bluuebunny/crossref_metadata_2025 huggingface dataset:
Flowering in the sweet orange.
Authors: Sauer MR
Published: November 2004

Anthesis in Navels and Valencias in the Mildura district normally takes place over a period of 5-6 weeks from late September to the end of October. The first flowers to open are terminal (distal) on leafless shoots. Flowers on leafy shoots are generally open about I week later. Terminal flowers open early, except solitary flowers on leafy shoots. The lowest (proximal) buds are next to attain anthesis, and subterminal flowers are last. Late-opening flowers have a better chance of producing fruit than those which open early, and in consequence most fruit are developed from subterminal flowers, or from those buds just below the subterminal. Most fruiting flowers open not earlier than the fourth week of the flowering season. Flowers which are slow to reach anthesis, but do not produce fruit, remain on the tree longer than flowers which develop early. Drop of flowers after blossoming is a continuous process; there does not appear to be any particular time or period of development which is critical. Flowers on the shaded side of the tree open about 1 week later than those exposed to the sunshine, but this does not result in a better set of fruit on the shaded side.
The influence of soil type on phosphorus toxicity in subterranean clover (Trifolium subterraneum L.).
Authors: Rossiter RC
Published: November 2004

Five soils were investigated in pot culture, using a wide range of levels of monocalcium phosphate. The amount of phosphorus required to produce phosphorus toxicity symptoms in subterranean clover (Trifolium subterraneum L.) varied widely between soils, even when all other nutrients were adequately supplied. Soil effects are ascribed largely to differences in capacity to "fix" soluble phosphorus in forms not readily available for plant growth. Wherever the problem is likely to occur in the field, poor nodulation may accentuate the malady.
Evapotranspiration from wheat and pasture in relation to available moisture.
Authors: Butler PF , Prescott JA
Published: November 2004

The changes of soil moisture to a depth of 5 f t in a simple crop rotation and under permanent pasture during 1948-1949-1950 have been followed in detail. Calculations have been made on a monthly basis of the water storage in the soil and of the evapotranspiration from wheat and pasture and of losses from a bare fallow. It is shown that in these experiments the relationship between evapotranspiration, evaporation from water, storage of water in the soil, and rainfall can be expressed in the form dItr /dW = ~ ( 2.4 – Itr), where Itr = Etr/Ew0.75= 2.4 when available water is no longer limiting, and c = 0.12 for wheat, c = 0.10 for pasture, Etr = evapotranspiration, Ew =evaporation from a free water surface, W = stored water plus rainfall = available water. Water losses from a bare fallow were found to be determined principally by rainfall and soil storage.
Selection for economic characters in Australian Merino sheep. V. Further estimates of phenotypic and genetic parameters.
Authors: Morley FHW
Published: November 2004

Estimates of heritability, genetic correlations, phenotypic correlations, and other parameters among eight characteristics were obtained from Merino sheep at Trangie Agricultural Experiment Station. One set of estimates was obtained by parent-offspring regressions from data obtained between 1943 and 1952. Another set was obtained by half-sib analyses from data from sheep with first adult shearings in 1953. Estimates of heritability were: greasy fleece weight, 0.40 ± 0.06; yield (per cent.), 0.39 ± 0.07; clean fleece weight, 0.47 ± 0.07; staple length, 0.56 � 0.07; crimps per inch, 0.47 ± 0.11; folds, 0.50 ± 0.07; body weight, 0.36 ± 0.08; birthcoat, 0.80 ± 0.10. The most important genetic correlation limiting genetic improvement in clean fleece weight is that between this trait and crimps per inch. Because of this the rate of improvement in fleece weight could be reduced by about 30 per cent. whenever crimps per inch is also selected. Other genetic correlations indicate antagonisms between characteristics, but these antagonisms appear to be of minor importance except that between clean fleece weight and crimps per inch. This sheep population does not appear to have reached a state of genetic homeostasis, a t least with respect to the characteristics studied. However, the findings emphasize the necessity for careful evaluation of the economic importance of different traits, and for accurate measurement, if maximum genetic progress is to be achieved.
Flower initiation in pasture legumes. I. Factors affecting flower initiation in Trifolium subterraneum L.
Authors: Aitken Y
Published: November 2004

The value of the annual legume Trifolium subterraneum L. (subterranean clover) in Australian agriculture warrants more precise knowledge of factors affecting flowering and prolific seeding. The effect of temperature and photoperiod on flower initiation in early and later flowering varieties has been investigated in an effort to determine the geographical limits of the use of subterranean clover in Australia. At any time of sowing, the length of the growing season of a variety depends greatly on the variety's response to the temperature level and to the photoperiod of the first few weeks after germination. In all varieties of subterranean clover so far examined flower initiation is accelerated by a period of low temperature. In the later varieties, flower initiation is prevented by an insufficient period of low temperature. The length of the necessary cold period is shortened under longer photoperiod. Early varieties are early flowering because they do not require so long a cold period or so low a temperature as late varieties.
Studies of soil manganese. I. The use of disodium calcium versenate for the extraction of divalent manganese from soils.
Authors: Beckwith RS
Published: November 2004

A new extractant has been developed for the estimation of divalent manganese in soils. The soil is extracted at pH 8.0 with a buffer of calcium and ammonium acetates containing 1 per cent. disodium calcium versenate. The extractant has been shown to give little attack on three precipitated oxides of manganese having respectively the structures of hausmannite, manganite, and manganous manganite. The attack of the extractant on these oxides is not increased in the presence of soils. The new extractant has been found of value for the removal of divalent manganese formed by treatment of soils with reducing agents. Preliminary results with three precipitated oxides indicate that the degree of attack by hydroquinone in the presence of the new extractant at pH 8 reflects the availability of these oxides to oats grown on a fen soil. Some applications of the new reagent are briefly discussed.
The function of cattle sweat glands.
Authors: Ferguson KA , Dowling DF
Published: November 2004

Evidence is presented that the apocrine sweat glands of cattle have a temperature-regulating function. Under the stereo microscope, sweat droplets could be observed forming at the openings of the sweat gland ducts in response to intradermal injections of adrenaline, and during exposure to hot conditions. The sweat spots could be stained macroscopically, and prints showing the location of the spots were obtained with bromothymol blue papers pressed onto the skin surface. Quantitative measurements indicate that the evaporation of this sweat is the main source of heat loss in hot environments.
Arsenic resistance in a strain of cattle tick Boophilus microplus (Canestrini) from Northern NSW.
Authors: Hitchcock LF , Roulston WJ
Published: November 2004

Laboratory trials were carried out with ticks of a northern New South Wales strain which had proved impossible to control by dipping in 0.2 per cent. As2O3. The concentration of arsenic required to prevent 50 per cent. of engorged female ticks of this strain from laying viable eggs was found to be approximately double that for females of a reference strain. The median lethal concentration of arsenic for larvae of the northern New South Wales strain was also found to be approximately double that for larvae of the reference strain.
Metal complexes in soils.
Authors: Beckwith RS
Published: November 2004

The release of manganese from organic soils by copper has been studied. The results obtained together with the titration curves of acid-washed organic soils, determined in the presence and absence of various added metal ions, support the suggestion of Bremner et al. (1946) that the metals of the first transition series of the periodic table are held in organic soils as complexes. The consequences of the results are discussed particularly in regard to the release of metal ions from soils and their uptake by plants.
The dominant N gene in New Zealand Romney sheep
Authors: Dry FW
Published: November 2004

The existence of the dominant N gene, derived from two different sources, has been established by monogenic ratios. The gene is variable in expression in the heterozygote, and is pleiotropic. Horns are a sex-influenced expression of this gene, being dominant in males and recessive in females, with exceptions of the order of one in 10 in both sexes. There are hints that the exceptions in rams have a genetic basis, and strong evidence that this is so in heterozygous ewes, a dominant gene, F, variable in expression, being postulated. In the birthcoat of heterozygotes the expression of the N gene varies over a range as wide as is possible. There is extreme variation in halo-coverage over the body in animals of N-abundance on the back, and all halo-grades, from borderline-N to no-halo, are found in the one-sixth of heterozygotes less than N-grade. There is evidence that some part in causing the heterozygote to be less than N-grade is played by genes which reduce the abundance of halo-hairs on the main area of the body in non-N lambs. Possibly one dominigene, not linked with N, is powerful in the heterozygote. Heterozygous dominant N-grade lambs, with very few exceptions, can be distinguished from homozygotes in having halo-hair abundance reduced below that of N-grade at the anterior end of the body, at least in a small area behind the shoulder which is called the shoulder patch. The absence of the shoulder patch in heterozygotes has a genetic basis. Very occasionally there appears to be overlap between the two genotypes in the opposite direction. Recently a very small number of lambs thought to be homozygotes have been a little short of full halo-hair abundance on the shoulder patch on either one or both sides of the body. It is also of some help in distinguishing the genotypes that homozygous ram lambs have lumps in the horn positions, while heterozygous ram lambs frequently have no lumps at birth. On the average homozygous fleeces are more coarsely hairy than heterozygous, and contain more secondary kemp. In setting out the facts from which the above circle of conclusions is drawn it is sometimes convenient to make use at an earlier stage of something which is not proved until later. This applies especially to distinguishing homozygote and heterozygote.
The comparative efficiency of a new spot test for the detection of Streptococcus agalactiae, in milk
Authors: Pulsford MF
Published: November 2004

Five methods for the detection of Strep. Agalactiae in milk samples were examined with special reference to their use as direct and indirect tests. Comparison was made of the sensitivity of all tests in detecting excretor cows. In the consideration of methods as direct tests particular attention was paid to their value for screening out frankly negative samples with the minimum amount of work. A newly developed test based on the CAMP reaction, the "spot" test, was found to combine high sensitivity and cheapness, and this is recommended for use under South Australian conditions.
A study in rate of pasture growth
Authors: Brougham RW
Published: November 2004

The growth curve of a pasture consisting of short-rotation ryegrass, red clover, and white clover was determined by measuring dry matter yields at intervals over a 9-week period in the spring of 1953. To determine the effects of temporary weather variations on growth, the experiment was replicated in time as well as space. The experimental technique is described. The curves of growth for ryegrass and total herbage were sigmoid. In the second phase of growth of approximately 6 weeks when rate of growth was constant, the daily increment in total herbage approached 150 1b dry matter per acre. Total herbage yields were separated into two parts to give a growth effect for a constant (mean) climate and an irregular weather effect. This latter separation showed agreement with fluctuations in temperature and rainfall. The results are discussed in terms of pasture management practices, and the possibilities of growth rate studies for future pasture experimentation are considered.
Legume "Little leaf", a virus disease of subtropical pasture species
Authors: Hutton EM , Grylls NE
Published: November 2004

A virus of legumes causing a disease described as "little leaf" has infected with differing degrees of severity some 40 per cent. of pasture legumes in experimental plots in subtropical Queensland. The symptoms are similar to those caused by the "big bud-witches' broom" complex of viruses of which it is probably another strain. Transmission studies have shown that the vector is the leafhopper Orosius argentatus (Evans) which also transmits tomato "big bud", lucerne "witches' broom", potato "purple top wilt", and tobacco "yellow dwar"' diseases. The O. argentatus taken direct from the field in Queensland, and its progeny reared in the laboratory, were efficient vectors of "little leaf" whereas the Canberra strain bred in the laboratory would not transmit 'little leaf' and was not an efficient vector of the other "yellows" viruses. The majority of species and strains tested in the genera Crotalaria, Desmodium, Indigofera, and Stylosanthes are susceptible to "little leaf". Within such genera there are a few resistant species or strains with promising agronomic characters. Lucerne and white clover are relatively resistant to "little leaf". The genera Arachis, Centrosema, Doliehos, Glycine, Lespedeza, Leucaena, Pueraria, Phaseolus, Vigna, and Zornia contain species and strains with marked field resistance. Most of the species and strains considered to be promising pasture legumes possess field resistance to "little leaf".
Selection for economic characters in Austrialian Merino sheep. VII. Interactions between genotype and plane of nutrition
Authors: Morley FHW
Published: November 2004

A number of groups of half-sibs were divided into two lots, one being exposed to a high plane of nutrition, the other to a low plane, from 3 to 17 months of age. Heritability, as indicated by the within sire correlation, did not vary with plane of nutrition. Genotype-treatment interactions were not present for any fleece characters or for 6-month body weight. Such interactions were large and highly significant for weight at 12 or 17 months. These findings indicate that the opinions of Hammond (1947) are not generally valid.
The chloride status of the irrigated sultana vine and its relation to vine health
Authors: Woodham RC
Published: November 2004

The chloride content of petioles from the middle leaves of shoots (which is higher than that of corresponding leaves) gives the best estimate of the chloride status of an irrigated sultana vine from bud burst until the middle of January. After this date, foliar samples may not give a reliable indication of the vine chloride status. The physiological age of the portion sampled and the normal seasonal chloride accumulation must be considered in interpreting foliar chloride values. A sample of the annual wood taken in winter may also give a suitable estimate. On an undrained loam which bears vines showing various degrees of salt injury, there is a close relation between petiole chloride, severity of the salt symptoms, and vine health. Vines with petiole chloride levels (dry basis) of 0.8 per cent. in early December showed slight burning of basal leaf margins, while chloride levels above 1.9 per cent. in early December or 2.5 per cent. in early January were accompanied by severe burning of the basal leaves, considerable restriction of growth, and very low fruit yields. On two other sites healthy vines with no obvious salt injury had petiole chloride contents of 1.7 per cent. in December in one case, and 2.0 per cent. in the other. Therefore a general petiole chloride level indicative of excessive salinity could not be established. To investigate whether local variations in vine health may be attributed to salt, adjacent healthy 'vines should be sampled in the same way for comparison, especially on those sites where leaf symptoms are absent. The leaf symptoms, as used in this study, may be assumed indicative of excess soil salts. On the sites examined there is no relation between total sulphur or boron content of petioles or leaves and the leaf burn symptoms described. In contrast to chloride values, both the total sulphur and boron contents of leaves are higher than those of petioles.
Changes in organic matter and pH in a podzolic soil as influenced by subterranean clover and superphosphate
Authors: Williams CH , Donald CM
Published: November 2004

A further investigation has been made on soils examined by Donald and Williams (1955) in a survey of the influence of superphosphate and subterranean clover (Trifolium subterraneum L.) on podzolic soils formed on granodiorite in the Crookwell district of New South Wales. The soil organic matter was found to have approximately constant proportions of carbon, nitrogen, sulphur, and phosphorus in the ratio 155 : 10 : 1.4 : 0.68, and it is suggested that the rate of build-up of soil organic matter under the clover pastures may have been limited by the amounts of sulphur supplied in the superphosphate top-dressings. The soil organic matter was found to have a cation-exchange capacity a t pH 7.0 of about 220 m-equiv./100 g, and increases in soil organic matter have led to substantial increases in the cation-exchange capacity of the soil. About 75 per cent. of the total cation-exchange capacity of the unimproved soils was due to organic matter while, in the most improved soils, this figure approached 90 per cent. The increases in cation-exchange capacity included increases in exchangeable hydrogen and were accompanied by decreases in soil pH. There were increases equivalent to 6.5 lb of exchangeable potassium, 25.5 Ib of exchangeable calcium, and 5.2 lb of exchangeable magnesium per acre in the surface 4 in. of soil for each hundredweight of superphosphate applied per acre. Increases in soil organic matter also resulted in increases in the field capacity which may reflect improvements in soil structure. Results indicate that heavier rates of superphosphate application would increase the rate of fertility build-up.
Experimental methods in haymaking trials
Authors: Shepherd W
Published: November 2004

During several haymaking trials, difficulties were encountered with experimental methods and in the interpretation of the results obtained. Most serious were those arising from variability of test material in both swath and windrow form, susceptibility of cured or partly cured material to mechanical damage during sampling, time involved in carrying out replicated field treatments, and techniques employed in assessing losses of weight or of individual nutrients during curing. Additional field and laboratory work has since been undertaken to establish more precise experimental methods. Methods recommended for solving or minimizing difficulties, based on this work and on experience obtained in the original trials, are discussed. In particular, precautions necessary in removing samples from cured or almost cured material are indicated, and a method for lifting swaths or windrows for periodical weighing is outlined.
Combining resistance to the root-knot nematode, Meloidogyne javanica (Treub) Chitwood, and Fusarium wilt in hybrid tomatoes
Authors: Giles JE , Hutton EM
Published: November 2004

Two tomato hybrids bred at the Hawaiian Experiment Station for resistance to Meloidogyne incognita (Kofoid & Thite) Chitmood proved also to be resistant to M. javanica, which is dominant in the Murray Valley and subtropical areas of Australia. These hybrids also possessed resistance to a range of Australian isolates of the fusarium wilt fungus (Fusarium bulbigenum var. lycopersicli(Brushi) Wollenweber & Reinking). Both these important characters were heritable and could be recombined with agronomic quality in hybrids. Fusarium wilt resistance showed positive potence in the progenies. Root-knot nematode resistance had an irregular pattern of inheritance. The potential of varieties as parents was first gauged from simple crosses. The desirable characters were then concentrated in progenies by a modified backoross followed by selfing and successive selection. Yielding ability has been maintained and suitable agronomic characters have been achieved in the hybrids by the breeding methods used. The work has indicated that suitable crop rotation will be necessary to prevent the selection of nematode strains capable of causing severe infection.
Witches' Broom disease of Lucerne. III. A greenhouse study on symptom expression and growth in relation to frequency of watering and cutting
Authors: Helms K
Published: November 2004

The effects of frequency of watering and cutting on symptom expression and growth of witches' broom-diseased lucerne (Medicago sativa L.) were studied in a greenhouse experiment. Clones of two strains of diseased lucerne and one clone of non-infected lucerne were given four treatment combinations of two rates of watering and two frequencies of cutting. The cultural treatments caused pronounced differences in the growth of diseased plants and small differences in the growth of non-infected plants. Symptoms of the two strains of witches' broom-diseased lucerne maintained their characteristic identities in all four treatments. For both strains, symptoms were consistently more severe in plants grown in soil of low moisture content and cut at intervals of 6 weeks rather than 12 weeks. In the spring some diseased plants of one strain, which were grown in soil of high moisture content and cut at 12-weekly intervals, showed partial masking of symptoms. A high mortality of diseased plants was associated with frequent cutting. The seasonal patterns of dry weight yield and moisture content were essentially the same for each cultural treatment and for both diseased and non-infected plants. The yield of non-infected plants was significantly greater than that of diseased plants. The total yield of all three clones was increased by cutting at 12-weekly intervals rather than at 6-weekly intervals. The greatest reduction in yield of diseased plants as compared with non-infected plants was in treatment combinations in which there was a low soil moisture and cutting was at 6-weekly intervals.
The interaction of competition for light and for nutrients
Authors: Donald CM
Published: November 2004

A new technique is described for the study of the interaction between competition for light and competition for a nutrient or for water. The technique was applied in a study of the competition between two grasses for light and for nitrogen. The aggressor species showed a negative interaction in the effect of the two modes of competition; it was slightly reduced in yield by competition for either factor alone, but when competition for both factors was operative, it achieved almost the same yield as in the absence of competition. The effect of the two modes of competition on the suppressed species showed a positive interaction; the depression in yield when there was competition for both factors greatly exceeded the sum of the effects of competition for the separate factors. An analysis is made of the nature of competition for one or more factors. Competition for even a single factor involves interaction between direct and indirect effects; when competition occurs for two factors, it leads to multiple interactions between two groups of effects and thus greatly intensifies the effects of competition for either factor operating alone.
Factors governing faecal nitrogen wastage in sheep
Authors: Hutchinson KJ
Published: November 2004

Dietary factors controlling faecal nitrogen loss in sheep have been examined in selected metabolism data. Two factors, total nitrogen and dry matter intake, accounted for a large part of the variation in faecal nitrogen. The first group of data consisted of 44 observations from sheep fed five "nitrogen- free" diets. This approach is commonly used to estimate metabolic faecal nitrogen (M.F.N.). Analysis showed that the regression of M.F.N. on intake of dry matter, for the combined data, had a significant intercept of +0.70 g/day. Hence the common expression of X.F.N. estimates in terms of unit intake will lead to errors. These would be important with the low levels of intake frequently associated with unpalatable "nitrogen-free" diets. When in addition an allowance is made for the small quantities of nitrogen contained in these diets, there is excellent agreement between observations from different sources. The second group of data consisted of 99 observations, from two sources of pasture diets, covering a wide range of nitrogen intakes. High correlations (r = +0.900 and + 0.936) were recorded between total faecal nitrogen and intake of dry matter. However, at high and low levels of total nitrogen intake there was evidence of departure from a common linear relationship. A positive effect of nitrogen per se was shown where total nitrogen intake was less than 8 or more than 46 g/day. The significance of these findings is discussed with reference to: (1) The applicability of faecal nitrogen index methods which have been proposed for the calculation of grazing intake. (2) The assumption that the metabolic component of total faecal nitrogen is constant.
The relationship of lamb birthcoat to adult fleece structure in a strain of Merino sheep
Authors: Schinckel PG
Published: November 2004

Variability of the lamb birthcoat has been studied in relation to adult fleece characteristics. Coarse birthcoats were associated with increased variability of fibre diameter and decreased crimp rate. The increased variability of fibre diameter resulted from a significant increase in the diameter of primary fibres and a small, but statistically non-significant, decrease in the diameter of secondary fibres. There was no relation between birthcoat grade and body weight, clean fleece weight, yield, staple length, follicle density, follicle ratio, mean fibre diameter, or skin folds. It is postulated that there is a gene system in the Merino the effect of which is to cause variation in the amount of wool produced by the different follicle types. Increased "dosage" of genes of the system endows primary follicles with increased productivity and secondary follicles with decreased productivity. This is expressed in the form of increased halo-hair abundance in the lamb and increased differences between the diameters of primary and secondary fibres in the adult.
Fertility investigations on the black earth wheatlands of the Darling Downs, Queensland. II. Moisture and evapotranspiration in relation to the wheat crop
Authors: Waring SA , Fox WE , Teakle LJH
Published: November 2004

The effects on wheat yields of available soil moisture at planting, rainfall during the growing period, and evapo-transpiration were examined for the years 1951-1954. The relation between free water surface evaporation, available soil moisture, and evapo-transpiration was examined for the years 1951 and 1952. Wheat yields were found to be correlated with available soil moisture at planting for the four years combined, the two drier years combined (1951 and l953), and the two wetter years combined (1952 and 1954). The relationship for the four years combined was sufficiently strong to suggest that available moisture at planting could be successfully used for yield prediction. Yield was correlated with evapo-transpiration only for the dry year 1953. The ratio of yield to evapo-transpiration was found to be lower for the years of high rainfall during the growing period, the mean values for the wet and dry years being 2.1 and 3.5 bus./in. respectively. Growing-perlod rainfall was correlated with yield only for the month of August for the two dry years of 1951 and 1953 combined. Evapotranspiration (Etr) was found to be correlated with free water surface evaporation (Ew) and Ew0.75 in the monthly data, the value for C in the relationship Etr = CEw0.75 being calculated as 0.53. Available soil moisture was correlated with evapo-transpiration using data from the beginning and end of the season in 1953, but was not correlated using monthly data. The method of calculating monthly available soil moisture is shown to be important in this correlation. A method of calculating available soil moisture over a monthly period, based on a mean daily figure for the month, is described.
Variation in fibre and staple length over the body of the sheep
Authors: Doney JM
Published: November 2004

Variation in staple length, fibre length, and the ratio between them was studied over 11 body sites on five Merino and five Border Leicester X Merino ewes. It was concluded that there are distinct but very slight trends in both staple and fibre length. Both decreased from neck to britch, and dorsally and ventrally from mid-lateral line. Fibres grown on the belly did not differ in length from those growing on the body, although staple length was considerably shorter. Apart from the belly there is no trend in the fibre/staple length ratio. Mean values of 1.46 ± 0. 05 for Merino and 1.45 ± 0.21 for crossbreds were found. It was concluded that no single conversion factor of staple to fibre length has general application even within a breed. A hypothesis is developed whereby variation in fibre length is related to changes in local density of fibre population.
Vital statistics for an experimental flock of Merino sheep. I. Death rates in adult sheep, in relation to method of selection, age and sex
Authors: Turner HN , Dolling CHS , Sheaffe PHG
Published: November 2004

Estimates of death rates are given for four mating groups in a flock of approximately 1000 Merino ewes, for each year of age from 1½ to 10½. Three of the groups are under selection for clean wool weight and other characters, and the fourth is an unselected control. The flock is run under extensive grazing conditions, and death rates are based on ewes dead or missing between one pen-mating and the next. Between 1951 and 1957, the average death rate for ewes 1½ to 7½ years old was 2.2 per cent. per annum, while at the older ages the average was no higher than 7.3 per cent. During the drought year 1957-58 losses averaged 3.8 per cent. for ewes up to 6½ years old, then rose steeply with age to 45.6 per cent. for ewes 9½ years old. In neither period did the selected groups differ from the unselected control. Starting with the 1953 drop, all rams in the unselected control group have been retained for the study of age effects on them. Average losses to date in each age group have been less than 5 per cent.
The susceptibility of hay species to mechanical damage. I. Effects of growing and curing conditions
Authors: Shepherd W
Published: November 2004

A laboratory method was developed for determining the susceptibi1ity of hay species to mechanical damage and the nature of mechanical losses likely to be encountered during field curing. Three legume species were considered: lucerne (Medicago sativa L.), white clover (Trifolium repens L.), and subterranean clover (T. subterraneurn L.). Twelve of the 17 growing and curing conditions investigated, e.g. maturity, drought, shading, and crushing, significantly affected fragility. Moisture content was particularly important and losses from carrying out field operations at unsuitable moisture contents could outweigh those from all other factors. Many types of damage contributed to the mechanical losses. Breaking up of individual leaflets, and fracture at the leaflet-petiole and petiole-stem junctions, were important but with the clovers the greatest losses resulted from fracture of petioles near the leaf-petiole junctions.
Host-pathogen relationship in tobacco plants with stems infected by Peronospora tabacina Adam
Authors: Mandryk M
Published: November 2004

Stem infection of tobacco (Nicotiana tabacum L. cv. Virginia Gold) with Peronospora tabacina Adam was established and its development studied. Mycelium of the pathogen spread from parenchyma tissue of the infected leaf blade into the vascular system of midrib and petiole and thence into the stem. In small seedlings mycelium was usually associated with all tissues and often killed the plant. In plants at the flowering stage necrosis was chiefly confined to the periphery of secondary xylem, the cambium, and the inner part of the external phloem region. As xylem aged it acted as a barrier to the spread of mycelium from external to internal phloem and to the pith. Cortex was not penetrated readily by the pathogen. When the pathogen became established in the cambium region of the stem at an early stage of plant growth, development of xylem was often inhibited. Such plants, when full grown, were brittle at the base and snapped off readily. Development of the pathogen in the stem was favoured by high humidity but was arrested by exposing the plants to benzol vapour, or to a daily temperature range of 75-105°F when humidity was not higher than 70 per cent. High temperature during the day followed by low temperature at night did not prevent spread of the pathogen from the leaves into the stem. Mycelium sometimes spread from infected stems into new axillary shoots with subsequent sporulation on leaves.
Criteria for expressing nutritional values of subtropical grasses
Authors: Milford R
Published: November 2004

The results from digestibility experiments made with 17 different subtropical grasses are discussed. The most suitable criteria for expressing nutritional values are crude protein content, crude protein digestibility, nitrogen balance, dry matter intake, and dry matter digestibility. Feeding standards based on starch equivalents and total digestible nutrients which are used in temperate environments are highly inaccurate when applied to these subtropical species. Large seasonal fluctuations occur in the nutritional value of subtropical grasses. At the height of the summer growing season values are very high and adequate for all forms of animal production. In the winter and early spring the grasses are generally of poor quality and are unable to meet the requirements for producing livestock. At this time the crude protein content and crude protein digestibility are low. Animals are also unable to obtain sufficient energy because the dry matter intakes and dry matter digestibilities of the grasses are low. The very low nutritive values obtained during winter and early spring usually occur after grasses have been killed by frost. Frost resistance is therefore an important criterion in selecting subtropical grasses which will maintain high nutritional values throughout the entire yew.
The effect of phosphorus, potassium, and calcium on the growth, chemical composition, and symptoms of deficiency of white clover in a subtropical environment
Authors: Andrew CS
Published: November 2004

The effect of the rates of application of sodium phosphate, potassium chloride, and calcium carbonate on growth, chemical composition, and visual symptoms of deficiency in Trifolium repens var. Irrigation White, grown in a low humic gley soil under subtropical conditions in Queensland, has been investigated. The surface soil is grossly deficient in phosphorus, potassium, and calcium and consists almost entirely of sand (92 per cent.). Additions of sodium phosphate, potassium chloride, and calcium carbonate each increased the yield of clover, increased the phosphorus, potassium, and calcium contents respectively, and conditioned the uptake of other nutrients. Plant material for chemical analyses consisted of petioles and leaves (less senescent and expanding leaves), harvested at the immediate pre-flowering stage of growth. Critical percentages for phosphorus, potassium, and calcium under these conditions were established at 0.23, 1.1, and 1.0 per cent. respectively. Visual symptoms of phosphorus, potassium, and calcium deficiencies are discussed in relation to yield and nutrient content. The sum of the equivalents of potassium, calcium, and magnesium is approximately constant. The mean value of 18 analyses covering all treatments was 136 m-equiv. per cent. with a range of 116-148.
Heat treatment of citrus for control of red scale. I. Trials on Washington Navel fruit in a dehydrator
Authors: Martin BH , Black RF
Published: November 2004

Heat treatments, ranging from 50 to 70°C and for varying durations, were carried out on freshly picked Washington Navel fruit infested with red scale. Counts of the living and dead scales were made 3 weeks after treatment. The time-mortality curves were approximately sigmoidal and similar to normal dosage-mortality curves. Reliable 100 per cent. "kills" were obtained for treatment periods ranging from 1 hr for the 70°C treatment to 2¼ hr for the 50°C treatment. However, the fruit damage effects of the 70°C treatment were severe and preceded the time required for 100 per cent. scale mortality, whereas with the 50°C treatment no fruit damage occurred until after this time and even then the damage was very slight. Raising the relative humidity of the treatment chamber from 12 to 40 per cent. in the 50°C treatment did not significantly alter the time required for either 50 per cent. or 100 per cent. scale mortality. It is considered that the killing of the scales was a temperature rather than a dehydration effect, and that it probably occurred at a fairly similar threshold lethal temperature for all temperature treatments used.
Stimulated decomposition of soil organic matter during the decomposition of added organic materials
Authors: Barrow NJ
Published: November 2004

When organic materials of high nitrogen content were allowed to decompose in soil, the accumulation of ammonium caused high pH. It vas shown that high pH caused increased production of carbon dioxide, sulphate, and mineral nitrogen from soil organic matter.
Skin follicle types, ratios, and population densities in Rajasthan sheep breeds
Authors: Narayan S
Published: November 2004

Observations are reported of skin follicle types, ratios, population densities, and percentages of medullated fibres in four Rajasthan sheep breeds – Chokla, Marware, Jaisalmere, and Malpura. Data from three body regions – shoulder, side, and breech – were available for a total of 21 sheep, and for 12 more there were observations for at least one of the three regions. The Chokla breed had the highest total and highest primary follicle population density (9.4 and 3.1 per mm2 respectively), as well as the highest ratio of secondary to primary follicles (2.1) and the lowest percentage medullation (24 per cent. of all fibres, 2 per cent. of secondary fibres). The Malpura breed had the lowest total and lowest primary follicle population density (5.6 and 2.5 per mm2), and was equal with the Marware breed for the lowest ratio (1.3). The Malpura breed had the highest percentage medullation (77 per cent. of all fibres, 60 per cent. of secondary fibres). Of the three body regions studied, the side had the highest ratio of secondary to primary follicles in all four breeds, while the breech had the highest percentage of medullated secondary fibres. The percentage of medullated primary fibres in the breech was equal to or greater than that in either of the other regions.
Studies on the carbohydrate metabolism of sheep. XII. Further studies on the diabetic nature of the metabolic abnormalities in ovine pregnancy toxaemia
Authors: Reid RL
Published: November 2004

Metabolic changes following lambing or death of foetuses in utero and after intravenous insulin injection have been studied in ewes with pregnancy toxaemia induced primarily by severe undernutrition. After lambing or death of foetuses in utero, blood glucose increased to hyperglycaemic levels which were maintained until the death of the ewe; ketones declined to levels approaching normal. In those cases examined, abnormally high plasma cortisol levels were also maintained until the death of the ewe. Blood glucose declined after intravenous insulin, particularly if the pre-injection glucose level was in the normal range or above, but there was definite resistance to the hypoglycaemic effect of insulin. Ketones also declined markedly in most cases. These data are discussed in relation to recovery from pregnancy toxaemia after lambing or after glycerol therapy. It is concluded that the metabolic changes observed are consistent with the hypothesis of a diabetic-like syndrome, characterized by excessive adrenal hyperactivity, possibly in the presence of insulin insufficiency.
Variation in feed intake as a cause of variation in wool production of grazing sheep
Authors: Schinckel PG
Published: November 2004

Observations were made to determine whether differences between sheep in wool production under field grazing conditions reflected differences between individuals in feed intake. Sheep were selected for high, intermediate, and low levels of clean wool weight per unit body weight under field grazing conditions, and the feed intakes and wool production of these sheep were subsequently measured under pen conditions. On controlled feed intakes differences between sheep and between groups were less than those under field grazing conditions or under ad libitum pen feeding conditions. It was concluded that a, significant portion of the differences in wool production at grazing was referable to differences in feed intake. The group of sheep having high levels of wool production per unit body weight were found to have higher efficiency of conversion of feed to wool and also to have higher levels of feed intake under ad libitum feeding conditions. The rate of wool production of the high group was 22 per cent. greater than that of the low group under conditions of equal feed intake and 37 per cent. greater under conditions of ad libitum feed intake.
Water consumption by lucerne in central Australia
Authors: Jackson EA
Published: November 2004

Observations on the loss of water from soil under irrigated lucerne have been made over a 12 month period at Alice Springs. The relationship between this water loss and tank evaporation has been determined and used to calculate mean monthly requirements of lucerne in this environment. The mean annual requirement is 90 in. Data are also presented showing the rate of water loss at different soil water contents, growth stages of the crop, and soil depths.
Soil fertility changes in the long-term experimental plots at Kybybolite, South Australia. I. Changes in pH total nitrogen, organic carbon, and bulk density.
Authors: Russell JS
Published: November 2004

Variously treated grassland plots at the Kybybolite Research Centre established in 1919 on solonetzic soils were sampled in 1957–58. Analyses of the soils and for pH and nitrogen were made and compared with earlier analyses made in 1938. Bulk density and organic carbon were also determined. Treatment with phosphorus fertilizers and grazing with sheep has resulted in large increases in the organic matter content of the surface soil. A large part of the increase has been concentrated in the 0–2 in. horizon. At the 6–8 in. level, increases have been small. When considered on the basis of pounds per acre, the increase in soil nitrogen in the surface 6 in. of some plots appears to be linear with time, and even after 39 years shows no signs of approaching an asymptotic value. However, there appears to be differential behaviour within the soil profile. The rate of increase of the 0–2 in. horizon in recent years shows signs of being much less than in the earlier years of the experiment. On the other hand, in the 2–4 and 4–6 in. horizons the recent rate of increase is similar to or greater than that in earlier years, which indicates that a deepening of the organic matter profile is occurring. There appears to be some relation between the increase in soil nitrogen and sheep-carrying capacity. The increase in soil nitrogen on the soils from the plots has been, on the average, equivalent to 14 lb of soil nitrogen per sheep per acre per year. Additional calcium applied with water-soluble phosphorus appears to result in higher levels of soil organic matter. Lime, in particular, appears to result in the highest levels of soil organic matter. Analysis of the soils shows that the increase in soil organic matter is associated with a slight decrease in pH. The soils also show a decrease in bulk density which is closely related to changes in organic matter content. Various aspects of organic matter accumulation are discussed, particularly the importance of the time factor in this process and the lack of a causal relationship between the amount of superphosphate applied and the increase in organic matter.
The breed structure and genetic analysis of the pedigree cattle breeds in Australia. II. The Poll Hereford
Authors: Barker JSF , Davey GP
Published: November 2004

(i) The breed structure and genetic history of the pedigree Poll Hereford breed in Australia are analysed by pedigree sampling methods. (ii) The basic pattern of the breed structure is similar to that found in other studies, but it is both diffuse and dynamic owing to the present rapid expansion of the breed. There are a number of herds moving into the major breeders' group and there are many new herds yet to find their level in the structure. (iii) An attempt is made to determine why particular herds become major breeders' herds. It is suggested that the use of imported animals is important, while there is evidence that those herds apparently moving into this group show a higher degree of selective registration of males. The relationship between herd size and importance of the herd is considered. (iv) The breed has developed since 1920 entirely from imported Poll Hereford and from imported and Australian-bred horned (pedigree Hereford) animals. The percentages of genes in the breed in 1949 derived from these animals are 64.3 and 35.7 per cent. respectively. (v) The most important herd in 1949 has a genetic contribution to the breed of 26.9 per cent. However, the genetic contributions of the four next most important herds are only 6.7, 6.1, 5.1, and 4.5 per cent. In the four-generation pedigrees from which these figures are derived, the genetic contributions of imported and horned animals are respectively 56.3 and 36.6 per cent. (vi) The animal with the highest relationship to the breed is Woodrow 1st (imp.), with direct relationships of 2.0 and 9.3 per cent. to the 1937 and 1949 samples respectively. Of the 14 sires and three dams whose direct relationships are 3.0 per cent. or over in either of the two sample years, nine sires and two dams are imported but none is horned. (vii) The degree of inbreeding (base year 1920) is calculated. The total inbreeding in 1949 (1.8 per cent.) comprises 0.8 per cent. current inbreeding, 0.6 per cent. long-term inbreeding, and 0.4 per cent. strain inbreeding. There is no evidence of subdivision of the breed into separate strains. (viii) The effective generation length is approximately 5.5 years. Nearly 50 per cent. of the animals in the 1949-50 sample are sired by bulls 4 years old or younger, while nearly 40 per cent. are from dams 4 years old or younger. (ix) It is not likely that there is much genetic variation between herds. Bulls from major breeders' herds are used widely throughout the breed while about 80 per cent. of sires and 60 per cent. of dams are bred in herds other than the one in which they are used.