Structural analysis of “annual ryegrass” (Lolium multiflorum Lam.) leaves under alkaline stress conditions

Abstract

Halomorphic soils, widespread in many regions globally, pose significant agricultural challenges due to their high salinity and sodicity. These conditions create unfavorable environments for crop cultivation, especially forage species. In this context, the demand for sodic- and salt-tolerant plants is rising as aridity intensifies worldwide. Lolium multiflorum Lam. (annual ryegrass), a cold-season forage grass, is recognized for its high nutritional value, palatability, and potential uses in medicinal applications and bioethanol production. The anatomical adaptations of ryegrass under sodic stress remain insufficiently explored. This study aimed to investigate the effect of sodic soils on the leaf anatomy of L. multiflorum, focusing on micrometric parameters in the epidermis and cross-sections of leaves. The experiment was conducted with 35 genotypes of L. multiflorum grown in controlled conditions: one group in typical argiudol soils without restrictions and another in halomorphic soils with high pH (9.4) and electrical conductivity (3.74 dS/m). Leaf samples were collected and analyzed using light microscopy. Measurements included leaf thickness, mesophyll cell dimensions, epidermal thickness, stomatal size, and bulliform cell parameters. Results showed significant anatomical changes in plants grown in sodic soils. Notable findings included increased dimensions of bulliform and sheath cells linked to improved water conservation and stress adaptation. Conversely, the size of mesophyll and stomatal cells decreased, which aided in minimizing water loss while maintaining stomatal density and index, thereby ensuring sufficient gas exchange. These changes highlight the adaptive strategies of L. multiflorum to tolerate sodic conditions. This research contributes to understanding the morpho-anatomical adaptations that enhance plant resilience in challenging environments. Identifying anatomical traits associated with stress tolerance lays the groundwork for selecting and breeding genotypes suited to halomorphic soils. These insights are critical for developing sustainable agricultural practices and ensuring forage productivity in regions affected by soil salinity and sodicity. Ultimately, this study underscores the potential of L. multiflorum as a promising species for cultivation in degraded soils, offering a sustainable solution to the global challenge of increasing aridity and environmental stress.EEA PergaminoFil: Gonzalez, Ana J. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Cultivo de Tejidos Vegetales; ArgentinaFil: Lagraña, Aldana A. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Cultivo de Tejidos Vegetales; ArgentinaFil: Acuña, Mariela Luciana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Mejoramiento genético de especies forrajeras; ArgentinaFil: Acuña, Mariela Luciana. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Escuela de Ciencias Agrarias, Naturales y Ambientales; ArgentinaFil: Pistorale, Susana M. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Cultivo de Tejidos Vegetales; ArgentinaFil: Pistorale, Susana M. Universidad Nacional del Noroeste de la provincia de Buenos Aires. Escuela de Ciencias Agrarias, Naturales y Ambientales; ArgentinaFil: Larraburu, Ezequiel E. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Cultivo de Tejidos Vegetales; ArgentinaFil: Larraburu, Ezequiel E. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin