Optimising the medium for producing arbuscular mycorrhizal spores and the effect of inoculation on grapevine growth

Abstract

Arbuscular mycorrhizae form obligate symbioses with the majority of vascular plants Propagation of these fungi relies on maintenance of pure pot cultures typically sterile sand supplemented with a nutrient solution is used However river sand is inappropriate for New Zealand species as it is denser than soils and prone to water logging Three different media (silica sand pumice and potting mix) at two particle sizes (5001000 micro;m and 10001400 micro;m) were mixed in nine combinations for the propagation of arbuscular mycorrhizae spores The results showed that the silica sand/pumice medium (5001000 micro;m bulk density of 1) produced the greatest (Plt;001) number of spores (170/ml of substrate) The density of the media had the greatest effect on spore formation Inoculations of grapevines with spores derived from these cultures significantly improved both root and shoot growth