Iron acquisition by mycorrhizal maize grown on alkaline soil

Abstract

Vesicular‐arbuscular mycorrhizal fungi (VAMF) are known to improve the mineral nutritional status of plants. Since information on effects of VAMF on plant iron (Fe) nutrition is limited, an Fe deficient‐susceptible maize (Zea mays L., ysi/ysi) was grown on alkaline Quinlan (Typic Ustochrept, pH 8.0) and Ulysses (Aridic Haplustoll, pH 7.8) soils with Glomus VAMF isolates G. etunicatum WV579A (Ge), G. diaphanum WV579B (Gd), and G. intraradices WV894 (Gi) to determine plant growth responses to VAMF associations and efficacy of these VAMF isolates to enhance Fe acquisition. Shoot and root dry matter (DM) were higher in mycorrhizal (+VAM) then in nonmycorrhizal (‐VAM) plants, and followed a sequence of Ge > Gd ≥ Gi > ‐VAM. Root DM of Ge plants was higher than other +VAM plants. Even though relatively low, leaf chlorophyll (SFAD unit) readings were higher in +VAM than in ‐VAM plants and followed a sequence similar to DM. Plants colonized with Gi had higher leaf Fe, phosphorus (P), and zinc (Zn) concentrations and contents than other +VAM as well as ‐VAM plants. Leaf concentrations and contents of other mineral nutrients had few changes among +VAM plants, but some differences between ‐VAM and +VAM plants were noted. The VAMF isolates improved Fe acquisition in maize grown under severe Fe deficiency conditions, but benefits to this fast growing plant was not sufficiently large to recommend that it be grown on fields where Fe deficiency is prevalent. Improved host plant root development and morphology and acquisition of P may have been involved in enhanced Fe acquisition by +VAM plants.