Sorghum genotypes grown in simple rhizotrons display wide variation in root system architecture traits

Abstract Aims Root system architecture (RSA) plays a crucial role in determining the efficiency of absorbing water in the different soil layers. Studies on the RSA, however, are limited partly because plant roots are found underground and difficult to observe them during plant development. This study aimed to assess the variation in the RSA traits of sorghum landraces at the seedling stage. Methods A set of one hundred sixty diverse sorghum genotypes were grown in soil-based rhizotrons and data on nodal root angles (NRA), days to nodal root emergence (DNRE), number of nodal roots (NNR), nodal root length (NRL), fresh root weight (RFW), dry root weight (DRW), root-to-shoot ratio (RSR), fresh shoot weight (FSW), dry shoot weight (DSW), leaf area (LA) were collected. Results The analysis of variance revealed the presence of high variation among genotypes for all the studied traits. Repeatability of the RSA traits ranged from 44.8% for RSR to 85.2% for NNR. The wide variation ranging from 16.3° to 53.0° and heritability (63.1%) of the nodal root angles allow the selection of desirable genotypes adapted to drought environments. Several diverse sorghum genotypes with narrow and wide nodal root angles were identified. Genotypes with narrow nodal root angles such as G141, G100, and G63 could be prioritized for use in developing cultivars suitable for dry areas. Conclusions This study illustrates the presence of promising sorghum genotypes in terms of RSA traits, which should be utilized for the development of novel cultivars that match cultivation environments differing in water availability.