Genotype- and Experiment-dependent Biomass Stability of Maize Lines B73, EV8728SR, and W438 under Water Deficit and Rhizophagus irregularis Inoculation
Eric-Olivier Tienebo *
Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843-2133, USA and Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
Kan Ulrich Urbain Konan
Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
Echua Elisabeth Jasmine Bilé
Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
Kouadio Kan Arnaud Parfait Koffi
Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
Kouakou Théodore Kouadio
Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
Kouabenan Abo
Unité Mixte de Recherche et d'Innovation - Sciences Agronomiques et Procédés de Transformation (UMRI-SAPT), Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), BP 1093, Yamoussoukro, Côte d'Ivoire.
*Author to whom correspondence should be addressed.
Abstract
Background: Water deficit is a major constraint on maize growth, while the effects of arbuscular mycorrhizal fungi can vary with host genotype and experimental context.
Aims: This study evaluated biomass stability and supporting physiological responses of B73, EV8728SR, and W438 under water deficit with or without Rhizophagus irregularis inoculation.
Study Design: We compared B73, EV8728SR, and W438 in a genotype-complete assay at 100% and 10% soil water-holding capacity (WHC), with non-inoculated (NM) and AMF Rhizophagus irregularis (Ri) treatments, and independently evaluated B73 and EV8728SR across 100%, 50%, and 10% WHC.
Place and Duration of Study: The experiments were conducted under controlled greenhouse conditions at Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), Yamoussoukro, Côte d'Ivoire; the common assay ran from February to March 2024.
Methodology: Total plant dry biomass was the primary endpoint. Positive outcomes were analysed with log-Gaussian factorial models and HC3 Type III tests; proportions were analysed using beta regression. Estimated marginal means were compared among all genotypes within each inoculation × water panel using Tukey adjustment, and biomass tolerance indices were estimated with 2,000 stratified bootstrap resamples.
Results: In the common assay, biomass differed by genotype (F2,37 = 14.74, P < 0.0001) and water regime (F1,37 = 151.58, P < 0.0001), but not by genotype × water (P = 0.410) or genotype × inoculation × water (P = 0.614). EV8728SR had the greatest estimated severe-stress biomass (11.77 g NM; 15.16 g Ri) and the largest stress tolerance index under severe stress (STI; 0.523 NM; 0.659 Ri). In the independent gradient, however, B73 exceeded EV8728SR overall (F1,51 = 10.44, P = 0.0022), while water deficit remained the dominant effect (F2,51 = 43.23, P < 0.0001). Ion leakage showed a water-dependent three-way interaction (χ² = 12.05, P = 0.0024), whereas leaf area showed genotype × water and inoculation × water interactions after multiplicity control. Biomass provided no evidence of a general or genotype-specific Ri buffering effect.
Conclusion: The contrasting genotype ranking between assays demonstrates that drought-tolerance claims should integrate absolute stress biomass, stability indices, and independent validation rather than relying on a single experiment or physiological proxy.
Keywords: Arbuscular mycorrhizal fungi, biomass stability, drought stress, genotype × environment interaction, maize, mycorrhizal responsiveness, Rhizophagus irregularis, stress tolerance index, tissue water fraction, water-holding capacity