Iranian Journal of Seed Research

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.

This experiment was conducted as a factorial experiment based on a completely randomized design with three replications at two locations: Agricultural and natural resource center of Ardebil province (Moghan) and seed and plant certification and registration institute of Karaj in 2013. The treatments included: planting date in three levels (10-May, 25-May and 9-Jun), seed moisture content at harvest time in four levels (30%, 25, 20 and 15) and seed size in three levels (flat, round and medium). The measured traits were a standard germination test, mean time of germination, seedling weight and length vigor index, germination percent in radical emergence test and germination percent in cold test. The results illustrated that delayed planting caused reduction of seed quality and this reduction was more obvious in delayed harvest (15%), also the reduction rate in round seeds was more than flattered and medium seeds. The minimum percentage of germination and vigor were seen in round seeds of third planting date and moisture harvest by 15%. So it is recommended for corn seed production to sow the seeds before the last week of May and when seed moisture content reached 30 percent, cob harvesting should be started and the harvest not is delayed.

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.

In order to study the responses of redstem filaree (Erodium cicutarium L.) seed germination to temperature levels, an experiment was carried out in a completely randomized design with four replications and twelve levels of temperature (0, 3, 5, 7, 10, 12, 15, 20, 25, 30, 35, 40 ⁰C). Results showed that the effect of treatments on germination properties of redstem was significant, so the highest percentage of germination was achieved at 15⁰C and reduced with increasing temperature and was totally inhibited at 40^ºC. Based on a linear regression between germination rate and temperature, the cardinal temperatures: minimum (Tmin), optimum (To) and maximum (Tmax) were determined: 0, 15.20 and 37.18 ºC, respectively. A significant difference was not observed in plumule length at a range of 5-30°C that showed that it is less sensitive to temperature in comparison with root length. Highest wet-dry weight was achieved at 20 °C that was not different by 10, 12 and 20°C. Above results suggest that redstem failure could grow in a wide range of growing conditions, but prefers temperate zones. The results of this study are important to understanding thermal requirements and improvement of management strategies of redstem filaree.

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.

 
 Highlights:

1. Introduction of wheat cultivars with more tolerance to salinity conditions at germination stage.
2. Study of eight different wheat cultivars in terms of germination indices under salinity stress conditions.

1. The effect of nanoparticles kind and concentration on seed germination indices and anthocyanin content of Niger seedling.
2. Investigating the interaction of nanoparticle type and concentration as the physical priming factor of seeds on seed germination of multi-purpose Niger plant.