Effects of seed priming and water potential on seed germination and emergence of wheat (Triticum aestivum L.) varieties in laboratory assays and in the field

Poor crop establishment is a major problem in wheat production due to low soil moisture. Two experiments were undertaken to determine the effects of seed priming on seed germination and seedling emergence of wheat varieties. The first experiment determined the effects of water potentials (0, -0.01, -0.1, -0.2, -0.5 and -1.5 MPa), seed hydro-priming treatments including non-primed, primed (without seed drying), primed and 12 h drying on seed germination of wheat varieties. The second experiment determined the optimum seed soaking duration in wheat for maximum emergence. The factors used were seed treatment (soaking for 0, 1, 2, 4, 8, 12, 16, 20 and 24 h and 12 h soaking and 12 h drying) and variety. In the first experiment, there was a significant (P < 0.01) interaction between seed treatment and water potentials. Seed germination percent for all the treatments decreased as water potentials decreased. The non-primed seeds had the greatest decrease in germination percent as water potential was lowered. At low water potentials (-0.2 and -0.5 MPa), priming improved the germination of all the varieties. In the second experiment, there was a significant (P < 0.05) seed treatment effect on wheat emergence. Priming resulted in an increased final percent emergence and lower time to 50% emergence when compared with the non-soaked seed. It was concluded that priming wheat seed up to 12 h may be recommended were soil water potential is low enough to limit emergence. Delay of planting after soaking for 12 h did not affect the final emergence.Key words: Seed priming, wheat, water potential, germination rate

Seed Priming of Trifolium repens L. Improved Germination and Early Seedling Growth on Heavy Metal-Contaminated Soil

Abstract Seed priming effects on Trifolium repens were analysed both in Petri dishes and in two soils (one unpolluted soil and a soil polluted with Cd and Zn). Priming treatments were performed with gibberellic acid 0.1 mM at 22 °C during 12 h or with polyethylene glycol (−6.7 MPa) at 10 °C during 72 h. Both priming treatments increased the germination speed and the final germination percentages in the presence of 100 μM CdCl2 or 1 mM ZnSO4. Flow cytometry analysis demonstrated that the positive effect of priming was not related with any advancement of the cell cycle in embryos. Seed imbibition occurred faster for primed seeds than for control seeds. X-ray and electronic microscopy analysis suggested that circular depressions on the seed coat, in addition to tissue detachments inside the seed, could be linked to the higher rate of imbibition. Priming treatments had no significant impact on the behaviour of seedlings cultivated on nonpolluted soil while they improved seedling emergence and growth on polluted soil. The two priming treatments reduced Zn accumulation. Priming with gibberellic acid increased Cd accumulation by young seedlings while priming with polyethylene glycol reduced it. Priming improved the light phase of photosynthesis and strengthened the antioxidant system of stressed seedlings. Optimal priming treatment may thus be recommended as efficient tools to facilitate revegetation of former mining area