Main content area

Inoculation with arbuscular mycorrhizal fungi has a more significant positive impact on the growth of open-pollinated heirloom varieties of carrots than on hybrid cultivars under organic management conditions

Keller-Pearson, Michelle, Liu, Yang, Peterson, Annika, Pederson, Kaley, Willems, Luke, Ané, Jean-Michel, Silva, Erin M.
Agriculture, ecosystems & environment 2020 v.289 pp. 106712
Daucus carota, Glomus mosseae, Rhizophagus intraradices, breeding programs, carrots, cultivars, farmers, farms, genotype, heirloom varieties, hybrids, intraspecific variation, mycorrhizal fungi, open pollination, organic foods, organic production, plant breeding, production technology, symbionts
To meet the high demand for organic produce, farmers must select crop cultivars that perform well under the low-input conditions of organic production systems. Most cultivars grown on organic farms are genotypes selected through conventional breeding programs, which may impact responsiveness to microbial symbionts. The use of biological inputs such as mycorrhizal inoculants offers the promise of improving yield, quality, and stress-responsiveness of crops, but evidence of efficacy in the field remains elusive. Moreover, interspecific and intraspecific variability may impact the ability of mycorrhizal inoculants to provide benefits. This work evaluated four cultivars (two heirlooms and two hybrids) of carrots and their propensities to benefit from inoculation with isolates of arbuscular mycorrhizal fungi in organic field conditions with and without late-season water restriction. Inoculants included geographically-distinct isolates from four species (Funneliformis mosseae, Rhizophagus clarus, Rhizophagus intraradices, and Septoglomus deserticola). Heirloom cultivars demonstrated a higher propensity to benefit compared to hybrid cultivars from inoculation with arbuscular mycorrhizal fungi. We observed benefits and costs with respect to yield associated with inoculation within four experiments over twoditions. Breeding histories of plant genotypes likely contribute to their mycorrhizal responsiveness.