This study was designed to investigate the effect of different grain priming methods on germination and seedling vigour of wheat cultivar (Gemmiza 9) was performed. Grains were primed for 8, 16 and 24 hours in 13 priming media (water, polyethylene glycol 6000 at 2.5, 5, 7.5 %; CaCl2 at 250, 500, 1000 ppm; ascorbic acid (AsA) at 25, 50, 100 ppm; salicylic acid (SA) at 50, 100, 150 ppm) beside dry grain as a control. In general, it was observed that a priming duration of 24 hr gave the highest values of all duration studied. In addition, results indicated that all grain priming in any priming materials significantly increased seedling vigour index (SVI) represented by germination %, length of seedling and fresh and dry weights of seedling. In most cases, SA at 100 ppm was the most effective in this regard. The greatest germination % was obtained due to 7.5 % PEG; 500 ppm CaCl2; 100 ppm AsA and 100 ppm SA. The highest seedling length was obtained due to 2.5 % PEG; 250 ppm CaCl2; 50 ppm AsA and 100 ppm SA. In addition, seedling dry weight was highest due to 7.5 % PEG; 1000 ppm CaCl2; 50 ppm AsA and 100 ppm SA. The highest SVI values were obtained due to 2.5 % PEG; 250 ppm CaCl2; 50 ppm AsA and 100 ppm SA. These results indicate that priming of grains had a significant effect to promote the germination and seedlings growth of wheat.

The effect of seed priming techniques in improving germination and early seedling growth of Citrullus lanatus Thumb (Water melon) was carried out in Odi, Bayelsa State, Nigeria. This experiment was conducted in a completely randomized design with three replications. The factors examined include four treatment groups of seed priming and control (without priming). The treatment groups include water, Sodium chloride (with concentration of 5 g/l), Ethylenediaminetetraacetic acid (with concentration of 5 g/l) and 1-Naphthaleneacetic acid (with concentration of 1 mg/L) for 12 h, respectively. In this experiment traits such as germination percentage, germination rate, radicle length and plumule length were measured. Data were analyzed by using SPSS (version 20.0) software and the differences between means were compared by Turkey’s HSD post-hoc analysis (P < 0.05). Comparison of seed germination characteristics and seedling vigor of the four different treatment groups showed that seeds primed by water had the highest percentage and rate of germination with 96% and 1.71, plumule length (36.57±9.52) and dry weight of seedling (0.603 g) of watermelon (Citrullus lanatus) except for the radicle length which NAA had the highest but there was no significant difference (p˂0.05) among the treatment. In conclusion, primed seeds with water improved Citrullus lanatus germination potential and seedlings growth.

Rice (Oryza sativa L.) provides about 55–80% of the total calories for people in South Asia, Southeast Asia, and Latin America. Elsewhere, it represents a high-value commodity crop. Change in the method of crop establishment from traditional manual transplantation of seedlings to direct seeding has been adopted in many Asian countries in the last two decades, in view of rising production costs, especially for labor and water. Seed invigoration is ascribed to beneficial treatments, applied to the seeds after harvest but prior to sowing, that improve germination or seedling growth or facilitate the delivery of seeds and other materials required at the time of sowing. Many seed invigoration treatments are being employed in a number of field crops, including rice, to improve seedling establishment under normal and stressful conditions. The treatments used to invigorate rice seed include hydropriming, seed hardening, on-farm priming, osmopriming, osmohardening, humidification, matripriming, priming with plant growth regulators, polyamines, ascorbate, salicylicate, ethanol, osmolytes, coating technologies, and more recently presowing dry heat treatments. In the wake of the day-to-day increasing cost of labor and shortage of water, direct seeding approaches in rice cropping systems are the subject of intensive investigation throughout the world and offer an attractive alternative to traditional rice production systems. In this regard, seed invigoration techniques are pragmatic approaches to achieving proper stand establishment in the new rice culture. They help in breaking dormancy and improving seedling density per unit area under optimal and adverse soil conditions. Induction and de novo synthesis of hydrolases, such as amylases, lipases, proteases; and antioxidants such as catalases, superoxide dismutase and peroxidases are reported to be the basis of improved performance using these techniques. The rice seed priming can be performed by soaking simply in water, a solution of salts, hormones, osmoprotectants, matric strain-producing materials, and other nonconventional means. Despite certain limitations, such as water potential, oxygen and temperature, rice seed invigoration has been worthwhile in improving rice yield and quality. Nevertheless, in-depth studies are imperative for understanding the physiological and molecular basis of rice seed priming.

Rapid seed germination and stand establishment are critical factors to crop production under salt‐stress conditions. In many crop species, seed germination and early seedling growth are the most sensitive stages to salinity stress. Salinity may delay the onset, reduce the rate, and increase the dispersion of germination events, leading to reductions in plant growth and final crop yield. The adverse effects of salt‐stress can be alleviated by various measures, including seed priming (a.k.a. pre‐sowing seed treatment). The general purpose of seed priming is to partially hydrate the seed to a point where germination processes are begun but not completed. Most priming treatments involve imbibing seed with restricted amounts of water to allow sufficient hydration and advancement of metabolic processes but preventing germination or loss of desiccation tolerance. Treated seeds are usually redried before use, but they would exhibit rapid germination when re‐imbibed under normal or stress conditions. Various seed priming techniques have been developed, including hydropriming (soaking in water), halopriming (soaking in inorganic salt solutions), osmopriming (soaking in solutions of different organic osmotica), thermopriming (treatment of seed with low or high temperatures), solid matrix priming (treatment of seed with solid matrices), and biopriming (hydration using biological compounds). Each treatment has advantages and disadvantages and may have varying effects depending upon plant species, stage of plant development, concentration/dose of priming agent, and incubation period. In this article, we review, evaluate, and compare effects of various methods of seed priming in improving germination of different plant species under saline and non‐saline conditions. We also discuss the known metabolic and ultra‐structural changes that occur during seed priming and subsequent germination. To maximize the utility of various seed priming techniques, factors affecting their efficiency must be examined and potential benefits and drawbacks determined. For example, quality of the seed before treatment, concentration/dose of priming agent, time period for priming, and storage quality of the seed following priming treatment must be carefully determined. Furthermore, such assessments must be based on large‐scale experiments if seed priming is to be used for large‐scale field planting. A better understanding of the metabolic events that take place in the seed during priming and subsequent germination will improve the effective application of this technology. The incorporation of advanced molecular biology techniques in seed research is vital to the understanding and integration of multiple metabolic processes that can lead to enhanced seed germination, and consequently to improved stand establishment and crop yield under saline and non‐saline conditions.

In order to evaluate the effect of seed priming on seedling emergence, grain yield and yield components of wheat, a 2-year experiment was conducted at Seed and Plant Certification & Registration Institute (SPCRI) in Karaj, Iran, from 2008-2010. Two cultivars (Azar-2, Sardare-101) × four priming media and control (unsoaked) were used in this experiment in field. Seeds were primed for 12 hour and 20°C in four priming media (PEG 10%, KCl 2%, KH2PO4 0.5%, distilled water) and control. Results of comparing means showed that osmotic priming with PEG10% had positive significant effects on emergence percentage, straw, grain and biological yield compared to other seed priming treatments (KCl 2%, KH2PO4 0.5% and distilled water). It was recognized that the maximum straw, biological yield, kernel weight, number of spikes per m 2 was obtained from Sardari-101 meanwhile the highest number of kernels per spike was achieved from Azar-2. Results of interaction between year × seed priming treatment showed that maximum seed yield was obtained from PEG 10% and Sardari-101 (with average of 420 gr/m2 ).