Percent Moisture and Seed Coat Characteristics of Alfalfa Seeds After Artificial Inoculation

Percent moisture and seed coat characteristics of alfalfa seeds after artificial inoculation

Kathleen T. Rajkowski

U. S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038

ABSTRACT

Naturally contaminated seeds have low pathogen levels.  Most reports on sanitizing efficacy used artificially inoculated seeds.  There is no standard procedure for artificially inoculating seeds with bacteria pathogens.  This study compared 15 published inoculation procedures as they impact the percent moisture of alfalfa seeds. The percent moisture after drying was similar for the 15 procedures, verifying that the inoculation method had no effect.  Using white and UV fluorescent light at 360 nm the physical characteristics of different alfalfa varieties’ seed coats were examined.  Exposed cotyledon fluoresced under the UV light making viewing of wrinkled, broken and cracked seed coats easier. The effects of wetting and drying on broken or cracked seed coats were photographed.  During inoculation, cracks or breaks in the seed coats became more pronounced and curled away from the cotyledon, thus bacteria cells in the inocula became trapped in the cracks or under the seed coat.  Upon drying the seed coat did not return to the original position.  Condition of the seeds used for artificial inoculation would therefore be expected to impact the result of a decontamination procedure.  Examination of seed lots using the UV fluorescent light could potentially be used to remove the cracked and wrinkled seeds.