Genotype-dependent Germination and Rhizophagus irregularis-associated Biomass Responses to NaCl in B73 and West African EV8728SR Maize Lines

Abstract

Aims: To determine how maize genotype, Rhizophagus irregularis inoculum, and NaCl affect germination and seedling performance, while distinguishing inoculum effects before root colonisation from responses after mycorrhizal establishment. Study Design: A 2 × 2 × 3 factorial experiment compared B73 and EV8728SR, R. irregularis inoculum or a non-mycorrhizal control, and 0, 68, or 102 mM NaCl. Place and Duration of Study: The five-day germination assay and subsequent greenhouse experiment were conducted at the Institut National Polytechnique Félix Houphouët-Boigny, Yamoussoukro, Côte d’Ivoire. Methodology: The germination assay used three independent dishes per combination; most greenhouse endpoints used 11 independent pots per combination. Responses included final germination, mean germination time (MGT), germination speed index (GSI), biomass, morphology, chlorophyll, electrolyte leakage, tissue water content, and root colonisation. Endpoint-appropriate factorial models and Tukey-adjusted comparisons were applied. Results: Final germination was statistically uninformative. EV8728SR germinated faster than B73 (MGT and GSI, P < 0.001), and GSI declined with NaCl (P = 0.019). Total dry biomass showed effects of genotype (P < 0.001), inoculum (P = 0.007), and NaCl (P < 0.001), with no significant interactions. At 102 mM, the descriptive Ri-associated biomass differences were 40.7% in B73 and 38.2% in EV8728SR. Mycorrhization intensity declined with NaCl (P = 0.011). Conclusion: EV8728SR was the stronger-performing genotype, and Ri inoculation produced a modest average biomass benefit. Because interactions were not significant, the larger percentage differences at severe salinity are descriptive. Germination responses represent the inoculum treatment, not established symbiosis.