatments. The highest recovery was observed in without the pod, followed by hydro-primed seeds. Recovery was observed in Pre-chilled and with pod speeds up to 7.9 and in hydro-primed and without pod speeds up to 8.9.
Efficient seed germination and rapid and uniform seedling emergence are important in commercial agriculture. Therefore, the use of strategies to improve germination and seedling establishment is necessary for increasing productivity. Hydropriming has been suggested as a simple pre-germination strategy to improve seed performance. In this study, the effects of different durations of hydropriming (10, 24, 48 and 72 hours) at different temperatures (10 and 25 ˚C) compared to unprimed seeds on the vigor and germination performance of five milk thistle accessions (Ahvaz, Sari, Esfahan, Dezfol and Gachsaran) were evaluated. An experiment was conducted as a factorial experiment based on a completely randomized design with three replications. Germination performance was evaluated by final germination percentage, mean daily germination, mean germination time, the coefficient of germination, Timson's index, time to reach 50% the final germination percentage, germination value, coefficient of uniformity of germination, length and dry weight of seedlings and vigor index. The results show that germination capacity, germination rate and seedling vigor indexes increase significantly in hydro primed seeds at a temperature of 10˚C, whereas a decrease in hydro primed seeds at a temperature of 25˚C. Our results also show that the efficacy of hydropriming on seedling emergence and vigor traits depends on the priming duration and temperature. Hydropriming at 10˚C indicated the most effective on germination indicators and seedling vigor when compared to unprimed seeds. In addition, the comparison of germination and growth indicators in different durations of hydropriming in five milk thistle accessions indicated that the best duration of hydropriming for Ahvaz and Gajsaran is 72h, for Sari and Dezfol is 48 and 72h and for Esfahan is 10 and 24h. Therefore, the effect of hydropriming on germination performance and seedling vigor depends on plant association and hydropriming time and therefore, the selection of the best condition for hydropriming will improve the seed germinability and vigor.
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.
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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), hydro-priming, 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.
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Conclusion: According to the results of this study, salicylic acid at certain concentration improves seeds germination of tomato plants through the regulation of physiologic and biochemical processes. It seems that salicylic acid led to increase in plant growth and improvement of seed germination and morphophysiological parameters of the tomato via affecting cell growth and division. Seed priming with salicylic acid at the concentration of 3 mg/l and in longer time frames had positive effect on most traits, whereas the results for each trait were different in relation to priming time.
1-Priming of tomato seed in distilled water for 18 hours reduces the time of seed germination.2-Salicylic acid can be used as an appropriate pretreatment for producing seedlings with better quantitative and qualitative characteristics by affecting the morpho-physiologic and biochemical properties of tomato seedlings.
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