Effects of native and nonnative arbuscular mycorrhizal fungi on growth and nutrient uptake of 'Pinot noir' (Vitis vinifera L.) in two soils with contrasting levels of phosphorus

The influence of arbuscular mycorrhizal fungi (AMF) on growth and nutrient uptake by 'Pinot noir' grapevine cuttings was studied in an alluvial valley soil (Chehalis series, Mollisol) and a red-hill soil (Jory series, Ultisol) to better understand the role AMF play in vineyards planted in different soils with contrasting levels of available P. The first experiment compared plant response in both soils to a mix of AMF species (Glomus mosseae, Glomus intraradices, and Scutellospora calospora) isolated from Jory soil. Results showed that vine growth was heavily dependent on AMF in Jory soil, but inoculated and non-inoculated vines grew equally well in Chehalis soil. The increase in plant dry mass (274%) of 'Pinot noir' grown with AMF in Jory soil was primarily due to enhanced P uptake (833% increase). Uptake of most other nutrients was also enhanced by AMF in Jory soil. Sulfur was the only nutrient taken up in greater quantity by AMF vines in Chehalis soil. Root colonization by AMF was lower in Chehalis soil compared to Jory soil. A second experiment compared plant response in both soils to either native or nonnative G. mosseae isolated from each respective soil type. Vine growth in Chehalis soil was not affected by either G. mosseae isolate, although both isolates increased P and Zn uptake and the native isolate enhanced Cu and S uptake by 'Pinot noir'. Both G. mosseae isolates enhanced vine growth in Jory soil, primarily due to improved P uptake; however, the nonnative isolate of G. mosseae colonized roots to a greater degree and was more effective in promoting growth and nutrient uptake than the native isolate. Results from these experiments show that 'Pinot noir' is dependent on AMF to obtain enough P for normal growth in red-hill soils, while growth in valley soils is not dependent on AMF, even though P uptake can be improved by AMF in this soil. Native or nonnative G. mosseae isolates performed equally well in promoting P uptake in Chehalis soil, however, the Chehalis soil fungus outperformed the Jory soil fungus in promoting P uptake in Jory soil and Cu and S uptake in both soils.