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

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-...

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Bibliographic Details
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
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Summary: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
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.106.1.179