bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersal of 32P-treated larvae of Spodoptera litura and Spodoptera mauritia (Lepidoptera: Noctuidae)
Authors: Persson B
Published: November 2004

32P-tagged fifth-instar larvae of Spodoptera litura (Fab.) and fourth-instar larvae of Spodoptera mauritia (Boisd.) were released in experimental plots, 10 by 10 m, of clover and grass respectively and traced once a day and once a night for 2 weeks by means of a Geiger counter. The clover had a patchy distribution and was mixed with grass. The dispersal pattern was not random. In the plot with S. mauritia more radiation readings were obtained in the upwind sectors. In the plots withS. litura the majority of the contacts were made in the clover, few in the grass. The results indicate that in both species the direction of the wind may have had an influence on dispersal.
The utilization by preruminant lambs of isolated soya bean protein in low protein milk replacers
Authors: Walker DM , Kirk RD
Published: November 2004

Preruminant male crossbred lambs, aged 2–5 days at the start of the experiment, were used in five experiments with low protein milk replacers (0.10 of total energy as protein). Experiment 1. A diet with isolated soya bean protein (ISP) as the sole source of protein was supplemented with different amounts of DL-methionine. The ISP contained 1.06 g methionine (M) and 1.04 g cystine (C) per 16 g nitrogen (equivalent to 9.1 mg M + C per 100 kJ diet). Maximum nitrogen balance was achieved when the M + C concentration was 15.3 ? 3.7 mg per 100 kJ (equivalent to 3.8 g M + C per 16 g nitrogen). Experiment 2. The ISP diet (plus DL-methionine), was supplemented with L-valine, or L-threonine, or L-isoleucine, or L-lysine monohydrochloride, or a mixture of essential amino acids, to raise their concentration in rsp to those in whole egg proteins (g per 16 g nitrogen). There was no significant improvement in nitrogen balance as aresult of adding amino acids other than DL-methionine. Experiment 3. The ISP diet was supplemented with either DL-methionine (2.4 and 14.8 mg/100 kJ), or L-methionine (2.4 and 1 4 8 mg/100 kJ), or methionine hydroxy analogue (MHA) (14.8 mg/100 kJ), or L-cystine (14 8 mg/100 kJ). Nitrogen balances were determined. It was concluded that the Dand L-isomers of methionine had similar biological activities when used to supplement ISP, and that MHA was as effective as DL-methionine. There was no significant increase in nitrogen balance with the L-cystine supplement. Experiment 4. The ISP diet (plus DL-methionine) was given to three lambs continuously for 33 days. There was no significant change in nitrogen balance with increasing age. Experiment 5. The ISP diet (diet A) and a diet of equivalent protein content based on cows' milk proteins (diet B) were supplemented with DL-methionine and given to groups of lambs over a wide range of intakes of gross energy (GE). The maximum intake of GE by lambs given the ISP diet ad libitum was 1147 kJ/day per kg0.73, an intake far lower than that which would have been taken by lambs given the cows' milk diet ad libitum. The apparent digestibilities of nitrogen and DM in diet A were significantly lower than those in diet B and, at the mean intake of apparently digested nitrogen of 538 mg/day per kg0.73, there were significant differences in the nitrogen balances: the values were 362 and 255 mg nitrogen/day per for the cows' milk and ISP diets respectively.
Studies of grain production in Sorghum bicolor (L. Moench). VI.* Profiles of photosynthesis, illuminance and foliage arrangement. 4. Profiles of Photosynthesis, Illuminance and Foliage Arrangement
Authors: Fischer KS , Wilson GL
Published: November 2004

Grain sorghum was grown at two population densities in the field, and photosynthetic rates compared at noon. Profiles of photosynthesis were established by combining measurements of 12CO2 exchange and 14CO2 uptake. Canopy structure and light penetration were measured. Factors responsible for the superiority of the higher density population were evaluated. Photosynthesis–radiation responses of leaves were similar between the populations and there was little difference in total light interception. The high density population had leaves which were more vertically displayed, more uniformly dispersed, smaller in both length and width, and distributed over a greater height of canopy. Light was therefore more uniformly distributed down the profile, and coefficients of light extinction were lower. Associated with this was a higher leaf area index. The overall consequence was the distribution of intercepted radiation over a larger leaf surface, at a lower illuminance and therefore a higher efficiency of photosynthetic conversion, resulting in greater total photosynthesis.

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** Part V, Aust. J. Agric. Res., 26: 31 (1975).
Chemosterilant as a booby-trapping agent for the Queensland fruit fly, Dacus tryoni
Authors: Smart P , Gilmour D
Published: November 2004

Females of Dacus tryoni, booby-trapped by topical application of 400 µg of N,N'-tetramethylenebis( 1-aziridinecarboxamide), sterilized males with which they copulated. Sterility in the males was complete and persisted for at least 10 days after mating contact. Booby-trapped females were less attractive to males than untreated females when the sterilant was applied before the flies reached sexual maturity. Attractiveness was not significantly impaired when the females were treated after reaching sexual maturity. Sterile males were as effective as fertile males in winning mates. The introduction of a small proportion (one-tenth) of booby-trapped females into a cage population caused a considerable drop in overall fertility, but the sterilant was probably spread more by attempted matings rather than by actual copulation.
Plasma urea nitrogen as an indicator of protein quality. II.* Relationships between plasma urea nitrogen, various urinary nitrogen constituents, and protein quality
Authors: Kirk RD , Walker DM
Published: November 2004

Preruminant male crossbred lambs aged 2–5 days at the start of the experiment were used. Plasma urea nitrogen (PUN) and nitrogen balance were significantly correlated (r = – 0.74) in lambs given a wide variety of plant and animal proteins in low protein diets (0.10 of total energy as protein). Nevertheless, lambs having identical intakes of nitrogen and energy from diets containing different proteins could have identical PUN values but significantly different nitrogen balances. It was shown with groups of lambs that PUN could be used to predict the minimum amount of DL-methionine that was required to give maximum nitrogen balance, when used as a supplement to isolated soya bean protein. It was also shown that there were significant daily variations in PUN and in the excretion of urinary nitrogen constituents (urea, ammonia, creatinine) between and within lambs given the same diet under strictly controlled conditions. It was concluded that no further increase in the precision of predicting protein quality from PUN (or urinary nitrogen constituents) was possible, unless an experimental design was used in which the values for individual lambs were compared before and after a change in dietary treatment.

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*Part I, Aust. J. Agric. Res., 27: 109 (1976).
The evaluation of formaldehyde-treated sunflower seed-casein supplement as a source of linoleic acid for ruminant lipids
Authors: Hogan JP , Hogan RM
Published: November 2004

Studies have been made of the digestion and utilization by sheep of a sunflower seed-casein supplement protected by formaldehyde treatment against ruminal degradation. Digestion studies suggested that about 40% of the linoleic acid (18:2) in the supplement was protected against hydrogenation, and that the 18:2 that passed from the stomach was almost completely absorbed from the small intestine. Four groups of lambs were offered diets designed to provide the same amounts of amino acids and net energy but varying amounts of volatile fatty acids, 18:2 and other long-chain fatty acids. The supplemented lambs grew at similar rates and the carcasses contained the same amounts of fat. It was estimated that 53–60% of the 18:2 absorbed from the small intestine was incorporated into carcass lipids. The incorporation was not affected by the relative proportions of metabolites derived from the diets. When the supplement was offered at two levels to lambs fed on lucerne hay, the intake of dry matter remained constant. Hence a reduction in the intake of lucerne hay occurred but the total intake of nutrients was substantially increased.
Comparative phosphorus responses in plants to a range of available phosphorus situations
Authors: McLachlan KD
Published: November 2004

The ranking in productivity of four species against a gradient of phosphorus availability in four soil situations was buckwheat > rye > crimson clover ≥ subterranean clover. Relative performance seemed to be a characteristic of the plant. Ranking between species changed little over the soil situations. Buckwhelt obtained more phosphorus and used it more efficiently in dry matter production than the other species. Differences in efficiency or use were associated with productivity rankings in the other species. Greater phosphorus uptake by buckwheat was associated with its ability to acidify the rooting medium. This did not result from exuded organic acids, but ions exchanged for cations taken up by the plant, particularly the calcium ion, seemed to be implicated. Productivity and eficiency of phosphorus use were associated with greater root weights, root volumes and root hair production. Root respiration and exocellular phosphatase activity were lower for high performance than for low performance species. The importance of root development seemed to be associated with absorptive area rather than metabolic activity. Phosphatase appeared to be an adaptive enzyme. Its activity could be used to distinguish species better adapted to use the existing phosphorus in low fertility situations.
Genetic differences in the copper nutrition of cereals. II.* Genotypic differences in response to copper in relation to copper, nitrogen and other mineral contents of plants
Authors: Nambiar EKS
Published: November 2004

Cereal genotypes differed considerably in their sensitivity to copper deficiency. Copper concentrations in the leaves and grains were determined to see whether they reflected the copper status of plants. Nitrogen, phosphorus, calcium, zinc and manganese in the grains from normal plants were determined and the interrelationships between the mineral-accumulating ability of genotypes and their sensitivity to copper deficiency were examined. Copper concentration in the shoot at mid-tillering, when copper deficiency may be recognizable, clearly distinguished severely copper-deficient plants from copper-sufficient ones. In deficient plants, the mean concentrations of copper in the youngest leaves and older leaves were <1.0 and <2.0 ppm respectively. However, after maturity, copper concentrations in flag leaves and grain did not reflect the copper status of the plants. Nor did the content and distribution of copper in the plants explain the differential sensitivity of genotypes to copper deficiency. Accumulation of nitrogen, phosphorus, calcium, zinc, manganese and copper in the grain varied between genotypes. Nitrogen and phosphorus concentrations in the grains of normal plants were related to the differential responses of genotypes to copper. Evidence shows that the cereal genotypes with higher grain protein contents are potentially more susceptible to copper deficiency than those with relatively lower grain protein.

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*Part 1, Aust. J. Agric. Res., 27: 453 (1976).
Adaptation to heterogeneous environments. II.* Phenotypic plasticity in response to spacing in Linum
Authors: Khan MA , Bradshaw AD
Published: November 2004

Six varieties of Linum usitatissimum, three of flax and three of linseed, were grown under field conditions at six different spacings, from 1 to 32 in. (2.5–81.3 cm) apart. There was abundant evidence of varietal differences in phenotypic plasticity in response to variation in spacing. This indicates that response to spacing is a genetically controlled and not an automatic phenomenon. The major differences were between the flax and linseed groups; linseed varieties were more responsive in branching. However, there were considerable differences between varieties within each group. Different characters showed very different patterns and degrees of response, which indicated that control of response operates on an individual character rather than on a whole organisms basis. Plausible explanations in terms of natural selection can be given for the origin of many of the differences in the response of varieties and in characters. Taken as a whole, the results suggest that there is precise genetic control of the epigenetic processes involved in the response of plants to spacing, and that evolution of different patterns of response can easily occur.

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*Part 1, Evolution, 22: 496-516 (1968).
Effect of calcium, pH and nitrogen on the growth and chemical composition of some tropical and temperate pasture legumes. I. Nodulation and growth
Authors: Andrew CS
Published: November 2004

The effects of a factorial combination of calcium (0.125, 2.0 mM calcium sulphate), pH (4.0, 4.5, 5.0, 6.0) and nitrogen (nil, 2.0mM ammonium nitrate) on the nodulation and growth of some tropical and temperate pasture legumes were determined. Macroptilium lathyroides and Lotononis bainesii were unaffected by low pH and low calcium (100% of plants nodulated at all treatments). In Stylosanthes humilis, Trifoliurn semipilosum, and T. rueppellianum reduced nodulation occurred only at pH 4.0. Desmodium uncinatum and Trifolium repens were sensitive to low pH, and nodulation was markedly reduced at pH 4.0 and below 5.0 respectively. Medicago sativa, M. truncatula, M. scutellata, and Glycine wightii were extremely sensitive, maximum nodulation occurring only at pH 6-0 and 2 . 0 mM calcium. Furthermore, the dry matter yields of plants that nodulated under inferior treatments were less than those of plants nodulated under optimum treatments. Nodulation and growth were strongly controlled by pH, and although interactions occurred with calcium treatment, these were primarily in the intermediate pH range. Dry matter yields of nodulated plants of S. humilis and L. bainesii were greater at the low calcium sulphate treatment (0.125mM) than at thc high treatment (2.0mM). The remaining legumes gave varying positive responses to the high calcium treatment. Root weight ratios of nodulated plants were decreased by the higher treatments, the minimum occurring at those treatments producing the highest dry matter. In the presence of applied nitrogen (no nodulation), the effects of pH and calcium on dry matter were small, but the trends were similar to those for nodulation and dry matter production of the nodulated plants in the Rhizobium series. Root weight ratios of plants in the nitrogen series were equal to or less than those for the maximum-yielding plants in the nodulation series. It is considered that both nodulation and subsequent plant growth are dominated by the hydrogen ion effect, and that the beneficial effect of calcium operates within certain pH limits. pH had little effect on plants that were well supplied with nitrogen.
Adaptation to heterogeneous environments. III.* The inheritance of response to spacing in flax and linseed (Linum usitatissimum)
Authors: Khan MA , Antonovics J , Bradshaw AD
Published: November 2004

Random F+3 families from two crosses of varieties of Linum usitatissimum were grown at two spacings and the following determined: (a) the characteristics of the families at each spacing; (b) the response of these characteristics to spacing, measured as the value at wide spacing divided by the value at close spacing. There were significant differences between the families for the characters at each spacing and for their responses. The heritability values for response, calculated from between-family variances, were significant and relatively high for all characters measured. There was no clear effect of spacing on genetic correlation between the characters, but low genetic correlations between the same character in the two spacings showed that high heritabilities in two spacings may be achieved by independent gene action. Genetic correlations between response characters were character and cross-dependent: there was no evidence of general stability of the genotypes. A separate experiment showed that there was no evidence for the induction of heritable changes by the application of different spacing treatments in the previous generation.

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*Part II, Aust. J. Agric. Res., 27: 519 (1976).
Frost injury to wheat stems and grain production
Authors: Banath CL , Single WV
Published: November 2004

Wheat plants which had suffered frost injury to stems in the field were studied to determine the effects on grain production. Damage was also induced artificially by freezing sections of stems of plants growing outdoors and in the glasshouse. Stem injury caused lodging or death of some tillers, and reduced the number of grains set in others. However, on many occasions, even in the field, there appeared to be no association between damage to stems and grain production. In no case was the size or composition of the grains significantly affected.
The inheritance of flowering time in Townsville stylo (Stylosanthes humilis)
Authors: Cameron DF
Published: November 2004

The inheritance of flowering time was studied in F1, F2 and F3 populations derived from a diallel cross among nine naturalized Australian lines of Townsville stylo (Stylosnnthes humilis) and in F1 and F2 populations from a small number of crosses between naturalized Australian lines and introductions from Mexico and Brazil. Strong dominance for lateness of flowering was observed in both the (Australian x Australian) and the (Australian x Mexican/Brazilian introductions) crosses, and some F2 and F3 progenies included small numbers of extremely early plants, flowering up to 55 days earlier than the earliest parent. The flowering time distributions of the (Australian x Australian) crosses could be explained by a three-locus model with multiple alleles at two loci. Proposed genotypes for the four maturity groups are as follows: late, LLM2M2EE; late-midseason, LLmmEE; mid-season, l2l2M2M2EE; early, l1l1M1M1EE; very early, LLM2M2ee. Only one major dominant gene for lateness of flowering could be detected from the distribution of the two (Australian x introduced line) F2 populations, but the segregation of extremely early types and the low recovery of the early-flowering phenotype suggested that other gene loci were segregating.
Water stress and phenology in wheat
Authors: Angus JF , Moncur MW
Published: November 2004

Single wheat plants (cv. Gabo) were sown in tall pots and top-watered so that growth proceeded without stress until the time of floral initiation. Having reached this stage, plants encountered increasing stress as soil water was depleted. At intervals after the dawn leaf water potential, ψ1, had reached values of –5, –10, –15 bars etc., the stress was relieved with water sufficient for unstressed development until anthesis. The anthesis dates of plants which had encountered mild stress (ψ1 down to about ndash;15 bars) were ahead of the well-watered control, while those which had encountered more severe stress (ψ1 from about ndash;25 to ndash;40 bars) flowered after the controls. The results are discussed in relation to the possibilities of including the effects of stress in crop development models.
Growth and distribution of dry matter in cotton (Gossypium hirsutum L.)
Authors: Constable GA , Gleeson AC
Published: November 2004

The leaf area index (LAI) and crop growth rate (CGR) of field-grown cotton were measured in four experiments to study the effects of season, node position, cultivar and row space on the production and distribution of dry matter. Growth varied widely between seasons, rainfall being associated with extensive and rapid vegetative growth. The middle segment of a plant produced more bolls than the bottom or top segments. It was estimated that it is necessary for assimilates for bottom bolls to be translocated from upper leaves. When fruit growth starts, vegetative growth also occurs in other parts of the plant, resulting in competition between lower bolls and upper leaves for assimilates. Maximum CGR was obtained at an Lar of about 3, but a high LA1 was not required for a high early boll growth rate (BGR), and the highest BGR was sometimes associated with the lowest LAI. The possible reasons for this association are discussed.
Superphosphate requirements of clover-ley farming. I. The effects of topdressing on productivity in the ley phase
Authors: Ayres JF , McFarlane JD , Gilmour AR , McManus WR
Published: November 2004

Experiments were undertaken on four farms in southern New South Wales to assess the requirements for superphosphate of clover-ley farming soils. The sites were selected to provide contrasts in initial soil phosphate status (medium v. high) in both low and high average annual rainfall conditions. At each site a sheep-grazing experiment with factorial arrangement of three annual topdressing rates (nil, 125, and 250 kg superphosphate ha-1) and two sheep stocking rates (district average, twice district average) was imposed for the duration of a normal ley phase (4 years). The response to topdressing depended on the initial soil phosphate status and was modified by seasonal rainfall conditions. At the high phosphate sites topdressing had little effect on pasture production, but at the medium phosphate sites topdressing increased pasture availability, and caused rapid and profound changes in botanical conlposition; topdressing induced grass dominance while omission of topdressing led to clover dominance. The changes in botanical composition had important effects on forage quality. With normal seasonal conditions there was no overall response to topdressing in sheep performance, but in poor years the pasture changes conferred by topdressing were reflected in a general increase in the level of sheep productivity.
Fertility following deposition of equal numbers of frozen-thawed ram spermatozoa by single and double insemination
Authors: Salamon S
Published: November 2004

Fertility results are presented for 90, 180 and 360 x lo6 total frozen-thawed motile spermatozoa deposited by single or double insemination. There was no difference between the mean lambing results for single (44.4%, 59/133) and double insemination (46.2%, 61/132). Number of inseminations within the sperm dose had no effect on fertility. Increasing the number of motile spermatozoa improved the fertility, the mean lambing rates for 90, 180 and 360 x l06 spermatozoa being 32.5% (29/89), 47.7% (42/88) and 55.7% (49/88) respectively.
The digestibility and voluntary intake of the leaves of trees and shrubs by sheep and goats
Authors: Wilson AD
Published: November 2004

The dried leaves of four species of shrub (Atriplex vesicaria, A. nummularia, Maireana pyramidata and Bassia diacantha) and four species of tree (Acacia pendula, Casuarina cristata, Geijera parvifora and Heterodendrum oleifolium) that are common to western New South Wales were fed to either sheep or goats to determine their digestibility. Four species were of low digestibility (< 50%) and one (C. cristata) had a digestibility of only 29%. Those of higher digestibility (A. nummularia 69%, M. pyramidata 58%, G. parviflora 59%) were only eaten sparingly: Digestibility alone gave a poor assessment of forage value because there was no correspondence between digestibility and organic matter intake. The intake of C. cristata (lowest digestibility) was much greater than that of A. nummularia or G. parviflora (highest digestibilities). There was good agreement (within 1 or 2 digestibility units) between in oitro (two-stage pepsin) and in vivo digestibility for six forages, but a greater disparity for M. pyramidata and H. oleifolium. For the trees the digestibility of cell wall constituents and acid-detergent fibre was low, in some cases less than 10%. This was not related to the amount of acid-detergent lignin in the fibre. Most samples were high in nitrogen (above 2%), which had a true digestibility ranging from 66 to 98%.
Effects of subsoil calcium on the root growth of some lucerne genotypes (Medicago sativa L.) in acidic soil profiles
Authors: Simpson JR , Pinkerton A , Lazdovskis J
Published: November 2004

The root growth of lucerne was examined in an acidic soil profile modified by varying additions of calcium carbonate to different layers of the subsoil. Root growth responded strongly to changes in the concentration of exchangeable soil calcium. Symptoms of thickening, distortion and poor lateral formation occurred under low calcium treatments. The results were in agreement with the interacting effects of calcium (at 0.5–5.0mM) and aluminium ions (at 0–20,µM) on lucerne in separate solution culture experiments. Differences in root penetration were observed between three lucerne clones selected from the cultivars Hunter River and Siro Peruvian. At the first harvest, the magnitude of these differences was increased by the addition of lime to the profiles. The three genotypes produced similar total dry weight yields, but differed in their distribution of growth between shoots and roots. This distribution was not affected by the addition of lime to the subsoil. However, the length of roots in the lower layer of the profile ( > 60 cm depth) was more responsive to subsoil treatment than was total dry weight. At the final harvest, the shoot yields of two genotypes were affected by lime treatments, but that of the deepest-rooted genotype was not. The results suggest that improved genotypes could be selected from Australian lucernes for establishment in areas with acidic subsoils, but that selection on root penetration alone would not necessarily lead to increased shoot yields.
Growth stimulation of subterranean clover with vesicular arbuscular mycorrhizas
Authors: Abbott LK , Robson AD
Published: November 2004

The growth of subterranean clover inoculated with two types of vesicular arbuscular endophytes was compared with that of uninoculated plants at five levels of applied superphosphate in a high phosphatefixing soil. Plants were grown in both untreated soil and soil steamed to eliminate the natural population of mycorrhizal fungi. Marked increases in the growth and phosphorus content of plants inoculated with a fungus isolated in Western Australia were apparent at intermediate levels of superphosphate in both soils. This fungus, which resembles Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, was more efficient at increasing growth and phosphorus content of subterranean clover than Glomus fasciculatus (Thaxter) Gerd. & Trappe. The greater growth response of plants inoculated with the fungus resembling G. mosseae was associated with a greater amount of mycorrhizal roots. Responses in nodulation closely paralleled responses in growth. Non-mycorrhizal plants produced more dry matter at a given phosphorus concentration in tops than did mycorrhizal plants.
The inheritance of the red leaf reaction of grain sorghum to sugarcane mosaic virus infection
Authors: Persley DM , Moore the late RF , Fletcher DS
Published: November 2004

The hypothesis that the necrotic red leaf and red stripe reactions of grain sorghum to sugar-cane mosaic virus – Johnson grass strain infection are independently inherited was tested. Five F1 and 15 F2 populations and one bc1F1 population were grown under both high (26.6–23.8°C) and low (15.5°) temperature regimes following manual inoculation with the virus. The results were consistent with the hypothesis that the presence of a homozygous recessive allele, termed rlf, conditions the expression of the necrotic red leaf reaction following exposure of plants to low temperatures. Plants express only mosaic symptoms in the presence of the dominant allele RLF and the absence of the N gene. The previously reported N gene and the rlf gene were shown to be independently inherited.
Studies of the Australian Illawarra Shorthorn breed of dairy cattle. II.* Genetic analysis
Authors: Herron ND , Pattie WA
Published: November 2004

A genetic analysis of the Australian Illawarra Shorthorn breed of dairy cattle has shown that the most important herd in 1973 made a genetic contribution to the breed of 29.5% and the next most important herd contributed 27.9%. The 12 most important herds combined contributed 70.5%. The sire with the highest relationship to the breed was 'Jean's Monarch of Blacklands' with direct relationships of 3.5, 4.0, 7.5 and 10.9% to the 1938, 1949,1960 and 1973 samples respectively. 'Sunny View Little Princess 30th' was the dam with the highest relationship to the breed with direct relationships of 0.5 and 8.6% to the 1960 and 1973 samples respectively. From 1930 to 1973 inbreeding increased a total of 7.6%. This comprised 1.6% current inbreeding and 6.0% non-current inbreeding. Strain inbreeding was at its maximum in the 1949 sample (2.02%) but had disappeared by 1973. The effective generation length was 5.23 years. Of animals in the 1973 sample, 72% were sired by bulls 5 years old or younger, while 50% of animals were from dams 4 years old or younger. It is shown that the bull requirements of the breed could be met by the progeny of performance-recorded animals.

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*Part I, Aust. J. Agric. Res., 28: 1107 (1977).
Pasture degeneration. II.* The importance of superphosphate, nitrogen and grazing management
Authors: Cook SJ , Blair GJ , Lazenby A
Published: November 2004

Fertilizer application and grazing management were shown to be important factors affecting trends in botanical composition in a 5-year-old perennial ryegrass–white clover pasture showing signs of pasture degeneration. In the absence of continuing superphosphate application, native and weed species invaded the pasture, irrespective of grazing management. However, where superphosphate was applied at 500 kg ha-1 year-1, the subsequent trends in botanical composition were dependent on the grazing strategy used. Pastures which were intensively grazed during the winter-spring period were invaded by red grass and other native grass species following a decline in the perennial ryegrass component, whatever the grazing management of other times of the year. In contrast, lax grazing, or pasture spelling, during this winter-spring period led to an increase in the basal area of ryegrass and checked the encroachment of unsown species. The role of superphosphate and grazing management in maintaining stable and productive pastures on the Northern Tablelands of New South Wales is discussed.

Part I, Aust. J. Agric. Res., 29: 9 (1978).
The induction of reproductive activity in lactating ewes
Authors: Restall BJ , Kearins RD , Herdegen J , Carberry P
Published: November 2004

In two experiments, Merino ewes that had lambed in either the autumn or spring were treated with various combinations of a progestagen (methylacetoxyprogesterone, MAP) and pregnant mare's serum gonadotrophin (PMSG), from 3 days post partum. Irrespective of the season of lambing, the treatments resulted in ovulation in nearly all ewes before day 15 post partum; oestrus was observed in all ewes that had lambed in the autumn but in only half the spring ewes. Regular oestrus activity was not resumed after the induced oestrus and/or ovulation. After further treatments with MAP and PMSG (days 15–26 post partum), 29% of the ewes showed oestrus (autumn and spring), with 47.1% and 58.3% of ewes ovulating in the autumn and spring respectively. Cystic and/or persistent corpora lutea (CP) were noted in 24% of the treated ewes. In spring-lambing ewes, 42% of ovulations before day 15 were judged to be abnormal. Fertilization rates were low in ewes that mated. The best results, 56% of ova fertilized, were from matings between 26 and 30 days post partum in spring-lambing ewes. In two further experiments, the fertility of ewes was examined at matings induced at various times post partum in crossbred ewes that had lambed in the spring. The fertility was low (=17%) up to 30 days post partum, but it improved in later matings (=30%). The incidence of a second oestrus succeeding the induced cycle was low (29%), but fertility was higher (50%). Approximately 50% of the untreated ewes lambed to matings between 30 and 60 days after lambing.
The effect of temperature on kernel development in cereals
Authors: Chowdhury SI , Wardlaw IF
Published: November 2004

A study has been made of the effect of temperature on kernel development and mature kernel weight of three contrasting cereals: wheat, rice and sorghum. Wheat and sorghum showed clear and well-separated optimum temperatures for individual kernel dry weights of 15/10° and 27/22°C respectively, while rice showed a relatively small change in weight over temperatures ranging from 21/16° to 30/25°. Rice kernel development was less affected by temperature extremes than sorghum, but was more sensitive to low temperature than wheat. At the lower temperatures (21/16°) the rate of development of individual kernels was greater in wheat than in the other species, while in sorghum, which had a more marked temperature response, the rate of kernel development was greater than in the other cereals at the higher temperatures (30/25°). A preliminary analysis of barley suggests that kernel development in this cereal responds to temperature in a similar way to wheat. Measurements of net photosynthesis of the flag leaf blade and ear of each cereal, at intervals after anthesis, suggested that at the completion of kernel development a source of carbohydrate was still available for continued development at all temperatures. A preliminary examination was carried out on the role of respiration and of translocation in limiting kernel development at high temperatures.
Effect of environment and cultivar on source limitation to grain weight in wheat
Authors: Fischer RA , HilleRisLambers D
Published: November 2004

The relative increase in final kernel weight (SR, %) with an artificial reduction of about 80% in the number of grains per spike was assumed to estimate the degree of post-anthesis assimilate or source limitation to grain weight in wheat. This assumption was supported by comparisons with other treatments designed to alter the ratio of source to grain number. SR was determined in crops grown under irrigation and high fertility in north-west Mexico over a 5 year period, in order to examine the effect of environment (year, sowing date) and cultivar on source limitation. Some old tall cultivars and many modern short cultivars of wheat (Triticum aestivum L., T. turgidum L.) and triticale (X Tritosecale Wittmack) were studied. For modern cultivars, kernel weight always appeared to be limited by source, SR averaging 21% over all years for eight such cultivars. For a given cultivar, environmental effects were considerable, being partly explained by a positive relationship between SR and mean temperature after anthesis. Each year SR was significantly affected by cultivar and, despite cultivar by year interaction, showed some consistency between years. Old bread wheats and triticales usually showed low source limitation (SR <10%), whereas most modern cultivars, regardless of species, showed higher source limitation (SR up to 50%) and higher grain yields, probably because of higher grain numbers per sq metre. Within this latter group, there was no relationship between SR and grain yield. The kernel weight attained as a result of grain number reduction, defined here as potential kernel weight, was a stable cultivar trait useful in understanding yield variation.
The epidemiology and control of tulip breaking virus in Victoria
Authors: Sutton J , Garrett RG
Published: November 2004

Rapid spread of tulip breaking virus (TBV) in Victoria was associated with aphid flights which occurred during the main tulip growing season from July to November. Attempts to control TBV by using chemical sprays and barrier crops were unsuccessful but aphid-proof cages over tulips prevented spread of the virus. Intensive roguing under the cages eliminated tulips infected with TBV. Healthy tulips grown 275 m distant from infected tulips, but unprotected from migrating aphids, did not become re-infected during two seasons.
Environmental factors affecting Escherichia coli and Salmonella typhimurium numbers on land used for effluent disposal
Authors: Chandler DS , Craven JA
Published: November 2004

Escherichia coli cells applied to soil and pasture in piggery effluent, or as a bacteria in water suspension, were found to be susceptible to desiccation in grey clay loam soil when the soil dry matter exceeded 90%, the approximate wilting point of this soil. Inoculation of the cells onto dry soil resulted in c. 99% reduction in cell numbers in 24 hr, even when the soil was shaded. Surviving cells were observed to persist for 8 weeks after inoculation. Salmonella typhimurium cell suspensions added to experimental plots displayed similar persistence characteristics to E. coli. E. coli cells in effluent or suspensions added to moist soil did not exhibit a rapid initial decline in number. The number of E. coli on the pasture diminished quickly even when the soil below was moist. Only a small percentage of inoculum cells were collected in run-off water from the plots after heavy rainfall, although the absolute number of cells was sufficient to pollute a large volume of water if discharged directly into a watercourse.
The nitrogen metabolism of sheep consuming Flinders grass (Iseilema spp.), Mitchell grass (Astrebla spp.) and mixed native pasture
Authors: Norton BW , Murray RM , Entwistle KW , Nolan JV , Ball FM , Leng RA
Published: November 2004

Some aspects of nitrogen metabolism of sheep given Mitchell grass (Astrebla spp.), Flinders grass (Iseilema spp.) and mixed native pasture were investigated. All diets were of low nutritive value as demonstrated by negative nitrogen and energy balances in sheep on these diets. Studies of urea metabolism demonstrated a significant relationship between plasma urea concentration, the rate of irreversible loss of urea from plasma and the rate of urea degradation in the digestive tract. On average, 81% of the urea synthesized in the body was transferred to the digestive tract and degraded to ammonia and carbon dioxide. The proportion of urea degradation occurring intraruminally was estimated during an intravenous infusion of 14C urea by measuring the rate of appearance of 14CO2 in ruminal fluid, the proportion degraded post-ruminally being obtained by difference. Urea degraded in the rumen accounted for 7–13% of the total quantity degraded in the digestive tract, and the rate of urea transfer (0.55 ± 0.13 g nitrogen/day) was not related to the rate of urea synthesis in the body. The lower digestive tract was the major site of urea degradation in sheep given these low protein diets, and the rate of urea transfer to this part of the digestive tract was linearly related to the rate of urea synthesis in the body. The implications of these findings are discussed in relation to nitrogen conservation in sheep given low quality diets.
Partitioning intake and outflow of nitrogen and water in cattle grazing tropical pastures
Authors: Siebert BD , Romero VA , Hunter RA , Megarrity RG , Lynch JJ , Glasgow JD , Breen MJ
Published: November 2004

The quantities of nitrogen and water consumed and excreted by cattle grazing tropical pastures were measured by means of a number of techniques made possible by surgical preparation of animals. The development of portable equipment permitted the continuous infusion of chemical markers and the continuous collection of body fluids. In the dry season the mean nitrogen intake of four steers grazing a native grass pasture was only 20 g/day. When the steers were transferred to a pasture improved with the legume Stylosanthes hamata, nitrogen intake increased to 48 g/day, a value in excess of their maintenance requirement c. 30 g/day. Water turnover values increased simultaneously. More detailed measurements of intake and output of nitrogen and water were made with two steers grazing a tropical pasture of low quality. The mean nitrogen intake of the animals, weighing 600 kg, was c. 90 g/day, most of which could be accounted for in the urine and faeces. The animals consumed some 45 l/day of water, of which approximately two-thirds came from drinking. More than a third was used in evaporation and a similar amount was egested as faeces. The significance of water and nitrogen use for nutritional and environmental reasons is discussed.
The diagnosis of sulphur deficiency in wheat
Authors: Freney JR , Spencer K , Jones MB
Published: November 2004

In a glasshouse experiment with wheat (Triticum aestivum L.), changes in the concentrations of total sulphur, sulphate sulphur, amide nitrogen, and total nitrogen/total sulphur ratio with age, plant part, and nitrogen and sulphur supply, were studied. This was done so that more reliable methods can be devised for the assessment of the sulphur status of this species.Each of the indices studied was strongly related to the current and subsequent sulphur status of the wheat plant. Amide nitrogen provided the greatest relative change in values between sulphur-deficient and sulphur-adequate plants, and on that basis was the most sensitive index. However, each of these indices had shortcomings which could preclude its general acceptance as a useful indicator of sulphur status. The most promising index of sulphur status was shown to be the proportion of total sulphur held as sulphate. This criterion was unaffected by nitrogen supply or plant age. The data suggest that wheat plants containing more than one-tenth of their sulphur as sulphate are adequately supplied with sulphur.
Effect of rainfall on the grain yield of spring wheat, with an application to the analysis of adaptation
Authors: Seif E , Pederson DG
Published: November 2004

The grain yields for nine cultivars of spring wheat grown at 11 sites in 5 years in the Central West of New South Wales have been previously analysed. The results suggested that the variability in yield was mainly attributable to a single environmental factor. Four components of annual rainfall are now defined, and it is found that each correlates positively with yield over the 37 trials carried out. The highest correlation is with spring rainfall, defined as the rainfall from 3 weeks before anthesis to 2 weeks after anthesis. Year, site and year x site effects are calculated for yield and for spring rainfall by means of a least-squares procedure. The correlations between rainfall and the mean yield of the nine cultivars are 0.983, 0.947 and 0.782 for year, site and year x site effects respectively, which indicates that spring rainfall or a weather factor closely correlated with spring rainfall is a major determinant of grain yield. An adaptation analysis with spring rainfall as the independent variable is compared with the more conventional analysis involving site mean yield as the independent variable. The former analysis is shown to have the advantage that the relative stabilities of the cultivars can be interpreted in terms of their response to rainfall.
The effects of cereal cyst nematode (Heterodera avenae) and Rhizoctonia solani on the growth and yield of wheat
Authors: Meagher JW , Brown RH , Rovira AD
Published: November 2004

Field trials in a sandy mallee soil in Victoria have shown that large increases (up to 323%) in grain yield are obtained by soil fumigation or the application of nematicides. Development of the plants was enhanced by control of soil-borne root pathogens. The occurrence of both cereal cyst nematode (H. avenae) and Rhizoctonia solani in patches of poor wheat in a field trial in South Australia indicate a possible association between these two pathogens. Glasshouse studies showed that the effects of H. avenae and R. solani on wheat were greater when both pathogens were together than with each individually.
The effect of Inoculation and cobalt application on the growth of and nitrogen fixation by sweet lupins
Authors: Chatel DL , Robson AD , Gartrell JW , Dilworth MJ
Published: November 2004

The response of sweet lupins, Lupinus angustifolius L., to a soil application of cobalt and to seed inoculation was examined in both field and glasshouse experiments. Plant growth was dependent on nodule-fixed nitrogen, and the addition of cobalt increased the nitrogen content and the growth of the lupins in the absence of inoculation. Bacteroids in the nodules of inoculated plants without cobalt were found to be fewer and longer than those with cobalt, which suggests that cobalt is involved in the mechanism of rhizobial cell division.
A quantitative examination of the growth of swards of Medicago truncatula cv. Jemalong
Authors: Silsbury JH , Adem L , Baghurst P , Carter ED
Published: November 2004

Shoot dry matter yield data for swards of Medicago truncatula cv. Jemalong established on two occasions at Adelaide in 1975 have been used to examine the influence of sowing rate on the seasonal growth pattern of this species. The patterns of dry matter growth are assessed: (i) by the use of a logistic function; (ii) by a growth stage approach involving an initial phase of approximately exponential growth (stage I) followed by a phase of almost constant growth rate (stage II). Two methods are given for determining the duration of these stages. It was found that stage I1 began at a shoot dry weight of about 300 g m-2, irrespective of sowing rate. End-of-season yield at about 10 t ha-1 was largely independent of sowing time and of sowing density. A maximum crop growth rate of 14.9 g m-2 d-1 was recorded for low density and late sowing. Sowing density had a marked effect on the shape of the growth curves; both the maximum crop growth rate and the average crop growth rate in stage II decreased with increase in sowing rate for each time of sowing.
The fibre diameter profile of wool staples from individual sheep
Authors: Jackson N , Downes AM
Published: November 2004

Variation in fibre diameter along the staple was measured on duplicate staples from five sheep from each of four lines selected for high and low staple length and high and low fibre diameter. It was found that the high and low fibre diameter lines differed in mean diameter and in variance along the staple, but did not differ in coefficient of variation along the staple. The high and low staple length lines also differed in mean diameter, but did not differ in variance or coefficient of variation along the staple. Individual sheep within selection lines differed in mean, variance along the staple, and coefficient of variation along the staple. The measurement technique was found to be highly repeatable between duplicate staples sampled from the same animal. Susceptibility to seasonal effects at particular positions along the staple was tested by analysing the interaction between staple segments and other factors, and was described by regressing the diameter at a position on the average diameter of all sheep at that position. It was found that the high and low fibre diameter lines differed in susceptibility (thus described) while the high and low staple length lines did not so differ. Individual sheep within selection lines also differed in susceptibility. The application of measured variation in diameter along the staple to sheep breeding must await more extensive genetic studies. The present study simply unmasks some previously unnoticed genetic and phenotypic differences and checks on the accuracy of the measurement method. It shows that there are non-susceptible individual animals and selection lines for which the variance of diameter along the staple is very low, and hence there exists the potential to reduce this variation on a nation-wide basis, or in local areas, if such a reduction be thought desirable from a woolprocessing viewpoint.