Roots elongation

Table 1. Primary root elongation rate of several species at various vermiculite water potentials... 

Fig. 4. Spatial distribution of (a) relative elemental elongation rate (longitudinal growth rate) and (p) osmotic potential in the apical 10 mm of maize primary roots growing at various vermiculite water contents (see Fig. 3). Growth distributions were obtained by time-lapse photographic analysis of the growth of marked roots points are means from 5 or 6 roots. Osmotic potentials were measured on bulked samples from 30-50 roots points are means s.d. (n = 3-7). Root elongation rates (a, inset) were constant when the measurements were made. Modified from Sharp et al. (1988, 1989).

Pritchard, J., Tomos, A.D. Wyn Jones, R.G. (1987). Control of wheat root elongation growth. I. Effects of ions on growth rate, wall rheology and cell water relations. Journal of Experimental Botany, 38, 948-59. 

Taylor, H.M. Ratliff, L.F. (1969). Root elongation rates of cotton and peanuts as a function of soil strength and soil water content. Soil Science, 108, 113-19. 

Glick BG, CB Jacobson, MML Schwarze, JJ Pasternak (1994) 1-Aminocyclopropane-l-carboxylic acid deaminase mutants of the plant growth promoting rhizobacterium Pseudomonas putida GR12-2 do not stimulate canola root elongation. Can J Microbiol 40 911-915. 

J. E. Loper and M. N. Schroth, Influence of bacterial sources of indole-3-acetic acid on root elongation of sugar beet. Phytopathology 76 386 (1986). 

Root elongation bloassay of root exudates. Five ml aliquots of the root exudates were pipetted onto three layers of Anchor1 germination paper In a 10 by 10 by 1.5 cm plastic petri dish. Twenty five radish or tomato seeds were placed in a 5x5 array in each petri dish. Radish seeds were incubated at 20C for 96 hours tomato seeds were incubated at 20C for 168 hours, before the root length was measured. Experimental design was a completely randomized design with three replications (dishes) per treatment per bioassay seed species. The bioassay was repeated each week for 23 weeks. 

Root elongation bloassay of root exudates. Only prickly sida root exudate significantly affected radish or tomato root elongation (Table II). It significantly inhibited radish root elongation and significantly stimulated tomato root elongation. 

Walker SJ, Llewellyn GC, Lillehoj EB, Dashek WV. Uptake and distribution of aflatoxin Bj in excised, soybean roots and toxin effects on root elongation. JEnviron ExperBot 1984 24 113-122. 

In the model, the internal structure of the root is described as three concentric cylinders corresponding to the central stele, the cortex and the wall layers. Diffu-sivities and respiration rates differ in the different tissues. The model allows for the axial diffusion of O2 through the cortical gas spaces, radial diffusion into the root tissues, and simultaneous consumption in respiration and loss to the soil. A steady state is assumed, in which the flux of O2 across the root base equals the net consumption in root respiration and loss to the soil. This is realistic because root elongation is in general slow compared with gas transport. The basic equation is... 

Ibble I. Response of Barley Root Elongation to Treatment with... 

Air-dried aerial plant material was solvent extracted with hexane to remove nonpolar constituents and then extracted with water according to Scheme I. The water extract was llquld/liquid extracted with ethyl acetate. A lettuce seed bloassay of the crude ethyl acetate extract (EA) (dried vacuo) showed a 22% reduction of root elongation at 200 ppm. The organic extract was extracted with aqueous sodium bicarbonate to produce acidic and basic fractions which were neutralized and extracted with ethyl acetate to achieve neutralized acidic (NA) and neutralized basic (NB) fractions. 

A portion of the dried ether extract was fractionated on a Sephadex LH-20 chromatographic column. Lettuce root growth blo-assay showed significant activity (68% and 77% reduction of root elongation) In two fractions. Each of these fractions was seml-preparatlvely chromatographed on a silica HPLC column. Three phenolic compounds, hydroqulnone [V, 0.002%(w/w) of dry plant wt.], caffelc acid [VI, 0.012%(w/w)] and arbutln [VII, 0.034%(w/w)] were... 

Isolated, crystallized and characterized. Pure commercial samples of each of the three phenols and p-benzoqulnone (VIII), the oxidation product of hydroqulnone (Included to evaluate the possible vivo oxidation of hydroqulnone), were tested In lettuce and leafy spurge root elongation tests and In leafy spurge cell cultures (Table II). 

Table II. The Effect of Chemical Constituents Occurring In Small Everlasting on the Growth of Lettuce Roots, Root Elongation and Cell Culture Growth of Leafy Spurge...

---