Tavares, G. I. S. | Search bioRxiv

bioRxiv2026

Phenotyping maize seed tolerance to storage after seed treatment using a Seed Treatment Tolerance Index

Neonicotinoid seed treatments protect maize during early growth but can induce phytotoxicity that intensifies during storage. Despite recognized genotypic variation in tolerance, standardized phenotyping methods are lacking. We evaluated nine commercial maize hybrids under three seed treatments (control, one neonicotinoid [1N], and two neonicotinoids [2N]) across two storage periods (0 and 6 months at 25 {degrees}C) using germination, accelerated aging, and cold tests. A Seed Treatment Tolerance Index (STTI) was analyzed through hierarchical clustering, principal component analysis, and multivariate analysis of variance. Results showed a significant triple interaction among genotype, seed treatment, and storage. Hybrids from female line A maintained STTI above 0.95, while female C hybrids showed germination reductions up to 48 percentage points and vigor losses up to 90 percentage points under 2N after six months. Tolerance was associated with hydrogen peroxide regulation by catalase and ascorbate peroxidase. The STTI proved a reliable tool for classifying genotypic tolerance, with direct applications for breeding programs and seed industry logistics.

plant biology↗

bioRxiv2026

Variability amongst maize genotypes treated with neonicotinoid and stored

Neonicotinoid insecticides used in seed treatment present phytotoxic potential that may accelerate seed deterioration during storage; however, how this effect interacts with genotype remains poorly understood. We evaluated the physiological quality of five maize genotypes sourced from the Maize Breeding Programme of the Federal University of Lavras, comprising three inbred lines (L44, L91 and L64) and two half-sib hybrids (H44 and H91), treated with a neonicotinoid-based insecticide formulation (thiamethoxam and cyantraniliprole) and stored for up to nine months at 25{degrees}C. Physiological quality was assessed through germination on rolled paper + vermiculite, cold test, primary root length, a phytotoxicity index, projection pursuit multivariate analysis, and scanning electron microscopy of pericarp and aleurone layer. Insecticide treatment reduced germination and increased phytotoxicity indices, with inbred line L44 showing the most severe response, reaching phytotoxicity values up to 15.89 percentage points above hybrid H91 at six months of storage. Scanning electron microscopy revealed that L44 presented a thinner pericarp and pronounced aleurone layer disorganisation following treatment, whilst L91 remained structurally preserved. Tolerance to post-treatment storage is highly genotype-dependent, and pericarp thickness may represent a useful morphological marker for selecting tolerant genotypes in maize breeding programmes.

plant biology↗