bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term benefits of limestone applications to soil properties and to cereal crop yields in southern and central New South Wales
Authors: Conyers M. K. , Mullen C. L. , Scott B. J. , Poile G. J. , Braysher B. D.
Published: March 2003

The cost of buying, carting and spreading limestone, relative to the value of broadacre crops, makes investment in liming a questionable proposition for many farmers. The longer the beneficial effects of limestone persist, however, the more the investment in liming becomes economically favourable. We re-established previous lime trials with the aim of measuring the long-term effects of limestone on surface acidity (pH run-down), subsurface acidity (lime movement) and grain yield. The study made use of experiments where there was adequate early data on soil chemical properties and cereal yields. We report data from 6 trials located at 4 sites between Dubbo and Albury in New South Wales. The rate of surface soil (0–10 cm) pH decline after liming was proportional to the pH attained 1 year after liming. That is, the higher the pH achieved, the more rapid the rate of subsequent pH decline. Since yields (product removal) and nitrification (also acid producing) may both vary with pH, the post-liming pH acts as a surrogate for the productivity and acid-generating rate of the soil–plant system. The apparent lime loss rate of the surface soils ranged from the equivalent of nearly 500 kg limestone/ha.year at pH approaching 7, to almost zero at pH approaching 4. At commercial application rates of 2–2.5 t/ha, the movement of alkali below the layer of application was restricted. However, significant calcium (Ca) movement sometimes occurred to below 20 cm depth. At rates of limestone application exceeding the typical commercial rate of 2.5 t/ha, or at surface pH greater than about 5.5, alkali and Ca movement into acidic subsurface soil was clearly observed. It is therefore technically feasible to ameliorate subsurface soil acidity by applying heavy rates of limestone to the soil surface. However, the cost and risks of this option should be weighed against the use of acid-tolerant cultivars in combination with more moderate limestone rates worked into the surface soil.There was a positive residual benefit of limestone on cereal grain yield (either barley, wheat, triticale, or oats) at all sites in both the 1992 and 1993 seasons. While acid-tolerant cultivars were less lime responsive than acid-sensitive ones, the best yields were generally obtained using a combination of liming and acid-tolerant cultivars.The long-term residual benefits of limestone were shown to extend for beyond 8–12 years and indicate that liming should be profitable in the long term.
Reduced growth and deterrence from feeding of the insect pest Helicoverpa armigera associated with fungal endophytes from cotton
Authors: McGee P. A.
Published: March 2003

More than 13 morphospecies of fungal endophyte were isolated from leaves of cotton collected from eastern New South Wales, Australia. Of the fungi tested, methanol extracts of 4 morphospecies offered with a food source reduced the larval growth rate of the insect pest Helicoverpa armigera. Extracts of different isolates of 1�common morphospecies had varying effects on growth rates of H. armigera and H. punctigera. The impact of the endophytes after inoculation to leaves of cotton also differed. Five of 10 selected isolates were associated with reduced feeding from leaf discs in a feeding-choice experiment with H. armigera. The data are consistent with the view that some fungal endophytes benefit their host through reduced herbivory of the plant.
Effects of fire on germination and viability of bellyache bush (Jatropha gossypiifolia) seeds
Authors: Bebawi F. F. , Campbell S. D.
Published: March 2003

If treatments imposed to control exotic plants also have a deleterious impact on their residual seed bank, the duration and extent of follow-up control may be reduced. Fire is one such technique that has this ability, particularly if seeds are located on or close to the soil surface. Three studies were undertaken in a riparian habitat in the dry tropics of northern Queensland to quantify the effects of spring burning on the seed bank of the exotic weed bellyache bush (Jatropha gossypiifolia). The first determined the distribution of seeds within the vertical profile of the trial site. The other 2 studies were experiments that quantified the effects of fire on germination and viability of both dispersed bellyache bush seeds and seeds held in mature capsules. Dispersed seeds of 2 types (intact and ant-discarded) were placed at the following 6 positions in the vertical profile of bellyache bush infestations: 0.5, 1, 2 and 4 cm depth below ground, on bare ground, and below fuel. Seeds held in capsules were located at random on the crown of bellyache bush plants. For both experiments, comparisons of burnt plots were made with unburnt controls. Fire was imposed in spring (September); the season in which burning for weed control in northern Queensland generally occurs. While maximum fire temperatures averaged 590 ± 46°C, the temperatures that seeds or capsules were exposed to depended on their location within the vertical profile, with temperatures decreasing in the following order: below fuel > crown of bellyache bush > 1 cm > 0.5 cm > bare ground > 2 cm > 4 cm below ground. There were negative correlations between seed germination and peak fire temperature and between viability and peak fire temperature. Seed viability was nil for seed under fuel but >80% for seeds placed on bare ground or ≥2 cm below ground. Fire reduced germination and viability of seeds held in capsules by 31 and 35%, respectively, when compared with unburnt seeds. While ant-discarded seeds generally had a higher germinability than intact seeds, they were more susceptible to fire. This may be attributed to loss of the external protective barrier of the seed coat (exotegmen) caused by the feeding of ants. Bellyache bush seeds were recorded across all soil depths, reaching a peak of 3.8 million seeds per hectare at 1–5 cm soil depth. These results suggest that while bellyache bush seeds are susceptible to fire, many are buried beyond the reach of lethal temperatures. Therefore, viable seeds will be available for post-fire recruitment and other measures, such as chemical control, may need to be employed in conjunction with burning.
Effect of seedbed cultivation techniques, variety, soil type and sowing time, on brassica dry matter yields, water use efficiency and crop nutritive characteristics in western Victoria
Authors: Jacobs J. L. , Ward G. N. , McDowell A. M. , Kearney G.
Published: March 2003

Effect of cultivation practice and sowing time on soil moisture retention at sowing, growth rates, dry matter yield, water use efficiency and nutritive characteristics (metabolisable energy, crude protein, neutral detergent fibre, water-soluble carbohydrates and starch) of turnip, pasja and rape was determined on 2 soil types (site A and B) over 2 years. Cultivation treatments were: optimum full inversion, an optimum non-inversion cultivation and over cultivated. At each site, cultivation treatments were imposed at 2 different times (early and late).Results showed few differences in soil moisture at sowing between the 3 cultivation systems. Where seedbeds were prepared earlier rather than later, soil moisture at sowing was higher. Given that there was relatively little difference in soil moisture between cultivation treatments within a sowing time, it is likely that rainfall events may have confounded cultivation effects.Apart from year 2 at site A, the water use efficiency of turnip was higher than for pasja and rape. It is proposed that the lower value in year 2 may be due to root development being retarded by low moisture availability, particularly at the later sowing date, thus leading to a lower dry matter yield.Despite no cultivation effects on soil moisture at sowing, there appeared to be clear advantages for the full inversion technique in terms of subsequent weed germination. Generally, weed numbers post germination were lower for this cultivation method compared with both non-inversion techniques. In conclusion, the cultivation techniques used had little effect on soil moisture at sowing and subsequent dry matter yields, provided the resultant seedbed was well-prepared, fine, firm and weed free. Full inversion cultivation techniques in areas where broad-leaved weeds are a problem may substantially reduce subsequent weed burdens. Early sowing where possible may reduce the likelihood of crop failure through the provision of adequate soil moisture at sowing and increase the incidence of rain during the growing period. Timing of sowing will vary according to paddock requirements during early spring (e.g. grazing or forage conservation), soil type, and trafficability for cultivation.
Is a rainfall simulator useful for estimating phosphorus runoff from pastures — a question of scale-dependency?
Authors: Cornish P. S. , Hallissey R. , Hollinger E.
Published: March 2003

Research on management practices that aim to reduce phosphorus in runoff from agricultural land has been hampered by the need to study large catchments over relatively long time periods to account for both the temporal and spatial effects of scale. The concentrations of pollutants such as phosphorus in runoff, similarly to suspended sediment, may diminish with increasing catchment scale. However, the runoff from well-covered dairy pastures contains predominantly soluble rather than particulate phosphorus. This paper examines the hypothesis that the concentration of soluble phosphorus in runoff from dairy pastures is insensitive to scale, and that small-plot rainfall simulators can be used to estimate concentrations of phosphorus in runoff at the farm or subcatchment scale.Over 2 years and 9 runoff events, the mean concentration of soluble phosphorus in runoff from a 140 ha dairy farm (0.95 mg/L) was not significantly different from a 4 ha representative subcatchment (paddock) within the dairy farm (0.66 mg/L). Relative concentrations from the 2 sources varied between events, depending on the duration of the runoff event. This variation was attributed to changes in the relative importance of different source areas as events progressed; runoff from the more distant parts of the larger catchment area, typically in higher positions in the landscape, apparently increased in importance in longer events.A hand-held rainfall simulator, with plots of only 1 m2, provided a quick, useful estimate of soluble phosphorus concentration in runoff. The mean concentration of soluble phosphorus in runoff from simulated rainfall at 9�locations in the 4 ha paddock (0.64 mg/L) was very similar to the value obtained from the paddock over a 2-year period (0.66 mg/L). We conclude that the concentration of soluble phosphorus in runoff from dairy pasture does depend on scale, and other variables, but the effect of scale was small for the catchment studied. A rainfall simulator may be used, with adequate replication, to estimate the soluble phosphorus concentrations in runoff that could be expected from dairy pastures over much larger areas.
Relative effectiveness of soil-applied zinc for four crop species
Authors: Brennan R. F. , Bolland M. D. A.
Published: March 2003

The yield and zinc content response of canola (Brassica napus L.), albus lupin (Lupinus albus L.), durum wheat (Triticum durum L.) and spring wheat (Triticum aestivum L.) to applications of zinc fertiliser were compared in a glasshouse experiment using 2 alkaline soils from south-western Australia. Five amounts of zinc applied as zinc sulfate were either added just before sowing (current zinc) or incubated in moist soil for 50 days (incubated zinc) before sowing seeds. Comparative zinc requirements were determined from yields of 40-day-old dried shoots for: (i) zinc already present in the soil (indigenous zinc); (ii) the amount of fertiliser zinc required to produce the same percentage of the maximum (relative) yield of dried shoots; and (iii) the zinc content of dried shoots (zinc concentration multiplied by yield of dried shoots). The concentration of zinc in youngest tissue and in dried shoots was used to determine critical concentrations for zinc in tissue. Albus lupin used indigenous, current and incubated zinc more effectively than canola, followed by spring wheat and then durum wheat. Albus lupin and canola were about 30 and 40% more effective at using fertiliser zinc than spring wheat. Durum wheat was about 20% less effective than spring wheat. Relative to current zinc, the effectiveness of incubated zinc declined by about 60% for both spring and durum wheat, and by 50% for canola and albus lupin. The critical zinc concentrations in the youngest tissue, associated with 90% of the relative yield, were (mg zinc/kg): 14 for spring wheat, 20 for durum wheat, 16 for albus lupin and 15 for canola. Corresponding values for dried shoots (mg zinc/kg) were: 32 for spring wheat, 25 for durum wheat, 22 for albus lupin and 23 for canola.
Lithium salts as a marker of intake of supplements by cattle
Authors: Dixon R. M. , Smith D. R. , Reid A.
Published: March 2003

In a series of experiments the appearance of lithium cation in plasma following ingestion or intravenous administration of lithium salts was measured in order to examine the suitability of lithium as a marker of supplement intake by cattle. In experiment 1, cattle were offered low quality hay ad libitum and 0.15, 0.4, 1.0 and 3.0 kg cottonseed meal (CSM) supplement per day. Following ingestion of lithium-labelled CSM, the lithium concentration in plasma reached a maximum after about 24 h and the subsequent decrease in concentration appeared to follow a single exponential relationship. The rate constant of this disappearance of lithium from plasma was greater (P<0.05) when 3.0 kg than when lesser amounts of lithium-labelled CSM were consumed. Plasma lithium concentrations 24 and 32 h after ingestion of lithium-labelled CSM were both linearly related to the amount of supplement consumed (r = 0.86 and 0.87, respectively, n = 32, P<0.001), indicating that the plasma lithium concentrations could be used to measure intakes of supplement by individual animals. In experiment 2, following intravenous administration of lithium chloride the disappearance of lithium from plasma over 96 h appeared to be best described by 3 exponential compartments. In experiment 3, cattle were offered molasses-based or loose mineral mix (LMM) supplement, or water, labelled with lithium and the rate constant of disappearance of lithium from plasma between 32 and 96 h was determined. The pattern of the decrease in plasma lithium concentration was similar to that observed in experiment 1. In experiment 4, the variation about the estimates of supplement intake was measured in heifers (n = 24) offered hay and water ad libitum and in addition a meal of 60 g of lithium-labelled molasses–urea supplement; between 20 and 28 h after ingestion of the lithium-labelled supplement the coefficient of variation (CV) among animals in plasma lithium concentration was about 15%. The likely errors associated with the use of lithium salts to measure intake of supplement are discussed. These experiments confirm that lithium salts can be used as a marker to estimate intake of supplement by individual animals.
Studies of the effects of energy, protein and mineral supplementation to cattle grazing naturalised pastures on the North Coast of New South Wales
Authors: Davies H. Lloyd , Petrie D. , Paliskis R.
Published: March 2003

A series of experiments were conducted to measure the response by cattle grazing 'native pastures' on the North Coast of New South Wales to supplements of energy, protein and the administration of mineral supplements.In all experiments there were liveweight responses to both energy and protein supplements. The magnitude of the response to the grain supplements was affected by treatment of the grain with extruded grain tending to give a superior liveweight response. The response to nitrogen supplements differed between non-protein-nitrogen (urea) and protein — always in favour of the protein supplement. There were no liveweight responses to copper cobalt or selenium. Supplemental copper administered in a variety of ways increased liver copper concentration, plasma copper and ceruloplasmin and coat colour changed from yellow to red. The low copper storage levels were not associated with high molybdenum values in the feed on offer. Administration of selenium did not increase the unsatisfactory pregnancy rate but did raise the level of circulating glutathione peroxidase.
Galactomannan content and composition in Cassia brewsteri seed
Authors: Cunningham D. C. , Walsh K. B.
Published: March 2003

Seed galactomannans function as both an energy reserve and a water reservoir in germinating seed of many leguminous plants, and are used commercially as gelling agents, mainly in processed foods. Cassia brewsteri is a leguminous tree endemic to eastern Queensland. The galactomannan content of 40 samples of C. brewsteri seed from throughout the distribution of the species ranged from 28.3 to 39.7% of seed dry weight. The galactomannan content of whole seed was 33.7 ± 0.4% (mean and s.e.m. on a dry weight basis). The mannose : galactose ratio ranged from 4.6 to 6.3 and averaged 5.4 ± 0.1. C. brewsteri gums prepared in a manner analogous to that used in the preparation of commercially available carob gum were tested for gel strength relative to the industrial gelling agents carob gum and Senna tora gum. The break force index (BFI) for the most effective C. brewsteri gum preparation was 107% relative to carob gum and 83% relative to Senna tora gum. On the basis of these biochemical and functional data, C. brewsteri has potential as a source of commercial seed galactomannans.
Optimising ripening temperatures of Cavendish bananas var. 'Williams' harvested throughout the year in Queensland, Australia
Authors: Bagnato N. , Klieber A. , Barrett R. , Sedgley M.
Published: March 2003

Varying banana ripening temperatures were examined throughout the year to ensure optimum quality and shelf life of commercially ripened fruit in Australia. Cavendish bananas (var. 'Williams') were harvested throughout the year 2000 and were ripened at 14, 16, 18 and 20°C with 300 μL/L ethylene on 2 consecutive days until fruit were more yellow than green and then subsequently stored at 22°C until the end of the experiment. Ripening bananas at 14 and 16°C extended shelf life by up to 50 and 32%, respectively. However, ripening bananas at 14 and 16°C did increase peel discolouration, especially on bananas chilled in the field in winter. Bananas ripened at 18 or 20°C throughout the year had an average shelf life of 6 days and consistently lower peel discolouration. Therefore, ripening at 18 or 20°C throughout the year results in a better visual appearance of the fruit, which is essential for consumers.
Ethephon promotion of crop abscission for unshaken and mechanically shaken macadamia
Authors: Trueman S. J. , McConchie C. A. , Turnbull C. G. N.
Published: March 2003

Promotion of fruit abscission in macadamia, Macadamia integrifolia (Proteaceae), has potential to reduce costs associated with prolonged harvesting of late-abscising cultivars. Effects of ethephon [(2-chloroethyl)phosphonic acid] on fruit removal force and crop abscission were monitored at 3 stages of the harvest season on both unshaken and mechanically shaken trees of the late-abscising macadamia cultivar A16. Ethephon application, tree shaking, or a combination of the 2 methods, accelerated crop removal from the tree at all stages during harvest. Early harvest before natural abscission resulted in little or no difference in nut-in-shell and kernel weight, kernel recovery and kernel oil content. Delaying ethephon application or tree shaking until commencement of natural abscission resulted in greater crop removal. Fruit removal force declined naturally towards 1 kgf at this stage, and was further reduced by ethephon application. The most effective approach for harvest acceleration was to reduce fruit removal force, before tree shaking, by spraying trees with ethephon.
Yield comparisons and cropping patterns of Kensington Pride mango selections
Authors: Bally I. S. E. , Harris M. A. , Foster S.
Published: March 2003

Thirty-three trees were identified from commercial orchards in Queensland during the 1990–91 and 1991–92 seasons to investigate the potential of improving the agronomic and fruit quality aspects of Kensington Pride mango. These selections were grafted and planted in a replicated field trial in the Burdekin district for comparative evaluation. Cropping characteristics were recorded annually until the trees reached 10 years of age. Small yield variations were observed between the selections, with no significant differences between the top 19�selections. No single selection had outstanding yields, however 2 selections had significantly lower yields than the rest. These findings indicate the difficulty in significantly improving Kensington Pride mangoes through selection from existing commercial germplasm. Sixteen of the best performing selections from the field trial were used as a top group to investigate the cropping characteristics of the cultivar. The average annual increase in yield and fluctuations from this average were modelled. The first significant crop was 15.7 kg per tree in year 4 and modelled yields increased by 23.3 kg per tree per year thereafter to year 10. There were significant annual fluctuations from the modelled trend with yields varying from between –44.7 to +35.7% of the expected yield. As fruit number per tree increased, average fruit weight decreased by 0.14g for every extra fruit.
Response of annual pastures to applications of limestone in the high rainfall areas of south-western Australia
Authors: Bolland M. D. A. , Allen D. G. , Rengel Z.
Published: March 2003

The yield response of long-term pastures growing on acidified soil to applications of limestone (0, 2.5, 5.0, 7.5 and 10.0 t/ha with adequate magnesium fertiliser, and 0 and 5 t/ha with no magnesium fertiliser) was measured in 5 field experiments on different representative soils of the high rainfall areas of south-western Australia. After application, limestone was incorporated 1 cm deep in 3 experiments, 3 cm deep in 1 experiment, and 7 cm in another experiment. The pastures comprised subterranean clover (Trifolium subterraneum), and annual and Italian ryegrass (Lolium rigidum and L. multiflorum), the dominant species found in intensively grazed dairy and beef pastures of the region. Yields were measured when ryegrass plants had 3 leaves per tiller, which is when pastures in the region are grazed to maximise utilisation by cattle.Subsoil acidity was a problem at 4 of the 5 sites, and was so severe at 1 site that, despite having the lowest soil pH to 50 cm depth, there was no yield response to limestone incorporated to 3 cm deep. Applications of fertiliser magnesium had no significant effect on pasture production, soil pH, aluminium and manganese, or concentration of magnesium in dried herbage in any of the 5 experiments. Increasing amounts of limestone consistently: (i) increased soil pH, by between 1–2 pH units in the top 5 cm of soil, and 0.5–1.0 of a pH unit in the 5–10 cm soil profile; and (ii) decreased, by up to 84–98%, the amount of exchangeable aluminium in the 0–5 and 5–10 cm soil profiles. During 3 years (1998–2000) there were: (i) no yield responses to limestone for a total of 9 assessments on a sand, or 11 assessments on a sandy gravel; (ii) 2 significant (P<0.05) yield responses to limestone, from a total of 8 assessments on a loamy clay and from 9 assessments on a loam; (iii) 9 significant yield responses from a total of 13 assessments on a sandy loam (2 from 5 assessments in 1998, 3 from 4 assessments in 1999, and all 4 assessments in 2000). The sandy loam had the largest amount of exchangeable aluminium in the top 5 cm of soil [about 1.6 cmol(+)/kg, accounting for 35% of the exchangeable cations]. Increasing limestone applications did not induce deficiency or toxicity of any nutrient elements in subterranean clover or ryegrass dried herbage and, for dried herbage of bulk samples of both species, had no effect on dry matter digestibility, metabolisable energy and concentration of crude protein.
Sheep coats can economically improve the style of western fine wools
Authors: Hatcher S. , Atkins K. D. , Thornberry K. J.
Published: March 2003

Wethers from a mixed bloodline flock in western New South Wales were coated for 12 months between August 1998 and August 1999. The coated and a similar number of uncoated control wethers from each of the 11�bloodlines (2 medium, 3 fine and 6 superfine) were grazed together as part of a larger mob. Dye bands were placed in the fleeces of each wether before fitting of the coats and were removed before shearing when a mid-side sample was taken and a number of subjective assessments made of each fleece. The major effect of the sheep coats was to improve the style of the coated wool by about 1 style grade. This was largely the result of the coated fleeces being whiter, with less tip weathering and lower levels of dust and vegetable matter. There was no significant difference between the 2 treatment groups in wool production, fibre diameter, staple strength or resistance to compression. A partial budgeting approach was used to evaluate the economic returns from using sheep coats based on the observed differences in wool quality. Clean prices and wool values per head for the coated and uncoated sheep from each of the 11 bloodlines were calculated using NSW Agriculture's wether trial software and the flock least squares means for each wool trait. The analysis established it would be economically viable to coat all the sheep except the medium-wool sheep. Even allowing for 20% improvement in the price differential for medium wool, coating them was not economically viable.
Post emergence spraying of clopyralid, picloram or pyridate in broccoli, Chinese cabbage, cabbage, or cauliflower kills weeds, with minimal crop damage
Authors: Henderson C. W. L. , Cairns R.
Published: March 2003

We investigated potential post-emergence herbicides for managing broadleaf weeds in broccoli, Chinese cabbage, cabbage, and cauliflower, as no products are currently registered for these uses in Australia. Subsequent to spraying clopyralid, picloram, or pyridate 5�weeks after direct-sowing broccoli or Chinese cabbage, or transplanting cabbage or cauliflower seedlings, we recorded crop phytotoxicity symptoms, measured marketable crop yields, and assessed weed control achieved. Neither maximum application rates of 90 g clopyralid/ha, nor 45�g clopyralid/ha mixed with 30 g picloram/ha, adversely affected vegetable yields. Spraying 60 g/ha clopyralid controlled burr medic (Medicago polymorpha), and suppressed common sowthistle (Sonchus oleraceus). Applying 90 g clopyralid/ha, or mixing 22.5 g clopyralid/ha with 15 g picloram/ha, controlled both burr medic and common sowthistle. At the rates tested, neither clopyralid nor picloram affected deadnettle (Lamium amplexicaule). Applying 450 g pyridate/ha caused chlorotic spotting of the sprayed vegetable leaves, but did not affect marketable yields of broccoli, cabbage or cauliflower. This rate controlled deadnettle, reduced sowthistle growth by only 30–50% compared with an unweeded control, and had no impact on burr medic. Spraying 900 g pyridate/ha increased the severity and persistence of chlorotic spotting, and resulted in lower broccoli and Chinese cabbage yields than obtained in the best treatments in the respective experiments. Cabbage and cauliflower yields were unaffected by spraying 900 g pyridate/ha. This rate improved sowthistle control to a commercially acceptable level. Our studies suggest that both clopyralid and pyridate could be successfully utilised in Australian vegetable brassica production, providing issues of the residual activity of clopyralid on following crops, and optimal application rates and timing for pyridate, were resolved.
Grasslands NuSiral white clover (Trifolium repens L.)
Authors: Ayres J. F. , Lane L. A. , Caradus J. R. , Clifford P. T. P.
Published: March 2003

Grasslands NuSiral is a medium–large-leaf white clover (Trifolium repens L.) cultivar with intermediate growth habit (midway between open and erect and dense and prostrate), early flowering maturity and high growing point density. G. NuSiral possesses the plant-type attributes known to be desirable for broad adaptation to dryland pasture conditions in Australia and has been developed for cattle and sheep pastures in both summer rainfall and winter rainfall areas where average annual rainfall exceeds 750 mm. G. NuSiral is expected to provide enhanced stolon survival and autumn recovery in environments where summer moisture stress is present but not intense, and winter growth comparable to cv. Haifa where mild winter conditions allow the expression of G. NuSiral's winter activity.
Changes in ginsenosides in Australian-grown American ginseng plants (Panax quinquefolium L.)
Authors: Wills R. B. H. , Du X. W. , Stuart D. L.
Published: March 2003

American ginseng (Panax quinquefolium) plants grown at 2 sites in Victoria were analysed for neutral ginsenosides in 7 plant sections at 7 growth stages over a full growing season. Individual ginsenoside concentrations and composition over the growth period were significantly different between plant sections but were similar to those reported for American ginseng grown in other countries. There was thus no detrimental effect of growing American ginseng in a eucalypt environment. The ginsenosides content of both aerial and root sections was at a maximum when fruit were established on the plant. At this maturity, the ginsenosides concentration was highest in the root hair followed by the leaf, lateral root, main root and stem in that order. The leaf contained about 30% of total plant ginsenosides and should be considered as a potential commercial product. This would require plants to be harvested before the current dormant stage when the leaf was still in a viable condition on the plant. A study of the ginsenosides in roots cultivated over a 13-year period revealed that the concentration of ginsenosides was directly correlated with root weight, more than with root age. This suggests that a faster-growing crop will not only have a higher saleable weight but also a higher concentration of ginsenosides.
Long-term persistence of aluminium-tolerant and sensitive Phalaris lines on acidic soils and associated changes in soil acidity
Authors: Ridley A. M. , Avery A. L. , Oram R. N. , Hunter J. , Shovelton J. B. , Mahoney G. P. , Müller W. J.
Published: March 2003

Persistence of an aluminium (Al)-tolerant phalaris F1 hybrid (Siro 1146 Phalaris aquatica × P.�arundinacea) was compared with that of 3 more Al-sensitive phalaris (P. aquatica L.) lines (cv. Australian and the progenitors of cvv. Sirosa and Sirolan) at 2 sites (Strathbogie and Baddaginnie) in north-eastern Victoria with strongly acidic soils 20 years after sowing. Soil pHCa and extractable aluminium (AlCa) were also measured to 1 m depth under Siro 1146 and annual grass pasture at each site. All grass treatments contained volunteer subclover. Siro 1146 persisted better than the other lines (P<0.05) at Strathbogie where the soil contained high AlCa concentrations down to 50 cm depth. Soils should be sampled and tested to at least this depth to determine their suitability for phalaris. At this site Australian phalaris persisted better than the progenitors of Sirosa and Sirolan (P<0.01), probably because Australian has more spreading ability and tolerance of set stocking than the winter active lines. At Baddaginnie, the soil contained lower concentrations of AlCa below 20 cm depth than at Strathbogie and persistence of the 3 Al sensitive phalaris lines was good despite the lower rainfall. The less drought-tolerant Siro�1146 persisted poorly at Baddaginnie, but had high ground cover due to high lateral spread of the survivors. At Strathbogie, the 10–20 cm layer of soil under Siro 1146 had a higher pHCa and lower AlCa than that under the other 4 phalaris and the annual grass treatments. Soil under Siro 1146 also had higher pHCa and lower AlCa down to 40�cm�depth compared with the annual grass treatment, the differences being significant in the 20–30 cm layer. These differences were reversed at 50–100 cm, but only the effect on Al was significant. Although soils were not sampled at the beginning of the experiment, adequate replication and randomisation of the grass treatments showed that it was statistically improbable for observed final differences to be due to initial soil differences. The final differences may be due to greater amounts of nitrate being taken up from the upper layers by Siro 1146 over its long growing season compared with the annual grasses, leading to greater nitrate leaching from the upper layers and greater nitrate uptake from lower layers under the annuals (i.e. spatial separation of acid generation and consumption processes within the profile). Another possible reason for the greater acidification below 50 cm by the perennial is that its roots may have taken up more cations in this zone. Because of rising concern in some sectors of the public about the off-site, environmental effects of agriculture, the future role of more acid-tolerant phalaris cultivars growing near native vegetation in the high rainfall zone is discussed.
Effects of lime on the botanical composition of pasture over nine years in a field experiment on the south-western slopes of New South Wales
Authors: Li G. D. , Helyar K. R. , Evans C. M. , Wilson M. C. , Castleman L. J. C. , Fisher R. P. , Cullis B. R. , Conyers M. K.
Published: March 2003

Two permanent pastures (annual pasture v. perennial pasture) were established in 1992 as part of the long-term field experiment, MASTER — Managing Acid Soils Through Efficient Rotations. The primary objective of the experiment was to develop an agricultural system that is economically viable and environmentally sustainable on the highly acidic soils in south-eastern Australia. This paper reports on the effects of lime on the botanical composition changes of annual and perennial pastures over 9 years. In general, lime increased the proportion of the desirable species, such as phalaris (Phalaris aquatica) in perennial pasture and subterranean clover (Trifolium subterraneum) in annual pastures, and decreased the proportion of the undesirable species, such as Vulpia spp., in both annual and perennial pastures, ultimately improving the quality of feed-on-offer to animals. As a result, the limed pastures carried 24% more sheep than the unlimed pastures, while maintaining individual animal performance similar for both limed and unlimed pastures. The phalaris-based perennial pasture was more stable in terms of maintaining the sown species than the annual pasture. Lime improved the persistence of phalaris and the longevity of the phalaris-based pasture should be at least 10 years. Lime changed the direction of plant succession of annual pastures. Without lime, Vulpia spp. gradually became more dominant while ryegrass and subterranean clover became less dominant in annual pastures. With lime, barley grass (Hordeum leporinum) gradually invaded the sward at the expense of ryegrass, thus reducing the benefits of lime, but this effect was less for the perennial pastures than for annual pastures. Liming perennial pastures should be more beneficial than liming annual pastures because of the beneficial effects on pasture composition. In addition, previously published work reported that liming perennial pastures improved sustainability through better use of water and nitrogen.
Response of vetch (Vicia spp.) to plant density in south-western Australia
Authors: Seymour M. , Siddique K. H. M. , Brandon N. , Martin L. , Jackson E.
Published: March 2003

The response of Vicia sativa (cvv. Languedoc, Blanchefleur and Morava) and V. benghalensis (cv. Barloo) seed yield to seeding rate was examined in 9 field experiments across 2 years in south-western Australia. There were 2 types of field experiments: seeding rate (20, 40, 60, 100 and 140 kg/ha) × cultivar (Languedoc, Blanchefleur, and Morava or Barloo), and time of sowing (2 times of sowing of either Languedoc or Blanchefleur) × seeding rate (5,�7.5, 10, 15, 20, 30, 40, 50, 75 and 100 kg/ha).A target density of 40 plants/m2 gave 'optimum' seed yield of vetch in south-western Australia. In high yielding situations, with a yield potential above 1.5 t/ha, the 'optimum' plant density for the early flowering cultivar Languedoc (85–97 days to 50% flowering) was increased to 60 plants/m2. The later flowering cultivar Blanchefleur (95–106 days to 50% flowering) had an optimum plant density of 33 plants/m2 at all sites, regardless of fitted maximum seed yield. Plant density in the range 31–38 plants/m2 was found to be adequate for dry matter production at maturity of Languedoc and Blanchefleur. For the remaining cultivars Barloo and Morava we were unable to determine an average optimum density for either dry matter or seed yield due to insufficient and/or inconsistent data.
Response of kabuli chickpea (Cicer arietinum L.) to sowing rate in Mediterranean-type environments of south-western Australia
Authors: Regan K. L. , Siddique K. H. M. , Martin L. D.
Published: March 2003

The effect of sowing rate (60–320 kg/ha) on the growth and seed yield of kabuli chickpea (cv. Kaniva) was assessed at 11 sites for 4 seasons in the cropping regions of south-western Australia. The economic optimum plant density and yield potential were estimated using an asymptotic model fitted to the data and calculating the sowing rate above which the cost of additional seed was equivalent to the revenue that could be achieved from the extra seed yield produced, assuming a 10 and 50% opportunity cost. On average for all sites and seasons, plant densities ranged from 10 plants/m2 when sown at 60 kg/ha to 43�plants/m2 when sown at 320 kg/ha. Assuming a mean seed weight of 400 mg and a germination of 80%, then on average 75% of viable seeds sown (or 60% of sown seeds) established as plants. The poor establishment rates are thought to be associated with reduced viability caused by mechanical damage, storage conditions, fungal infection in the soil, and unfavourable seed bed moisture and temperatures. In general, there was a positive relationship between sowing rate and seed yield. Seed yield increases at higher sowing rates were mainly associated with the greater number of plants per unit area. There were fewer pods per plant at higher sowing rates, but there were more pods per unit area. Changing the sowing rate had little effect on mean seed weight and the number of seeds per pod. The economic optimum plant density varied from 8 to 68 plants/m2, depending on the location, but the mean (27�plants/m2) was within the range currently recommended in southern Australia (25–35 plants/m2). Due to the low establishment rates observed in this study, we estimate a sowing rate greater (160–185 kg/ha) than currently suggested (110–160 kg/ha) to achieve this density. There was a strong relationship between economic optimum plant density and seed yield potential (r2 = 0.66, P<0.01), which allows an estimation of the most profitable sowing rate, depending on the seed yield potential of the site. For most crops yielding about 1.0 t/ha in southern Australia, a plant density of 25 plants/m2 is most profitable, while in higher-yielding situations (>1.5 t/ha) plant densities >35�plants/m2 will produce the most profit.
Phosphorus fertiliser placement for lupins in southern New South Wales
Authors: Scott B. J. , Carpenter D. J. , Braysher B. D. , Cullis B. R. , Evans C. M.
Published: March 2003

Research in Western Australia and South Australia indicated that fertiliser phosphorus (P) banded below the seed of narrow leaf lupin (Lupinus angustifolius L.) at sowing was a more effective method of applying P�fertiliser than the usual placement of P with the seed. This technology has not been investigated in southern New South Wales where lupins have been known to be unresponsive to fertiliser P.We conducted 4 field experiments to examine the effect on lupin yield of applying 6 rates of P (0, 5, 10, 15, 20 and 40 kg/ha) either by placement with or below the seed. To further test responsiveness to P, an additional set of treatments was used; applying P at 40 kg/ha before sowing and then placing additional P below the seed at the 6�rates of application. The grain yield of lupin was increased by P application at all sites, despite the medium to high P�status of 3 of the 4 sites used in these experiments. However, the technique of banding P fertiliser below the seed depth rather than placing it in direct seed contact had only a small advantage in grain yield responsiveness to applied fertiliser P (P = 0.09). Fitted response curves indicated that when P was applied at 15 kg/ha, grain yield increased by 60 kg/ha at one site and 30 kg/ha at the other 3 sites, if P was deep-placed rather than applied in seed contact. This advantage of deep placement of P fertiliser was much smaller than has been reported in Western Australia.Placement of P below the seed of lupin when sown on the red earth and red-brown earth soils of southern New South Wales slightly enhanced the availability of fertiliser P. This applied even when sowing was quite shallow (2–3�cm), provided recommended rates of P fertiliser were used at conventional row spacing (17 cm). Separation of seed and fertiliser to avoid reduced germination may be an advantage when using double row spacing and higher P�application rates.
Adaptation and potential contribution of temperate perennial legumes to the southern Australian wheatbelt: a review
Authors: Dear B. S. , Moore G. A. , Hughes S. J.
Published: March 2003

Deep-rooted perennial pasture plants can play an important role in solving the environmental problems of rising watertables, dryland salinity and soil acidification in the wheatbelt of southern Australia. These problems are attributed to the extensive clearing of perennial native vegetation and its replacement with shallow-rooted winter-growing annual crops and pastures. Deep-rooted, herbaceous perennial legumes, particularly lucerne (Medicago sativa L.), are seen as making an increasing contribution in the cropping zones where high rates of symbiotic nitrogen fixation and increased water use are high priorities. This paper reviews the current use and the potential of a range of temperate perennial legumes for the wheatbelt of southern Australia. The genera examined include Medicago, Hedysarum, Trifolium, Onobrychis, Lotus, Galega, Astragalus, Lathyrus, Anthyllis, Psoralea, Dorycnium, Lespedeza and Securigera. There is considerable scope to expand the use of lucerne; however, there is also a need for alternative perennial species to increase biodiversity and to fill niches where lucerne is less suited. Based on current knowledge, the species with the most promise to complement lucerne include sainfoin (Onobrychis viciifolia Scop.) and sulla (Hedysarum coronarium L.) on alkaline soils, strawberry clover (Trifolium fragiferum L.) in wet or mildly saline niches and Lotus and Dorycnium spp. on waterlogged and/or acid soils.
Variability in pathogenicity among Greek isolates of Phytophthora cactorum to four peach rootstocks
Authors: Thomidis T.
Published: March 2003

Studies on 8 isolates of Phytophthora cactorum recovered from different plants identified the presence of diversity in pathogenicity. All isolates appeared pathogenic to tested peach rootstocks but with variable levels of aggressiveness. The peach and almond isolates were the most aggressive. In contrast, the apple and strawberry isolates were least aggressive. Generally, the aggressiveness of P. cactorum isolates did not differ among peach rootstocks. The weak aggressiveness of isolates of P. cactorum from apple trees and strawberry plant suggests that these isolates are not a serious threat to peach rootstocks. This study also confirms that laboratory techniques, such as the excised-twig assay, correlate well with field evaluations.
Field measurements of windbreak effects on airflow, turbulent exchanges and microclimates
Authors: Cleugh H. A.
Published: March 2003

While there has been considerable research into airflow around windbreaks, the interaction of this airflow with the exchanges of heat and water vapour has received far less attention. Yet, the effects of windbreaks on microclimates, water use and agricultural productivity depend, in part, on this interaction. A field and wind tunnel experimental program was conducted to quantify the effects of windbreaks on microclimates and evaporation fluxes. This paper describes the field measurements, which were conducted over a 6-week period at a tree windbreak site located in undulating terrain in south-east Australia.

The expected features of airflow around porous windbreaks were observed despite the less than ideal nature of the site. As predicted from theory, the air temperature and humidity were elevated, by day, in the quiet zone and the location of the peak increase in temperature and humidity coincided with the location of the minimum wind speed. However, this increase in temperature and humidity was small in size and restricted to the zone within 10 windbreak heights (H) of the windbreak. This pattern contrasts with that for the near surface wind speeds, which were reduced by up to 80% in a sheltered zone that extended from 5 H upwind to over 25 H downwind of the windbreak. Similar differences were found between the turbulent scalar (heat, water vapour) and velocity terms. While both are reduced in the quiet zone, the turbulent scalar terms near the surface were substantially enhanced at the location where the wake zone begins. Here the mean wind speed is reduced by 50% and the turbulent velocity terms return to their upwind values.

Wind speed reductions varied linearly with [cos (90 – α)], where α is the incident angle of the wind, for sites located 6 H downwind. This means that the spatial pattern of wind speed reduction applies to all wind directions, provided that distance downwind is expressed in terms of streamwise distance. However, shelter in the near-break region is slightly increased as the wind blows more obliquely towards the windbreak.

The atmospheric demand in the quiet zone was reduced when the humidity of the upwind air was low. In such conditions, windbreaks can 'protect' growing crops from the impact of dry air with high atmospheric demand. The corollary is that in humid conditions, the atmospheric demand in the quiet zone can be increased as a result of shelter.