Evaluating Seed Surface Disinfection Methods Using a New Apparatus

Results of germination experiments can be affected by contamination of seeds by fungi
and bacteria. Seed surface disinfection is a useful method of reducing seed contamination. M. Pahl of the Alberta Environmental Centre has developed an apparatus to facilitate the disinfection of many seed lots at one time. This experiment was conducted to evaluate several methods of seed disinfection using this apparatus. Four native grass species, broadglumed wheatgrass (Agropyron violaceum), Festuca brachyphylla, alpine bluegrass {Poa alpina), and spike trisetum {Trisetum spicatum) were used. Seeds of each species were subjected to surface disinfection using 0.5, 1.0, 1.5, and 2.0 % sodium hypochlorite (NaOCl) solutions, with and without the surfactant Tween 80. Seeds were immersed for 5, 10, or 15 min. One seed lot of each species was not given any treatment and was used as a control. An alcohol pretreatment prior to surface disinfection was also used for some treatments. In addition, several seed lots that were not surface disinfected were treated with the fungicides Vitaflo 280 Fl (14.9% carbathiin and 13.2% thiram), Vitavax Single Solution (23% carbathiin), and Captan (80% captan). Seeds were germinated on filter paper in petri dishes and germination was recorded until day 28. Treatments were arranged factorially within a randomized complete block design. For species studied in this
experiment, a concentration of 2% NaOCl for 10 min provided acceptable surface disinfection without affecting germination. The addition of Tween 80 to the NaOCl solution did not improve disinfection. An alcohol pretreatment prior to disinfection with NaOCl reduced contamination but in some cases it had a detrimental effect on germination rate. Fungicides applied to seed reduced germination and/or germination rate even though they effectively controlled contamination in most cases.