bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the sultana vine. VII. A comparison of crop regulation by pruning with crop regulation by disbunching
Authors: Antcliff AJ , Webster WJ , May P
Published: November 2004

An experiment comparing crop regulation by pruning with crop regulation by disbunching is described. For three out of four seasons both methods of regulation gave similar yields, and only in one season did disbunched vines yield somewhat better than more severely pruned vines with the same number of bunches. This better yield appeared to be due to larger berries on the disbunched vines. Increased vegetative growth on the disbunched vines was not accompanied by improved fruit bud formation or by better bud burst in the following season. It is concluded that the leaf/fruit ratio has little effect on the yield of sultanas under Murray Valley conditions, and that methods of crop forecasting and regulation by pruning developed for this region should not be affected by the variation in leaf / fruit ratio to which they give rise.
Studies in the ecology of the Riverine plain. III. Phenology of a Danthonia caespitosa Gaudich. Grassland
Authors: Williams OB
Published: November 2004

The Danthonia caespitosa grassland of the Riverine Plain is a degraded semi-arid community with many annual and perennial grasses and herbs. Data are presented to show the leafing and flowering phenology of these species during the 5 year period 1949-1953. There were two groups of species distinguishable on flowering behaviour. One group composed of exotics and a few- indigenes can flower only in spring, and the other, composed exclusively of indigenes, flowers in both spring and autumn. Winter rains are more reliable than summer rains, so that flowering in spring is more frequent than flowering in the autumn. The effects of seasonal drought, grazing, and sod fertility are discussed, in relation both to phenological observations and to the development of the degraded grassland from the climax community of Atriplex nummularia Lindl. (saltbush).
Effects of inbreeding on four families of Peppin Merinos. IV. The expression of heterosis
Authors: Doney JM
Published: November 2004

Whereas Inbreeding in Merino sheep seems to have an adverse effect on many fitness characters, it does not appear to limit the potential maternal ability of the ewes in respect to the rearing of a single lamb. There is, however, a complex effect on fertility such that inbred ewes appear to be more variable in their response to environmental fluctuations in terms of successful pregnancies. The variance of body weight is significantly increased by inbreeding, as would be expected following a disturbance of the "developmental homeostasis". However, the variance of fleece weight, which is a character strongly depressed by inbreeding, does not appear to be affected. It is suggested that the 'inbreeding syndrome' is related to excess homozygosity but that the variance changes in the depressed characters result from the consequent disturbance of physiological mechanisms. Outcrossing, both between two Inbred lines from the same strain and between inbred lines and unrelated sheep of the same strain, produces the same results, namely, a reversion of the progeny to the normal characteristics of the original random-bred populations.
The loss of phosphorus from sandy soils
Authors: Ozanne PG , Kirkton DJ , Shaw TC
Published: November 2004

Leaching losses of phosphorus were measured in seven field trials. .Phosphorus was broadcast as superphosphate. Soils used were mostly loamy sands. Losses from the top 4 in. layer of soil ranged from 17 to 81% of the applied phosphorus. This seems to be the first report of such large losses from soil under pasture and receiving only 22 in. mean annual rainfall. Percentage losses remained fairly constant over a wide range of application rates. The surface 4 in. retained more applied phosphorus than did the lower layers. Phosphorus leached from the topsoil was removed beyond the reach of most clover roots. Mixing superphosphate with an equal weight of lime increased clover growth and phosphorus uptake in the establishment year only. It did not increase retention of phosphorus by the soil. The use of sufficient lime to raise the soil pH from 4.9 to 5.5 only increased phosphorus retention from 11 to 1676 of that applied. Applying phosphorus as slightly soluble rock phosphate increased soil retention from 56 to 850j,, but decreased phosphorus uptake by the pasture to only half that obtained if superphosphate were used. A close negative correlation was found between phosphate loss and both the native phosphorus content and the loss on ignition. Soils containing less than 100 p.p.m. native phosphorus or giving less than 6% ignition loss showed appreciable losses of phosphorus. Results show that the rate of accumulation of fertilizer phosphorus may be very slow in some soils unless steps are taken to prevent phosphorus from leaching.
A study of pathogenic factors in experimental bovine oesophagostomosis. I. An assessment of the importance of anorexia
Authors: Bremner KC
Published: November 2004

Pathogenetic factors in bovine oesophagostomosis have been investigated by comparing, in calves of the same breed subject to equalized feeding in pairs, the state of health and thriftiness of infected and control groups. Infection was produced by the administration of 7000 Oesophngosfomum rutiintum larvae. The resulting disease varied from mild to moderately severe in its effects, and was of comparatively brief duration. First signs were seen at 3-5 weeks, improvement began at 10 weeks, and the animals were recovering well at 14 weeks. Infected calves developed an anorexia which was first made evident by a rapid reduction in the mean daily feed intake during the fourth week following infection, succeeded by a slow return to the pre-infection level of' intake about 14 weeks later. In control calves, the same reduction in food intake was imposed over the same period by withholding some of the ration. In control calves the only definite departure from normal was a reduction in the rate of gain in body weight that would be expected in similar calves fed ad libitum, and some retardation in growth. Infected calves on the same feed intake as control animals showed a much greater departure from normal in respect of rate of gain in weight, and their growth was more severely retarded. The mean feed utilization of these calves was 0.039 lb per pound of feed, as compared with 0.095 lb per pound of feed for the worm-free controls. Furthermore there was observed, only in the infected animals, diarrhoea, a normochromic normocytic anaemia, and a hypoproteinaemia. The most severe pathological changes in the hosts occurred when the helminths were in the early fifth stage of development. It is concluded that anorexia is a factor which, through reduction of food intake, contributed considerably to pathogenesis. Other factors together exercised an effect almost as great. These other factors have yet to be investigated and defined.
Fertility changes in soils cultivated for wheat in southern New South Wales.
Authors: Williams CH , Lipsett J
Published: November 2004

A study has been made of red-brown earth�s cultivated for wheat on a narrow rotation of fallow-wheat-volunteer pasture in the Ariah Park district of Xew South Wales. Surface soil samples from 55 cropped paddocks currently under fallow and from matched adjoining areas with no history of cultivation were examined in laboratory, pot culture, and field studies. Many of the soils had carried at least 20 crops since being brought under cultivation and had lost an average of 30% of their organic matter during this period. However, only 17% of the organic phosphorus had been mineralized. The mean ratio of carbon : nitrogen : sulphur : organic phosphorus in the uncultivated soils was 178.3 : 10 : 1.37 : 0.63 while that for the cultivated soils was 170.9 : 10 : 1.41 : 0.74. As a result of the decrease in organic matter content the cation exchange capacity decreased under cultivation. Losses of the exchangeable cations also occurred, but the relative proportions of the metal ions in the cultivated soils were the same as those in the uncultivated. Removal of cations in crops could not account for all of the losses observed. There had been a net loss of sulphur from the surface soils over and above that likely by crop removal. The nitrate content of the surface samples was insufficient to provide the nitrogen uptake by the crop either in pots or in the field. Evidence is presented suggesting that other sources, including leached nitrate, were utilized in the field. Mineralization of organic phosphorus and fertilizer addition had increased the amounts of inorganic, plant-available forms, but the total phosphorus was unchanged in the cultivated soils. However, the phosphorus status of' the cultivated soils was still extremely low and responses to phosphorus were obtained at all sites. There seems little prospect of reducing current superphosphate rates on these soils.
Centrosema mosaic: A new virus disease of Crotalaria SPP. in Papua and New Guinea
Authors: Van Velsen RJ , Crowley NC
Published: November 2004

A study has been made of an undescribed virus disease which has been called Centrosema mosaic. Observations on its occurrence and symptoms, and data on its host range and modes of transmission are presented. The virus occurs naturally in the field on Crotalaria anagyroides H.U.K., C. goreensis Guill. & Perr., C. retusa L., C. mucronata Desv., Calopogonium mucunoides Desv., Centrosema pubescens Benth., and Desmodium distortum (Aubl.) Macbride. The host range appears to be restricted to the Leguminosae, and mainly to Crotalaria spp. The virus is mechanically transmissible, has a thermal inactivation point between 55 and 58°C, a dilution end-point of 1 in 2000, and a longevity in vitro of less than 6 hr. It is transmitted in a non-persistent manner by the aphids Aphis gossypii Glover, Aphis craccivora (Koch), Myzus persicae (Sulz.), and Brachycaudus helichrysi (Kalt.) var. warei (Theob.) and by two species of plant bugs of the genus Nysius. It is readily transmitted by Cuscuta campestris Yuncker, but not by seed or soil.
The effect of mild inbreeding in two lines of White Leghorn
Authors: Morris JA
Published: November 2004

The reaction of two flocks of White Leghorn to slow inbreeding has been examined. One flock, the M line, has been subject to continuous selection for egg production or an associated character since 1947, and the other, the C line, has been propagated by means of random mating without artificial selection for a corresponding period. Mean inbreeding, as measured by Wright's coefficient (F), increased steadily in both flocks to reach a maximum of 25.1% in the M line and 16.2% in the C line. Significant intra-year regressions of survivors' production (72 weeks), hatchability of fertile eggs, and egg production during the winter months of June–July, on computed F values, were observed for both lines. In addition, significant regressions for the 72-week production index, age at first egg, and pauses during June–July were observed for the M line. Viability of chickens, both during early rearing (hatching date to 3½ weeks of age) and during adult stage (approximately 20 weeks to 72 weeks of age), was not affected by small changes in degree of inbreeding. Intra-year regressions on F of age at death and production up to time of death were non-significant for both lines. Highly significant differences between yearly regressions of egg production, and pauses during the two winter months, on F values were observed. These differences could indicate a differential sensitivity of response to inbreeding associated with seasonal adversity. It was not possible to substantiate the existence of a differential response to a stress factor when mortality during a severe heat wave was examined, as the mean computed F value of birds dying was not significantly greater than the corresponding F value of survivors. The stress was reasonably severe, as 15.4% of all birds died within a couple of days.
The influence of leaf area and radiation on the growth of clover in swards
Authors: Stern WR , Donald CM
Published: November 2004

A study was made of the light regime and the growth of clover: (a) in mixed swards with varying proportions of grass; (b) in specially designed cultures in which grass and clover competed for light alone. The growth of the clover showed direct dependence on the level of radiation at the surface of the clover leaf canopy; it was positive when radiation values were above about 60–80 cal/cm²/day but fell to zero or negative rates at lower radiation levels. A relationship is presented between the level of radiation, the leaf area index, and the crop growth rate. It is shown that the optimum leaf area index increases with increasing levels of radiation; and further that as the leaf area index increases, the level of radiation required for maximum growth rate also rises. The implications in agricultural practice are discussed briefly.
Studies on translocation of herbicides in skeleton weed (Chondrilla juncea L.)
Authors: Greenham CG
Published: November 2004

These studies relate to the translocation of orthoarsenic acid and 2,4-D from the above-ground parts of skeleton weed, usually the leaves, to the roots. Poor translocation of orthoarsenic acid is to be attributed to some factor other than poor oxygenation of the soil, possibly unfavourable source-sink relationships. The apparently anomalous unimpaired translocation of both herbicides after old plants were subjected to darkness for 4 days is related to a sustained high carbohydrate content of the leaves. Other factors also affect translocation. Orthophosphate, 0.25M at pH 3.0, significantly increased translocation of radioactive 2,4-D in comparison with equimolar citrate or glycine. Phosphate metabolism, perhaps ATP content, is regarded as influencing translocation. Maximum radioactivity in the roots was found some 7 days after labelled 2,4-D was applied to the leaves, which showed that absorption and translocation were prolonged. Radioactivity within treated young plants progressively lessened from the petioles to the roots, there being no focal point of concentration limiting translocation. At first proportional radioactivity, then total radioactivity found in the roots, decreased as the concentration of labelled 2,4-D applied to the leaves was increased. Injury to the leaf tissue or the phloem, or both, is regarded as a major factor limiting the translocation of such poisons to the roots.
Comparative responses to copper of some tropical and temperate pasture legumes
Authors: Andrew CS , Thorne PM
Published: November 2004

Five tropical and five temperate pasture legumes were grown in pots containing an acutely copper-deficient soil, and in water culture. Growth responses and copper contents of the tops, roots, and seed are reported. In soil culture, the relative dry matter yields of the tops of Desmodium uncinatum (Sacq.) DC., Phaseolus lathyroides L., Centrosema pubescens Benth., Indigofera spicata Forsk., and Stylosanthes bojeri Vog. on the nil treatments were 60, 46, 45, 21, and 7% respectively of their maximum yields obtained with optimum copper additions to the soil. Yields of Trifolfum repens L., Trifolium fragiferum L., Trifolium alexandrinum L., Medicago sativa L., and Medicago tribuloides Benth. on the nil treatments were 38, 31, 3, 17, and 14% respectively of their maxima. Thus Trifolium alexandrinum and Stylosanthes were the most sensitive to copper deficiency, Desmodiurm and Trifolium repens the least sensitive, the remaining species showing intermediate responses. The sensitive species required additions of copper of up to the equivalent of 4 lb copper sulphate per acre to produce maximum growth, while the relatively insensitive species required only the equivalent of ½ lb per acre. Similar results were obtained in the water culture experiment. The copper concentrations in the dry plant material from the various species did not vary significantly at any one level of application. The range of copper concentration over all treatments was 1.7–11.3 p.p.m., but the species did not differ greatly in their copper requirements for normal growth. The relatively sensitive species such as Trifolium alexandrinum and Stylosanthes were much less efficient at extracting copper in both soil and water culture than Desmodium, Trifolium repens, and Trifolium fragiferum. However, on the basis of copper uptake per unit weight of root tissue Stylosanthes had a high value, which was largely controlled by top/root ratios. Copper accumulated more in the roots than in the tops of most species, particularly at high rates of copper application; however, Stylosanthes and Trifolium alexandrinum also had relatively high copper contents in their roots on the low treatments. The seeds of these two species had higher copper contents per unit weight than the other species. It is considered that, for legumes, a copper concentration above 5 p.p.m. in the plant material is satisfactory, while 4–5 p.p.m. is marginal and less than 4 p.p.m. indicates copper deficiency. The occurrence of high copper contents in some plants showing foliar symptoms and yield depression as a result of copper deficiency is discussed.
An exploratory survey of the ecology of Rhizobium meliloti in inland New South Wales and Queensland
Authors: Hely FW , Brockwell J
Published: November 2004

The ability of Rhizobium meliloti occurring naturally at 26 sites to nodulate three test species of Medicago was investigated. Bacteria able to nodulate Medicago sativa L. were found, in the absence of this host, at all sites sampled and frequently in appreciable numbers, even under dry conditions. Bacteria able to nodulate Medicago denticulata Willd. were found at 25 sites, but usually in lower numbers; they also occurred independently of this species. Organisms able to nodulate Medicago laciniata (L.) Mill. were detected at 18 sites but only in low numbers; they were found at eight sites in the absence of M. laciniata and were not detected at three sites where this medic was present. High numbers of bacteria able to nodulate M. sativa and M. denticulata were related to high frequencies of Medicago minima (L.) Bart. in the field. Associations were found between high numbers of Rh. Meliloti in the topsoil and the texture of the soil, the plant size of the annual species of Medicago in the sample area, and the condition of the native grasses.
Grazing management of native pastures in the New England region of New South Wales. II. The effect of size of flock on pasture and sheep production with special reference to internal parasites and grazing behaviour
Authors: Southcott WH , Roe R , Turner HN
Published: November 2004

The effect of flock size on pasture and animal productivity, on parasitic infection, and on grazing behaviour was investigated in a grazing experiment over a period of 3 years. Merino sheep, undrenched, and stocked at the rate of one sheep per acre on native pasture dominated by Bothriochloa ambigua S.T. Blake, were used in five flock sizes, vie. 2, 4, 8, 16, and 30 animals. Flock size did not significantly affect the forage available or the botanical composition of the pastures, but liveweight gains and wool production were significantly lower in the flock of two sheep than in the other flocks. Observations indicated that the reduced productivity of the smallest flock was associated with reduced grazing time consequent on changes in grazing behaviour. No consistent significant differences in worm egg counts were observed in faecal samples from the different flocks. The results indicate that although under fairly extensive grazing conditions a unit of two sheep may be unsatisfactory in some respects, flocks of four sheep could give information on pasture or animal production or on parasitism comparable with that from larger flocks of up to 30 animals.
Some functional manifestations of the protein depletion of sheep tissues
Authors: Masters CJ , Horgan DJ
Published: November 2004

In order to elucidate the alterations in tissue function of Merino sheep feeding on a low protein, low energy diet, the sequential measurement of a number of clinical parameters has been performed. Emphasis has been directed to the protein storage tissues, and the following indices were measured: bromsulphthalein clearance; serum levels of glutamic oxalacetic transaminase, glutamic pyruvic transaminase, total cholesterol, cholesterol esters, total proteins, electrophoretic protein fractions, and urea; urinary volume, and urine creatine, creatinine, and urea. Alterations in these indices were consistent with a marked degree of liver dysfunction occurring after several weeks on the experimental diet. No significant changes were apparent in the functional ability of kidney or muscle.
The copper metabolism of warm-blooded animals with special reference to the rabbit and the sheep
Authors: Beck AB
Published: November 2004

Groups of rabbits were fed for 12 weeks on the same diet at two levels of copper intake (8.5 and 30 p.p.m. Cu). There was no real increase in the liver copper levels at the higher copper intake. When rabbits were injected intravenously with 1 mg Cu, the excess copper was eliminated from the liver in 96 hr. Some copper was excreted through the bile and some appears to have been excreted directly into the caecum. Experiments are described which show that, by contrast, the sheep very slowly lost excess copper from the liver. The rate of loss was the same whether the copper had been given orally or intravenously. The patterns of copper storage and excretion in warm-blooded animals are outlined, and it is postulated that the unusual copper metabolism of the sheep IS due to a limited capacity to excrete excess copper from the liver.
Effect of environment on the maintenance requirements of Merino wethers
Authors: Lambourne LJ , Reardon TF
Published: November 2004

Small groups of Merino wethers were maintained at virtually constant liveweight in four "environments" and their maintenance feed requirements estimated from the relationship between their fluctuations in liveweight over 14-day periods and their feed intakes, measured directly or estimated by chromium oxide dilution and faecal nitrogen concentration. When adult wethers of equal size but a varying degree of fatness were fed on fresh pasture herbage in metabolism pens, liveweights of 26, 32, and 46 kg could be maintained on a daily intake of approximately 200, 300, and 420 g digestible organic matter (D.O.M.) respectively. When the metabolism pens were placed outdoors in winter the maintenance requirements rose, the rise appearing to be greatest for the thin sheep. When wethers were allowed to graze for about 1½ , 2½, and 4 hr in abundant pasture, liveweights of 26, 33, and 46 kg were maintained on intakes of approximately 420, 480, and 490 g D.O.M. respectively. When the same wethers were allowed to graze freely and weight was controlled by the scarcity or abundance of the pasturage, the same liveweights were maintained on intakes of about 750, 780, and 560 g D.O.M. respectively. The rise in maintenance requirements on short pasture seems too great to be explained by the increased energy cost of locomotion and grazing. The possibility of an endocrine stimulation of metabolic rate is pointed out.
Properties of Dermatophilus dermatonomus zoospores in relation to the transmission of mycotic dermatitis
Authors: Roberts DS
Published: November 2004

Zoospores from cultures of Dermatophilus dermatonomus were examined with respect to properties considered relevant to their role as the infective agent of ovine mycotic dermatitis. An account is given of nutritional and gaseous requirements for motility, and of several factors which inhibit motility, including salts at relatively low concentrations, pH values outside the range from 6 to 8, osmotic tensions above 0.4 osmole, and the presence of other aerobic organisms. Froin these and other observations it is concluded that the zoospore is ill equipped for prolonged survival in the external environment. The viability of the zoospores is greatest in the first hours after their release from the mycelium. This quality is associated with a highly impermeable cell membrane, a complete independence of external nutrient sources, and a tendency to germinate rapidly even under conditions relatively unfavourable for growth. The zoospores exhibit a negative aerotaxis which seems likely to facilitate their attainment of the skin surface prior to invasion. It is suggested that the probability of a susceptible skin area becoming infected would be high when the sheep in an infected flock were wetted by rain, and even greater if some vector or mechanism were available to expedite the transfer of zoospores from sheep to sheep. The incidence of infection would then depend on the number and extent of the susceptible skin areas on individual sheep.
Plasma protein-bound iodine and growth rates of beef cattle
Authors: Post TB
Published: November 2004

Plasma protein-bound iodine (P.B.I.) levels determined in February and August at Rockhampton, Qld., in 177 grazing heifers and steers were compared with post-weaning gains during summer (October to March) and winter (March to October). In contrast to a large difference in average gain between summer (96 lb) and winter (41 lb), reflecting changes in nutrition, there was no seasonal difference in P.B.I. Significantly lower mean gains in British (Hereford x Shorthorn) breed groups (40 lb) than in F1 (96 lb) or F2 (71 lb) Zebu (Brahman and Africander) x British crossbreds, and in F2 than in F1 crossbreds, were accompanied by similar breed differences in P.B.I. (British 2.91 µg %, F1 crossbreds 3.94 µg %, F2 crossbreds 3.55 µg %). P.B.I.'s were repeatable between seasons (r = 0.4) but gains were not (r = –0.07). Coefficients of correlation between summer gain and both summer and winter P.B.I. were significant in the British and F2 Zebu x British crosses, averaging about 0.5, but were near zero in the F1 crosses. Poor nutrition may have been responsible for the failure to observe significant correlations between winter gains and P.B.I. In summer, differences in P.B.I. accounted for about 25% of differences in gain between British and F2 Zebu x British crossbreds, and among animals within these breeds. The relationship between P.B.I. and gain was linear over the whole range of P.B.I. observed, which indicated that optimal levels of P.B.I. had not been exceeded. These data suggest that summer heat in the tropics may depress thyroid activity to an extent which imposes limitations on growth rates. Differences in performance among animals and breeds of beef cattle may be due in part to differences in ability to maintain adequate thyroid function under heat stress.
The effect of diet on the secretion of parotid saliva by sheep. I. The daily secretion of saliva by caged sheep
Authors: Wilson AD , Tribe DE
Published: November 2004

Two sheep with unilateral parotid fistulae were used to record the effect of individual dietary factors on parotid salivary secretions. The volume of saliva secreted was not affected by the addition of urea and molasses to a straw diet, by the drying of pasture containing 20% dry matter, or by restricting or increasing the water intake. Parotid secretion was increased by increasing the dry matter intake. With a constant food intake, the secretion was increased by 25% when the hay ration was ground through a 1/16 in. screen, but was decreased by 61% when ground through a finer screen. The intraruminal infusion of artificial saliva or 1%sodium chloride decreased the secretion by a mean of 59%. Food intake was of greater importance than other dietary factors, excluding fine grinding, in determining the volume of parotid saliva secreted.
Interactions between heredity and environment in the Australian Merino. II. Strain x location interactions in body traits and reproductive performance
Authors: Dunlop AA
Published: November 2004

Further results are presented of an experiment in which five strains of the Australian Merino were run as breeding groups in three wool-growing regions. Strain x location interactions were estimated as indicators of adaptation of specific strains to particular environments. The characters for which results are presented here are measurements of body weight, body length, width of hips, width of shoulders, depth of chest, and length of fore leg, gradings of skin folds on the neck and body and of face cover, and finally number and weight of lambs born and weaned.Real interactions of strain and location were found in most of these attributes, but they were generally of moderate to small size and accounted for only a minor fraction of the variance. Frequent year x location interactions may account for the unimportance of strain x location interactions. In these characters, as in wool traits, it appears that specific adaptations are not important in the choice of the strain of sheep to be used in particular areas. In feproductive traits, strain differences are of small importance in contrast to marked and consistent differences between strains in other attributes.
The influence of subterranean clover pastrues on soil fertility. I. Short-term effects
Authors: Watson ER
Published: November 2004

Under a subterranean clover pasture on a light-textured soil at Kojonup, Western Australia, soil nitrogen accumulated at a fairly steady rate of 42 lb/acre/year over a 5 year period. The increase in soil nitrogen accounted for differences in wheat production following the clover ley whether measured as total dry weight, yield of grain, or uptake of nitrogen. The clover treatments had little effect on the percentage of nitrogen in the grain or on the baking quality of the flour. Each additional year of clover gave an additional yield of 120 lb of wheat grain per acre for the first crop. Yields for second crops were considerably lower than the first but residual effects were evident. A practical implication of the results is that short leys of 1 to 2 years' duration followed by a single cereal crop could be a suitable cropping practice for the Kojonup area.
Weight gain and faecal nitrogen excretion in grazing British and Zebu crossbred steers
Authors: Ashton GC
Published: November 2004

The excretion of faecal nitrogen by 16 grazing steers, eight Hereford x Shorthorn and eight Zebu crossbreds, was determined at intervals over a period of 11 months. It was found that the non-dialysable faecal nitrogen fraction was the one most strongly correlated with gain. Statistically this fraction accounted for 68% of the variation in average gain of the two breed groups between measurement intervals, and for 75% of the variation in weight gain between individual steers during the summer gain period. The data gave no indication of inherent breed differences in intake, as judged by non-dialysable nitrogen excretion.
Tiller dynamics, growth, and persistency of Lolium perenne L. and of Lolium rigidum Gaud.
Authors: Silsbury JH
Published: November 2004

Changes in the size and composition of the tiller populations of single plants (20 cm spacing) of summer-dormant and non-dormant types of L. perenne and of L. rigidurn have been determined at Adelaide over a 13 month period. Dry matter yield, summer survival of plants and tillers, and the degree of reproductive development were also recorded. A seed vernalization technique was used in an attempt to obtain developmental variation within each species or cultivar. The role of vegetative tillers in summer survival was found to be extremely small, since less than 10% of the visible vegetative tillers present at the commencement of summer regrew the following autumn. Regrowth after summer came principally from axillary buds at the base of the fertile tillers. The interrelationships between summer dormancy, regrowth, and tiller ecology are discussed. The vernalization treatment resulted in increased dry weight and tiller number per plant during the first growing season: with autumn planting it had no marked effect on time of heading, but in some cases increased the proportion of fertile tillers.
The effect of temperature, variety and age on the response of Saccharum spp. to applied gibberellic acid
Authors: Bull TA
Published: November 2004

The effects of gibberellic acid (GA) on the growth of Saccharurn spp. was determined for I-month-old plants from three varieties and 6-month-old plants of one variety grown at four temperatures (35, 29, 23, and 17°C) and over an 8 week period. GA treatment increased stalk length, fresh weight, and fibre and sugar contents, decreased leaf area and leaf weight, but had no effect on node number. The magnitude of the response differed with variety, age of plant, and temperature of growth. Young plants responded relatively more at low temperatures, whilst older plants tended to exhibit greater responses at higher temperatures.
Survival of root-nodule bacteria in dry soils exposed to high temperatures
Authors: Marshall KC
Published: November 2004

An investigation has been made of the survival of root-nodule bacteria in autoclaved soils which, after inoculation, were dried at 30°C and subsequently exposed to higher temperatures. Rhizobium trifolii died in grey and yellow sands heated to 70° but survived in red sands and soils of heavier texture. Amendment of a grey sandy soil with 5% (w/w) of montmorillonite, illite, fly ash, or haematite protected R. trifolii from the lethal effects of exposing the dry soil to high temperatures. Kaolinite and goethite did not protect the clover root-nodule bacteria. After three successive exposures at 50° for 5 hr R. trifolii disappeared in a grey sandy soil, but still survived after four exposures in the presence of montmorillonite. The greater survival in heavy-textured soils and red sands can be attributed to the presence of appreciable amounts of illite or haematite or both in these soils, the grey and yellow sands containing only kaolinite and possibly goethite, neither being protective. Another fast-growing species of the root-nodule bacteria, R. meliloti, also failed to survive heating to 70° in a grey sandy soil. On the other hand, the slow-growing R. lupini and R. japonicum were comparatively resistant to the effects of high temperature and desiccation in the same grey sand, a fact which may explain the survival of R. lupini in certain field soils where R. trifolii fails to survive.
Studies on frost injury to wheat. II. Ice formation within the plant
Authors: Single WV
Published: November 2004

The formation of ice crystals within leaves, stems, and ears of wheat plants (Triticum aestivum L.) was studied at temperatures of –3.0 to –5.0°C. The mean velocity of propagation of the ice front in leaves at –3°C was 120 ± 4.1 cm/min. In other plant parts it was slower and more variable. Values recorded for stem internodes ranged from 76 to 0.02 cm/min and for reproductive organs from 1.0 to 0.04 cm/min. Some stem and rachis nodes (in winter-grown plants only) arrested the spread of ice crystals for several hours. This appeared to be an important mechanism for protecting young ears from frost, as they remained super-cooled for long periods if inoculation from external sources was prevented.
Relationship in annual species ofMedicago. I. Number and morphology of chromosomes
Authors: Simon JP , Simon A
Published: November 2004

Ideograms are presented of the haploid chromosome set of 22 annual species and varieties of Medicago belonging to sections Spirocarpos and Orbiculares. Differences in the number, size, and morphology of the chromosomes among these species have been found. In section Spivocarpos, the 2n = 16 species belonging to subsection Pachyspirae have similar karyotypes but considerable variability occurs among species within subsection Leptospirae. Counts of 2n = 14 were recorded in 48 accessions of the three species, M. polymorpha L., M. rigidula (L.) All., and M. praecox DC. Similarity in chromosome morphology was found between the three species, but differences in the karyotypes, not correlated with the external morphology of the plants and pods, were observed between some accessions of M. polymorpha L.
Extension growth of grass tillers in the field
Authors: Williams CN , Biddiscombe EF
Published: November 2004

Growth-recording instruments were used to measure extension growth of grass tillers under a variety of outdoor conditions. Variation in the rate of extension growth between tillers was fairly high, but nevertheless was found to be highly correlated with field temperature while only poorly correlated with light energy. By using these instruments, estimates of growth activity can be made rapidly and over relatively short periods of time; and it is suggested that the method may have use in assessing species for sensitivity to temperature.
The rates of production of volatile fatty acids in the rumen. II Measurements of production of volatile fatty acids in the rumen
Authors: Gray FV , Weller RA , Jones GG
Published: November 2004

(1) The production of acetic, propionic, and butyric acids was measured in an artificial rumen of the dialysing type: (a) by direct analysis, and (b) by the isotope dilution technique with 14C-labelled fatty acids. Estimates of production by the latter method agreed closely with the direct measurements when due allowance was made for small losses of the radioactive labels from their respective acids. (2) Rates of production of the three acids in the rumen of the sheep were measured simultaneously by the isotope dilution technique. The small losses of 14C from the acids were measured in the same material fermented in an artificial rumen which was shown to produce a mixture of the acids in the same proportions as the fermentation in 'the rumen itself.
Investigation of the vaginal smear (Allen-Doisy) assay of oestrogen in ovariectomized ewes
Authors: Lamond DR , Lang DR
Published: November 2004

The vaginal smear (Allen-Doisy) assay for oestrogens has been studied with ovariectomized ewes. Variation between ewes was considerable and the slopes of the log dose-response lines were low. The value of the assay for quantitative determination of oestrogen is limited by lack of precision. The oestrogenic content of red clover (Trifolium pratense) was estimated in terms of micrograms of injected stilboestrol per kilogram of dry matter. Considerable variation in sensitivity to the standard was observed. Intraruminal administration of stilboestrol reduced its activity about 100-fold compared with subcutaneous administration. Ewes were given carbon tetrachloride to cause liver damage but the vaginal response to red clover was not altered.
Studies on the use of mutagenic agents in plant breeding. II. The effects of dose and seed moisture content on mutation production in Lupinus angustifolius by X-Rays
Authors: Gladstones JS , Francis CM
Published: November 2004

Seeds of Lupinus angustifolius were given X-ray doses of 2.5, 5, 10, and 20 kr at each of 12 moisture contents ranging from 6.1 to 18.1 % (wet weight basis). Various measures of injury were recorded in the X1 generation, and the types and rates of mutations in the X2. At moisture contents below 16%, total mutation rates were closely correlated with X1 injury. Injury and mutation rate decreased with increasing moisture up to 11–12% moisture, and thereafter remained at a constant minimum up to 16%. Between 16 and 18% moisture there was again an increase in X1 injury, but not in mutation rate. Between 6 and 12 % moisture, a linear relationship was found between moisture content and the logarithm of the dose required to cause a given level of injury or mutation. A possible mechanism for such a pattern of protection is discussed. Lethal mutations increased as a proportion of all mutations as dose and mutation rate increased. There were also proportionately more lethals at high moisture contents than in lower moisture treatments giving the same mutation rates. It is concluded that lethal and seedling chlorophyll-deficient mutations could be misleading when used as indicators of total and viable mutation rates, and that, contrary to the conclusions of some previous authors, no advantage is likely to be gained in practical breeding work from irradiating at high seed moisture contents.
The effect of growth temperature, level of ammonium nitrate, and light intensity on the growth and nodulation of cowpea (Vigna sinensis endl. ex hassk.)
Authors: Dart PJ , Mercer FV
Published: November 2004

The nodulation and growth of cowpea plants (Vigna sinensis Endl. ex Hassk. var. Poona), grown in the CERES phytotron glasshouses, were examined. The plants were grown under six controlled temperature regimes (21, 24, 27, 30, 33, or 36°C day temperature) with ammonium nitrate (NH4N03) additions of 0, 10, 30, and 90 mg nitrogen per pot of six plants; and were grown either under natural daylight or under natural daylight reduced in intensity by one-third by mesh screens. Primary root nodulation was significantly affected by temperature, NH4NO3 level, and light intensity, with an optimum temperature of 24°C. Secondary root nodulation was also affected by light intensity and temperature, but the nodulation pattern (with an optimum temperature of 33°) was almost the inverse of the primary root pattern. Temperature significantly influenced the fresh weight of nodules per plant and the nodule size, with a lesser effect of the NH4NO3 level. Plant dry weight production (tops and roots) was governed by the temperature, NH4NO3 level, and light intensity, the maximum total dry weight being produced at 27°C. Temperature, light intensity, and NH4NO3 level all influenced the plant combined- nitrogen uptake. The nodule leghaemoglobin concentration was significantly reduced at the two extreme temperatures 21° and 36°C. Temperature also markedly affected the nodule structure – particularly the distribution of starch within the nodule.
Air speed effects during drying of harvested pasture material
Authors: Shepherd W
Published: November 2004

Laboratory and field investigations indicated effects of air speed on the drying rates of harvested clover and ryegrass. In laboratory tests, the drying rates of material of high moisture content increased with increasing air speed to 0.4 m sec-1 past single units or through bulked material, and to 4 m sec-1 over bulked material. These critical air speeds decreased as drying progressed. Critical through-speeds, initially unattainable even with high speeds over bulked material, could then be attained at moderate over-speeds. The effects were confirmed during field tests involving material bulked into swaths and windrows such as are employed in the field drying of mown pasture for conservation as hay. Effective external (surface) resistances of material in swaths and windrows were estimated to be 8–12 times those of plant units exposed singly. Evidence is presented that "turning" of material during field drying, to release entrapped water vapour, is necessary even on windy days in the early stages of drying, and on still days in the later stages. Under still but otherwise favourable conditions, turning appears necessary also as a substitute for the continuous supply of warm air to spaces within the bulk.
The relation between yield and the reproductive phase in cocksfoot (Dactylis glomerata L.) in a winter rainfall environment
Authors: Knight R
Published: November 2004

Studies were made of six genotypes of Dactylis glomerata grown in defoliated clonal swards in the Mediterranean-type environment of southern Australia. Differences between genotypes in timing of reproductive phase stem elongation was the main cause of yield differences for 5 months of the growing season. This latter period compares with the 3–4 weeks for differentiation of ecotypes found in northern temperate regions, and is a result of the winter growing season and lower latitude. High yields were obtained under midwinter conditions from early genotypes. The yield of late genotypes was affected by moisture stress in the spring of some years, and their production was very erratic from year to year. The ranking of the genotypes was affected by the date of the previous harvest. Initiation of reproductive buds was variable between genotypes, and some genotypes carried initiated buds throughout the year.
Vital statistics for an experimental flock of Merino sheep. II. The influence of age on reproductive performance
Authors: Turner HN , Dolling CHS
Published: November 2004

Estimates are given for various characteristics associated with reproduction rate, at each age of ewe from 2 to 10 years. In general, reproduction rate rose with increasing age to a peak, with a subsequent fall, the 10-year-old figure, however, being in most cases above the 2-year-old one. The peak occurred at 5–6 years for number of ewes lambing per ewe joined, at 6 years for survival rate of both single and twin lambs and for number of lambs weaned per ewe joined, at 7 years for number of lambs born per ewe joined, and at 7–8 years for number of multiple births per ewe joined. The estimates are used to predict the reproduction rate of flocks with different age structures, the conclusion being that the average number of lambs weaned per ewe joined would increase with the age of the oldest group of ewes even up to 8–9 years. Data from other sources are summarized for comparison. If survival rate can be improved, particularly for lambs from multiple births, then the older ewes will show an even greater advantage. Formulae are given which enable various criteria for reproduction rate, such as lambs weaned per ewe joined, to be broken into components whose relative importance can be assessed.
Root distribution in a deep sand and its relationship to the uptake of added potassium by pasture plants
Authors: Ozanne PG , Asher CJ , Kirton DJ
Published: November 2004

The distribution of roots and the uptake of 42K from various depths in soil were studied in glasshouse and field experiments on 12 temperate annual pasture species. Root/top weight ratios were mostly higher in grasses than in legumes or herbs. This ratio decreased with increasing maturity of the plants. The concentration of roots under field swards decreased exponentially with depth, from 10 cm downwards. Large differences in root distribution were noted between species. The most shallow-rooted were lotus, subterranean clover, and silver grass. The deep-rooted species were cape-weed, erodium, oats, lupins, and serradella. Some ecological implications of these differences in rooting depth are discussed. The effective rooting depth in the field was correlated with root penetration rates measured on young plants. The possibility of using root penetration rate as a means of predicting potential rooting depth is discussed. All species had a high proportion of their roots in the top 10 cm of soil and took up most 42K from this layer. As the depth increased, both the concentration of roots in the soil and the amount of potassium absorption decreased. The amount of roots at the sites of 42K placement was closely related to both the concentration and the total amount of 42K in the tops.
The growth of safflower (Cathamus tinctorius L.) in a low latitude environment
Authors: Stern WR , Beech DF
Published: November 2004

At the Kimberley Research Station, W.A., growth studies on safflower were made on a uniform crop in one year, and in the following year on a density experiment and a time of nitrogen application experiment. Density treatments extended from 25 to 1120 plants m-2, to exploit as fully as possible the light environment in the crop canopy. In the nitrogen treatments, 90 kg ha-1 of nitrogen was applied at seeding, elongation, and budding in an attempt to increase grain yield by increasing the size of the terminal inflorescences. Although at higher densities the light microenvironment was exploited early there was no increase in total dry matter, and grain yield was highest with densities of about 100 plants m-2. In the nitrogen experiments the early indications of higher yields due to treatment did not materialize as the crop matured, because rising temperatures at flowering and during seed development retarded further growth. On the average, grain yield or economic yield constituted 20% of the total dry matter of tops. There was a greater difference in total dry matter and grain yield between years than between treatments within one year, and this was interpreted as a time of planting effect. The effects of rising temperatures during seed formation are discussed. Avenues for further work are suggested.