Symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii collected from pastures in south-western Victoria

Summary. The whole-soil inoculation method was used to assess the symbiotic effectiveness of rhizobia populations in soils collected from 18 randomly-selected pastures in south-western Victoria. This was part of a larger study which described the condition of pasture within this region. Based on the shoot weights of test subterranean clover plants, cv. Mount Barker, effectiveness varied from 36 to 94% depending on the site of rhizobia collection. This range was wider than that found in an earlier survey of rhizobia effectiveness conducted nearby. WU95, the commercial inoculant for subterranean clover, was significantly more effective than 9 of the rhizobia samples. Rhizobia from 2 sites were especially poor and their effectiveness (37%) was not significantly different from the nil inoculum control (28%). Symbiotic effectiveness was not related to soil pH, available sulfur, available phosphorus, total nitrogen or mean annual rainfall for each site where rhizobia were collected. After pooling data for all sites, the shoot weights were significantly related to the proportions of plants with nodules assigned high nodulation scores. In contrast, low scores, within 1 of 6 categories, did not significantly affect shoot weight. The technique of using mean nodulation score was less capable of discriminating differences in symbiotic effectiveness, compared with assessment based on test plant weight.

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Diversity and symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii isolates from pasture soils in south-western Australia

Soil Research ◽

10.1071/sr01052 ◽

2002 ◽

Vol 40 (8) ◽

pp. 1319 ◽

Cited By ~ 13

Author(s):

M. T. Collins ◽

J. E. Thies ◽

L. K. Abbott

Keyword(s):

Western Australia ◽

Rhizobium Leguminosarum ◽

Subterranean Clover ◽

Most Probable Number ◽

Enzyme Linked Immunosorbent Assay ◽

Symbiotic Effectiveness ◽

Probable Number ◽

Pcr Fingerprinting ◽

Rapd Pcr ◽

Inoculant Strain

The abundance of the Australian inoculant strain of Rhizobium leguminosarum bv. trifolii for subterraneum clover (WU95) and the diversity of naturalised rhizobia were assessed in 3 subterranean clover pastures in the Albany region of south-western Western Australia. Most probable number, enzyme linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) techniques were used. A putative strain similar to inoculant strain WU96 was uncommon at one site (South Stirling) and not isolated at 2 other sites. Randomly amplified polymorphic DNA (RAPD) PCR fingerprinting using the RPO1 primer identified 45 different profiles amongst the 208 isolates examined. RAPD-PCR fingerprinting using the primers RPO4 and RPO5 confirmed most groupings based on RPO1 fingerprint patterns and revealed further genetic diversity within some groups. Overall, 54 putative strains were defined by RAPD-PCR fingerprint profiles across the 3 sites. Subterranean clover rhizobia at the Manypeaks and Mount Shadforth sites were dominated by isolates with 1 or 2 RPO1 RAPD profiles at 2 sampling times, while the population at South Stirling was much more diverse. The symbiotic effectiveness of 11 rhizobial isolates, representing the major RPO1 RAPD profile groups within naturalised rhizobial populations, were compared in pot culture with those of the 2 commercial inoculant strains for subterranean clover, WU95 and TA1, on 3 cultivars. Differences in effectiveness among 3 of the 11 isolates were observed in comparison to both the commercial strains and other naturalised isolates. The nitrogen fixing effectiveness of 8 isolates representing different subgroups from one RP01 group was not the same. The use of all 3 primers increased the precision in defining putative strains of Rhizobium leguminosarum bv. trifolii, and although naturalised rhizobia from these pastures are saprophytically competent, their dominance in nodules does not appear to be linked to symbiotic effectiveness.

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Persistence of introduced strains of Rhizobium leguminosarum bv trifolii in acidic soils of north-eastern Victoria

Australian Journal of Experimental Agriculture ◽

10.1071/ea98150 ◽

1999 ◽

Vol 39 (7) ◽

pp. 829 ◽

Cited By ~ 14

Author(s):

J. F. Slattery ◽

D. R. Coventry

Keyword(s):

Rhizobium Leguminosarum ◽

Soil Amendments ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Nodule Occupancy ◽

Acidic Soils ◽

High Background ◽

Poor Tolerance ◽

Acidic Sites ◽

Commercial Inoculant

Summary. A 5-year study was undertaken to establish if introduced rhizobia with higher tolerance to Al than the current inoculant Rhizobium can persist and continue nodulating subterranean clover (Trifolium subterraneum L.) in acidic soils. Two Rhizobium leguminosarum bv trifolii strains were introduced as seed inoculants with subterranean clover at 2 acidic sites (pHCa 4.1 and pHCa 4.3), where lime and gypsum had been applied as soil amendments. Strain NA3001 was selected for its tolerance to high Al concentrations when grown on an agar medium and WU95, which is a widely used commercial inoculant strain, for its relatively poor tolerance to Al when grown on agar. Liming the soil increased its pH and reduced the concentration of extractable Al at both sites. In the year the subterranean clover was sown, strain WU95 had nodule occupancy of 20–49%, decreasing with time to 4–7% after 5 seasons (1991–95). The nodule occupancy of strain NA3001 was initially lower than strain WU95 (14–16%), but its occupancy did not vary with time (significant strain x time interactions, P<0.05). These data indicate that the acid-tolerant strain NA3001 has the potential to persist in these strongly acidic soils and, despite the presence of high background populations of naturalised rhizobia, to continue initiating nodulation. The use of soil amendments (lime and gypsum) to increase pH and reduce soluble Al concentrations did not affect the nodule occupancy of either NA3001 or WU95 with time, nor did it slow the rate of decline in nodule occupancy of WU95.

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Effect of grazing strategy, ryegrass overdrilling and herbicide application on vulpia content, tiller density and seed production in perennial pastures

Australian Journal of Experimental Agriculture ◽

10.1071/ea06144 ◽

2008 ◽

Vol 48 (5) ◽

pp. 632 ◽

Cited By ~ 2

Author(s):

K. N. Tozer ◽

D. F. Chapman ◽

P. E. Quigley ◽

P. M. Dowling ◽

R. D. Cousens ◽

...

Keyword(s):

Soil Seed Bank ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Integrated Approach ◽

Annual Rainfall ◽

Herbicide Application ◽

Effective Strategies ◽

Annual Grasses ◽

Western Victoria ◽

Tiller Density

Vulpia species C.C. Gmel. are annual grass weeds that can reduce the productivity of perennial pastures throughout southern Australia. To develop more effective strategies to manage vulpia, a 3-year experiment was established in western Victoria (average annual rainfall: 625 mm) comparing different methods currently used to control this weed. Overdrilling perennial ryegrass (Lolium perenne L.) seed and simazine application treatments were applied to phalaris (Phalaris aquatica L.) pastures that were set-stocked or rotationally grazed (either as a four-paddock or strategic rotation) with Merino ewes. The content of vulpia, subterranean clover (Trifolium subterraneum L.) and other annual grasses as a proportion of total dry matter increased, and the proportion of phalaris decreased in most grazing treatments throughout the experiment. The mean vulpia content was lowest and the phalaris content was highest in the four-paddock rotation, whereas vulpia content was greatest and phalaris content was lowest under set-stocking. Simazine application in June with or without ryegrass overdrilling reduced the number of vulpia tillers/m2 in 2000 and 2001 and vulpia panicle production in 2000, although vulpia populations increased to pretreatment levels in herbicide-treated swards by 2002. The number of vulpia seeds in the soil seed bank was not affected by any of the treatments. The most effective treatment was a combination of ryegrass overdrilling and herbicide application in the four-paddock, rotationally grazed pastures. This experiment highlights the need for an integrated approach to manage vulpia since relying on herbicide application alone is ineffective. This is particularly the case when competitive pasture species are unable to adequately utilise available resources and prevent a recovery in vulpia populations.

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Acid-tolerance and symbiotic effectiveness of Rhizobium leguminosarum bv. Trifolii isolated from subterranean clover growing in permanent pastures

Soil Biology and Biochemistry ◽

10.1016/0038-0717(94)00143-o ◽

1995 ◽

Vol 27 (1) ◽

pp. 111-115 ◽

Cited By ~ 14

Author(s):

J.F. Slattery ◽

D.R. Coventry

Keyword(s):

Rhizobium Leguminosarum ◽

Acid Tolerance ◽

Subterranean Clover ◽

Symbiotic Effectiveness

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Nitrogen fixation characteristics of Rhizobium surviving in soils 'equilibrated' with sewage biosolids

Australian Journal of Agricultural Research ◽

10.1071/ar01008 ◽

2001 ◽

Vol 52 (10) ◽

pp. 963 ◽

Cited By ~ 6

Author(s):

Kellie J. Munn ◽

Jeffrey Evans ◽

Phillip M. Chalk

Keyword(s):

N2 Fixation ◽

Soil Type ◽

Rhizobium Leguminosarum ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Subterranean Clover ◽

Isotope Dilution Method ◽

Dilution Method ◽

Symbiotic Effectiveness ◽

Amended Soils

To determine the effects of urban sewage biosolids on the symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii and N2 fixation, glasshouse and laboratory studies were carried out with several soils, biosolids, and biosolid application levels. Symbiotic effectiveness of R. l. trifolii was estimated as the dry weight or N content of seedlings of subterranean clover grown with only N2 fixation and seed N as the available nitrogen sources. The N fixed by legumes in unamended and biosolid-amended soils was determined using the 15N isotope dilution method. Six soils were represented in the experiments. Each of these was equilibrated over a period of 12 months with dried, finely ground biosolids (DWS) from the Malabar sewage treatment plant, at biosolids levels ranging from the equivalent of 60 to 240 t DWS/ha. One of the soils was also equilibrated with each of 4 other biosolids. The maximal concentration of heavy metals in soil amended with biosolids was 1026 mg/kg. The effect of biosolids on symbiotic effectiveness depended on the soil type and biosolid applications level. Thus, biosolids reduced the symbiotic effectiveness of R. l. trifolii in 2 of the 6 soils, although at different levels of biosolid. In most soil treatments N2 fixation was detected in subterranean clover, confirming the persistence of symbiotically effective rhizobia in most biosolids-amended soils. In addition, in strongly acidic soils plant N and N2 fixation increased significantly with biosolids addition, probably in response to higher soil pH, exchangeable Ca, and available P. In the treatments in which the symbiotic effectiveness of R. l. trifolii was reduced by biosolids, this was reflected in poor N2 fixation. However, symbiotic effectiveness did not correlate well with N2 fixation, probably because increases in soil nitrate at higher biosolids levels inhibited N2 fixation. Nevertheless, there were instances at 240 t DWS/ha where this was unlikely to explain the decrease in N2 fixation. It was concluded that adverse effects of biosolids on symbiotic effectiveness depend first on soil type, and then on biosolid type and application level; and the response in symbiotic effectiveness to adding biosolids to soil needs to be determined for each distinctively different site of biosolids reuse.

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Integrated management of vulpia in dryland perennial pastures of southern Australia

Crop and Pasture Science ◽

10.1071/cp07445 ◽

2009 ◽

Vol 60 (1) ◽

pp. 32 ◽

Cited By ~ 2

Author(s):

K. N. Tozer ◽

D. F. Chapman ◽

P. E. Quigley ◽

P. M. Dowling ◽

R. D. Cousens ◽

...

Keyword(s):

Seed Production ◽

Integrated Management ◽

Subterranean Clover ◽

Trifolium Subterraneum ◽

Summer Rainfall ◽

Annual Rainfall ◽

Herbicide Application ◽

South Wales ◽

Fertiliser Application ◽

Western Victoria

Vulpia (Vulpia species C.C. Gmel.) are annual grass weeds that can reduce pasture quality and stock-carrying capacity of perennial pastures throughout southern Australia. To develop more effective strategies to control vulpia, an experiment was established in western Victoria (average annual rainfall 565 mm) in phalaris (Phalaris aquatica L.) pastures comparing the effects of control methods [comprising combinations of fertiliser addition (Fert), a single herbicide (simazine) application (Sim), and pasture rest from grazing (Rest)] on vulpia populations. A further herbicide treatment [paraquat-diquat (SpraySeed®)] was imposed on some of these treatments. Measurements included botanical composition, phalaris and vulpia tiller density, seed production, and number of residual seeds in the soil. Vulpia content remained unchanged in the Sim-Rest treatment but increased in all other management treatments over the duration of the 3 year study and especially where paraquat-diquat was applied, despite paraquat-diquat causing an initial reduction in vulpia content. Vulpia content was lowest in the Fert-Sim-Rest treatment. The Fert-Sim treatment and in some cases paraquat-diquat application reduced vulpia tiller production. Vulpia seed production and the residual seed population were not influenced by any of the management treatments, while the single paraquat-diquat application increased vulpia seed production 18 months after application. Phalaris content was enhanced by the Sim-Rest and Fert-Sim-Rest treatments and initially by paraquat-diquat. No treatment affected phalaris tiller production and basal cover. The subterranean clover (Trifolium subterraneum L.) content declined during the experiment, but to a lesser extent where paraquat-diquat was applied. Volunteer species content was initially suppressed in the year following paraquat-application, although populations recovered after this time. Of the two Vulpia spp. present (V. bromoides (L.) S.F. Gray and V. myuros (L.) C.C. Gmelin), V. bromoides was the most prevalent. Results show how a double herbicide application can increase vulpia fecundity and rate of re-infestation of herbicide-treated sites. Pasture rest shows some promise, but to a lesser extent than in the New South Wales tablelands, where summer rainfall may increase the growth of perennial species. In lower rainfall, summer dry areas, responses to pasture rest may be slower. Despite this, integrated management (which combines strategies such as pasture rest, herbicide application, and fertiliser application) increases the perennial content and reduces vulpia seed production, thus improving vulpia control.

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Effect of plant density on the winter production of annual clovers grown in monocultures

Australian Journal of Experimental Agriculture ◽

10.1071/ea01003 ◽

2002 ◽

Vol 42 (2) ◽

pp. 135 ◽

Cited By ~ 5

Author(s):

P. M. Evans ◽

S. Walton ◽

P. A. Riffkin ◽

G. A. Kearney

Keyword(s):

Plant Density ◽

Unit Area ◽

Subterranean Clover ◽

Dry Weight ◽

Equal Weight ◽

Harvest Time ◽

Higher Plant ◽

Plant Weight ◽

Plant Densities ◽

Western Victoria

The small-seeded annual clovers, balansa and Persian, are often assumed to be poor winter producers. Their small seed size, of about 1 mg or less, and poor regeneration, possibly due to inappropriate grazing management in many instances, contributes to this perception. To test the hypothesis that early growth of these clovers is determined by the weight of germinating seed, as it is in subterranean clover, an experiment with 2 cultivars of subterranean clover, Leura and Trikkala, 2 cultivars of balansa clover, Paradana and Bolta, and 1 of Persian clover, Nitro Plus, was established in the field at Hamilton, western Victoria, at 6 sowing densities. The winter production at 2 additional sites, Lake Bolac and Streatham, in their third and second and third seasons, respectively, was also examined. Plant density varied from 30 to 37000 plants/m2 across sites and species. With equal weight of germinating seed per unit area at sowing, balansa and Persian clovers produced more herbage in winter than did the 2 subterranean clover cultivars Leura and Trikkala (P<0.05). Even though there was high correlation between seed weight and seedling weight across all species shortly after emergence (r2 = 0.99), by harvest time no differences in plant weight existed between any treatments growing at the same plant density. From this we conclude the following: (i) for the same weight of germinable seed per unit area, balansa and Persian clovers produced more dry weight per hectare than subterranean clover, because they had higher plant densities; (ii) there were no differences in dry matter production per hectare between species growing at similar plant densities by harvest time at the end of winter; (iii) it appeared that in winter the small-seeded species exhibited a higher relative growth rate than the 2 subterranean clovers.

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THESIS SUMMARY STUDIES OF ALFALFA MOSAIC VIRUS AND SUBTERRANEAN CLOVER RED LEAF VIRUS

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1979.41.1530 ◽

1979 ◽

pp. 163-164

Author(s):

P.B. Teh

Keyword(s):

Mosaic Virus ◽

Alfalfa Mosaic Virus ◽

Subterranean Clover ◽

Test Plant ◽

Transmission Frequency ◽

Virus Source ◽

Leaf Virus

AMV was shown to be transmitted by sap, aphids and through lucerne seed, but not by Cuscuta. Virus source and test plant influenced transmission frequency. Sap-inoculation tests showed that 20 species of plants were susceptible to this virus. Thirteen species of plants from the fields where AMV had been detected were tested but only three were found to be infected with the virus.

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