Influence of pre‐storage drying conditions and duration of storage on the effectiveness of root inoculum of Glomus aggregation 1

Abstract

A greenhouse experiment was undertaken to evaluate the influence of pre‐storage drying treatments and duration of storage on the effectiveness of root inoculum of Glomus aggregatum. Conditions under which roots were dried prior to storage had little or no effect on the level of arbuscular mycorrhizal (AM) effectiveness measured in terms of pinnule phosphorus (P) content of Leucaena leucocephala leaves after the first 14 days of storage. As duration of storage was further prolonged the time required by root inocula for initiating AM effectiveness and attaining peak levels of effectiveness was progressively prolonged relative to that required by the crude inoculum. However, the two sources of inoculum had similar peak AM effectiveness in many instances. Roots dried in the greenhouse or in the oven at 40°C were significantly inferior to that dried at 60°C. Root inocula stimulated growth of the indicator plant to the same extent as the crude inoculum after 14 days of storage. However, the effectiveness of root inocula in stimulating growth declined with further increase in duration of storage. Among root inocula tested, that dried at 60°C prior to storage was relatively more effective than that dried in the greenhouse or in the oven at 40°C. The overall inferiority of root inocula to that of the crude inoculum appears to be related to loss of viability of root inocula with increase in duration of storage.