Physiological quality of Urochloa brizantha seeds submitted to priming with calcium salts

ABSTRACT Seed priming provides a variety of benefits, including seed invigoration and reduced dormancy. Urochloa brizantha seeds are typically primed with difficult-to-acquire potassium nitrate (KNO3). In this sense, calcium salts stand out as an alternative, but it is important to determine whether they provide the same benefits as potassium nitrate. This study aimed to evaluate the physiological quality of U. brizantha seeds after priming with calcium salts, and compare the results to those obtained with potassium nitrate. Seeds were submitted to priming with calcium nitrate [Ca(NO3)2] and calcium sulphate (CaSO4) at -0.55 MPa and -1.10 MPa, for 12 h and 24 h, and potassium nitrate (KNO3) at -1.10 MPa for 12 h, as well as to no priming (control). A completely randomized design, with ten treatments and four repetitions, was used. Priming promoted a higher germination percentage and lower seed dormancy, with a greater seedling emergence in a shorter time period. CaSO4 did not differ from KNO3 in shoot dry weight of seedlings, but reduced the electrical conductivity of seeds. Calcium nitrate and calcium sulfate show a promising potential for use in the osmotic priming of Urochloa brizantha (BRS Piatã cultivar) seeds, since they are as efficient as potassium nitrate, as well as less costly and easier to purchase. Calcium sulfate priming at -0.55 MPa for 12 h, at 25 ºC, is recommended to replace the potassium nitrate solution.