bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic ovine hepatosis following feeding of Macrozamia reidlei nuts
Authors: Gardiner MR
Published: November 2004

The chronic liver disease caused by the nuts of Macrozamia reidlei was studied experimentally in sheep given up to 4 kg over a period of 1-11 months. Similar degrees of liver damage were produced by this amount of powdered nut whether consumed in 3 or in 11 months. The liver pathology was similar in some respects to that caused by toxic lupins where a direct relationship to copper concentration in the liver has been established. The botanical and ecological aspects of M. reidlei in relation to other plants of the order Cycadales are considered.
Response to partial selection on clean fleece weight in South Australian strong-wool Merino sheep
Authors: Mayo O , Cooper DW , Brady RE , Hooper CW
Published: November 2004

The associations between 10 production characters and fertility at the R blood group, haemoglobin, and transferrin loci have been examined in two flocks of South Australian Merino sheep. The production characters were birth weight, hogget body weight, hogget wrinkle score, greasy fleece weight, clean fleece weight, staple length, degree of crimp, fibre diameter, fleece density, and skin thickness. No evidence of any real association was found. The significant associations which were found are ascribed either to chance or to the impossibility of eliminating sire effects from the analysis.
Response to salinity in Glycine. VI. Some effects of a range of short-term salt stresses on the growth, nodulation, and nitrogen fixation of Glycine wightii (Formerly Javancia)
Authors: Wilson JR
Published: November 2004

Well-nodulated plants of Glycine wightii (formerly G. javanica) grown in sand culture were subjected to 14 days of salinity ranging from nil to 148 m-equiv. sodium chloride per litre of nutrient solution, and the response compared with that of similarly treated nitrogen-fertilized plants. The latter showed less tissue injury and a smaller reduction in growth rate at high salinity than the inoculated plants. During salinity treatment the development of new nodules, and nitrogen fixation by the existing nodules, were greatly inhibited, with a resulting marked decline in plant nitrogen concentration, especially in the laminae and nodules. Despite the severity of the salt effect on the inoculated plants, the nodules developed prior to salt treatment appeared remarkably resistant to stress, and rapidly regained pigmentation and efficiency of nitrogen fixation when the sodium chloride was removed from the culture solutions. Salt accumulation in the nodules was limited and the sensitivity of the symbiosis to salinity appeared primarily dependent on the host. These factors indicate the adaptability of the symbiosis to increases in substrate salinity.
The distribution of 14C-labelled assimilates in mature lemon trees
Authors: Kriedemann PE
Published: November 2004

The translocation of 14C assimilates within fruiting branches was examined by supplying 14CO2 to selected leaves and then collecting the respiratory CO2evolved by the importing fruit. The distribution pattern of labelled photosynthate within the tree was then established by autoradiography. Developing fruits obtained photosynthate mainly from the leaves on the same growth cycle that produced the fruit. Adjacent foliage, corresponding to the previous growth cycle, supplied 14C photosynthate to terminal fruits and to the basipetal translocation stream. Leaves on an earlier growth cycle (two cycles earlier than that of the fruits) did not supply labelled assimilates to the fruit; translocation was entirely basipetal. Similarly, lateral shoots made no photosynthetic contribution to fruits, but 14C assimilates were translocated into the root system of the tree.
The effects of plant density and frequency of cutting on the growth of cocksfoot (Dactylis glomerata L.). II. Yield in the vegetative and reproductive phases
Authors: Knight R
Published: November 2004

The effects of plant density and cutting frequency on the reproductive phase and yield in cocksfoot (Dactylis glomerata L.) were investigated. The plants of a clone were established at nine spacings that increased geometrically from 4 in. (10 cm) to 17 in. (42.5 cm) between plants to provide densities from 9 plants per sq ft to 0.5 plant per sq ft. They were cut every 2,4, or 8 weeks or cut once at the end of the growing season. Early in the season when growth was purely vegetative the highest yield per unit area was obtained with plants at high densities. Later, in some treatments, but while the plants were still vegetative, the combined effect of very frequent cutting and high density weakened the plants and the highest yields were then obtained at somewhat lower densities. When the plants first became reproductive, the highest yields per unit area were at low densities, as these plants were the earliest to become reproductive and their elongated tillers led to high yields. The optimal density for yield changed with time towards greater density as plants at these greater densities in turn became reproductive. Frequent cutting and high density reduced both the vegetative and reproductive fractions of the plant but the reduction was greater in the reproductive fraction. As high yields were associated with the reproductive fraction, the highest yields for the season were obtained from the uncut plants or from plants cut infrequently (8-week intervals).
The effect of sheep on the recycling of phosphorus in hayed-off pastures
Authors: Bromfield SM , Jones OL
Published: November 2004

The mineralization of plant organic phosphorus during digestion by sheep was examined by comparing the intake of inorganic and organic phosphorus from a range of feeds with that excreted in the dung. Up to 80% of the organic phosphorus in spring feed was mineralized but net mineralization did not occur in hayed-off summer feeds. Under field and laboratory conditions inorganic phosphorus leached slowly from intact dung pellets. Laboratory studies showed that in general a larger proportion was leached from summer samples than from either spring or autumn samples. Light crushing increased the rate of leaching in the initial stages. The unleached inorganic phosphorus was completely soluble in dilute acid and slightly soluble in water. The recovery of inorganic phosphorus indicated that mineralization of organic phosphorus had not occurred to any extent within the dung during 6 months' decomposition and leaching. Most of the organic phosphorus resisted leaching and net mineralization but a little was extracted in the first leachate. This stable organic phosphorus was soluble in sodium hydroxide but not in dilute acid. The effects of grazing on the availability of inorganic phosphorus and the accumulation of organic phosphorus in pastures are discussed in the light of these results.
Quantitative aspects of phytooestrogen metabolism in sheep fed on subterranean clover (Trifolium subterraneum cultivar clare) or red clover (Trifolium pratense)
Authors: Shutt DA , Weston RH , Hogan JP
Published: November 2004

Studies have been made of the digestion and metabolism in Merino wethers of the isoflavones in subterranean clover (Trtfolium subterraneurn cv. Clare) and red clover (T. pratense). The dietary intake of isoflavones with both clovers was about 9 g per day. With the subterranean clover, the isoflavones were predominantly genistein and biochanin A, and slight teat length increases in the wethers ingesting this clover indicated a low level of oestrogenicity. With the red clover formononetin represented 60% of the isoflavone present and the wethers on this diet exhibited maximal teat length increases indicating a high level of oestrogenicity. Less than 1 % of the daily intake of the isoflavones was excreted as such in the faeces and urine; hence most of these compounds were metabolized or retained in the sheep. The dietary isoflavones were found to disappear rapidly from the rumen, and it was estimated by using marker techniques that the removal of these compounds from the stomach (rumen, reticulum, omasum, and abomasum) was virtually complete. Equol (7,4'-dihydroxyisoflavan), a metabolite of formononetin, was the predominant phyto-oestrogen in the digesta and excreta when red clover was given. The excretion of 3.9 g/day of this compound, mainly in urine, was equivalent to 70% of the intake of formononetin. It was calculated that about 86% of the equol produced in the rumen was absorbed from that organ; the mean residence time for equol in the rumen was estimated to be 1.7 hr. The isoflavones were present in blood plasma mainly in conjugated forms. Equol predominated with both clovers. The levels of equol were much lower with the subterranean clover than with the red clover diet; the concentrations of the conjugated form were respectively 13 and 300-440 �g/100 ml. Equol in the free form, although not detectable with the subterranean clover, was present at 4-10 �g/100 ml with red clover. The data were considered to be consistent with the conclusion that equol accounts for most of the phyto-oestrogenic activity in sheep fed on clovers containing high levels of formononetin.
Fertility following synchronization of oestrus in the sheep with intravaginal sponges. III. Effects of supplementary oestrogen during treatment, duration of treatment, and number of inseminations
Authors: Robinson TJ
Published: November 2004

A factorial test is described, involving 1104 ewes, in which was studied the effects on lambing performance of (a) the inclusion of oestradiol-17G (0, 10, or 50 �g) in Cronolone-impregnated sponges, (b) two doses of Cronolone, (c) treatment for 12 or 16 days, (d) insemination on detection of oestrus or on a fixed time basis, and (e) one or two inseminations. Both dose levels of oestradiol delayed the time of onset of oestrus (P < 0.05) but did not affect its incidence. The higher dose resulted in a 7.4% reduction in the lambing percentage (P < 0.05). Dose of Cronolone (P < 0.01) and duration of insertion of sponges (P < 0.10) affected the time of onset of oestrus but did not affect the percentage of ewes which lambed. Two inseminations half a day apart increased the lambing percentage by 11 .4 %. The optimum treatment - use of sponges impregnated with 30 or 50 mg Cronolone alone (i.e. without oestrogen) followed by two inseminations of all ewes at fixed times relative to withdrawal of sponges - resulted in lambing of 61 .8 % of ewes which received such treatment. It is concluded that this is the best available estimate of the potential of this treatment when used on a large scale.
Effects of single injections of stilboestrol at various stages in the oestous cycle on behavioural oestrus and ovarian function in Romney ewes
Authors: Tervit HR , Welch RAS
Published: November 2004

Mature Romney ewes were injected with either 10, 100, or 1000 �g stilboestrol on days 5,10,14, or 15 of the oestrous cycle (oestrus = day 1) and then observed twice daily for oestrus. The day 5 ewes were subjected to a laparotomy and then slaughtered 1 day after their next natural oestrus, the day 10 ewes were slaughtered 1 day after their next oestrus, and the day 14 and 15 animals slaughtered 2 days after oestrus. None of the ewes receiving stilboestrol on days 5 or 10 ovulated in response to the administration but animals receiving the highest dose often showed induced oestrus. Injections of 1000 or 100 �g stilboestrol given on days 5 and 10 were luteolytic in the present experiment. Some ewes receiving stilboestrol on days 14 and 15 showed induced oestrus and, of the ewes not displaying an induced oestrus, most experienced longer cycles after treatment.
Comparison of three Australian Merino strains for wool and body traits. I. Genetic means of studs and strains and their interactions with years and sexes
Authors: Jackson N , Roberts EM
Published: November 2004

Samples of breeding age rams and ewes were taken from seven studs representing three strains of Australian Merino, and run in a single environment at Hay, N.S.W. Measurements taken from the ram and ewe progeny of these sheep, born at Hay in 1964 and 1965, were used for a comparative study of wool and body traits of the seven studs. The traits measured were body weight, face cover, folds, greasy fleece weight, yield, clean fleece weight, quality number, character, handle, colour, staple length, crimp frequency, fibre diameter, fibre density, two estimates of the value of wool production per head, and the value of wool production per pound. Large strain and stud within-strain effects were present for both wool and body traits. Strain x year interactions in wool values were attributed to fluctuations in the wool market. Strain x year interaction in fibre diameter reflected variation between the strains in their response to changes in environment, as did stud within-strain x year interactions in greasy fleece weight, yield. and clean fleece weight. Strain x sex interactions were interpreted in relation to a proposed new classification of interactions. The amount of migration between pairs of studs was not related to the present genetic difference between them, for any trait. Schemes for extending the present study to a large number of studs are discussed. Preliminary results of selection experiments have suggested that strains may vary in their response to equal selection pressures.
Comparison of three Australian Merino strains for wool and body traits. II. Estimates of between-stud genetic parameters
Authors: Jackson N , James JW
Published: November 2004

Data from two-tooth rams and ewes representing seven Australian Merino studs were analysed to provide estimates of between-stud genetic variances and between-stud genetic correlations for 20 wool and body traits. The estimates were used to compare two methods of choosing foundation animals for a new stud: selection within one stud or selection within each of several studs. Where only one trait was considered in selection, and provided that accurate estimates of stud mean breeding values were available, selection from a single stud was superior, although there were some differences between traits in the degree of superiority. Where more than one trait was considered the conclusion depended on the relative magnitudes and signs of the between and within-stud genetic and phenotypic correlations. In the particular case of selection for high clean fleece weight and fine fibre diameter, a strong unfavourable between-stud genetic correlation shifted the emphasis more toward selection from several studs, but selection from a single stud was still superior when accurate estimates of stud mean breeding values for clean fleece weight were available. When response to subsequent selection, as well as immediate gain in choice of founders, was considered, the conclusions were reversed. For a single trait, selection from several studs was always superior in the long term (three or more generations), and also in the short term when accurate estimates of stud mean breeding values were not available.
Effects of nitrogen, copper, and zinc fertilizers on the copper and zinc nutrition of wheat plants
Authors: Chaudhry FM , Loneragan JF
Published: November 2004

The effects of nitrogen, copper, and zinc fertilizers on dry matter yields and on copper and zinc absorption and distribution were studied in Gabo wheat plants grown in pots of an acid loamy sand from Badgingarra, Western Australia. Plants were harvested three times during vegetative growth and at maturity. Copper and zinc fertilizers had no effect on vegetative or grain yields unless nitrogen fertilizer was also added. Nitrogen fertilizer overcame symptoms of severe nitrogen deficiency and increased growth five- to eightfold. Nitrogen induced slight symptoms of copper deficiency and of zinc deficiency after 80 days' growth and induced severe symptoms of copper deficiency at maturity. Nitrogen severely depressed the concentrations of copper and zinc in plant tops and roots by diluting the absorbed copper and zinc: two effects of nitrogen on growth contributed to dilution of copper and zinc - a large increase in total growth and a marked increase in top relative to root growth. Deficiencies of copper and of zinc each depressed vegetative growth and delayed maturity: at maturity, each deficiency enhanced straw yields and depressed grain yields. Copper deficiency was aggravated by zinc sulphate, which depressed copper concentrations of tops and roots. Zinc depressed copper concentrations mainly by depressing copper absorption: it depressed the amount of copper absorbed, depressed the rate of copper absorption per gram root in early growth, and had no effect on the distribution of copper between roots and tops. The combined effects of zinc and nitrogen fertilizers induced such severe copper deficiency at maturity that they almost eliminated grain yield. Zinc deficiency was aggravated by copper sulphate, which depressed zinc concentrations of tops and roots. Copper depressed zinc concentrations in plants partly by increasing growth but primarily by depressing zinc absorption: copper depressed the amount of zinc absorbed, depressed the rate of zinc absorption per gram root in early growth, and had no effect on the distribution of zinc between roots and tops. It is suggested that nitrogen fertilizer could induce copper and zinc deficiencies in cereal crops growing on soils with marginal copper or zinc supplies. Zinc fertilizers would aggravate the effect of nitrogen on copper deficiency, and copper fertilizers would aggravate the effect of nitrogen on zinc deficiency.
Quantitative responses of wheat to photoperiod and temperature in the field
Authors: Marcellos H , Single WV
Published: November 2004

The developmental behaviour of 10 spring wheats and one winter wheat was studied under field conditions in terms of the responses of ear initiation and ear peep to photoperiod and temperature. Mean daily temperatures and photoperiods in the field varied within the ranges 5-25�C and 11-15 hr respectively during the course of the experiment. Serial sowings between March and September, and the use of low intensity supplemental illumination provided additional variation in the field environment. There were no marked alterations in phenological patterns of development among spring wheats with later sowing. Rather there was a gradual alteration in the durations of pre-initiation and post-initiation phases, resulting in an overall reduction in the duration of development. Furthermore, the relative maturities of the cultivars generally remained the same over all sowing dates. The length of the ear initiation to ear peep phase was strongly dependent on the timing of ear initiation. The phenological data obtained for Australian wheat varieties showed that if marked alteration in the pattern of phasic development was to be effected in new cultivars, stronger control mechanisms over ear initiation and speed in completing post-initiation phases must be sought. The durations of pre-initiation and post-initiation phases were highly correlated with photoperiod and temperature. Coefficients of multiple determination for the duration of the pre-initiation phase varied between 80 and 90 % for vernalized plants of the spring cultivars and between 59 and 80% for unvernalized plants. Coefficients of determination for the ear initiation to ear peep phase ranged between 90.4 and 97.5 %.
Epidemiology of leaf scald of barley
Authors: Ayesu-Offei EN , Carter MV
Published: November 2004

Studies on the spread of leaf scald of barley from an infection focus showed that infected straw was the source of primary inoculum. The disease progressed mainly between adjacent plants but pockets of infection appeared in the crop at isolated positions several metres away from the source of inoculum. Sporulation occurred when free water was available and the conidia were trapped simultaneously with rainfall or irrigation. Some conidia were caught under windy but rainless conditions. Conidia were trapped at any time of day or night but few were obtained at any one time.
Nutrient cycling in grazed pastures.IV.The fate of sulphur-35 following its application to a small area in a grazed pasture
Authors: Till AR , May PF
Published: November 2004

Simultaneous measurements of sulphur content and specific radioactivity were made on soil fractions, two pasture species, and the fleece of grazing animals following the application of high specific radioactivity gypsum labelled with sulphur-35 (35S) to small randomly located sites in grazed pastures. The results show that the extractable soil sulphate was a precursor of plant sulphur and that the organic sulphur fractions in the soil were the source of replenishment of the extractable sulphate pool. Applied sulphur was shown to remain predominantly in the top 7.5 cm of the soil over a period of c. 600 days, and it was from this region that the plants drew their sulphur. The uptake of applied sulphur was initially different between plants of different species. These differences gradually decreased and finally disappeared as the applied sulphur became mixed into all soil sulphur fractions. A wide range of rates of mixing indicated that some fractions of the organic sulphur were recycling very slowly. Positive evidence of recycling of sulphur voided by the animals on the unlabelled areas of the pasture was found, and the rate of translocation of sulphur from the sites of its application to the remainder of the paddock was measured at two rates of stocking.
The effects of continuous intravenous and intraruminal infusions of urea on nitrogen metabolism in sheep
Authors: McIntyre KH
Published: November 2004

Urea was infused into sheep both intravenously and intraruminally, and at several increasing rates. The infusions were continuous for at least 6 days for each quantity of urea infused. Three predominantly roughage rations were used. Two of these had the same roughage constituents; both had relatively low protein contents, but one contained starch. The amount of urea nitrogen retained in the body from the urea infused was greatest on the ration containing starch, when the nitrogen balance improved by as much as 4.3 g/day. The concentration of ammonia in the rumen increased linearly with the amount of urea infused by either route of administration, but was much higher in the sheep infused intraruminally. Plasma urea nitrogen concentrations increased linearly with each quantity of urea infused until they reached about 30 mg/100 ml. They increased above this concentration only in the sheep fed on the low protein roughage ration without starch. The results suggest that a renal mechanism for urea excretion may control the plasma urea nitrogen concentration at about 30 mg/100 ml under certain conditions.
Digestion by ruminant lambs of a diet containing formaldehyde-treated casein
Authors: Faichney GJ , Weston RH
Published: November 2004

Digestion of a diet containing 10% casein, either untreated or treated with formaldehyde, was studied in crossbred wether lambs. The treatment prevented breakdown of the casein in rumen liquor in vitro. There was a highly significant decrease in organic matter digestion in the rumen when the treated casein diet was given to the lambs. This was accounted for by increases in the amounts of protein and starch passing to the intestines. There was a 60 % increase in the amount of non-ammonia nitrogen and a 55 % increase in the amount of starch digested in the intestines. The concentrations of volatile fatty acids and ammonia in the rumen were significantly lower. There were increases in the plasma levels of insulin and �-amino nitrogen and a decrease in the plasma urea level in response to the treatment.
Pathogenic specialization in Fusarium graminearum
Authors: Purss GS
Published: November 2004

Isolates of Fusarium graminearum from crown rot of wheat, stalk rot of maize (both in Australia and in the United States), and head blight of wheat are all shown to be capable of causing head blight of wheat to a significant level. Stalk rot of maize is shown to be caused by isolates of F. graminearum from stalk rot of maize, crown rot of wheat, and head blight of wheat. Isolates of F. culmorum from foot rot of wheat and barley are also capable of causing stalk rot of maize. Typical crown rot of wheat is shown to be caused to a significant extent only by the isolates from this disease syndrome. The conclusion is drawn that a specialized form of F. graminearurn is responsible for crown rot in wheat.
The comparative response of tropical and temperate grasses to varying levels of nitrogen and phosphorus nutrition
Authors: Wilson JR , Haydock KP
Published: November 2004

Ten temperate and nine tropical grasses were compared in glasshouse trials in their response to a wide range of nitrogen and phosphorus nutrition. For all attributes there was a gradation in species response within the temperate and tropical groups; the means for the two groups were different although the spread of values showed some degree of overlap between the groups. In general, the temperate grasses had more tillers per plant and a lower top/root ratio than the tropical grasses. The tropical grasses grew better than the temperate grasses at low nutrient combinations but the reverse was true for the high nutrient combinations. The linear response to nitrogen of the tropical group of species was lower than that of the temperate group but was probably a consequence of the ability of the tropical grasses to grow at low nitrogen levels since the curvature in nitrogen response was similar for all species. Within both groups of grasses, the proportional response to nitrogen increased with increase in the species potential for yield. The temperate grasses accumulated nitrogen and phosphorus to higher concentrations in the plant tops, and were higher in digestibility, than the tropical grasses. Nevertheless, the tropical grasses would appear to have the potential for higher quality forage than is generally produced in field situations.
Embryo dormancy in subterranean clover seeds. II. Its value relative to impermeability in field germination regulation
Authors: Quinlivan BJ
Published: November 2004

Less than 20% of the viable seeds of three subterranean clover cultivars survived exposure to typical summer field environments in the absence of protection from embryo dormancy and impermeability. The survival rate of seeds was no higher when protected by embryo dormancy only. By contrast, when the seeds were protected by both embryo dormancy and impermeability the survival rate of viable seeds was 70% or higher. It is concluded that fully mature dry seeds of subterranean clover receive little protection from embryo dormancy during the summer, although the mechanism may well be important in preventing germination during the late seed maturation period. It is suggested that in breeding and selection programmes impermeability should receive priority as a germination-regulating mechanism.
The absorption of amino acids from the rumen of the sheep. II. The transfer of histidine, glycine, and ammonia across the rumen epithelium in vitro
Authors: Leibholz J
Published: November 2004

The transfer of L-histidine, glycine, and ammonia across the rumen epithelium of sheep was determined with in vitro preparations. The transfer of L-histidine and glycine was less than that of ammonia, but the transfer of L-histidine, glycine, and ammonia increased with increasing concentration. The transfer of L-histidine across the epithelium was unidirectional and specific for L-histidine, and was reduced by the presence of 2,4-dinitrophenol and iodoacetate and the presence of other amino acids in the test solution. Less than 5 % of the L-histidine and glycine was metabolized by the rumen epithelium. Starvation of the sheep prior to slaughter resulted in a twofold increase in the transfer of L-histidine and glycine across the rumen epithelium and no change in the transfer of ammonia.
Nychthemeral patterns of thermoregulation in high-yielding dairy cows in a hot dry near-natural climate
Authors: Berman A , Morag M
Published: November 2004

The thermoregulatory responses of Israeli Holstein cows (33 kg milk/day) were determined during 4 days at 3-hr intervals in summer and in winter in their normal environment. The mean ambient conditions in summer and winter were 31.8 and 16.8�C black globe temperature, 32 and 43 % relative humidity, and 1.6 and 1.2 mlsec wind velocity respectively. Seasonal changes in cows from winter to summer were: 0. 11�C increase in tympanic membrane temperature, 0.37 and 2.6�C increments in rectal and mean trunk skin temperatures respectively, 57 % reduction in non-evaporative heat loss, 47 % increase in sweating rate, 47 % increase in respiratory frequency, and 23 % reduction in total heat production. This indicates that the lower summer heat production is not necessarily associated with depressed milk production. Distinct nychthemeral (24 hr) cycles in vasomotor, respiratory, and sweating activity were found in both seasons. Similar maximal values were attained in both seasons. This suggests a considerable seasonal shift in thermal sensitivity. Heat-dissipating functions were activated at lower levels than in comparable climatic chamber studies. These results cast doubt on the validity of climatic chamber studies for the assessment of thermoregulatory capacity.
Effects of oestrogen on the fertility of ewes at progesterone-synchronized oestrus
Authors: Fletcher IC
Published: November 2004

Estimates were made of the endogenous oestrogen production of ewes at progesterone- synchronized oestrus. The duration of oestrous behaviour was 11.5 hr shorter at the first period of synchronized oestrus after treatment with progesterone than at the second, and it was estimated from bioassay with spayed ewes that this represented a difference in endogenous oestrogen production equivalent to 5.2 pg of oestradiol benzoate. In a subsequent field test, however, the injection of 5 �g of oestradiol benzoate at intervals of up to 4 days after progesterone withdrawal failed to improve fertility at the first oestrus after progesterone treatment.
The contribution of stem reserves to grain development in a range of wheat cultivars of different height
Authors: Rawson HM , Evans LT
Published: November 2004

Six wheat cultivars with more than a twofold range in stem height and weight were grown at 21/16°C in 16-hr days of high light intensity. Changes with time in photosynthesis, respiration, dry weight, and the distribution of 14C fed to the flag leaf or ear of the main stem were followed in all cultivars. The effects on grain yields, stem weights, and 14C distribution of prevention of photosynthesis by the ears or by the rest of the plant during grain filling were also examined. Substantial losses of dry weight from the stem occurred during the most rapid period of grain filling, but stem weights then rose again in most cultivars. About one-third of the early loss in stem weight of control plants was due to stem respiration, the remainder to mobilization, but cultivars differed in these proportions, the respiration rate of stems per unit dry weight being higher in the shorter cultivars. The assimilates mobilized from the stems were equivalent to 2.7–12.2% of final grain weight in control ears. Mobilization increased when photosynthesis was reduced, particularly that from the lower internodes, which indicated that grain yields in the control plants were not limited by lack of assimilate. Balance sheets derived from gas analysis measurements supported this conclusion. The amount of material lost from the stems of plants in all the conditions employed, measured as dry weight or as 14C, was unrelated to stem height. Tall cultivars were no more dependent than short ones on stem reserves, and no more able to draw on reserves for grain filling in conditions limiting photosynthesis. Nor was there evidence that stem growth in tall cultivars was more likely to compete with grain growth. The cultivars differed more than threefold in the rate of ear filling. High growth rate per ear was associated with high yield and grain number per ear and with slow initial growth of the grains.
Genetic stability of Australian Phalaris (Phalaris tuberosa L.) under domestication
Authors: McWilliam JR , Schroeder HE , Marshall DR , Oram RN
Published: November 2004

Thirty isolates of the Australian cultivar of phalaris (Phalaris tubevosa), sampled over the range of its distribution in south-eastern Australia, were evaluated as seeds and seedlings in controlled environments and as spaced plants and swards in the field. The variation found within and between the populations for a number of morphological, developmental, chemical, and agronomic characters indicates that the species has undergone little, if any, ecotypic differentiation during almost 90 years of cultivation in Australia. The results also indicate that the cultivar was derived from a single ancestral population of P. tuberosa and are consistent with the earlier claims that this population was of Italian origin. The evolutionary conservatism and the apparent lack of ecological adaptation in the cultivar are not due to a lack of genetic variability, but rather to the longevity and adaptability of individual plants, and the absence of natural regeneration in established stands, all of which have reduced the scope of natural selection.
Analysis of a fertility trial with Droughtmaster cows
Authors: Williams WT , Haydock KP , Edye LA , Ritson JB
Published: November 2004

Data were obtained from a grazing experiment with 96 Droughtmaster cows on a Townsville stylo-spear grass pasture. There were two replicates of 12 treatments, which were factorial combinations of stocking rate (two levels), superphosphate application (three levels), and conservation of hay (two levels). Analyses were undertaken to determine (i) any significant treatment effects on conception, and (ii) whether any such effects were solely attributable to liveweight differences or to a direct, independent effect. It is shown that the results cannot be treated on an annual basis, since the paddocks exhibit synchronous conception failures. The method of establishing this phenomenon is outlined. The analytical methods used were the analyses of variance and covariance, manifold contingency analysis, and multiple predictive analysis, both on per cow and per paddock means. Only superphosphate significantly affected conception, this effect being associated only with the highest level of superphosphate. Seven of the analyses strongly indicated a direct effect of superphosphate not attributable to liveweight difference, though this could be almost obscured by cows attaining abnormally high or low liveweights during mating. The exception, covariance analysis of per paddock means, failed to achieve significance, but this is probably attributable to the greater sensitivity of per paddock means to outlying single values in a continuous model.
Uredospore movement and observations on the epidemiology of wheat rusts in north-east Australia
Authors: Rees RG
Published: November 2004

The overseasoning of wheat rusts (P graminis and P recondita) and the movement of uredospores have been examined in Queensland during three seasons. Wheat rusts over summer on volunteer cereals and certain grasses in the main wheat-growing areas of north-eastern Australia. The local foci of rust appear to be adequate to provide the initial inoculum each season. Large-scale long-distance aerial transport of uredospores is unnecessary in the epidemiology of the diseases and is probably abnormal. The aerial transport of small numbers of uredospores is adequate to distribute genetical novelty rust organisms over vast areas.
The effect of total water supply, and frequency of application, upon lucerne. I. Dry matter production
Authors: Snaydon RW
Published: November 2004

The total quantity of water supplied to an established lucerne stand, and the frequency of water application, were varied independently. The total quantity of water supplied during summer, autumn, and early winter was expressed as a proportion of class A pan evaporation (Epan), and ranged from 0.04 to 3.5 Epan. Dry matter production, at total water supply equal to Epan, varied between 8.6 kg ha-1 day-1 in early winter (May–June) and 97 kg ha-1 day-1 in summer (January–February), and was correlated (r = 0.99) with mean minimum temperature. The form of the response curve of log, dry matter production to water supply, relative to Epan, was similar during all seasons. Dry matter production increased approximately logarithmically with increasing water supply up to the equivalent of 0.5 Epan reached a maximum at about 1.5 Epan, and declined above this. A response surface was constructed, based upon total water supply and mean minimum temperature.Frequency of application, at a given total water supply, had no significant effect on dry matter production when total supply exceeded 0.5 Epan in any season. At a total water supply equal to 0.2 Epan, frequent small applications of water (5 mm) produced 50% more dry matter than less frequent large applications (20 and 80 mm) during summer, but only 30% as much as the less frequent applications in the subsequent autumn. Water use efficiency (ratio of dry matter production to total water supplied) was greatest at 0.5 Epan at all frequencies of application in summer. During the 6 months after irrigation treatments ceased, dry matter production was generally related to the amount of available water in the soil, but production was less, even 18 months later, on plots that had previously received the heaviest irrigation (130mm month-1). Frequency of application had no significant effect upon subsequent yield, but frequent small applications in one summer reduced the capacity of lucerne to extract soil water at low water potentials in the following summer.
Genetic studies with wild diploid Trifolium ambiguum M. Bieb. with respect to time of nodulation
Authors: Hely FW
Published: November 2004

Population studies made with an alpine diploid form of the perennial rhizomatous Trifolium ambiguum, inoculated with moderately effective (best available) strain of Rhizohium trifolii from the margin of the restricted natural habitat of this plant, showed great variation within the host with respect to time of nodulation. When progenies derived from paired crossings between early-nodulating parents and similarly from late-nodulating parents were studied under standardized conditions, differences in time to initial nodulation between progenies of early-nodulating plants and progenies of late-nodulating plants were highly significant. Analysis revealed that parents within each group differed with respect to their general and specific combining abilities. Indications were that selection of parents following diallel crossing would permit faster selection responses to be obtained than were brought about following phenotypic selection and polycrossing. Nevertheless, at the beginning of the programme an effective selection response for early nodulation was achieved over four generations by polycrossing and single plant selection alone. This plant material and a combination of these phenotypic and genotypic plant selection techniques has resulted in the development of a registered cultivar (Summit) suitable for use at high altitudes.
Pathogenic specialization in Phytophthora vignae
Authors: Purss GS
Published: November 2004

Pathogenic changes in Phytophthora vignae detected in the field in southern Queensland are documented. Evidence presented demonstrates that at least four distinct pathogenic races of P. vignae exist. At least three resistant genes are available in a collection of c. 500 cowpea strains and cultivars examined. The danger of needlessly exposing resistant cultivars to infection is discussed. It is concluded that field or generalized resistance should be explored more fully.
Production of cervical mucus in ewes treated with exogenous progestagen and oestrogen
Authors: Allison AJ
Published: November 2004

The production of cervical mucus was measured at intervals of 6 hr about the onset of oestrus in ewes treated with exogenous progestagen administered by the intramuscular or intravaginal route. There was a quadratic pattern of production with peak values early in the oestrous period. Although there were no differences between groups in the total amount of mucus produced, levels recorded in untreated ewes were lower in the pre-oestrous period. Within the intravaginal progestagen group, those ewes which exhibited oestrus within 42 hr of sponge withdrawal produced greater quantities of cervical mucus than did animals which came into heat after this time. This relationship was not evident within the intramuscular progesterone group. It was concluded that the variable cervical mucus response observed after the cessation of treatment may contribute to the lowered fertility commonly observed following the synchronization of oestrus. The cervical mucus response to injected steroids was recorded in spayed ewes. This was a specific linear response to exogenous oestrogen. Progesterone priming resulted in higher levels of cervical secretions from 24 to 42 hr after the administration of oestradiol benzoate (ODB). Intravenous administration of ODB caused an earlier but short-lived response.
The influence of CCC (2-chloroethyltrimethylammonium chloride) and temperature on dry matter and assimilate accumulation in wheat
Authors: Lowe LB , Carter OG
Published: November 2004

The effect of CCC m controlling plant height during internode elongation and assimilate accumulation, during grain filling and at grain maturity, was investigated in plants growing under three temperature regimes. With increasing temperature the plants matured earlier and the maximum height achieved became smaller. The effectiveness of CCC in controlling internode elongation was reduced. Analysis of the distribution of 14C-labelled compounds assimilated as 14CO2 by the flag leaves after ear emergence, showed no difference between the control and CCC-treated plants. It is suggested that the early application of CCC has a limited effect on metabolism of the plant during grain filling.
The rate of loss of DDT on cattle in relation to protection from reinfestation by the cattle tick Boophilus microplus
Authors: Schnitzerling HJ , Roulston WJ , Stone BF , Wilson JT , Thompson PG
Published: November 2004

Australian Illawarra Shorthorn cattle were sprayed with 0.5% w/v DDT on 31 consecutive occasions at intervals of 4 weeks. Spraying was rotated amongst three groups of cattle. The rate of loss of DDT was determined on the barrel for all occasions and concurrently on the flank and escutcheon for the last 16 occasions. A protective period, defined as the minimum period cattle were protected against reinfestation by the cattle tick, was determined concurrently from observations made on the flank and escutcheon. A cyclic change in the rate of loss of DDT occurred on all sites. The rate was highest in summer and lowest in winter, and was in antiphase with corresponding changes in the protective period. The magnitude of the change of rate of loss of DDT was greater on the flank than on either the barrel or the escutcheon. The rate of loss from the three sites was always in the sequence flank > escutcheon > barrel. The mean deposits of DDT present on the flank and escutcheon when protection had just ceased were respectively 0.29 mg/g hair and 0.054 mg/sq. in., and the protective periods did not differ significantly. The protective period on the barrel was not measured, but it was calculated from data on the DDT deposits to be longer than on either of the other sites, even allowing for the fact that laboratory tests showed that DDT on barrel hair was relatively less effective against larvae than similar weights of DDT on flank hair.
Effect of pre-harvest rain on germination in the ear and α-amylase activity of Australian wheat
Authors: Moss HJ , Derera NF , Balaam LN
Published: November 2004

Australian wheat varies in flour paste viscosity owing to differences both in α-amylase activity and in the susceptibility of the starch to attack by this enzyme. α-Amylase activity is very low except in abnormally wet harvests, when germination in the ear can occur. All Australian cultivars have white grain, which is associated with susceptibility to germination in the ear. However, differences were found in the rate of generation of α-amylase; Mendos, Spica, and Gamenya were more susceptible than Emblem and Festiguay. Falcon starch was the most resistant to α-amylase, while Olympic, Mendos, and Spica were the most susceptible.
Agropyron scabrum and its role in the epidemiology of Puccinia graminis in north-eastern Australia
Authors: Rees RG
Published: November 2004

The perennial A. scabrum var. plurinerve is an important graminaceous host for P. graminis f. sp. tritici in north-eastern Australia. Rust uredosori were present on the grass in at least some localities during a 3-year period. The grass is of particular significance in the oversummering of P. grarninis f. sp. tritici, supplementing survival on volunteer cereals. Two distinct forms of the variety plurinerve have been identified. One is largely confined to the heavy black clay soils of the Darling Downs and parts of northern New South Wales and is of particular importance in the epidemiology of P. graminis. P. graminis f. sp. tritici, P. graminis f. sp. secalis, and a range of intermediate types occur on the grass, which is apparently a convenient site for somatic hybridization between different formae speciales and strains of P. graminis. P. graminis f. sp. tritici is particularly prevalent on the grass during the summer while the wheat-avirulent intermediate types normally predominate during the balance of the year. The occasional isolation of older strains of P. graminis f. sp. tritici from A. scabrum var. plurinerve suggests that development on the grass acts to some extent as a gene reservoir for the rust population.
Ecotypic variation in Avena fatua L., A. sterilis L. (A. ludoviciana), and A. barbata Pott. in New South Wales and southern Queensland
Authors: Whalley RDB , Burfitt JM
Published: November 2004

Some 53 samples of wild oat seeds were collected in the wheat belt of eastern Australia in an area extending from Collingulie in southern New South Wales to Dalby in Queensland and grown under uniform environmental conditions. Three species of wild oats were collected, Avena sterilis L. subsp. ludoviciana (Dur.) G. & M. mainly concentrated in the north, A. fatua L. subsp. fatua (L.) Thell. mainly concentrated in the south, and A. barbata Pott. confined to the Southern Tablelands and nearby slopes and plains. A high degree of physiological and morphological variability was evident, A. sterilis exhibiting the greatest variability and A. barbata the least. The variation was mainly local with only a suggestion of ecoclinal variation, and is probably the result of multiple introductions. The two samples of A. barbata tested exhibited a vernalization requirement for flowering and one sample of A. sterilis from the same area also gave a strong response to vernalization, but A. fatua did not.