Different plant species exhibit contrasting root traits and penetration to variation in soil bulk density of clayey red soil

Abstract

AbstractHigh bulk density reduces yields in almost every soil and management system worldwide. Using pioneer plants was one of the practical solutions to remediate the adverse effects from high bulk density. The objectives of this research were to investigate the effect of soil bulk density on root traits and penetration of different pioneer plants (rape [Brassica napus L. cv. Huashuang 4]; deep rape [Brassica napus L. cv. Xinan 28]; lucerne [Medicago sativa L. cv. Ladino]; vetiver [Chrysopogon zizanioides L. cv. Wild]) under controlled and field conditions. Replicated field and laboratory studies were conducted in a soil composition of high clay percentage, high oxides content, and low organic matter content. Seedling and matured root traits of four plants under contrasting bulk density in controlled study and field were analyzed. Under controlled situations, soil with a bulk density of 1.4 g cm–3 had thicker roots (higher diameter) than soil with a bulk density of 1.2 g cm–3, whereas soil with a bulk density of 1.6 g cm–3 had reduced root lengths (RL), branch number, root tip angle, and root elongation rate than soil with a bulk density of 1.4 g cm–3. Similar changes of root diameter (RD) and root length density (RLD) with bulk density also appeared in the field. Generally, the penetration ability of plant species displayed in the order of vetiver > lucerne > deep rape > rape. Vetiver showed the highest penetrating ability due to its high RD (0.7 mm in field), percentage of medium roots (20–50%) and RLD, and small root tip angle to ensure penetration through hard layers. The results demonstrated that vetiver will be an effective pioneer plant for red soil management.