MYCORRHIZAL INFECTION AND GROWTH OF TRIFOLIUM SUBTERRANEUM: COMPARISON OF NATURAL AND ARTIFICIAL INOCULA

Abstract

SUMMARYMycorrhizal infection and growth of Trifolium subterraneum have been measured, using plants grown in soil/sand mixtures containing natural inoculum, and plants grown in sterilized soil/sand mixtures to which mycorrhizal T. subterraneum roots were added as an artificial inoculum. As control treatments, plants have been grown in sterilized soil/sand mixtures without the addition of roots, or in soil/sand mixtures with the addition of non‐mycorrhizal roots.In one experiment, the two methods of inoculation resulted in similar increases in leaf numbers and in weight. In the second experiment, the growth responses of plants artificially inoculated were less than those of plants with natural inoculum and this was related to delayed mycorrhizal infection. In the third experiment, mycorrhizal infection was again delayed when artificial inoculum was used: this experiment was terminated before increases in weight occurred. The extent and location of mycorrhizal infection from artificial inoculum depended on the location (in the pots) of the added inoculum. The advantages and disadvantages of these two methods of studying mycorrhizal infection are assessed in relation to the different aims of investigations of the mycorrhizal symbiosis.