An exploratory survey of the ecology of Rhizobium meliloti in inland New South Wales and Queensland

1962 ◽  
Vol 13 (5) ◽  
pp. 864 ◽  
Author(s):  
FW Hely ◽  
J Brockwell
Keyword(s):  
Rhizobium Meliloti ◽  
New South ◽  
Plant Size ◽  
Annual Species ◽  
Test Species ◽  
High Frequencies ◽  
South Wales ◽  
Exploratory Survey ◽  
Dry Conditions ◽  
Medicago Sativa L

The ability of Rhizobium meliloti occurring naturally at 26 sites to nodulate three test species of Medicago was investigated. Bacteria able to nodulate Medicago sativa L. were found, in the absence of this host, at all sites sampled and frequently in appreciable numbers, even under dry conditions. Bacteria able to nodulate Medicago denticulata Willd. were found at 25 sites, but usually in lower numbers; they also occurred independently of this species. Organisms able to nodulate Medicago laciniata (L.) Mill. were detected at 18 sites but only in low numbers; they were found at eight sites in the absence of M. laciniata and were not detected at three sites where this medic was present. High numbers of bacteria able to nodulate M. sativa and M. denticulata were related to high frequencies of Medicago minima (L.) Bart. in the field. Associations were found between high numbers of Rh. Meliloti in the topsoil and the texture of the soil, the plant size of the annual species of Medicago in the sample area, and the condition of the native grasses.

Influence of soil pH on the development of symbiosis in field-grown acid-sensitive and acid-tolerant annual medics

1992 ◽  
Vol 32 (2) ◽  
pp. 167 ◽  
Author(s):  
RR Young ◽  
J Brockwell
Keyword(s):  
Soil Ph ◽  
Rhizobium Meliloti ◽  
New South ◽  
Annual Species ◽  
Resident Population ◽  
Growing Period ◽  
South Wales ◽  
Normal Expression ◽  
Acid Tolerant ◽  
Annual Medics

Relationships between soil pH, resident population of Rhizobium meliloti in the soil, rhizobial colonisation of the rhizosphere, and nodulation of annual species of Medicago were examined. Established swards of M. truncatula (acid-sensitive) and of M. murex and M. polymorpha (acid-tolerant) growing at 6 different locations in central and western New South Wales were sampled to measure soil pH, to enumerate the populations of R. meliloti resident in the soil and colonising plant rhizospheres, and to assess the extent of nodulation. Soil pH (0.01 mol CaCl2/L) varied from 4.70 to 7.25, soil populations from 3 to 100000 rhizobialg, and rhizosphere populations from 10 to >1 x 106 rhizobia/plant. Nodulation varied from poor to good, depending on growing period and location, but was consistently poorer on M. truncatula than on M. murex or M. polymorpha. Regression analysis showed a consistent and significant (P<0.01) relationship between rhizobial colonisation of the rhizosphere and extent of nodulation. There was also a significant (P<0.001) correlation over all 44 sampling sites between soil pH and the population of R. meliloti resident in the soil. The relationships between soil pH and rhizosphere colonisation, and between soil pH and nodulation, were significant for M. truncatula (P<0.01, P<0.02, respectively) but not for either M. murex or M. polymorpha. These data suggest that the range of soil pH at which M. truncatula was growing (4.80-7.25, but mainly 4.8-5.6) spanned the threshold at which unfavourable soil pH began to obstruct normal expression of its symbiosis, whereas, the critical soil pH levels for symbiotic development of M. murex and M. polymorpha were below this range.

Factors Associated With Density of Mitchell Grass Pastures in North-Western New South Wales.

1997 ◽  
Vol 19 (1) ◽  
pp. 40 ◽  
Author(s):  
AM Bowman ◽  
DJ Munnich ◽  
KY Chan ◽  
J Brockwell
Keyword(s):  
Plant Density ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Good Condition ◽  
Grazing Pressure ◽  
Annual Species ◽  
Basal Diameter ◽  
Poor Condition ◽  
South Wales

Thirty-eight paddocks on 23 properties in the Walgett Shire of north-westem New South Wales were surveyed in April and May 1993 to identify factors that affected Mitchell grass (Astrebla lappacea) plant density. Low densities of Mitchell grass were associated with the occurrence of at least one flood in the last 20 years. Soils from paddocks described by landholders as in poor condition, and where Mitchell grass density was low, were more alkaline and had significantly higher electrical conductivity than soils from paddocks described as in good condition, and where Mitchell grass density was high. Paddocks in poor condition had higher organic carbon and mineralisable nitrogen levels and higher soil populations of Rhizobium meliloti. These latter characteristics were attributed to these pastures having a high component of annual species, including Medicago species, which returned substantial amounts of carbon and nitrogen to the soil. Where Mitchell grass density was moderate, other palatable species were common and biodiversity was high. However, in paddocks with the lowest densities of Mitchell grass, both annual species and unpalatable perennials were common. Low basal diameter of Mitchell grass plants and low Mitchell grass density, were associated with higher grazing pressure. The data suggested that the Mitchell grass ecosystem in north-westem New South Wales is prone to deterioration on the more alkaline and saline soils and where inundation by flooding or waterlogging is common.

Corrigendum - Frequency of annual species of Medicago on the major soil groups of the Mcquarie region of New South Wales

1960 ◽  
Vol 11 (5) ◽  
pp. 705
Author(s):  
WD Andrew ◽  
FW Hely
Keyword(s):  
New South ◽  
New South Wales ◽  
Salt Content ◽  
Acid Group ◽  
Soluble Salt ◽  
Annual Species ◽  
South Wales ◽  
Soil Groups ◽  
Soil Habitat ◽  
Poor Drainage

The frequency of eight annual species of Medicago was determined on 10 soil groups in a region climatically favourable for medics. They occurred on nine of these, the overall frequency being in the order M. minima (L.) Bart. > M. denticulata Willd. > M. laciniata (L.) Mill., M. praecox DC., M. tribuloides Desr., and M. orbicularis (L.) Bart. > M. arabica (L.) Huds. and M. confinis Koch. M. minima was more tolerant of variation of soil habitat than any other medic in the region. M. denticulata was most commonly found on the soils of high soluble salt content and showed the greatest tolerance of poor drainage conditions. M. laciniata occurred in greatest abundance on soils of the well-drained brown acid group. M. praecox was most commonly found on soils with a compact gravelly surface. M. tribuloides was recorded on five soil groups but was common only on the black earths. M. orbicularis was confined to the black earth and red loam soils. M. arabica was rarely found, being restricted to lower, fertile, well-drained parts of the landscape, and M. confinis occurred only occasionally and then in association with M. denticulata.

Effects of depth and time of sowing on emergence of Danthonia richardsonii Cashmore and Danthonia linkii Kunth

1993 ◽  
Vol 44 (6) ◽  
pp. 1311 ◽  
Author(s):  
GM Lodge ◽  
AJ Schipp
Keyword(s):  
New South ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Maximum Temperature ◽  
Sowing Time ◽  
Sand Mixture ◽  
South Wales ◽  
Seed Field ◽  
Dry Conditions ◽  
Soil Temperatures

Two experiments examined the effects of sowing time and depth (surface and 10, 25, 50 mm) on emergence of Danthonia richardsonii Cashmore and Danthonia linkii Kunth. Experiment 1 was conducted from January to December 1990 on a loam/sand mixture in boxes. Emergence was highest in both species for seeds sown onto the soil surface in summer and autumn (P < 0.05). Sowing at any depth at any time of the year, or surface sowing in winter and spring, markedly reduced emergence. Experiment 2 was conducted in the field at Tamworth, northern New South Wales from September 1991 to August 1992, on a red brown earth and a black earth. This study confirmed that emergence in both species was highest from surface sown seed. Field emergence was lowest in winter, but in contrast to experiment 1, it was higher in spring, particularly on the black earth. Seedling emergence appeared to be related to mean maximum temperature, decreasing in winter as it declined below 20�C, and increasing in spring when it was greater than 23�C. Differences in seed weight were reflected in emergence of D. richardsonii and D. linkii in experiment 1. Similar emergence was recorded for the loamlsand mixture and sand, indicating that there was little effect of texture. Phalaris aquatica L. cv. Sirosa surface sown in December had lower emergence ( P < 0.05) than both Danthonia spp., but emergence of this larger seeded cultivar was higher at depths of 10 and 25 mm. Laboratory studies to determine reasons for the low emergence of D. richardsonii and D. linkii from depth, indicated that neither had an obligate light requirement for germination. Depth, however, reduced germination (P < 0.05) compared with surface sowing of seed. Seedlings at depth also were observed to have slower rates of shoot and root elongation. In the field, the most successful establishments of D. richardsonii and D. linkii seedlings are likely to occur from surface sowings in April and May. Sowing in spring may also be possible if mean maximum soil temperatures exceed 23�C, and seedlings can establish before the onset of hot, dry conditions in summer.

Rhizobium as a factor in the re-establishment of legume-based pastures on clay soils of the wheat belt of north-western New South Wales

1998 ◽  
Vol 38 (6) ◽  
pp. 555 ◽  
Author(s):  
A. M. Bowman ◽  
D. M. Hebb ◽  
D. J. Munnich ◽  
J. Brockwell
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Clay Soils ◽  
Natural Fertility ◽  
Fixed Nitrogen ◽  
South Wales ◽  
Annual Medics ◽  
North Western

Summary. Populations of Rhizobium meliloti in self-mulching clay soils (Vertisols) at 48 sites on 27 properties in north-western New South Wales were classified according to number and ability to fix nitrogen with several species of Medicago. Rhizobia were counted using serial dilution, nodulation frequency, plant infection tests. Abilities of the soil populations to fix nitrogen were determined in the laboratory with whole-soil inoculation of Medicago seedlings in test tubes with shoots exposed to the atmosphere and roots within the tubes under bacteriological control, and in the field using a technique based on the natural abundance of 15N in the soil. The majority of soils contained >1000 cells of R. meliloti per gram. The major component of those populations fixed nitrogen with lucerne (Medicago sativa) and some components of some soils also fixed nitrogen with M. polymorpha, M. scutellata, M. littoralis, M. tornata, M. laciniata and Trigonella suavissima. However, a number of soils were located which contained few if any rhizobia effective in nitrogen fixation with M. polymorpha. Overall, the effectiveness of nitrogen fixation of the naturally occurring populations of R. meliloti in association with M. polymorpha, M. scutellata, M. littoralis and M. tornata was only 46% of the effectiveness of standard strains. At one particular site, where 10 lines of annual Medicago spp. were growing experimentally, fixed nitrogen as a proportion of shoot nitrogen averaged only 28%. At that site, there were no effective rhizobia for M. scutellata and it was wholly dependent on the soil as the source of its nitrogen. The results are discussed in relation to the need for a substantial input of legume nitrogen for restoring the natural fertility of self-mulching clay soils in degraded wheat lands of north-western New South Wales. It is suggested that lucerne, or perhaps other perennial Medicago spp., might fill this role better than annual medics such as M. polymorpha and M. scutellata that are more dependent than lucerne on specific strains of R. meliloti to meet their requirements for symbiotic nitrogen fixation.

Recruitment of Curly Mitchell Grass (Astrebla Lappacea) in North-Western New South Wales.

1996 ◽  
Vol 18 (1) ◽  
pp. 179 ◽  
Author(s):  
MH Campbell ◽  
AM Bowman ◽  
WD Bellotti ◽  
DJ Munich ◽  
HI Nicol
Keyword(s):  
Seed Bank ◽  
Seedling Recruitment ◽  
New South ◽  
Rainfall Events ◽  
South Wales ◽  
Grazing System ◽  
Dry Conditions ◽  
Annual Weeds ◽  
North Western ◽  
Germinable Seed

The recruitment of Astrebla lappacea was studied from 1986 to 1995 in a pasture in north-western NSW where the density of plants had declined from 1 to 3 plants/m2 in 1970 to 0.023 plants/m2 in 1986. Three treatments were imposed: ungrazed-sprayed-slashed, where annual weeds were treated with herbicides and slashing to reduce competition during recruitment; ungrazed-only; and grazed-only. The seed bank of A. lappacea was measured on four occasions and densities of A. lappacea plants determined after major rainfall events mainly in summer and autumn. On the ungrazed treatments the seed bank of A. lappacea increased from 0 in 1988 to 908, 898 and 286 germinable seed/m2 in, respectively, 1992, 1993 and 1995. Flowering and seedling recruitment occurred each year from 1988 to 1995 but seedlings only survived to become mature plants from the 1988 and 1992 recruitments. The major reason for the death of seedlings was dry conditions in the latter half of the year (1 10 to 135 mm of raid6 months). Frosts and competition from Brassicaceae weeds (mainly Raphistrum rugosum) in winter and spring also contributed to death of seedlings. Recruitment of seedlings and their survival to mature plants was higher on the ungrazed-sprayed-slashed treatment than on the other treatments. Recruitment and survival on the ungrazed-only treatment occurred because Brassicaceae weeds did not establish when recruiting rains fell in summer. Plant densit increased from 0.023 plants/m2 in 1986 to, respectively, 0.86, 0.64 Y and 0.004 mature plantdm and 7.88, 6.37, 0.10 seedlings/m2 on the ungrazed-sprayed-slashed, ungrazed-only and grazed-only treatments in 1995. On the grazed-only treatment the methods used to detect seeds revealed none in the soil during the experiment. However, some seeds were present because there was a low level of recruitment none of which survived to mature plants. The number of mature plants declined from 0.023 to 0.004/m2 indicating that under the present grazing system the complete elimination of A. lappacea from pastures in north-western NSW is possible if some form of managed recruitment is not devised.

Reducing losses of surface-sown seed due to harvesting ants

1979 ◽  
Vol 19 (101) ◽  
pp. 706 ◽  
Author(s):  
MH Campbell ◽  
AR Gilmour
Keyword(s):  
Rhizobium Meliloti ◽  
New South ◽  
Untreated Seed ◽  
Powder Formulation ◽  
South Wales ◽  
Wettable Powder ◽  
Oil Formulation ◽  
Treated Seed ◽  
Ant Nest ◽  
Number Of Seeds

Four experiments were carried out at Orange, New South Wales, in 1978 to test the effect of coating seeds with insecticides on their removal by seed harvesting ants (Pheidole sp.). Treated or untreated seeds of Phalaris aquatica were placed 10 cm from the entrance to an ant nest and the number of seeds taken by ants noted daily. Further experiments tested the effect of coating seeds with insecticides on the germination of P. aquatica and Medicago sativa and on the viability of rhizobia applied to the seed. Permethrin, at 1.50 and 2.25 g a.i. kg-1 seed and bendiocarb at 0.75, 1.50 and 2.25 g a.i. kg-1 seed significantly reduced the rate of removal of seed by ants when compared with the rate of removal of untreated seed. Ants removed untreated seed at > 150 seedsinest day-1 while treated seed was removed at an average of 5 seedslnest day-1 over a 14 day period. The wettable powder formulation of permethrin was as effective as the miscible oil formulation. The activity of ants from nests that took treated seed was reduced by the higher rates of bendiocarb, but not affected by permethrin and the low rate of bendiocarb when compared with the activity of ants from nests that took untreated seed. The miscible oil formulation of permethrin reduced the rate of germination of P. aquatica, but the wettable powder formulation of both permethrin and bendiocarb had no deleterious effect on germination. Neither permethrin nor bendiocarb had deleterious effects on the survival of Rhizobium meliloti or R. trifolii.

Frequency of annual species of Medicago on the major soil groups of the Mcquarie region of New South Wales

1960 ◽  
Vol 11 (5) ◽  
pp. 705
Author(s):  
WD Andrew ◽  
FW Hely
Keyword(s):  
New South ◽  
New South Wales ◽  
Salt Content ◽  
Acid Group ◽  
Soluble Salt ◽  
Annual Species ◽  
South Wales ◽  
Soil Groups ◽  
Soil Habitat ◽  
Poor Drainage

The frequency of eight annual species of Medicago was determined on 10 soil groups in a region climatically favourable for medics. They occurred on nine of these, the overall frequency being in the order M. minima (L.) Bart. > M. denticulata Willd. > M. laciniata (L.) Mill., M. praecox DC., M. tribuloides Desr., and M. orbicularis (L.) Bart. > M. arabica (L.) Huds. and M. confinis Koch. M. minima was more tolerant of variation of soil habitat than any other medic in the region. M. denticulata was most commonly found on the soils of high soluble salt content and showed the greatest tolerance of poor drainage conditions. M. laciniata occurred in greatest abundance on soils of the well-drained brown acid group. M. praecox was most commonly found on soils with a compact gravelly surface. M. tribuloides was recorded on five soil groups but was common only on the black earths. M. orbicularis was confined to the black earth and red loam soils. M. arabica was rarely found, being restricted to lower, fertile, well-drained parts of the landscape, and M. confinis occurred only occasionally and then in association with M. denticulata.

Effects of topdressed superphosphate on the sheep and pasture production of dryland lucerne in central western New South Wales

1975 ◽  
Vol 15 (75) ◽  
pp. 475 ◽  
Author(s):  
H Brownlee ◽  
BJ Scott ◽  
RD Kearins ◽  
J Bradley
Keyword(s):  
New South ◽  
Soil Phosphorus ◽  
New South Wales ◽  
Stocking Rate ◽  
Gross Margin ◽  
Pasture Production ◽  
Wool Production ◽  
South Wales ◽  
Dry Conditions ◽  
Soil Phosphorus Test

Merino ewes at 3.7, 4.9 and 6.2 ha-1 grazed dryland lucerne (Medicago sativa cv. Hunter River) topdressed annually with superphosphate at 0, 125 and 251 kg ha-1, from September 1969 until December 1972, in an experiment at Condobolin, New South Wales. Superphosphate increased ewe liveweights, total forage available and phosphorus content of the forage by a small amount but did not increase wool production per head. The Bray soil phosphorus test in the top 8 cm of the soil profile rose from 8 p.p.m. to 48 p.p.m., but most of the phosphorus was concentrated in the 0-4 cm layer, where we consider that dry conditions reduced its availability to the lucerne. As stocking rate increased, ewe liveweights and wool production per head decreased and the sheep required more handfeeding for survival. The treatment with the greatest gross margin was the lowest stocking rate with nil fertilizer.

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