Exploring rhizosheath formation as a target trait for selecting Sorghum bicolor adapted to combined drought and heat stress

Abstract Although rhizosheath formation (RF) is linked with plant abiotic stress tolerance, it remains neglected and underutilized in plant breeding, yet it could be a selection target trait. A study was conducted at two sites under combined drought and heat stress (CDHS) conditions investigating how root system architectural (RSA) traits, rhizobacteria relative abundance and soil chemical properties associated with RF in sorghum. Six genotypes, i.e., three pre-release lines and three check varieties were laid out at two sites, in a randomized complete block design (RCBD) with two replications. RF, 16 S rRNA amplicon sequencing, RSA traits, soil chemical properties and grain yield (GY) data were collected. RF significantly ( P < 0.05) varied with sorghum genotypes and correlated ( r = 0.456) with GY performance. In addition, RF exhibited up to 94% trait heritability and greater variability than GY. RSA traits, rhizobacteria relative abundance and soil chemical properties significantly associated with RF explaining up to 90.46% variation and achieving up to 84.78% K-fold_R 2 value suggestively demonstrating good model generalization ability to unseen data. Study findings suggest the possible application of RF as a target trait in sorghum selection for adaptability to CDHS, specifically at post-flowering crop growth stage. The pre-release genotype i.e. ICSV111IN, exhibited high stable GY performance and RF superiority. The winning genotype can be recommended for further field yield testing for possible release targeting stress-prone agro-ecologies. Evidence generated from this study could help guide breeders on how RF can be applied as a target trait in plant selection.