Root elongation rate is correlated with the length of the bare root apex of maize and lupin roots despite contrasting responses of root growth to compact and dry soils

In most crop species, growth of the shoot is more sensitive to salt stress than root growth. Avocado [Persea americana Mill.] is very sensitive to NaCl stress. Even low concentrations of salt (15 mm) inhibit tree growth and decrease productivity. Observations in experimental orchards have suggested that root growth in avocado might be more restricted by salinity than shoot growth. In the present study, we evaluated quantitatively the inhibitory effects of salt stress on growth of the avocado root in comparison to the shoot. Seedling plants of the West-Indian rootstock `Degania 117' were grown in complete nutrient solution containing 1, 5, 15, or 25 mm NaCl. The threshold NaCl concentration causing root and shoot growth reduction occurred between 5 and 15 mm. At all concentrations, root growth was much more sensitive to salinity than shoot growth. A concentration of 15 mm NaCl, which did not affect the rate of leaf emergence on the plant and decreased leaf biomass production only 10%, induced a 43% reduction in the rate of root elongation and decreased root volumetric growth rate by 33%. Under 25 mm NaCl, leaf biomass production, leaf initiation rate and leaf elongation rate were reduced 19.5%, 12%, and 5%, respectively, while root volumetric growth and root elongation rate were reduced 65% and 75%, respectively. This strong root growth inhibition is expected to influence the whole plant and therefore root growth under salinity should be considered as an important criterion for rootstocks' tolerance to NaCl.

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Relationship between root elongation rate and diameter and duration of growth of lateral roots of maize

Plant and Soil ◽

10.1007/bf02370419 ◽

1989 ◽

Vol 119 (2) ◽

pp. 271-279 ◽

Cited By ~ 93

Author(s):

M. D. Cahn ◽

R. W. Zobel ◽

D. R. Bouldin

Keyword(s):

Root Elongation ◽

Lateral Roots ◽

Elongation Rate ◽

Root Elongation Rate

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Coarse root elongation rate estimates for interior Douglas-fir

Tree Physiology ◽

10.1093/treephys/20.12.825 ◽

2000 ◽

Vol 20 (12) ◽

pp. 825-829 ◽

Cited By ~ 10

Author(s):

A. Richardson

Keyword(s):

Root Elongation ◽

Douglas Fir ◽

Elongation Rate ◽

Coarse Root ◽

Root Elongation Rate

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Alleviation of Al toxicity by Si is associated with the formation of Al-Si complexes in root tissues of sorghum

10.1101/229625 ◽

2017 ◽

Author(s):

Peter M. Kopittke ◽

Alessandra Gianoncelli ◽

George Kourousias ◽

Kathryn Green ◽

Brigid A. McKenna

Keyword(s):

Cross Sections ◽

Root Elongation ◽

Elongation Rate ◽

In Planta ◽

X Ray ◽

Root Elongation Rate ◽

Root Tissues ◽

Wall Loosening ◽

Nutrient Solutions

AbstractSilicon is reported to reduce the toxic effects of Al on root elongation but the in planta mechanism by which this occurs remains unclear. Using seedlings of soybean (Glycine max) and sorghum (Sorghum bicolor), we examined the effect of up to 2 mM Si on root elongation rate (RER) in Al-toxic nutrient solutions. Synchrotron-based low energy X-ray fluorescence (LEXRF) was then used for the in situ examination of the distribution of Al and Si within cross-sections cut from the apical tissues of sorghum roots. The addition of Si potentially increased RER in Al-toxic solutions, with RER being up to ca. 0.3 mm h−1 (14 %) higher for soybean and ca. 0.2 mm h−1 (17 %) higher for sorghum relative to solutions without added Si. This improvement in RER could not be attributed to a change in Al-chemistry of the bulk nutrient solution, nor was it due to a change in the concentration of Al within the apical (0-10 mm) root tissues. Using LEXRF to examine sorghum, it was demonstrated that in roots exposed to both Al and Si, much of the Al was co-located with Si in the mucigel and outer apoplast. These observations suggest that Si reduces the toxicity of Al in planta through formation of Al-Si complexes in mucigel and outer cellular tissues, thereby decreasing the binding of Al to the cell wall where it is known to inhibit wall loosening as required for cell elongation.

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Influence of Day and Night Temperature Differentials on Root Elongation Rate, Root Hydraulic Properties, and Shoot Water Relations in Chrysanthemum

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.125.3.383 ◽

2000 ◽

Vol 125 (3) ◽

pp. 383-389

Author(s):

Pauline Helen Kaufmann ◽

Robert J. Joly ◽

P. Allen Hammer

Keyword(s):

Root Elongation ◽

Dark Period ◽

Stem Elongation ◽

Elongation Rate ◽

Light Period ◽

Night Temperature ◽

Diurnal Patterns ◽

Root Elongation Rate ◽

Temperature Regimes ◽

Maximum Root

The difference between night and day temperature (DIF = day - night temperature) has been shown to affect plant height. A positive DIF (+DIF), cooler night than day temperature, increases stem elongation while a negative DIF (- DIF), warmer night than day temperature, decreases stem elongation. The physiological mechanism underlying the growth response to DIF is not understood, however, and the effects of day/night temperature differentials on root permeability to water and root elongation rate have not been studied. The objective of this study was to describe how +DIF and -DIF temperature regimes affect leaf water relations, root water flux (Jv), root hydraulic conductivity (Lp), and root elongation rates of `Boaldi' chrysanthemum [Dendranthema ×grandiflora Kitam. `Boaldi' (syn. Chrysanthemum ×morifolium Ramat.)] plants over time. Leaf turgor pressure (ψp) was 0.1 to 0.2 MPa higher in plants grown in a +6 °C DIF environment throughout both the light and dark periods, relative to those in a -6 °C DIF environment. Jv differed markedly in roots of plants grown in +DIF vs. -DIF environments. Rhythmic diurnal patterns of Jv were observed in all DIF treatments, but the relative timing of flux minima and maxima differed among treatments. Plants grown in positive DIF regimes exhibited maximum root flux at the beginning of the light period, while those in negative DIF environments had maximum root flux during the first few hours of the dark period. Plants grown in +DIF had significantly higher Lp than -DIF plants. Plants grown in +DIF and -DIF environments showed differences in the diurnal rhythm of root elongation. During the dark period, +DIF plants exhibited minimal root elongation rates, while -DIF plants exhibited maximal rates. During the light period, the converse was observed. In -DIF temperature regimes, periods of rapid root elongation coincided with periods of high Jv. Results of this study suggest that negative DIF environments lead to leaf turgor reductions and markedly alter diurnal patterns of root elongation. These changes may, in turn, act to reduce stem elongation.

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Effect of aluminium on root elongation in two Australian perennial grasses

Functional Plant Biology ◽

10.1071/pp97134 ◽

1998 ◽

Vol 25 (2) ◽

pp. 165 ◽

Cited By ~ 7

Author(s):

Simon A. Crawford ◽

Sabine Wilkens

Keyword(s):

Root Growth ◽

Root Elongation ◽

Root Apex ◽

Perennial Grasses ◽

Root Tips ◽

Al Stress ◽

Control Growth ◽

Hematoxylin Staining ◽

Inhibition Of Root Elongation ◽

Nutrient Solutions

Inhibition of net root elongation and patterns of hematoxylin staining were used to assess relative tolerance to phytotoxic Al in Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br. According to net root elongation, M. stipoides is significantly more tolerant of phytotoxic Al than D. linkii. In nutrient solutions with Al concentrations of 370 µM and higher, root elongation is stopped in D. linkii after 24 h while in M. stipoides root elongation is maintained at 60–70% of control rates over 72 h. After removal of Al-stress, root growth in M. stipoides from all Al-treatments recovered to be at or above control growth after 72 h. In D. linkii, root elongation in plants exposed to Al levels that caused a reduction in growth (<370 µM), but not complete cessation, recovered after removal of Al stress. Greater intensities of hematoxylin staining were seen in Al-stressed root tips of D. linkii compared to M. stipoides, suggesting that inhibition of root elongation is associated with increased accumulation of Al in root tips. Roots of M. stipoides seedlings exposed to all Al-treatments showed a short band of intensely stained tissue, correlating with the position of the root apex at the exact point of initial Al- exposure. New root growth after this band did not stain with hematoxylin, indicating activation of a mechanism of Al-exclusion in roots of M. stipoides.

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