The use of sterilised millet seed as a substrate for the long-term preservation of Rhizoctonia cultures by the L-drying method

Abstract

The effectiveness of the L-drying method of lyophilisation for long-term preservation of different groups of Rhizoctonia, using sterilised, colonised millet seed as a substrate, was compared with colonised wheat straw. The L-drying method proved to be highly successful for long-term preservation of 16 isolates from a wide range of different Rhizoctonia groups. The recovery of 13 Rhizoctonia isolates from vacuum-sealed ampoules of L-dried colonised millet was generally excellent and comparable with the recovery of seven isolates from L-dried colonised wheat-straw pieces. For a few isolates on either substrate, recovery was poorer after heat treatment for 1h at 100°C compared to 1 h at 25, 50 or 75°C. Colonised millet seed provided more propagules per ampoule than colonised wheat straw.