bluuebunny/crossref_metadata_2025 huggingface dataset:
Ascospore deposition in Eutypa armeniacae
Authors: Carter MV
Published: November 2004

An open-circuit wind-tunnel designed for spore deposition studies at wind speeds up to 9 m/sec is described. Deposition of Eutypa ascospore octads on three components of the host surface was investigated at four wind speeds. The efficiency of deposition on petioles exceeded that on leaves or stems; and for all surfaces, the deposit increased with wind speed within the range 1–5 m/sec. Deposited ascospores were readily removed from leaves by brief contact with water, and must therefore be regarded as available for redispersal in rain wash and rain splash. The deposit of ascospores on defoliated shoots was only 3.5% of that on the corresponding foliated structures; thus the risk of ascospores reaching the infection courts is markedly diminished by leaf fall. In an apricot orchard, winds of less than 2 m/sec predominated close to the tree foliage at 2 m above ground level. Comparative studies with rigid artificial surfaces of gross dimensions similar to those of apricot petioles suggested that the efficiency of deposition of E. armeniacae octads on such narrow surfaces may be influenced by the shape and mobility of the target surface.
Interrelations in the growth and development of Lolium. I. Some effects of vernalization on growth and development
Authors: Silsbury JH
Published: November 2004

The responses of Lolium rigidum Gaud. and L. perenne L. to low temperature seed vernalization were determined by comparing the growth and development of vernalized and unvernalized plants raised in the field and in a controlled environment cabinet. Vernalization did not appear to influence growth in the vegetative phase, but usually induced earlier heading and a greater proportion of reproductive tillers. Comparisons of vernalized (reproductive) and unvernalized (vegetative) plants show increased reproductive development to be associated with higher growth rates, lower tillering, and greater weight per tiller. High growth rates during the reproductive phase are considered to be due to the ability of reproductive tillers to grow more rapidly than vegetative tillers through the growth of true stem functioning as a "sink" for assimilate. Generalized growth curves for vernalized and unvernalized ryegrass grown under long days are presented and discussed.
Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) I. Effects of temperature
Authors: Rossiter RC , Beck AB
Published: November 2004

Two strains of subterranean clover – Yarloop and Mt. Barker – were grown at controlled temperatures ranging from 36/31° to 9/4°C under long-day conditions. Leaf material was analysed for the three isoflavones formononetin, genistein, and biochanin A. In the Mt. Barker strain, the formononetin concentration was low (< 0.2% dry wt.) and varied little with temperature. Otherwise, isoflavone levels generally rose from very low values at 36/31° to a peak at 15/10°, and then decreased again to 9/4°. For both strains the total concentration of the three isoflavones and also the total amount of isoflavones per leaf were highest at 15/10°. This temperature was lower than that at which maximum growth occurred. The data are discussed in relation to evidence on the effects of temperature on the formation of flavonoid (especially anthocyanin) compounds. We conclude that temperature is unlikely to be a major factor in the incidence of "clover disease".
The relationship of grain yield to vegetative growth and post-flowering leaf area in the wheat crop under conditions of limited soil moisture
Authors: Fischer RA , Kohn GD
Published: November 2004

Trials were conducted in 1961 and 1962 at Wagga Wagga in southern New South Wales to investigate the yield physiology of the wheat crop. Various cultural treatments were applied to a single variety (Heron). This paper covers aspects directly related to grain yield. In the rate of sowing and fertilizer trials relative differences in grain yield were invariably less than relative differences in total dry weight at or before flowering. In some cases increased vegetative growth depressed grain yield. These results appear to be mainly the consequence of increased post-flowering competition for limited soil moisture in denser crops. High soil nitrogen had an additional detrimental effect. When as a result of later sowing flowering was delayed, both vegetative growth and post-flowering plant water status decreased; as a consequence grain yield decreased with successively later sowings. For the 1962 crops, grain yield was closely correlated (r = 0.969**) with leaf area duration after flowering, which in turn was related to leaf area index at flowering and to the rate of senescence of photosynthetic tissue. Increased rates of senescence were usually associated with reduced post-flowering plant water status, as indicated by the relative turgidity of the leaves. These results are discussed in relation to the importance of numerical components of grain yield and to improvement of grain yield in the wheat crop.
The energy values and nutritive value indices of Digitaria decumbens, Sorghum almum, and Phaseolus atropurpureus
Authors: Minson DJ , Milford R
Published: November 2004

Two subtropical grasses, Digitaria decumbens and Sorghum almum, and one legume, Phaseolus atropurpureus (var. Siratro), cut at different ages were fed to sheep indoors to measure voluntary intake and apparent energy digestibility. Energy values of dry matter ranged from 4.11 to 4.48 kcal/g and those of organic matter from 4.47 to 4.94 kcal/g. There was a positive correlation between the energy value of organic matter and the crude protein content (r = 0.84, P < 0.01). The apparent digestibility of feed energy was correlated with species, age, and dry matter digestibility but there were significant differences between the regression equations for each species. Age was the most important factor determining the digestible energy content of the three species, and the energy value of digestible organic matter varied from 3.860 to 4.801 kcal/g. This value was positively correlated with protein content. The intake of digestible energy (kcal/kg0.75) was approximately four times as great for young cuts as for mature cuts of both grasses. Nutritive value index (N.V.I.) was closely correlated with the intake of digested energy for the three species (r > 0.998, P < 0.001), but the regression coefficient for S. almum was significantly different from those for D. decumbens and P. atropurpureus. The relative merits of the digestible energy and N.V.I. methods of expressing the energy value of pasture are discussed, and it is concluded that digestible energy is the more suitable method.
The physiological assessment of the nutrient status of plants. II. The effect of the nutrient status of the plant with respect to phosphorus, sulphur, potassium, calcium, or boron on the pattern of leaf area response following the transfer to different nutrient solutions
Authors: Bouma D , Dowling EJ
Published: November 2004

In a series of experiments, young subterranean clover plants were raised at several levels of phosphorus, sulphur, potassium, calcium, or boron respectively, and then transferred to complete nutrient solutions and to solutions without the previously varied element. Response patterns based on relative leaf area increases revealed quantitative relations with the nutrient status of the plants at transfer in the experiments with different phosphorus, potassium, or boron levels. In the sulphur experiment the response pattern indicated only the presence or absence of stress. In the calcium experiment the picture was somewhat obscured by premature death of leaves following collapse of the petioles. In a second series of experiments it was shown that the presence or absence of specific stresses could be determined from the patterns of leaf area response after transfer of plants to complete solutions and to solutions each without one of the five elements.
The physiological assessment of the nutrient status of plants. III. Experiements with plants raised at different nitrogen levels.
Authors: Bouma D , Dowling EJ
Published: November 2004

Young subterranean clover plants were raised at several levels of nitrogen supply, and then transferred to complete solutions and to solutions without nitrogen Subsequent leaf area response patterns were not related to the supply of combined nitrogen before transfer. The relative differences m leaf area between the two solutions were thought to depend on differences In nodulation caused by differences In the supply of combined nitrogen before transfer. Further experiments showed that the rates of leaf area Increase of inoculated and well-nodulated plants In solutions without nitrogen were similar to those of corresponding plants receiving combined nitrogen Plants that had not been inoculated showed markedly smaller leaf growth rates after transfer to solutions without nitrogen than in complete solutions Even when the previous supply of combined nitrogen had been adequate, plants transferred to solutions without nitrogen were unable to maintain leaf area Increases at rates comparable with those of the corresponding plants in complete solutions for more than 3 days. Reasons for the marked differences between these results and those of experiments with phosphorus, sulphur, potassium, and boron are discussed
Population suppression in the Queensland fruit fly, Dacus (Strumeta) Tryoni. I. The effects of male depletion in a semi-isolated population
Authors: Bateman MA , Friend AH , Hampshire F
Published: November 2004

An experiment designed to assess the usefulness of a male attractant, 4-(p-acetoxypheny1)butan-2-one, for the control of relatively isolated populations of the Queensland fruit fly, is described. Traps baited with the lure and an insecticide were distributed at fairly high density throughout a small town and its immediate surroundings, while a similar town nearby was left untreated for purposes of comparison. The numbers of males killed each week in the treated town were estimated, and in both towns regular measurements were made of: (i) ratios of males to females; (ii) rates of insemination of mature females; and (iii) rates of infestation of fruit. The results show that there was a clear effect of the treatment in the early part of the season, but that this diminished as the season progressed until finally there was little difference between the populations. We conclude that this male attractant, used alone, is unlikely to provide effective control of the Queensland fruit fly, except perhaps when used against thoroughly isolated populations. It may, however, be more useful if used in combination with other methods which provide some protection against inseminated females.
The flowering responses of crop and pasture species in Australia I. Factors affecting development in the field of Lolium species (L. rigidum Gaud., L. perenne L., L. multiflorum Lam.)
Authors: Aitken Y
Published: November 2004

Cultivars of three species of ryegrass (Lolium rigidum Gaud., L. perenne L., and L. multiflorum Lam.) were grown in the open and in the glasshouse at Melbourne (lat. 38° S.), with additional lighting and vernalization when required. They were sown at different times through the year and were compared for times of flower initiation and heading and for leaf numbers to heading. They included two early cultivars (Wimmera, Kangaroo Valley), four mid-season ones (Victorian, Grasslands Ruanui, Tasmanian No. 1, Grasslands Paroa), and one late one (S.23) from England. For all cultivars studied, some cold was required for flower initiation, while long days hastened it somewhat; development between initiation and heading was hastened by both warmth and long days. The early group with a small cold requirement initiated in winter and spring and headed in spring and summer. The mid-season group with a larger cold requirement initiated only in spring, and headed in mid spring to early summer. The late cultivar headed scantily or not at all, the winter temperature being too high for initiation.
Nutrient potential and capacity. II. Relationship between potassium potential and buffering capacity and the supply of potassium to plants
Authors: Barrow NJ
Published: November 2004

The potassium status of 22 soils with low reserves of non-exchangeable potassium was assessed by measuring: (a) the potassium potential (the free energy of exchange of potassium for calcium plus magnesium); (b) the soil's capacity to resist a change in potential ("buffering capacity"); (c) the amount of exchangeable potassium and its percentage saturation. The ability of these measures to predict the supply of potassium was tested by growing subterranean clover (Trifolium subterraneum L.) in pots and determining its potassium content at successive harvests. The soil's buffering capacity was found to affect the supply of potassium even when uptake was small. It is suggested that this was partly because buffering capacity affects the rate of supply by diffusion to plant roots. As the uptake of potassium became progressively larger, the potential became increasingly unsuitable as a single index of availability, but a multiple regression containing terms for potential and for buffering capacity continued to account for a large proportion (89%) of the variation. The relationship obtained can be used to indicate the amount of potassium required to bring a deficient soil to a desirable status.
Fertilization and early embryonic losses in ewes that had grazed oestrogenic pastures for 6 years
Authors: Turnbull KE , Braden AWH , George JM
Published: November 2004

Ewes that had grazed native, improved, or red clover pastures over 6 years were slaughtered 1–2 days, 30 days, or 60 days post coitum (pc.). Their reproductive tracts were examined for the distribution of spermatozoa, for the presence of fertilized eggs or embryos, and for cystic endometrial hyperplasia (C.E.). The severity of the C.E. was significantly greater in ewes grazed on red clover (P < 0.02), but there was no significant difference between the ewes that had grazed the native or the improved pastures. Fewer of the ewes with > 10 cysts in the cervix had sperm in the fallopian tubes, as compared with ewes that had < 10 cysts (P < 0.005). Of the ewes with > 10 cysts in the cervix, or in the uterus, a smaller proportion were pregnant 30 days p.c. than in ewes with < 10 cysts (P < 0.005). Increasing the number of services per ewe resulted in an increased proportion of ewes in which sperm were found in the tubes, and in an increased proportion of the eggs being fertilized. The major cause of the infertility in ewes that have grazed oestrogenic pastures over long periods appears to be non-fertilization due to absence of sperm from the fallopian tubes. Death of embryos in the first 60 days p.c. also appears to contribute to the low fertility in ewes with C.E.
The components of variation in an intervarietal cross in Leucaena leucocephala (Lam.) de wit
Authors: Gray SG
Published: November 2004

An intervarietal cross in Leucaena leucocephala between the contrasting varieties Bald Hills and Guatemala was studied in an experiment incorporating .the two parental varieties, an F2 population, and 37 F3 families. Characters examined were length of main stem and stem number. Phenotypic variances for the F2 population were low in relation to the estimated non-genetic variance. In length of main stem 3 months after planting, genetic variance accounted for 21.9% of the total variance, and partition of variation showed the presence of strong non-genetic and additive genetic components, and absence of any non-additive genetic component. In length of main stem at the end of the season and in stem number, no genetic variance could be demonstrated. Polysomic inheritance is suggested as an explanation of this restricted segregation. Differences between F3 family means were highly significant in each of the characters measured. Length of main stem and stem number were highly correlated (r = 0.5 and 0.7), which suggests that these characters are not inherited independently but are both related to plant vigour. Applications to plant breeding are discussed.
Seasonal evapotranspiration of irrigated cotton in a low-latitude environment
Authors: Stern WR
Published: November 2004

Evapotranspiration (Et) from irrigated cotton was determined on a sequence of plantings covering a whole year. Averaged over the year, evapotranspiration directly after irrigation (Et1) was greater than the Penman estimate of potential evaporation (E) but less than the evaporation from a standard Australian tank (Etank). The mean annual ratios were 1.2 for Et1/E and 0.9 for Et1/Etank. The rate of evapotranspiration was a function of soil moisture, declining rapidly as the available moisture fell below 60 %. Because of the high variability in the estimates of evapotranspiration it was not possible to evaluate precisely the influence of growth stage on evapotranspiration. Although there was evidence that evapotranspiration varied with the stage of growth, meteorological factors were a dominant influence because of the high watering regime. Overall, a crop planted in the wet season used little more water than a crop planted in the dry season. After the maximum leaf area index (LAI) had been reached, evapotranspiration in the wet season crop declined more rapidly and fell to a lower value than evapotranspiration during the corresponding period in the dry season crop. Water was used more efficiently by the wet season crop than by the dry season crop. The conclusion was reached that in this environment advection of energy persisted for most of the year, and that during periods of rapid height increases, particularly when ground cover was incomplete, crop surface roughness enhanced evapotranspiration. The possible interactions of some of the factors influencing evapotranspiration in a crop in the field are discussed.
Nitrogen Metabolism During Storage in Relation to the Breakdown of Apples. I. Changes in protein nitrogen level in relation to incidence
Authors: Martin D , Lewis TL , Cern y
Published: November 2004

Protein nitrogen content was followed in fruits of four apple varieties during cool storage under conditions designed to induce different rates of water loss. Increase in protein nitrogen content during cool storage did not appear to be related to the development of breakdown. High nitrogen level in the fruit, high relative humidity in the storage atmosphere, and advanced maturity at harvest all increased susceptibility to breakdown, but only the first of these factors influenced the protein nitrogen level. An inverse relationship between percentage water loss and breakdown incidence was demonstrated.
Studies on the diet of the grazing animal. II. The effect of physiological status in ewes and pasture availability on herbage intake
Authors: Arnold GW , Dudzinski ML
Published: November 2004

The digestible organic matter intake (DOMI) of ewes grazing Phalaris tuberosa–Trifolium subterraneum pastures was studied under controlled conditions. The variables studied were pasture conditions, breed, and physiological status of the ewe. The DOMI's of dry, pregnant, and lactating ewes were significantly related, in asymptotic form, to pasture conditions. About 40% of the variability in DOMI was accounted for by the total dry matter available per acre. Further variability was taken out by multiple regression in which diet digestibility, green pasture dry matter per acre, and leaf length were used. Regression models were similar for dry, pregnant, and lactating ewes. Dry and pregnant ewes within both breeds (2-year-old Border Leicester x Merino and 5-year-old Corriedale ewes) had similar DOMI's. The DOMI of lactating ewes was significantly higher than that of dry ewes within both breeds. The increase at the mean maximum intake was 50% for Border Leicester x Merino ewes and 25% for Corriedale ewes. The relative increase was greater at lower pasture yields and shorter leaf lengths. Intakes of Border Leicester x Merino ewes were substantially higher than those of Corriedale ewes although the ewes of both breeds were of similar weight. Reasons for this difference and the difference in lactation response on intake are discussed. Differences in grazing time and rate of eating were found between breeds and between ewes of different physiological status within breeds. The need for more detailed knowledge of grazing behaviour before these differences can be correctly interpreted is stressed.
Phytotoxicity from plant residues. I. The influence of rotted wheat straw on seedling growth
Authors: Kimber RWL
Published: November 2004

Cold aqueous extracts of wheat straw, that had been rotted for periods up to 6 weeks, have been shown to inhibit the growth of wheat and oats grown under aseptic conditions. The degree of inhibition varied with the time of rotting and was at a maximum after 2–6 days. Roots were far more sensitive than shoots to inhibitors. Wheat shoots were inhibited more than oat shoots, but oat roots were inhibited more than wheat roots. Prolonged storage of straw or weathering of wheat stubble in the field reduced this inhibitory effect
The fate of labelled mineral nitrogen after addition to three pasture soils of different organic matter contents
Authors: Simpson JR , Freney JR
Published: November 2004

Ammonium and nitrate labelled with 15N were added separately to three soils representing different stages of organic matter accumulation under pasture. The fate of the labelled nitrogen was determined after 6 weeks, and again after a further 29 weeks in the presence and absence of ryegrass plants. Recoveries of the labelled nitrogen within the soil–plant system were high (90–l00%), except where nitrate was added to the high-nitrogen soil (69%). The labelled ammonium was immobilized rapidly, particularly in the low-nitrogen soil, but nitrate reacted with the soils much more slowly. Thus recovery of labelled nitrate nitrogen by the plants was generally greater than that of ammonium. However, the total mineral nitrogen (labelled and indigenous) in unplanted soils and the total plant uptake of nitrogen were not appreciably affected by the chemical form of the added nitrogen. This suggested that an isotopic exchange reaction had occurred between the labelled mineral nitrogen and indigenous organic nitrogen. The greatest increase in total nitrogen uptake by the plants after addition of nitrogen (i.e. the apparent fertilizer efficiency of the added nitrogen) occurred in the low-nitrogen soil (85% and 81% recovery for ammonium and nitrate respectively). The highest recovery of labelled nitrogen by the plants occurred where nitrate was added to the low- and intermediate-nitrogen soils (both 80%). The indigenous organic nitrogen of the three soils was distributed between four fractions in similar patterns. The labelled nitrogen was incorporated into each of these organic fractions, but there was a tendency for greater amounts to remain in the non-distillable acid-soluble fraction.
Free and conjugated isoflavones in the plasma of sheep following ingestion of oestrogenic clover
Authors: Shutt DA , Axelsen A , Lindner HR
Published: November 2004

The plasma of sheep grazing various species of oestrogenic clover contained water-soluble conjugates of daidzein, formononetin, genistein, and biochanin A, chiefly in the form of glucuronides, in concentrations up to 40 µg/100 ml. In sheep pen-fed on red clover or subterranean clover (cv. Dinninup and Yarloop) the total concentration of these four isoflavones 3–5 hr after feeding ranged from 150 to 720 µg/100 ml plasma, of which 1–2% only was present in "free" (i.e. unconjugated) form; by 24 hr the plasma level had fallen to < 5 µg/100 ml plasma. Preconditioning the pen-fed sheep to oestrogenic clover, or adding lucerne to the diet, had no significant effect on the concentration of "free" or conjugated isoflavones in the plasma and had no inhibitory effect on the uterine weight response. Comparison of the composition of circulating isoflavones to that of the clover ingested indicated partial demethylation of formononetin to daidzein and of biochanin A to genistein, and suggested that genistein and biochanin A were degraded more rapidly than formononetin or daidzein in the sheep. Equol, a metabolite previously isolated from the urine of sheep treated with formononetin, was present in the plasma at a concentration of 50–170 µg/100 ml 24 hr after feeding.
Varietal and environmental variations in isoflavone concentrations in subterranean clover (Trifolium subterraneum L.)
Authors: Morley FHW , Francis CM
Published: November 2004

The concentrations of formononetin, genistein, and biochanin A in leaves of 151 lines belonging to three subspecies of T. subterraneum L. and of 8 lines of T. israeliticum D. Zoh. & Katzn, were measured from plants grown in the field at Perth and Canberra, and in a glasshouse at Perth. The average concentrations did not differ significantly between locations, but did between sampling dates. The components of variance were greater for subspecies, and for varieties within subspecies, than for environmental variables other than error. Interactions were negligible, although some were greater than zero. The component correlations between concentrations of different isoflavones were generally positive where determined by environment, but tended to be negative where determined by genotype, especially that between genistein and biochanin A. Differences among subspecies In level and pattern of isoflavone concentration could be of limited value for taxonomic classification. Differences among varieties within subspecies are sufficient to promise progress in selection for low levels of individual isoflavones by conventional techniques of plant breeding. Selection for low levels of total isoflavones would be hindered, but not prevented, by the negative genotypic correlations between concentrations of genistein and biochanin A.
Factors limiting the intake of feed by sheep. III. The mean retention time of feed particles in sections of the alimentary tract
Authors: Weston RH
Published: November 2004

The mean retention time of feed particles in the alimentary tract of sheep was measured by means of a stained-particle technique, when lucerne hay or a diet of wheaten straw + wheaten hay (1 : 1) was offered ad libitum. The levels of intake of the straw diet and lucerne hay were equivalent to 11.8 and 25.8 g organic matter/day/kg body weight. The mean retention time of particles in the entire alimentary tract when the straw diet was offered was 57.5 hr, this consisting of 36.3 hr in the rumen + omasum and 21.2 hr in the abomasum + intestines. The retention time in the rumen + omasum was calculated to consist of (a) 19.7 hr during which the particles were being degraded to a size at which transfer from the rumen could be readily effected, and (b) 16.6 hr of residence in the rumen + omasum as small particles. With lucerne hay, the retention times were shorter: small particles spent 10.8 hr in the rumen + omasum and retention time in the abomasum + intestines was 16.1 hr. It was calculated that only a small proportion of the difference between the straw diet and lucerne hay in organic matter intake could be attributable to differences between the diets in the rate of removal of finely divided particles of organic matter from the rumen.
Variation in the yield and composition of milk of grazing Merino sheep
Authors: Corbett JL
Published: November 2004

A technique for estimating the yield and composition of milk produced by grazing ewes is described. Ewes were milked by machine, after the intravenous injection of 3 i.u. posterior pituitary extract, at the rate of 20 to 30/hr, and then returned to pasture with their lambs which were prevented from sucking by covering the udders. Approximately 4 hr later the ewes were milked again; the yield over the known time interval was recorded and sampled for analysis. There was no significant variation in the yield, or fat and protein contents, or the milk obtained over six different 4 hr periods in a day. It was concluded that the technique gave reliable estimates of the rate of secretion and that these could be converted directly to estimates of yield per day of milk and its constituents. Such estimates, if made once or twice weekly, would also be likely to give reliable data on the course of lactation, which would be determined primarily by the mutual behaviour, largely undisturbed, of ewe and lamb. The lactations of 50 fine-wool Merino ewes grazing improved pastures that provided abundant feed were recorded. For the majority of ewes, daily yield increased until a mean maximum of 1400–1600 g/day was attained at 3 weeks post partum, and then declined at the rate of 15–20 g/day for 6 to 8 weeks. The total yield over 10 weeks was about 80 kg and at 14 weeks was 90–100 kg; half or more of these amounts had been produced by the end of the fifth week. Fat and protein contents declined in the early weeks of lactation and then rose so that the highest values were observed at the end of lactation. Lactose contents showed the opposite trend.
The influence of maternal handicap, inbreeding, and ewe's body weight at 15–16 months of age on reproduction rate in Australian Merinos
Authors: Lax J , Brown GH
Published: November 2004

The influence on number of lambs born per ewe joined of the ewe's age, type of birth, body weight at 15–16 months, and inbreeding level, and the inbreeding of the foetus, has been investigated in a flock of medium Peppin Merinos run at Cunnamulla, Queensland. The influence on survival rate to weaning of these variables (except dam's birth type), plus gestation and lamb's birth weight, has been examined for single-born lambs. Age of ewe had a marked influence on the number of lambs born, but not on survival rate. Number of lambs born increased with age of ewe and then declined. Ewes born in multiple births produced 4.0 more lambs per 100 ewes joined than those born as singles. The ewe's body weight at 15–16 months had a marked influence on the number of lambs born and a small influence on the survival rate, but the effect was linear throughout the range with no evidence for a "critical" weight. Each 10 lb increase in body weight produced 8 more lambs born per 100 ewes joined, whilst survival rate increased by 5 per 100 lambs born for rams and 2 for ewes. Inbreeding had a marked deleterious effect on reproduction rate. Inbreeding of the dam was nine times as important as the inbreeding of the foetus on the number of lambs born. This effect was reversed for survival rate. Survival rate showed a curvilinear relationship with both birth weight and gestation period, the greatest survival rate occurring at or slightly above the mean birth weight, but the birth weight effect was highly significant while that for gestation period was not. The effect of high birth weight was not as marked as that for low birth weight in reducing survival.
Nutrient cycling in grazed pastures. I. A preliminary investigation of the use of [35S] in gypsum.
Authors: May PF , Till AR , Downes AM
Published: November 2004

[35S]Gypsum was applied to six strips covering a total of approximately 1/32 of the area of a pasture grazed by sheep. The specific activity of samples of soil, plants, ingesta, faeces, and wool was measured. The results were as would be expected from uniform labelling of the whole paddock, and enabled translocation to untreated areas to be measured. They indicate that doses of the order of 1–10 mc should be detectable on paddocks up to 4 ha in area for periods of up to 1 year. When animals were put onto or removed from the treated pastures, changes in the specific activity of wool indicated that 100–150 days were required for the sulphur in the sheep and pasture to reach equilibrium. Animals continuously maintained on the pasture were still producing wool at 60% of the maximal specific activity after 600 days, which indicated a continuing recycling of the applied sulphur. From calculation of the isotope dilution it appears that only a small fraction of the total soil sulphur was available for plant uptake, and the continuing cycling of this over a period exceeding 600 days indicates a high residual value of the initial application.
Studies on salt tolerance of sheep. VIII. The tolerance of grazing ewes and their lambs for drinking waters of the types obtained from underground sources in Australia
Authors: Peirce AW
Published: November 2004

Groups of 50–60 ewes grazing sown pastures near Adelaide, S.A., were offered various solutions as drinking waters. In two experiments these comprised: (1) reservoir water (control group); (2) synthetic water containing salts in the proportions found in many underground waters in South and Western Australia ("chloride water") with a total salt concentration of 1.30%; (3) synthetic water resembling the waters obtained in Queensland from the Great Artesian Basin ('bicarbonate water') with a total salt concentration of 0.50%. In a third experiment one group received reservoir water and another group received a chloride water containing I .00% total salts. The ewes were mated, they lambed, and they reared their lambs in the paddocks while receiving the various waters. In at least one experiment, pregnant ewes, lactating ewes, and weaned lambs received the saline waters during the months of high environmental temperatures, with associated high water intakes. The chloride water with a total salt concentration of 1.30% led to a reduction in the percentage of ewes that lambed in one experiment, but not in the other. It also led to decreased body weight gains of the lambs in both experiments, and in addition to diarrhoea and increased mortality in one experiment. Chloride water with 1.00% total salts led to decreased body weight gains and reduced wool production, without apparently adversely affecting the health of the lambs. Bicarbonate water with a total salt content of 0.50% had no adverse effect on the lambs in either experiment, but in one of these experiments it did lead to a reduction in the percentage of ewes that lambed. The implications of the findings in relation to the use of saline drinking waters under field conditions are discussed.
Ecological studies of the cattle tick, Boophilus microplus, in the north coast district of New South Wales
Authors: McCulloch RN , Lewis IJ
Published: November 2004

During the years 1962–1965, engorged female ticks (Boophilus microplus (Canestrini)) were exposed at frequent intervals at diverse sites in northern New South Wales, and egg laying, egg development, and the survival of larval populations observed and recorded. Ticks were also exposed in Stevenson screens (in humidified containers), where temperature could be measured. From the results the following conclusions are drawn: (1) The maximum longevity of the non-parasitic stages of the cattle tick in Australia would be 7½ months. An earlier record placing the figure at 10½ months is shown almost certainly to be erroneous. The great majority of larvae die within 6 months of the parent leaving its host. (2) In the warmer parts of the Tick Quarantine Area ticks falling in favourable situations may lay viable eggs in any month. Thus winter checks development but does not prevent it. The tick population is at its lowest level in September. (3) The cattle tick could probably survive as a pest as far south as Newcastle. (4) The time of year for the start of an eradication campaign would not be of first importance. For a programme of strategic dipping aiming at economical control, the optimum time for beginning would be early October in the areas most favourable to the tick.
Stipple streak disease of French bean caused by a tobacco necrosis virus in Queensland
Authors: Behncken GM
Published: November 2004

A disease of beans in the Nambour district of Queensland has been shown to be stipple streak disease caused by a tobacco necrosis virus. Symptoms include leaf vein necrosis, stem necrosis, and occasionally necrotic lesions on the pods. In glasshouse tests symptoms developed more rapidly, and were more severe, at temperatures of 80–88°F than at 62–70°. The virus was readily transmitted by zoospores of a lettuce isolate of the fungus Olpidium brassicae (Wor.) Dang. Serological evidence is presented which indicates that the virus is an "A" serotype strain of tobacco necrosis virus. No evidence for the presence of an associated satellite virus was found.
Ecological studies of root-nodule bacteria introduced into field environments. I. A survey of field performance of clover inoculants by gel immune diffusion serology
Authors: Dudman WF , Brockwell J
Published: November 2004

A gel immune diffusion procedure for identifying strains of rhizobia has been used to follow the persistence of two strains of Rhizobium trifolii introduced simultaneously into soil by clover seed inoculation. Isolations of rhizobia were obtained from nodulated clover at intervals between 3 and 42 months after sowing. Of 456 isolates examined, 53.3% were recognized as inoculum strains but one strain, TA1, was recovered more than 11 times as frequently as the other, UNZ29. At one place, the inoculum was recovered 30 months after sowing but at another it had disappeared after 18 months. There was a significant trend for the proportion of recoverable inoculum strains to diminish with Iapse of time between sowing and isolation. Even in places where natural populations of Rh. Trifolii were small or undetectable, there was no evidence to suggest that the strains introduced as seed inoculant were likely to become permanently established as a large proportion of the nodule bacteria in the soil.
Ecological studies of root-nodule bacteria introduced into field environments. II. Initial competition between seed inocula in the nodulation of Trifolium subterraneum L. seedlings
Authors: Brockwell J , Dudman WF
Published: November 2004

The ability of three strains of Rhizobium trifolii used in legume inoculants to form nodules on inoculated Trifolium subterraneum L. was examined in field experiments on a soil containing a large natural population of clover rhizobia. The identity of cultures isolated from nodules on young seedlings was established by a gel immune diffusion technique. When a mixture of broth and peat inocula was applied to seed, a large proportion of nodules was attributable to peat-borne rhizobia. In competition with the natural population in the production of nodules on the roots of the host legume, strain WA67 = TA1 > UNZ29. In competition with each other as well as with the naturally occurring rhizobia, WA67 > TAI > UNZ29. The significance of the findings in relation to the persistence in soil of Rhizobium strains applied as inoculant to clover seed is discussed.
Reproduction in Heteropogon contortus. I. Photoperiodic effects on flowering and sex expression
Authors: Tothill JC , Knox RB
Published: November 2004

The flowering behaviour of selected Australian and African populations of Heteropogon contortus in response to a range of photoperiods was assessed in the Canberra phytotron (CERES) under a 30/25°C day/night temperature regime. Photoperiods comprised 8 hr of natural light supplemented with low intensity incandescent illumination to give a range between 10 and 18 hr in each photocycle. The patterns of response showed H. contortus to be a short-day plant. Lines from both Australian and African populations originating from lower latitudes, and late-flowering when grown in a grass garden, flowered only in photoperiods shorter than 12 hr, remaining vegetative at longer day lengths. These were qualitative short-day plants. In contrast, the early-flowering lines showed either a qualitative or a quantitative short-day response; the latter flowered in all photoperiods but more rapidly at shorter day lengths. The nature of the early- and late-flowering behaviour is explained on the basis of the short-day responses and climatic adaptation. Since the inflorescences are polygamous, a sex ratio was calculated for all inflorescences formed by using the ratio of number of male+male spikelet pairs v. the number of female+male spikelet pairs. Increasing the photoperiod resulted in inflorescences containing more male spikelets and fewer awned female spikelets. From this it appears that day length exerts some influence over the determination of sex, and thus of seed production, in H. contortus. Versatility of this kind may well have adaptive significance depending on the breeding system in that it can partially control population heterogeneity and thus be of phytogeographic significance.
A study of Merino sheep grazing a cotton-bush (Kochia aphylla)–grassland (Stipa variabilis–Danthonia caespitosa) community on the riverine plain
Authors: Leigh JH , Wilson AD , Mulham WE
Published: November 2004

A study was made of Merino sheep continuously grazing a cotton-bush (Kochia aphylla R.Br.)–grassland (Stipa variabilis Hughes–Danthonia caespitosa Gaudich.) community over a 2 year period. Observations were carried out at two stocking rates (0.75 and 0.375 sheeplacre) and comparisons were made with plots from which K. aphylla had been mechanically removed. The aim of the study was to define the contribution made by K. aphylla (a drought-resistant chenopodiaceous shrub) to animal production and to examine the effects of the seasonal variation in composition, availability, and food value of the pasture on animal behaviour and performance. At the low rate of stocking K. aphylla contributed little to the diet of the sheep (max. 2% in autumn) despite its being at no time less than 20% of the forage available. At the high stocking rate its maximum contribution to the diet was 7% in late autumn. The major constituents of the diet in spring were the annuals Hedypnois rhagadioloides (L.) Willd. and Hypochoeris spp. and in summer the perennials Danthonia caespitosa and Kochia pentagona R.H. Anderson. D. caespitosa was also the main component during autumn at the low stocking rate but at the high stocking rate it was replaced in the diet by a high proportion of dead matter and Medicago burr. Seasonal variations in wool growth were greater at the high stocking rate than at the low rate, the lowest production occurring in autumn. Body weight and wool growth were not significantly altered by the presence of K. aphylla at either of the stocking rates. The lowest recorded value for dietary crude protein was 8.8%. Wool growth was closely related to the in vitro digestibility of the forage eaten and to the availability of green feed within the pasture.
Dormancy in seeds of Avena ludoviciana and A. fatua
Authors: Quail PH , Carter OG
Published: November 2004

Seeds of Avena ludoviciana after-ripened more rapidly with increasing temperatures up to 30°C and with increasing relative humidities between 16 and 100%. In continuous light, these seeds after-ripened more rapidly than in the dark. Seeds of different species and strains of wild oats after-ripened at different rates; primary seeds after-ripened more rapidly than secondary. One week after anthesis 60% of the viable primary seeds of A. ludoviciana were dormant, compared with 100% at maturity. The importance of these findings to studies on the physiology of dormancy and to the control of wild oats in the field is discussed.
Some effects of water restriction on nitrogen metabolism of cattle
Authors: Thornton RF , Yates NG
Published: November 2004

Water restriction was found to decrease nitrogen retention in cattle when compared with periods of similar digestible energy intake but unrestricted water intake. The decreased nitrogen retention was associated with increases in both faecal nitrogen output and urinary urea excretion. The rise in urinary urea nitrogen excretion appeared to be mediated through increased plasma urea nitrogen concentration.
Flowering in tobacco: The course of floral induction under controlled conditions and in the field
Authors: Hopkinson JM , Hannam RV
Published: November 2004

Experiments were done with the objective of describing floral induction in tobacco. A short-day mutant, grown in controlled-environment cabinets, was used to define the stages of development, and the results were used to interpret the behaviour of both short-day and day-neutral plants grown in the field. The shoot apex passed through an apparent juvenile phase, characterized by a progressive increase in its size. Next, in the absence of floral induction it entered an equilibrium stage during which its size, staining properties, and activity remained constant. After 10 inductive cycles, apices of short-day plants became committed to flower. The rate of leaf inception increased, the apical meristem became domed, and the region of intense pyronin staining (indicative of RNA) spread to the central zone. Differentiation of the inflorescence followed, and the terminal flower was recognizable about 20 days after the start of induction. The apices of field plants remained juvenile for very much longer than did apices of cabinet-grown plants, and floral induction did not take effect until after recovery from transplanting. Apices of day-neutral plants then passed directly to the induced state, whilst those of the mutant remained indefinitely vegetative in the equilibrium stage, natural day lengths at the time being non-inductive. The protracted juvenility of field plants was attributed to the stresses of seed-bed conditions and transplanting damage.
Developmental growth and body weight loss of cattle. V. Changes in the alimentary tract
Authors: Carnegie AB , Tulloh NM , Seebeck RM
Published: November 2004

This paper describes an investigation of the effects of developmental growth and body weight loss on the alimentary tract of Angus steers. Two groups of steers were used: group A which grew continuously, and group B which grew like group A and were then subjected to a period of weight loss before slaughter. Corresponding animals in both groups were killed at the same body weights. Group A animals (and group B animals before the commencement of weight loss) were fed on a high quality ration ad libitum. During their period of weight loss the group B animals were given a restricted intake of oaten straw. Statistical analysis was by analysis of covariance of the weights of components converted to logarithms. As empty body weight (EBW) increased, the weight of the empty, fat-trimmed alimentary tract (GT), the weight of each component of GT (oesophagus, rumenreticulum, omasum, abomasum, small intestine, caecum, colon-rectum), and the weight of contents in each component of GT decreased as proportions of EBW. Apart from the oesophagus and the caecum, GT and each of its components did not change significantly in weight as the live body weight of the animals increased from 250 to 400 kg. Thus, developmental growth of the alimentary tract had almost finished when the experiment began. The effect of weight loss on the components of the alimentary tract was independent of EBW except for weight of the rumen-reticulum. This component lost weight in all animals but the loss was relatively smaller in the heavier animals than in the lighter ones. When group A and group B animals were compared at the same EBW, the weight of GT in group B animals was significantly less than in the group A animals. However, the components of GT did not all behave in the same way. Thus the weight of the oesophagus was greater, weights of the abomasum and small intestine were less, and weights of the omasum, caecum, and colon-rectum were not significantly changed in group B animals when compared with group A. Also, there was more digesta and its dry matter percentage was less in group B than in group A. The overall loss of weight of GT during body weight loss was an indication that GT was used as a source of protein and energy. The changes in the weights and relative proportions of the components of GT during weight loss were thought to be a reflection of the change both to a poor quality ration and to a reduced food intake.