Rapid response of the yield threshold and turgor regulation during adjustment of root growth to water stress in Zea mays

• Published in: Plant physiology (Bethesda) Vol. 108; no. 1; pp. 303 - 312
• Main Authors: Jürgen Frensch, Hsiao, Theodore C.
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.05.1995
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cell growth; Cell walls; cells; cellule; celulas; Corn; cortex; crecimiento; croissance; Dehydration; drought stress; Economic plant physiology; estres de sequia; Fundamental and applied biological sciences. Psychology; growth; growth rate; indice de crecimiento; Kinetics; largura; length; longueur; matematicas; mathematical models; mathematics; mathematique; measurement; medicion; mesure; modele mathematique; modelos matematicos; osmotic pressure; Plant physiology and development; Plant roots; Plants; presion osmotica; pression osmotique; propiedades hidraulicas del suelo; propriete hydraulique du sol; racine; raices; Root growth; roots; soil hydraulic properties; Solutes; stress du a la secheresse; taux de croissance; turgencia; turgescence; turgor; Turgor pressure; Water and solutes. Absorption, translocation and permeability; Water relations, transpiration, stomata; Whole Plant, Environmental, and Stress Physiology; zea mays; Monocotyledones; Zea mays; Root; Turgor; Growth; Hydraulic conductivity; Water stress; Cereal crop; Cell wall; Regulation(control); Gramineae; Angiospermae; Spermatophyta
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.108.1.303

Responses of cortical cell turgor (P) following rapid changes in osmotic pressure were measured throughout the elongation zone of maize (Zea mays L.) roots using a cell pressure probe and compared with simultaneously measured root elongation to evaluate: yield threshold (Y) (minimum P for growth), wall extensibility, growth-zone radial hydraulic conductivity (K), and turgor recovery rate. Small increases in osmotic pressure (0.1 MPa) temporarily decreased P and growth, which recovered fully in 5 to 10 min. Under stronger osmotic pressure (up to 0.6 MPa), elongation stopped for up to 30 min and then resumed at lower rates. Recoveries in P through solute accumulation and lowering of Y enabled growth under water stress. P recovery was as much as 0.3 MPa at osmotic pressure = 0.6 MPa, but recovery rate declined as water stress increased, suggesting turgor-sensitive solute transport into the growth zone. Under strong osmotic pressure P did not recover in the basal part of the growth zone, in conjunction with a 30% shortening of the growth zone. Time courses showed Y beginning to decrease within several minutes after stress imposition, from about 0.65 MPa to a minimum of about 0.3 MPa in about 15 min. The data concerning Y were not confounded significantly by elastic shrinkage. K was high (1.3 X 10(-10) m2 s-1, MPa-1), suggesting very small growth-induced water potential gradients.