1Department of Crop Science, School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana
2Centre for Resource Management and Environmental Studies (CERMES), The University of the West Indies, Cave Hill Campus, P.O. Box 64, Bridgetown BB11000, Barbados
3Department of Soil Science, School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana
| Received 05 Jul 2022 |
Accepted 17 Oct 2022 |
Published 15 Dec 2022 |
Due to roots’ physical and physiological roles in crop productivity, interest in root system architecture (RSA) and plasticity in responses to abiotic stresses is growing. Sorghum is significant for the food security of millions of people. Phosphorus deficiency is an important limitation of sorghum productivity. There is little information on the RSA-based responses of sorghum to variations in external P supply ([P]ext). This study evaluated the phenotypic plasticity and RSA responses to a range of [P]ext in 2 sorghum genotypes. The results showed that both genotypes responded to [P]ext but with significant variations in about 80% of the RSA traits analyzed. Aboveground biomass and most RSA traits increased with increasing [P]ext. Plasticity was both genotype- and trait-dependent. For most RSA traits, the white sorghum genotype showed significantly higher plasticity than the red genotype, with the former having about 28.4% higher total plasticity than the former. RSA traits, such as convex area, surface area, total root length, and length diameter ranges, showed sizeable genetic variability. Root biomass had a high degree of plasticity, but root number and angle traits were the leading contributors to variation. The results suggested 2 root trait spectra: root exploration and developmental spectrum, and there was an indication of potential trade-offs among groups of root traits. It is concluded that RSA traits in sorghum contribute to variability and plasticity in response to [P]ext. Given that there might be trade-offs among sorghum root traits, it would be instructive to determine the fundamental constraints underlying these trade-offs.
