Quantitative Studies on Root Development. III. Further Observations on Growth in the Seedling Phase

Abstract

The influences of light intensity, rooting medium, and the excision of various organs on the early phases of root growth in barley seedlings (cv. Piroline) were explored. The emergence of root axes was affected by light intensity and excision of roots, endosperm or shoot, but was not altered by the rooring medium. Elongation of the emerged axes was similarly responsive. The elongation rate of both the set of axes and individual axes fell wi4h time. The elongation rate of laterals was less than that of the axes and was sensitive to the excision of seedling organs. The data are discussed in relation to the hypothesis that the growth of the root system is determined by the availability of substrate.

Modification of Respiration and Carbohydrate Status of Barley Roots by Selective Pruning

“…The seminal roots of a single plant are quite uniform, in spite of their differing developmental origin; excision of one or more seminals thus changes the amount, but not the morphology, of the root system. Such partial root pruning results in an increased relative growth rate of the remaining root system {Crossett, Campbell & Stewart, 1975) and, under certam conditions, the retention of high elongation rates by seminal axes whilst those of control axes fall {Rahman, Aspinall & Paleg, 1975). Such experiments have been used to suggest that substrate availability determines root growth {Rahman et al, 1975) although firm evidence is lacking.…”

“…Such partial root pruning results in an increased relative growth rate of the remaining root system {Crossett, Campbell & Stewart, 1975) and, under certam conditions, the retention of high elongation rates by seminal axes whilst those of control axes fall {Rahman, Aspinall & Paleg, 1975). Such experiments have been used to suggest that substrate availability determines root growth {Rahman et al, 1975) although firm evidence is lacking. Any limitation due to substrate is unlikely to be due to tbe ability of the phloem to transport it, since seminal roots of wheat are capable of mass transfer in the phloem ten-fold higher than they normally sustain (Passioura & Ashford, 1974).…”

Use of morphometric analysis for characterization of tobacco root growth in relation to infection byPhytophthora parasitica var.nicotianae

“…The developmental model has been used most often to describe development of root systems of various field crops grown under different fertilization regimes, light intensities, or other imposed treatments (Hackett, 1971;May et al, 1965;May et al, 1967;Rahman et al, 1975;Tennant, 1976). Bloomberg (1979aBloomberg ( , 1979b has utilized this model to quantify root system development of Douglas-fir seedlings.…”

Effects of rooting media on root growth and morphology of Brassica rapa seedlings

“…There were consistent patterns of root number and length increase in the B. rapa seedlings. This trend has long been established in many crops, including barley (May et al 1965;Rahman et al 1975) and wheat (Tennant 1975). An interesting feature, however, is the observation here that number and RMR of first-order LRs was altered by the nature of the medium in which the roots were growing and that a medium effect on RMR was evident between 2 and 5 DAT for R500 and between 2 and 8 DAT for IMB211.…”