A CUVETTE SYSTEM DESIGNED TO ENABLE MONITORING OF GROWTH AND SPREAD OF HYPHAE OF VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI EXTERNAL TO PLANT-ROOTS

Vesicular-arbuscular mycorrhizal fungi live in close contact with host plants by forming abundant fungal structures (arbuscules, vesicles, hyphae) among and within the root cells. At the same time the mycelium of the symbiotic fungi spreads externally from the roots to colonize the soil. A cuvette system was used in which the colonization of the trap or the receiver plants separated from the inoculated donor plants by root-free soil compartments, was periodically examined to measure indirectly the spread of external hyphae through soil. The cuvette system has also been used to monitor hyphal spread through field-cut soil monoliths, fitted into the cuvettes. The cuvette system described in this chapter facilitates study of the growth and spread of external vesicular-arbuscular mycorrhizal hyphae. The system is composed of individual cuvette units that may be assembled in many experimental arrangements. The net sandwich separating cuvettes provides sufficient integrity to prevent contamination among units. With careful watering contamination by splashing can be prevented. The cuvettes are in close contact and contain a large volume of soil which reduces variation in moisture and temperature among treatments. The monitoring of the dynamics of spread of external mycorrhizal hyphae using the cuvette technique should ideally be supplemented by biomass studies in which total length of mycelium is measured. © 1992 Academic Press Limited