Phytotoxicity of aluminium to wheat plants in high-pH solutions

2003 ◽  
Vol 43 (5) ◽  
pp. 497 ◽  
Author(s):  
G. Ma ◽  
P. Rengasamy ◽  
A. J. Rathjen

Phytotoxicity of aluminium in acid soils is well known. At pH ≥6.3, aluminate [Al(OH)4–] is the principal hydroxo-aluminium species in soil solutions; however, its phytotoxicity has not received much attention. Sodic subsoils in Australia are generally alkaline and have pH above 9. During our survey of 8 subsoils in South Australia, we found aluminate ions at concentrations greater than 0.8 mg/L (29.7 μmol/L of aluminium) in soil solutions when pH was greater than 9, with corresponding high uptake of aluminium by wheat plants. We studied the phytotoxicity of aluminium to wheat plants in solution culture by maintaining the pH of alkaline solutions at 9.2.Relative root lengths of wheat plants, compared with those in reverse-osmosis deionised water, were significantly reduced in alkaline solutions and CO2-free air indicated toxicity of hydroxy, carbonate and bicarbonate ions. Further reduction of root lengths due to aluminate toxicity was also evident. Relative root lengths of wheat plants, when comparing between +aluminium and –aluminium treatments, were reduced up to 50% in alkaline solutions containing as low as 1 mg/L of aluminium. Aluminium accumulated mainly in the roots, thereby reducing their growth. In bicarbonate solutions, aluminium toxicity under alkaline pH was highly significant (P<0.001). However, at the same level of added aluminium in carbonate solutions, relative root length was not reduced. This study concludes that when aluminium species are present at a concentration of about 1 mg/L in soil solutions with pH greater than 9, the growth of wheat plants could be significantly affected.


Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 663 ◽  
Author(s):  
EA Close ◽  
HKJ Powell

This paper examines the use of short extraction times, and the determination of aluminium with chrome azurol S (CAS), for the estimation of 0.02 M CaCl2-soluble aluminium in soils. It reports the correlation between CAS-reactive aluminium in 5 min extracts and percent maximum yield of white clover (Trifolium repens) for a series of acid soils. The reactivity of soluble and colloidal aluminium species with the metallochromic reagent CAS has been assessed. ~ l ( a q ) ~ + , simple hydroxy species and complexes of weakly binding ligands (salicylic acid, tannins) are CAS-reactive (2 rnin). In contrast, complexes of strongly binding ligands (citric acid, fulvic acid) are not CAS-reactive ([Al] ~ [L] ~ [CAS] ~ 1-2~10-5 M). For a series of six limed phosphated topsoils and subsoils (pH 4.2-5.5), 0.02 M CaCl2- soluble aluminium, as determined with CAS, was negatively correlated against the percent maximum yield of white clover; r2 = -0.73** (5 min extraction), n = 20. This correlation is similar to that for yield against total aluminium as determined by atomic absorption spectroscopy after 60 min extraction (r2 = -0.77**). However, the colorimetric analysis is more convenient and sensitive; further, it does not measure colloidal and polymeric aluminium species (which may not be plant-available). The satisfactory correlation achieved for short extraction times suggests use of CAS for a rapid field method for aluminium toxicity in soils.



2008 ◽  
Vol 48 (4) ◽  
pp. 499 ◽  
Author(s):  
B. J. Scott ◽  
M. A. Ewing ◽  
R. Williams ◽  
A. W. Humphries ◽  
N. E. Coombes

A rapid (7 day) solution-based screening test was developed using 15 annual Medicago cultivars and one M. sativa. Based on a relative root regrowth after exposures to aluminium (Al), Zodiac (M. murex), Orion (M. sphaerocarpos) and the M. polymorha cultivars Santiago, Cavalier and Serena had the greatest Al tolerance. Herald (M. littoralis) and Rivoli (M. tornata) were most sensitive. Ranking for Al tolerance from the solution culture correlated well (r = 0.80) with ranking for tolerance of the 16 genotypes grown in an acidic soil (unlimed pHCa 4.1). We screened 17 Australian populations of lucerne (M. sativa) using a 24 h ‘pulse’ of 75 µmol/L Al, and a three day ‘recovery’ of 10 µmol/L Al. We identified and recovered plants with a root regrowth of ≥5 mm in all 17 populations with selection intensities of 2 to 4%. Four of these selected populations (Aurora, UQL-1, A513 and TO2-011) were polycrossed within each population to produce four populations of seed from the cycle 1 selections. The length of root regrowth under Al stress was improved for all four populations of cycle 1 selection (P ≤ 0.001; from 2.6 mm for the original populations to 6.3 mm for the cycle 1 selections). In a subsequent experiment the cycle 2 selections from Aurora, UQL-1 and TO2-011 had significantly greater root regrowth than both the cycle 1 selections (P ≤ 0.001; 8.3 cf. 6.6 mm) and the unselected populations (3.0 mm). The selections from TO2-011 appeared to have greater improvement in the average length of root regrowth after 2 cycles of selection. Selected germplasm was more tolerant than GAAT in our evaluation. Based on estimation of realised heritability, it seemed likely that higher selection intensities would give more rapid improvements in tolerance. Our studies have not investigated the physiological basis of any tolerance of Al which we observed.



1965 ◽  
Vol 16 (5) ◽  
pp. 757 ◽  
Author(s):  
DN Munns

On some acid sandy loam soils, lucerne required large additions of phosphate to grow normally unless lime was also applied. Plant symptoms, and analyses of plants, soil solutions, and 0.01M calcium chloride extracts, supported the hypothesis that, in the unlimed soils, additions of phosphate overcame aluminium toxicity as well as phosphorus deficiency. Both lime and large additions of phosphate lowered the concentrations of aluminium in the soil solutions and in the plants. Lime did not significantly affect either the equilibrium concentrations or the rates of release of phosphate in the soils. Yet at rates of phosphate adequate in the presence of lime, plants without lime looked phosphate-deficient, grew poorly, and usually contained deficient concentrations of phosphorus. The principal effects were consistent with effects of aluminium and phosphate in solution culture at the same concentrations as those observed in the soils. Aluminium toxicity was associated with 10 to 100 µM concentrations of aluminium in the soil solution and 3 to 10 µg atoms/g dry weight in the plant tops. Phosphorus deficiency was associated with phosphate concentrations of the order of 1µM or less in the soil solutions and 100 µg atoms/g or less in the plant tops.





Author(s):  
F. P. C. Blamey ◽  
D. C. Edmeades ◽  
C. J. Asher ◽  
D. G. Edwards ◽  
D. M. Wheeler


1985 ◽  
Vol 36 (5) ◽  
pp. 695 ◽  
Author(s):  
RA Culvenor

Tolerance to excess manganese in 13 Mediterranean accessions and 3 Australian cultivars of phalaris was determined in solution culture with manganese concentrations from 0.5 to 210 ppm. The effect of aluminium (0, 2.5, 5-0 ppm) on the response of two accessions to excess manganese was studied in a second experiment. Phalaris was very tolerant to excess manganese. Shoot yield at 150 ppm manganese ranged from 25 to 50% of the maximum yield, which was achieved at 0.5 ppm in some lines and at 40 ppm in others. The cultivars Australian and Sirosa were among the most tolerant types. With one exception, Algerian accessions were the least tolerant. These accessions were of similar tolerance to Egret, the most tolerant wheat cultivar examined. All phalaris lines were much more tolerant than Isis wheat, Clipper barley, Woogenellup subterranean clover and Jumbuck rape. Variation in tolerance of high internal manganese levels was the principal determinant of relative tolerance within phalaris. Shoot manganese concentrations causing 10% yield reduction ranged from 730 to 2200 8g g-1 dry wt. The greater tolerance of phalaris compared with the other species was due to lower manganese uptake and higher internal tolerance. Presence of aluminium in the solution did not increase the susceptibility of phalaris to manganese toxicity. Aluminium strongly reduced manganese uptake in phalaris. It is concluded that selection for manganese tolerance need be only of low priority in developing a phalaris cultivar with improved tolerance of acid soils.



1934 ◽  
Vol 11 (4) ◽  
pp. 539-546
Author(s):  
J. W. Shipley

The a.-c. electrolysis of sodium carbonate solutions at voltages as high as 110, even when arcing occurs on the electrodes, does not cause the evolution of carbon dioxide. In the a.-c. electrolysis of aqueous bicarbonate solutions with platinum electrodes, hydrogen, oxygen and carbon dioxide are evolved freely until all the bicarbonate has been transformed to carbonate, after which the evolution of carbon dioxide ceases and only hydrogen and oxygen are given off. In a.-c. electrolysis of sodium bicarbonate solutions and solutions of the sodium salts of aliphatic acids, a deposit of finely divided platinum is formed on the electrodes. This deposit inhibits the evolution of carbon dioxide, hydrogen and oxygen, but does not affect the current flow. The decomposition potential of bicarbonate solutions in respect to the evolution of carbon dioxide on smooth platinum and with d.c. was found to be 2.2 volts, and of carbonate solutions, 3.5 volts. The anodic discharge potential of HCO3− is − 1.45 to − 1.50 volts, and of CO3−−, − 1.90 to − 1.95 volts. The evolution of carbon dioxide does not appear to cause any polarizing effect on the anode.



Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 149 ◽  
Author(s):  
TJV Hodge ◽  
DC Lewis

Areas of low soil pH in the south-east of South Australia were delineated by using previously submitted soil samples and soil association maps. A survey was then undertaken in the major soil associations to determine the severity and characteristics of highly acid soils. The acid soil types identified were a siliceous sand over clay (Db/Dy) and a siliceous sand over organic matter/sesquioxide pan (Uc). The top 2.5 cm of both soil types was significantly less acid than the remaining portion of the A horizon, with pH decreasing rapidly with depth until the B horizon, where a substantial soil pH increase occurred. As soil pH (0.01 M CaCl2) decreased below 4.5, extractable soil aluminium (0.01 M CaCl2) increased rapidly, to a maximum extractable concentration of 17 �g g-l. These soil types were also found to be deficient in both phosphorus and potassium, with 65% of the sites having extractable phosphorus concentrations below the critical value of 20 �g g-1 and 35% below the critical value for extractable potassium of 80 �g g-l. For subterranean clover, significant positive correlations were observed between soil pH and plant calcium and sulfur, and between extractable soil aluminium and plant aluminium. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium and magnesium. For ryegrass, significant positive correlations were observed between extractable soil aluminium and plant aluminium and manganese. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium. No other significant correlations were obtained. The results are discussed in relation to further acidification and management of these acid siliceous sands.



1988 ◽  
Vol 39 (2) ◽  
pp. 171 ◽  
Author(s):  
SJ Hetherington ◽  
CJ Asher ◽  
FPC Blamey

The aluminium (Al) tolerance of three sugarcane (Saccharum spp.) cultivars was compared with one cultivar each of navybean (Phaseolus vulgaris), soybean (Glycine max), and maize (Zea mays) in a short-term solution culture experiment. The experiment was conducted under closely controlled conditions of pH (adjusted daily to 4.2 � 0.02) and root temperature (28�C) over a wide range of Al levels expressed as the sum of activities of monomeric A1 species (mean +aAL mono 0, 4, 14, 54, and 222 8M). The three sugarcane cultivars, Q77, Q113 and Q117, were found to be considerably more tolerant of Al in solution than were the other three species. At 14 8M +aAL mono toxicity symptoms on the sugarcane roots were slight, but were well developed on the roots of the other three species. At 220 8M +aAL mono the distance from the root tip to the first visible lateral was reduced by 9-30% in the sugarcane cultivars compared with 79% in maize and navybean, and 91% in soybean. Interpolation of curves fitted to root length data indicated critical (i.e. 10% total root length reduction) +aAL mono of 11-21 8M for the sugarcane cultivars compared with 2.0 8M, 1.8 8M, and 1.0 8M for soybean, maize, and navybean, respectively. Implications for the management of sugarcane tand are discussed briefly.



2000 ◽  
Vol 51 (1) ◽  
pp. 29
Author(s):  
V. P. Ila'ava ◽  
C. J. Asher ◽  
F. P. C. Blamey

Good growth in acid soils suggests that sweet potato may be tolerant of acid soil infertility factors such as Al toxicity or Ca deficiency. In a conventional solution culture experiment, 4 cultivars responded positively when solution Ca concentration was increased from approximately 4 to 1300 □М. However, a subsequent flowing solution culture (FSC) experiment showed no significant (P > 0.05) differences in growth by most of the 15 cultivars studied when solution Ca concentration was increased from 45 to 400 □М. Hence, it was concluded that sweet potato could be fairly tolerant of low Ca supply. In contrast, soluble Al markedly decreased growth of the 15 sweet potato cultivars studied. The results of the present study indicate that Al rather than low Ca supply would be more important in limiting sweet potato growth in acid soils. Furthermore, tolerance to low Ca and soluble Al appears to be linked in sweet potato. These results highlight the importance of selecting sweet potato cultivars for specific soil conditions such as soil acidity.



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