The effect of nitrogen supply on the early growth and nodulation of several annual Medicago species

1990 ◽  
Vol 41 (3) ◽  
pp. 489 ◽  
Author(s):  
MA Ewing ◽  
AD Robson
Keyword(s):  
Inorganic Nitrogen ◽  
Acid Soils ◽  
Early Growth ◽  
Solution Culture ◽  
Nitrogen Supply ◽  
Fixed Nitrogen ◽  
Nodule Number ◽  
Annual Medicago ◽  
Medicago Species ◽  
Nutrient Solutions

Differences in nodulation amongst species of annual Medicago (medics) on moderately acid soils could be explained by differences in response to the form or level of nitrogen supply. We compared the growth and bulk soil pH changes when four annual medic species (M. truncatula, M. littoralis, M. polymorpha and M. murex) were supplied with ammonium, nitrate or biologically fixed nitrogen. Growth and nodule number were measured for M. polymorpha grown in solution culture at constant nitrogen supply (1 mM) but variable ammonium to nitrate ratio (1:0, 3:1, 1:1, 1:3, 0:1). Similar measurements were also made on M. truncatula, M. polymorpha and M. murex exposed to different concentrations of nitrate (0, 0.1, 1.5, 10 mM) during nodulation. When uninoculated, all medic species grew at the same rate when given equivalent levels of inorganic nitrogen as either ammonium or nitrate. All species similarly decreased the pH of soil around their roots when supplied with ammonium, and increased pH when supplied with nitrate. Nutrient solutions were acidified when M. polymorpha was supplied with ammonium and neutralized when nitrate was supplied. However, when ammonium and nitrate were added simultaneously solutions acidified, indicating a more rapid uptake of ammonium than nitrate. Nodule number of all medic species was reduced by nitrate concentrations in solution as low as 0.1 mM. M. truncatula formed fewer nodules than M. polymorpha and M. murex at all concentrations of nitrate.

The effect of solution pH and external calcium concentration on the early growth and nodulation of several annual Medicago species

1990 ◽  
Vol 41 (5) ◽  
pp. 933 ◽  
Author(s):  
MA Ewing ◽  
AD Robson
Keyword(s):  
Calcium Concentration ◽  
Acid Soils ◽  
Early Growth ◽  
Low Ph ◽  
Solution Ph ◽  
Nodule Number ◽  
Low Calcium ◽  
Wide Range ◽  
Effects Of Ph ◽  
Annual Medics

The study tested the hypothesis that annual medic species which nodulate well in acid soils in the field (M. murex Willd. and M. polymorpha L.) will nodulate better in acid solutions with low calcium concentrations than annual medics which nodulate poorly in acid soils (M, truncatula Gaertn.). Effects of pH (5.5 and 6.5) and calcium concentration (0.2, 0.5, 1 and 2 mM) on the early growth and nodulation of three annual medic species (M. truncatula, M. polymorpha and M. murex) were investigated. Increasing pH or calcium concentration did not increase plant growth for any of the species. However, nodulation was generally depressed by low pH for all species. Increasing calcium concentration in solution increased nodulation in all species. Effects of low pH and low calcium concentration in decreasing nodule number were much greater for M. truncatula than for M. polymorpha and M. murex. At pH 5.5, M. truncatula failed to nodulate at any calcium concentration, whereas a large proportion of M. murex plants nodulated at 1 mM calcium and some M. polymorpha plants nodulated at 2 mM calcium. At pH 6.5, M. polymorpha required 1 mM calcium in solution for maximum nodule number, and M. murex only 0.5 mM calcium, whereas nodule number for M. truncatula increased up to 2 mM calcium, the highest concentration used. The results provide the basis for a simple screening system to distinguish differences among annual medics in nodulation tolerance to acidity. The maintenance of ranking among species with respect to nodulation over a wide range of stresses induced by combinations of low pH and calcium concentration suggest that screening using a single stress combining these two components would be adequate. Nodulation differences between species can be simply and effectively assessed using a scoring system combining number size and location of nodules.

Tolerance of aluminium toxicity in annual Medicago species and lucerne

2008 ◽  
Vol 48 (4) ◽  
pp. 499 ◽  
Author(s):  
B. J. Scott ◽  
M. A. Ewing ◽  
R. Williams ◽  
A. W. Humphries ◽  
N. E. Coombes
Keyword(s):  
Average Length ◽  
Aluminium Toxicity ◽  
Solution Culture ◽  
Al Tolerance ◽  
Physiological Basis ◽  
Root Regrowth ◽  
Selection Intensities ◽  
Annual Medicago ◽  
Medicago Species ◽  
Relative Root

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.

Nodulation and growth of Medicago truncatula on acid soils. I. Effect of calcium carbonate and inoculation level on the nodulation of Medicago truncatula on a moderately acid soil

1970 ◽  
Vol 21 (3) ◽  
pp. 427 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Soil Ph ◽  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
Acid Soil ◽  
Acid Soils ◽  
Acid Tolerant ◽  
Annual Medicago ◽  
Medicago Species

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.

Nodulation and growth of Medicago truncatula on acid soils. II. Colonization of acid soils by Rhizobium meliloti

1970 ◽  
Vol 21 (3) ◽  
pp. 435 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan
Keyword(s):  
Calcium Carbonate ◽  
Medicago Truncatula ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Sandy Soils ◽  
Acid Tolerant ◽  
Second Year ◽  
Annual Medicago ◽  
Medicago Species ◽  
Better Than

Six strains of Rhizobium meliloti varied greatly in their ability to colonize two moderately acid sandy soils (pH 5.0-5.1 in 115 suspension of soil in 0.01M calcium chloride) in the year of sowing inoculated lime-coated seeds of Medicago truncatula. The strains also varied in their ability to nodulate M. truncatula in the year after sowing. With all rhizobial strains and on both soils, calcium carbonate applied in the year of sowing strongly promoted colonization in the year of sowing. It also greatly increased nodulation and growth of M. truncatula in the year after sowing. Apparently calcium carbonate increased second year nodulation by promoting the colonization of the acid soils by R. meliloti in the year of sowing. Differences among strains in second year nodulation appeared to be related to differences in the ability of the strains to colonize the soils in the year of sowing. Strains isolated from moderately acid sandy soils were markedly superior in both properties, and on both soils, to strain SU47 from commercial inoculum, but were generally no better than strain U45 from commercial inoculum. Even the most acid-tolerant strains colonized the acid soils relatively slowly. It is suggested that R. meliloti strains in general have a poor ability to colonize acid soils and that this property is a major factor limiting the growth and persistence of annual Medicago species on acid soils in the field.

Inorganic nitrogen uptake rate of Picea asperata curtailed by fine root acclimation to water and nitrogen supply and further by ectomycorrhizae

2021 ◽  
Author(s):  
Lulu Xie ◽  
Xingmei Zhou ◽  
Qinghua Liu ◽  
Chunzhang Zhao ◽  
Chunying Yin
Keyword(s):  
Nitrogen Uptake ◽  
Uptake Rate ◽  
Fine Root ◽  
Inorganic Nitrogen ◽  
Nitrogen Supply ◽  
Picea Asperata ◽  
Nitrogen Uptake Rate

scholarly journals Differential expression of TLP, ERF1, and R2R3MYB in annual Medicago species under salinity conditions

2015 ◽  
Vol 14 (3) ◽  
pp. 10152-10164 ◽  
Author(s):  
F. Gharaghani ◽  
F. Rafiei ◽  
N. Mirakhorli ◽  
E. Ebrahimie
Keyword(s):  
Differential Expression ◽  
Annual Medicago ◽  
Medicago Species

An improved method for artificial hybridization in annual Medicago species

1994 ◽  
Vol 45 (7) ◽  
pp. 1329 ◽  
Author(s):  
W Pathipanawat ◽  
RAC Jones ◽  
K Sivasithamparam
Keyword(s):  
Success Rate ◽  
Fold Increase ◽  
Modified Technique ◽  
Established Method ◽  
Artificial Hybridization ◽  
Annual Medicago ◽  
Improved Technique ◽  
Medicago Species ◽  
First Time ◽  
Selection Of

An improved technique for successful artificial hybridization in annual medic (Medicago spp.) is described. Using a previously reported method, only four out of seven species were successfully crossed, with the percentage of success ranging from 3 to 22%. Initial modifications to this technique gave a 7-8 fold increase in the successful crossing rate in M. murex and M. polymorpha medic, from 9 to 64% with M. murex and from 10 to 82% with M. polymorpha. Further modifications to the technique resulted in a success rate of 100% in both species. The numbers of seeds per pod obtained from crosses in both species were also increased by using the modified techniques compared to the established method. Selection of larger, more mature flowers, differences in flower cutting position, as well as post pollination position were the main modifications which accounted for the greatly improved success rate. The modified technique was subsequently applied successfully to obtain for the first time inter-specific crosses involving M. polymorphax M. murex, M. polymorphax M. sphaerocarpos, M.murexx M. sphaerocarpos, M. solerolii x M. littoralis/M.truncatula hybrid, M. solerolii x M, tornata, and M. littoralis/M.truncatula hybrid x M. sphaerocarpos.

Strategies for control of Phoma black stem in annual Medicago species

1989 ◽  
Vol 29 (5) ◽  
pp. 635 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Disease Severity ◽  
Medicago Truncatula ◽  
Field Trial ◽  
Subsequent Development ◽  
Field Site ◽  
Infected Seed ◽  
Annual Medicago ◽  
And Control ◽  
Medicago Species ◽  
Selection Of

Strategies for control of Phoma black stem disease in annual Medicago species through selection of cultivars with increased resistance to Phoma medicaginis, fungicidal spray applications to swards, and fungicidal control of seedborne infection, were investigated. Fiftyseven annual Medicago cultivars and lines were screened for resistance in the field in 1 m rows over 2 consecutive seasons. There were significant differences in resistance among species and also between lines and cultivars of any particular species. Three M. rugosa cultivars were very highly resistant and most cultivars and lines showed some resistance. In a field trial, the fungicides benomyl, carbendazim, flutriafol, propiconazole, thiabendazole and triadimefon were tested for their efficacy in controlling Phoma black stem disease. All fungicides reduced disease severity in the sward and, except for thiabendazole, the percentage burrs with Phoma lesions. The role and control of seed-borne P. medicaginis in causing Phoma black stem disease in Medicago truncatula and M. polymorpha var. brevispina at a field site was also investigated. Seed-borne P. medicaginis caused subsequent development of Phoma black stem disease in swards sown with infected seed. Disease appeared earlier, developed faster and became much more severe in M. truncatula cv. Cyprus than in M. polymorpha cv. Serena. Application of benomyl seed treatments (0.1 and 0.5% w/w) resulted in only a 4-5 week delay in the onset of Phoma black stem symptoms.

Tolerance of Phalaris aquatica L. lines and some other agricultural species to excess manganese, and the effect of aluminium on manganese tolerance in P. aquatica

1985 ◽  
Vol 36 (5) ◽  
pp. 695 ◽  
Author(s):  
RA Culvenor
Keyword(s):  
Wheat Cultivar ◽  
Maximum Yield ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Solution Culture ◽  
Yield Reduction ◽  
Manganese Tolerance ◽  
Manganese Uptake ◽  
Selection For ◽  
Manganese Concentrations

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.

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