A Comparative Study of Bicarbonate Inhibition of Root Growth in Calcicole and Calcifuge Grasses

Abstract

SUMMARYA study has been made of the effects of bicarbonate on the root growth of a number of calcicole and calcifuge grasses. Differential effects of bicarbonate concentrations likely to be encountered in a calcareous soil solution (o-io m-equiv./litre) were found between the species. In general the root growth of calcifuge species was more strongly inhibited than was the root growth of calcicoles. Using the technique of colchicine-induced metaphase accumulation the mitotic index of the roots of the bicarbonate-inhibited calcifuge Deschampsia fiexuosa was measured and the effects of bicarbonate were then studied. No effect of bicarbonate on cell division was detected and it was concluded that the inhibitory effect of bicarbonate was mainly on cell elongation. Using H^*C03 it was found that the maximum rates of dark-fixation occur in those zones of cell elongation where the main inhibition of growth takes place.

Soil~Plant Relationships

“…An indirect influence is the possibility of an interaction with iron availability. However, there is some evidence that bicarbonate ion restricts root elongation in non-calcicoles (Lee and Woolhouse 1969). Are calcicoles affected by low iron availability?…”

Current Knowledge in Physiological and Genetic Mechanisms Underpinning Tolerances to Alkaline and Saline Subsoil Constraints of Broad Acre Cropping in Dryland Regions

“…This has been demonstrated by growing maize plants in solution at pH 8.0 with the buffer HEPES, without HCO 3 − . The high pH due to HEPES buffer did not cause any reduction of root and shoot elongation (Lee & Woolhouse, 1969;Romera et al, 1992). …”

“…Higher HCO 3 − concentrations can inhibit root respiration and may result in reduced root growth (Bingham & Stevenson, 1993;Alhendawi et al, 1997). This inhibitory effect may also be related to high accumulation and compartmentation of organic acids such as malate and citrate in root cells (Lee & Woolhouse, 1969;Yang et al, 1994). A bicarbonate-induced build-up of surplus organic acids, particularly malate, in the elongation zone appeared to be related to inhibition of root elongation by bicarbonate in calcifuge plant species (Lee & Woolhouse, 1969).…”

“…This inhibitory effect may also be related to high accumulation and compartmentation of organic acids such as malate and citrate in root cells (Lee & Woolhouse, 1969;Yang et al, 1994). A bicarbonate-induced build-up of surplus organic acids, particularly malate, in the elongation zone appeared to be related to inhibition of root elongation by bicarbonate in calcifuge plant species (Lee & Woolhouse, 1969). Abscisic acid (ABA), an important stress-induced hormone, is produced in the roots and leaves, transferred from the roots to the leaves in the xylem and from the leaves back to the roots in the phloem (Wolf et al, 1990).…”

Iron uptake in a bicarbonate-resistant cell line of tobacco

“…High HCO, -concentration in the solution have the effect of raising the pH value of the soil markedly, as well as acting as a strong buffer at high pH, which lowers the concentrations of soluble inorganic iron. High HCO)-concentration has also been demonstrated to inhibit root growth (Lee and Woolhouse 1969), and affect the uptake, translocation, and utilization of iron in plants (Mengel et al 1984). The extent to which HCO,-influences iron deficiency, or "limeinduced chlorosis," in alkaline soils depends on the plant species and the type of root response to iron deficiency (Marschner 1995).…”