Does Primed Seed Improve Stand Establishment and Yield of Broccoli?

Abstract

The effect of matric and osmotic seed priming on stand establishment and maturity of broccoli (Brassica oleracea L. var. italica) was investigated in three years at two locations in Virginia. Seeds (`Earlidawn') were primed at 1.1 MPa (68F for 7 days) either osmotically in polyethylene glycol (8000 molecular weight) or metrically in vermiculite (horticultural grade no. 2). In the frost year of the study, seeds were hand-seeded in August into crustprone soil with a mean temperature of 82F, and there were no differences in the percentage or mean time of seedling emergence between osmotic- and matric-primed seeds. Under cooler temperatures during the remaining two years of the study, priming increased the percent emergence and decreased the mean time of emergence by about 15 hours. Primed seeds did not increase yields or accelerate maturity in two out of three years. In the third year, the spread of seedling emergence times was less for primed seeds, which reduced plant-to-plant competition and hastened maturity. The primary benefit of primed broccoli seeds was faster emergence, which increased stands by reducing exposure to stresses that decrease emergence.