Investigating soil-root interactions and mucilage secretion under varying soil mechanical resistance in maize cultivars

Background and aim This study explores how variations in soil mechanical resistance (SMR) impact two maize cultivars, 703 and 704, with a specific focus on root mucilage secretion and associated plant responses. Understanding these dynamics is crucial for optimizing crop growth in soils with varying compaction levels. Methods SMR was systematically manipulated through soil compaction at five different bulk density levels (1.56, 1.6, 1.66, 1.69, and 1.71 Mg m(-3)) and through cementation in loamy sandy soil while keeping the matric potential constant. This approach allowed for a controlled analysis of how increased soil resistance influences maize root development and physiological responses. Results Increased SMR resulted in increased mucilage exudation, which initially seemed to mitigate resistance to root penetration. However, when the SMR reached specific thresholds (bulk density > 1.6 Mg m(-3) or SMR > 1.8 MPa), root water uptake was significantly reduced beyond this point. Additionally, soil cementation consistently impedes plant growth. A significant correlation was observed between SMR, mucilage exudation, and total root water uptake (TRWU), suggesting that mucilage secretion plays a critical role in managing root interactions with compacted soils. Conclusions This study did not identify a specific SMR threshold at which plant responses abruptly change. Instead, mucilage exudation metrics may serve as indicators of critical SMR limits. Analyzing the properties of root mucilage provides valuable insights into SMR thresholds, offering potential strategies for improving crop resilience under varying soil conditions.