Dormancy of Sclerotium cepivorum sclerotia in New Zealand soils

Abstract

Sclerotium cepivorum sclerotia require incubation in soil to overcome constitutive dormancy a condition where the sclerotia will not germinate even when stimulated In Trial 1 artificial onion extract diallyl disulphide (DADS) was used to stimulate sclerotial germination of laboratory produced sclerotia after 1 2 and 3 month conditioning periods when incubated in two different soil types The results showed that soil type and fungal isolate did not affect dormancy and that approximately 16 33 and 21 of the sclerotia germinated after 1 2 and 3 month conditioning periods respectively In Trial 2 DADS significantly increased sclerotial germination compared with the control after 2 3 4 5 and 6 month conditioning periods Sclerotia required 6 months in soil before high rates of germination occurred (>89) when stimulated When a natural population of sclerotia (8 weeks old) (Trial 3) was exposed to DADS 51 of the population germinated compared with 21 in the control (Plt;0001)