Laboratory Germination and Sand Emergence Responses of Alfalfa Seed to Radiofrequency Electrical Treatment1

Abstract

The use of radiofrequency (RF) dielectric heating was studied for rendering hard seeds of alfalfa (Medicago sativa L.) permeable to water. The treatment increased laboratory germination and greenhouse‐sand emergence of several alfalfa seed lots that contained high percentages of hard seed. The treatments produced corresponding reductions in hard‐seed percentages and, at proper exposures, did not damage seed viability. At moisture contents from 2.7 to 9.8%, effectiveness of treatment improved as seed moisture content was lowered before treatment. At normal contents of seed moisture (about 6 to 8%), treatments that reduced hard seed content without detrimental effects resulted in final seed temperatures of about 70 to 80 C. Greenhouse‐sand emergence tests and normalseedling counts in laboratory germination tests were generally in good agreement. Numbers of abnormal seedlings in treated and untreated samples were not significantly different. Quality of RF‐treated seed, maintained in storage at 4 C and 50% relative humidity for up to 15 years after treatment, was as good as that of untreated control seed.