title: Effects of substrate water potential in root growth of Agave salmiana Otto ex Salm-Dyck seedlings.
abstract: The objective of this study was to test the hypothesis that root of maguey (Agave salmiana Otto ex Salm-Dyck) seedlings reacts during the first 24 h to low substrate water potential (PsiW), by anatomical modifications. Three-4 cm root length seedlings were planted in vermiculite for 24 h at PsiW between -0.03 and -2.35 MPa. Root dimensions, proline content and anatomy were evaluated. Substrate PsiW between -0.65 and -2.35 MPa did not significantly affect longitudinal root growth. However, proline content significantly increased from 1.6 to 2.1 micromoles mg(-1). Significant reductions of transverse root area (41%), thickness of mucilage covering the epidermis (47%), thickness of epidermis (between 15 and 46%), area of the parenchyma (between 35 and 41%) and number of vessels (up to 28%) were observed with PsiW of -2.35 MPa. In contrast, thickness of xylem wall, diameter of xylem vessels and the number of cells of the cortex of the differentiation root region significantly increased (64, 17, and 97%, respectively). The anatomical changes associated with low substrate PsiW indicate a net increase of root apoplatic paths; structures involved in water conduction increased their diameter under low substrate PsiW conditions and anatomical changes occurred during the first 24 h of water stress.
authors.affiliation: Botánica, Colegio de Postgraduados, Km 35.5 Carretera México-Texcoco, Montecillo, México-Texcoco, México 56230. cecilia@colpos.mx
authors.forename: Cecilia B
authors.initials: CB
authors.lastname: Peña-Valdivia
authors.forename: Adriana B
authors.initials: AB
authors.lastname: Sánchez-Urdaneta
mesh_terms: D027882:Agave / Q000254:growth & development* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D036226:Seedlings / Q000254:growth & development* / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water