Formation and stabilization of rhizosheaths of Zea mays L.: effect of soil water content

• Published in: Plant physiology (Bethesda) 1994-09, Vol.106 (1), p.179-186
• Main Authors: Watt, M. (Carleton University, Ottawa, Canada), McCully, M.E, Canny, M.J
• Format: Article
• Language: English
• Subjects: ABSORCION DE SUSTANCIAS NUTRITIVAS; ABSORPTION DE SUBSTANCES NUTRITIVES; Agricultural soils; ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; Arid soils; CONTENIDO DE AGUA EN EL SUELO; Corn; Desert soils; Environmental and Stress Physiology; EPIDERME; EPIDERMIS; ETAPAS DE DESARROLLO DE LA PLANTA; Pedogenesis; PELOS RADICALES; Plant roots; Plants; POIL ABSORBANT; RACINE; RAICES; Root hairs; Soil water; Soil water content; STADE DE DEVELOPPEMENT VEGETAL; TENEUR EN EAU DU SOL; TRASTORNOS DEL CRECIMIENTO; TROUBLE DE LA CROISSANCE; ULTRAESTRUCTURA; ULTRASTRUCTURE; ZEA MAYS
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.106.1.179

Field observations have shown that rhizosheaths of grasses formed under dry conditions are larger, more coherent, and more strongly bound to the roots than those formed in wet soils. We have quantified these effects in a model system in which corn (Zea mays L.) primary roots were grown through a 30-cm-deep prepared soil profile that consisted of a central, horizontal, "dry" (9% water content) or "wet" (20% water content) layer (4 cm thick) sandwiched between damp soil (15-17% water content). Rhizosheaths formed in dry layers were 5 times the volume of the subtending root. In wet layers, rhizosheaths were only 1.5 times the root volume. Fractions of the rhizosheath soil were removed from individual roots by three successive treatments; sonication, hot water, and abrasion. Sonication removed 50 and 90% of the soil from rhizosheaths formed in dry and wet soils, respectively. After the heat treatment, 35% of the soil still adhered to those root portions where rhizosheaths had developed in dry soil, compared with 2% where sheaths had formed in wet soil. Root hairs were 4.5 times more abundant and were more distorted on portions of roots from dry layers than from wet layers. Drier soil enhanced adhesiveness of rhizosheath mucilages and stimulated the formation of root hairs; both effects stabilize the rhizosheath. Extensive and stable rhizosheaths may function in nutrient acquisition in dry soils