Response of Grapevine Rootstocks to Soil Inocula from Different Sources

Abstract

Although arbuscular mycorrhizal (AM) fungal inoculants are widely used as bioinoculants in plant nurseries, it is not clear whether this practice is beneficial for grapevine rootstocks. Here, a greenhouse study was conducted to compare the effects of locally sourced soil microbial inocula with two commercial mycorrhizal inocula on root colonization and early growth and physiology of grapevine rootstocks Riparia Gloire, 101–14 Mgt and SO4. Mycorrhizal colonization varied widely; the greatest colonization (63%) occurred with a commercial inoculum, followed by a local inoculum composed of native-plant root fragments (19%). The other inocula produced poor or no colonization. Colonization by a commercial and a local inoculum increased leaf greenness in SO4 vines. Greater root and shoot biomass and shoot length were observed in Riparia Gloire and 101-14 Mgt vines treated with local inocula compared to commercial inocula. The inconsistent effects among rootstocks and inocula indicate that the effectiveness of mycorrhizal inocula for enhancing plant growth is unpredictable.