The use of arbuscular mycorrhizal inoculum in viticulture is not always positive: a systematic review

Abstract

For more than 70 years, the scientific literature has demonstrated that arbuscular mycorrhizal fungi (AMF) have positive effects on plant growth and stress tolerance. However, AMF have only been widely implemented in agricultural systems in the last decade. Recent reviews indicate AMF are key to the sustainability of viticulture. To explore the universality of the positive effects of AMF inoculation on grapevines, we created a database of the results from 30 publications that performed 169 experiments comparing the development of grapevine plants inoculated with AMF against control vines. We calculated inoculation dependence, as ID = ((mean of inoculated treatment – mean of control)/mean of inoculated treatment) * 100), to compare the effects of AM inoculation on the growth of grapevine plants between different experiments. In most studies, the experimental conditions differed significantly from commercial conditions, since 75% of the studies were conducted under greenhouse conditions and 71.8% of studies compared the growth of inoculated plants with plants growing in a sterilized substrate. High variability was observed in the ID of different response variables, be-tween the various rootstocks tested, and between different species compositions of AMF inoculum, demonstrating that the effects of mycorrhizal inoculation in vineyard growth are highly context dependent. This study demonstrates further research is required to characterize the effects of AMF under field conditions. Moreover, this work indicates that specific trials are needed to determine the effect of particular mycorrhizal strains on individual rootstocks under specific growing conditions before the use of AMF can be recommended to vine-growers.