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.

Characterisation of naturalised strains of Trifolium subterraneum var. brachycalycinum cv. Clare in northern New South Wales

1994 ◽  
Vol 34 (1) ◽  
pp. 33 ◽  
Author(s):  
GM Lodge
Keyword(s):  
Seed Weight ◽  
New South ◽  
New South Wales ◽  
Trifolium Subterraneum ◽  
Summer Rainfall ◽  
Median Number ◽  
South Wales ◽  
The Mean ◽  
Floral Characters ◽  
Number Of Seeds

Burrs were collected from paddocks on 3 properties in northern New South Wales where the age of the Trifolium subterraneum var. brachycalycinum cv. Clare swards varied from 19 to 28 years. At 1 site burrs were also sampled from swards sown 2 and 10 years previously. Twenty seedlings from these burrs and 20 plants of certified cv. Clare were grown as spaced plants in a nursery. These were assessed for vegetative and floral characters, flowering time, number of seeds per burr, seed weight, and percentage hardseed after storage at 25/25�C for 6 months and 25/45�C for a further 6 months. For most plants the mean number of days from sowing to first flower was similar to that of Clare. Compared with the naturalised strains, Clare had the lowest (P<0.05) mean number of seeds per burr: about 25% below the mean of the strains (2.7 seeds per burr). While the lowest mean seed weights of the strains were not significantly different from those of Clare, the seed weights of plants from 3 sites were higher (P<0.05) than those of Clare. After storage for either 6 or 12 months, hardseed levels were also lowest (P<0.05) for Clare. Plants from the 2-year-old sward had the same median number of seeds per burr (2.0) as Clare. As sward age increased, the median number of seeds per burr increased to 2.8. Hardseed percentages were lowest for plants of Clare and for those from the 2-year-old sward after 6 months, and for Clare after 12 months. These studies indicated the presence of divergent strains in old swards of Clare in a summer rainfall environment. Natural selection among variability within Clare is the most likely reason for the development of these strains in an environment marginal for the long-term persistence of this softseeded cultivar. Although strains had the same vegetative and floral markings as Clare, differences in ecologically important characters such as number of seeds per burr, seed weight, and hardseededness may result in plants that are better adapted to the environment in which they evolved. From these studies 23 plants of T. subterraneum var. brachycalycinum were selected for further evaluation.

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.

Soil pH is a major determinant of the numbers of naturally occurring Rhizobium meliloti in non-cultivated soils in central New South Wales

1991 ◽  
Vol 31 (2) ◽  
pp. 211 ◽  
Author(s):  
J Brockwell ◽  
A Pilka ◽  
RA Holliday
Keyword(s):  
Soil Ph ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Acid Soils ◽  
Alkaline Soils ◽  
Naturally Occurring ◽  
South Wales ◽  
Dominant Soil ◽  
The Relationship

Measurements were made of soil pH, frequency of occurrence of annual species of Medicago (medics) and populations of Rhizobium meliloti at 84 sites on 7 dominant soil groups of the Macquarie region of central-western New South Wales. Over all sites, soil pH (0-10 cm; 1:5 soil: water) ranged from 5.26 to 8.07, medic frequency from 0 to 100% and most probable numbers of R. meliloti from undetectable to 675 000/g soil. There was a highly significant (P<0.001) relationship between soil pH and number of R. meliloti. Above pH 7.0, the mean soil population of R. meliloti was 89000/g; below pH 6.0, it was 37/g. Medics occurred most frequently on the more alkaline soils and with least frequency on the more acid soils, but the relationship between soil pH and medic frequency was weaker than between pH and R. meliloti number. Medics were more tolerant of low soil pH than their rhizobia were; at 2 sites, of pH 5.49 and 5.35, medics occurred at 100% frequency but R. meliloti was undetected. There was an indication of some acidification in these soils over a period of 35 years but this remains to be confirmed.

Dispersal of seeds of giant Sporobolus spp. after ingestion by grazing cattle

1995 ◽  
Vol 35 (3) ◽  
pp. 353 ◽  
Author(s):  
TS Andrews
Keyword(s):  
New South ◽  
Heavy Rain ◽  
North Coast ◽  
The North ◽  
Fresh Manure ◽  
Grazing Cattle ◽  
South Wales ◽  
Cattle Faeces ◽  
Viable Seeds ◽  
Number Of Seeds

Samples of fresh cattle faeces were taken from 2 grazing paddocks on the North Coast of New South Wales. One paddock was heavily infested with giant Parramatta grass (GPG, Sporobolus indicus var. major) and the other paddock had a medium-light infestation. Fifty-two and 14 viable GPG seeds/kg were recovered from the dung samples collected in May from these paddocks, respectively. Seeds of GPG and giant rat's tail grass (GRTG, S. pyramidalis) were fed to caged Friesian heifers in 2 experiments, and the time taken for all of the seeds to be excreted was measured: 4 days in experiment 1 and 7 days in experiment 2. Consequently, a 7-day withholding period is suggested for cattle grazing pastures infested with giant sporobolus. The number of viable seeds excreted was estimated as a proportion of seeds fed to each heifer using average viability of seeds recovered, concentration of viable seeds collected daily, and daily manure weights. Based on this, the number of seeds ingested by gazing stock was estimated to be 8300 and 2200 seeds/head.day for the paddocks with heavy and medium-light infestation, respectively. Manure collected 2 and 3 days after feeding had the highest concentrations of viable seeds. This manure was placed outdoors in styrofoam boxes and left for 7 months. No GPG seedlings or plants were present in the manure after this time, and further subsampling of the manure indicated that no viable seeds remained. Processes that disperse fresh manure, such as heavy rain or the hosing down of transport vehicles, may allow successful germination and emergence of giant sporobolus seeds. However, where dung pats are left intact for some months, establishment of giant sporobolus plants is unlikely. Adhesion to machinery and the hair of stock are likely to be more important causes of dispersal of giant sporobolus than ingestion by stock.

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.

Studies on seed pelleting as an aid to legume seed inoculation. 2. Survival of Rhizobium meliloti applied to medic seed sown into dry soil

1970 ◽  
Vol 10 (45) ◽  
pp. 455 ◽  
Author(s):  
J Brockwell ◽  
RDB Whalley
Keyword(s):  
Survival Rate ◽  
Rhizobium Meliloti ◽  
New South ◽  
Legume Seed ◽  
Seed Inoculation ◽  
South Wales ◽  
Inoculation Techniques ◽  
Medicago Littoralis ◽  
Dry Soil ◽  
Western Division

Seed of Medicago truncatula and Medicago littoralis, with and without lime pelleting and inoculation, was sown dry into medic-free, Rhizobim meliloti-free soils at 12 sites in the Western Division of New South Wales. At the different sites, periods between 1 and 88 days elapsed before germinating rain fell. Seedling nodulation was used as the index of inoculant survival. Nodulation was variable, but the variation was independent of the time between sowing and germination. Best nodulation occurred in treatments in which peat inoculant was incorporated within a lime pellet around the seed. These treatments were superior to others where broth inoculant was incorporated in the pellet or where peat inoculant was applied externally to pelleted or unpelleted seed. Nodulation was improved by incorporating an increased level of peat inoculant in the pellet. In storage, a very low survival rate was recorded in all treatments except those incorporating peat inoculant within the pellet. The results are discussed in relation to the practicalities of pre-inoculation techniques and of sowing inoculated medic seed into dry seed beds.

Symbiotic characteristics of Rhizobium meliloti from the brown acid soils of the Macquarie region of New South Wales.

1961 ◽  
Vol 12 (4) ◽  
pp. 630 ◽  
Author(s):  
J Brockwell ◽  
FW Hely
Keyword(s):  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Acid Soils ◽  
Nodule Formation ◽  
Seed Inoculation ◽  
South Wales ◽  
High Level ◽  
Bacterial Groups ◽  
Selection Of

Thirty-three isolates of Rhizobim meliloti were obtained from the brown acid soils of the Macquarie region of New South Wales and their symbiotic behaviour in association with 11 species of Merlicago and three species of Melilotus was investigated in the laboratory. In respect of nodule formation, there were two distinct types of Rhizobiurn and the hosts formed three groups. In respect of nitrogen fixation there were six strain types and seven host, groupings. These host and bacterial groups could be arranged in a series. Several of the strains of rhizobia, and one in particular, were found to fix a high level of nitrogen with a number of hosts, but, except for ;Medicago denticulata Willd. and Melilotus indica (L.) All. which behaved identically in all features of the symbiosis studied, no definit'e groupings on this criterion were apparent in either hosts or bacteria. The possible application of the results to the selection of strains of' Rhizobium meliloti suitable for seed inoculation is discussed.

Variation in the acidity of cropped and uncropped light-textured red soils of central western New South Wales

1999 ◽  
Vol 39 (8) ◽  
pp. 981 ◽  
Author(s):  
R. R. Young ◽  
C. L. Alston ◽  
C. J. Chartres
Keyword(s):  
Soil Acidity ◽  
Rhizobium Meliloti ◽  
New South ◽  
New South Wales ◽  
Soil Surface ◽  
Aluminium Toxicity ◽  
Total Carbon ◽  
Agricultural Activity ◽  
Barrel Medic ◽  
South Wales

Summary. The light-textured, red, gradational and duplex soils in semi-arid central western New South Wales were found to be on a pH threshold for suitability for the traditional cultivars of barrel medic (Medicago truncatula), an important pasture legume in the region, and other acid sensitive species. However, there was little evidence that cropping over a long time increased soil acidity. Over the 38 sampling sites, mean pHCa in the soil surface 0–20 cm was significantly higher in cropped compared to contiguous uncropped and usually timbered control areas. The return of cations and associated alkali in standing timber to the soil surface when trees were pushed and burnt is a plausible explanation. In the surface (0–20 cm) layers of 10 of 38 cropped paddocks, mean pH in 0.01 mol CaCl2/L was <5, sufficient to severely obstruct growth and the nitrogen fixing capacity of barrel medic. All but 4 sites had pHCa <6, where some reduction in nitrogen fixation would be expected to occur. Variation in pH within transects within paddocks was large, which is consistent with the common observation of poor and patchy growth of barrel medic. Exchangeable calcium, important for Medicago–Rhizobium meliloti symbiosis function, decreased with increasing acidity. The potential for manganese toxicity appeared low with aluminium toxicity likely only at some sites with pHCa ≤4.5. Total carbon decreased with increasing soil acidity and was less under cropping at any pHCa. Although acidification of these soils due to agricultural activity was not apparent from paired sampling of cropped and contiguous uncropped transects, they seem likely to be prone to acidification.

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.

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