Quantitative Measurement of the Velocity of Water Absorption in Individual Root Hairs by a Microtechnique

Abstract

POPESCO (11) credits the first observations on the absorption of solutes by roots to the work of MARCELLUS MALPIGHI in the seventeenth celntury. POPESCO writes that, in his work entitled Anatomne Plantarnin which appeared in 1675, MALPIGHI maintained that nutritive substances were absorbed by the roots at the level of the region of the root hairs. Since not all plants bear root hairs, MALPIGHI stated further that the entire epiderlial surface funetioned in absorption when root hairs were absent.According to POPESCO, many early investigators following MALPIGHI were not in agreement with these conelusionis: GREW in 1682 said t.hat the roots absorbed water and nutritive substances from the earth through their tips, especially through the root cap; HALES in 1727 and DE LA BAISSE in 1733 supported GREW'S contention stating in addition that the role of root hairs was secondary. Many of the observers in the beginning of the nineteenth century also believed that water and solutes were absorbed thlrotuo the very tip of the root but in 1865 SACHS contended that the plant absorbed water from the earth by means of the root hairs, that the surface area of absorption was greatly increased by the preseniee of root hairs, and that volume absorption was proportionally iniereased. Subsequently, SCHWARZ calculated that the epidermal area in roots of corn was increased six times and in roots of peas twelve times when root hairs developed on these roots in moist air (10).Such outstanding investigators of the early part of the twentieth century as JOST, MOLISCH, and PFEFFER also maintained that the principal role of water absorption in hairy roots was played by root hairs but several of their contemporaries disagreed, especially DE LAVISON (11)

Advancements in Root Growth Measurement Technologies and Observation Capabilities for Container-Grown Plants

“…As early as the seventeenth century, researchers began to realize that plants absorbed water rather than soil and that nutrient substances were absorbed by the roots at the level of the root hairs [ 15 , 16 , 17 ]. Typical root hairs have a cylindrical, straight form with a dome-shaped tip, that often form a right angle with the main root surface.…”

Water Relations of Plant Cells and Tissues

“…Brooks & Brooks (13) cite other values and the existence of a considerable range of values is to be expected since permeability to water may vary from cell to cell and from tissue to tissue. Rosene (97) concluded that different parts of a given cell may vary in permeability to water as she found different rates of water intake through different parts of the same root cell. Perme ability varies with time and is involved in endogeneous rhythms manifested by plants [BUnning (32)].…”

Root hairless 2 (rth2) mutant represents a loss-of-function allele of the cellulose synthase-like gene OsCSLD1 in rice (Oryza sativa L.)

“…In rice, Lan et al (2010) reported that the high-affinity K + transporter gene (OsHKT2;4), which is expressed in root hairs and vascular parenchyma cells, can function as a Ca 2+ -permeable cation channel. Importance of the root hairs in the water absorption was confirmed by the micropotometry experiment, a technique to measure water uptake directly using glass capillaries (Rosene 1943, Rosene andWalthall 1949).…”