bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed-setting in subterranean clover (Trifolium subterranean L.). III. The effect of plant density
Authors: Yates JJ
Published: November 2004

Various aspects of seed production in a number of strains of subterranean clover sown at fire seeding rates at two sites in the Western Australian wheat-belt were investigated. Dry matter yields and percentage leaf in the foliage were also recorded. Percentage leaf increased with plant density in the earlier-maturing, stemmy strains, so that differences amongst strains diminished as density increased. The differences amongst strains in number of inflorescences when grown as single plants were largely eliminated under dense sward conditions, so that the two main factors in seed production were number of seeds per inflorescence and mean seed weight. The proportion of burrs above and below ground varied widely amongst strains, and was influenced by plant density in some strains. It is postulated that the extent of burr burial depends on the interaction between strain, environment, and condition of the surface soil. Burr burial improved the efficiency of seed-setting, particularly in the more severe environment. Strain differences in seeds per inflorescence below ground were relatively small, but within each strain, values were higher in the more favorable environment. The efficiency of seed-setting above ground differed considerably amongst strains and between the two environments, and tended to increase with plant density particularly in the earlier-maturing strains. Correlations were established between seeds per inflorescence above ground and the amount of plant cover in these strains. An artificial covering of wood-wool also improved seed-setting above ground. Mean seed weight followed the same general pattern as seeds per inflorescence.
Some characteristics of "Carnamah", a very early-flowering strain of Trifolium subterraneum L., when grown as single plants
Authors: Rossiter RC , Millington AJ
Published: November 2004

A very early-flowering strain of subterranean clover was discovered in 1957 at Carnamah, W.A. From extensive studies at several field centres, it was demonstrated that the new strain – now called Carnamah – commenced flowering from 30 to 10 days before Dwalganup (the standard commercial "early" strain) when sown in the autumn-early winter period. With very early planting – late March – the difference in flowering time was even greater (about 45–50 days). The very early-flowering nature of the Carnamah strain is associated with early flower initiation. Rate of flower development (from flower initiation to flower appearance) in relation to temperature was similar for Carnamah and Dwalganup. Under spaced-plant conditions the total production of Carnamah was much less than that of Dwalganup, a finding which conforms to the results of previous single-plant studies. The new strain was not readily distinguished from Dwalganup, but several minor differences in morphology are mentioned. The chromosome number was normal for the species (2n = 16). The relevance of these data to sward conditions is discussed briefly, and it is suggested that the Carnamah strain may be more effective than Dwalganup in extending the "clover belt" inland in southern Australia.
Rhizobium numbers in the rhizospheres of red clover and paspalum in relation to soil treatment and the numbers of bacteria and fungi
Authors: Rovira AD
Published: November 2004

Estimates of the numbers of fungi, bacteria, and clover rhizobia in the rhizospheres of red clover and paspalum grown in a krasnozem (pH 4.8) have shown that the stimulation of fungi and general soil bacteria is limited to that soil in immediate contact with the roots. The stimulation of rhizobia by the red clover roots appears to be more extensive, with high numbers occurring in the soil, even 10–20 mn from the roots. Paspalum roots increased the numbers of rhizobia in the soil immediately surrounding the roots, but to a lesser degree than did clover. Amelioration of the soil increased the levels of bacteria and fungi in the soil and in the rhizosphere, with spectacular increases in the numbers of rhizobia in the rhizosphere of red clover.
Photoperiodism and sexual activity in Merino ewes. II. The effect of equinoctial light on sexual activity
Authors: Radford HM
Published: November 2004

Merino ewes were subjected to equinoctial light for 2 years; some continued to exhibit seasonal variation in sexual activity while others exhibited continuous sexual activity. Continued seasonal variation in sexual activity in equinoctial light is at variance with existing hypotheses for photoperiodic control of sexual activity in ewes, and alternative explanations for such behaviour are discussed. Two groups, each of five Merino ewes, were subjected to a light environment of 12 hr light : 12 hr dark, the one group from the autumn, the other from early in the spring of the same year. In the first group, all ewes failed to experience anoestrus during their first spring, but two ewes experienced anoestrus during the spring of the second year. In the second group, three ewes experienced anoestrus later in the spring in which treatment commenced, and the same three experienced anoestrus during the spring of the second year of the experiment. In these five ewes which exhibited seasonal variation in sexual activity, the anoestrous periods were of shorter duration, but occurred at the same season as those in ewes of two control groups.
Measurements of wool production and its physiological components in a group of South Australian Merino sheep.
Authors: Hutchinson KJ
Published: November 2004

Data for wool production, feed intake, and body weight were recorded for a group of 31 rams selected from the South Australian strong-woolled Merino flock at Roseworthy. Measurements were made during (a) grazing, and (b) ad libitum pen feeding. A locally developed faecal nitrogen method was used to estimate intakes at pasture. For the pen diet, which contained 15% crude protein, two measurements of apparent dry matter and nitrogen digestibility were made for each sheep. The repeatability of gross conversion efficiency of feed into wool under grazing versus pen feeding was highly significant, viz. r = +0.79. While the repeatability of wool production was also highly significant, viz. r = +0 77, the repeatability of feed intake was not significant in these data, viz. r = +0 12 In pens, voluntary feed intake was found to vary with body weight to the power of + 1 09, the 99% fiducial limits extending from +0.81 to + 1 37 and thus excluding fractional powers conventionally assigned to basal metabolic nee&, e.g. +0.7. The physiological components of wool production were studied with the use of' the pen data. An identity was used which involved three terms, viz. gross conversion efficiency of feed into wool, gross feed intake per unit body weight, and body weight. Of these, gross conversion efficiency was the prime determinant of wool production. Gross feed intake per unit body weight was significantly associated with wool production (P<0.05), while the relationship between wool production and body weight was not significant in these data. In the pen experiment 'the regression relationship between voluntary feed intake and body weight accounted for approximately one-half of the variation in voluntary feed intake. A negative association between body weight and efficiency was also revealed. However, the general significance of this latter finding is doubtful, particularly in view of the variable relationships recorded between body weight and clean fleece weight for rams in 5 years' data from the general Roseworthy flock. For the experimental group of 31 rams, substantial differences were recorded in individual apparent digestive efficiencies for both dry matter and nitrogen. The ranges of individual values, expressed as four standard deviations, were 9.2 and 12.2% respectively. However, these differences did not contribute to differences in gross conversion efficiency of feed into wool, which suggests that the latter resides in either general or special aspects of metabolism.
The chemical composition of cattle skin.
Authors: Tulloh NM
Published: November 2004

Skin samples taken from the midsides of Hereford, Angus, and Shorthorn cattle of the same age were analysed for water, crude protein (N x 6.25), and fat contents. Water and crude protein contents were calculated as percentages of fat-extracted fresh skin and fat-extracted dry skin respectively. Breed differences in Chese components were small and not significant. Mean values obtained for all cattle were: water, 69.84�S.E. 0.16; crude protein, 100.68�S.E. 0.29. When fat content was calculated as a percentage of total dry matter, Angus cattle had a significantly lower skin fat content than Shorthorns and Herefords, the mean values for each breed being: Shorthorn 7.40�S.E. 0.88; Hereford, 5.51 �S.E. 0.57; Angus, 3.72�S.E. 0.26. The difference between values for Herefords and Shorthorns was not significant. At slaughter, rib cuts were collected from each beast and dissected into bone, muscle, and fat. The correlation coefficient between the percentage of fat in dry skin samples with the percentage of dissected fat tissue in fresh rib cuts was +0.18 (not significant). In a group of Hereford cattle the effect of plane of nutrition on skin composition was investigated. The percentages of water and crude protein present in skin were almost unaffected by plane of nutrition. However, the absolute contents of water and crude protein increased in animals fed to either gain or lose weight. The percentage of fat in skin increased when animals were gaining weight and decreased when they were losing weight. It is concluded that analyses of skin samples are not likely to be useful in predicting body composition of cattle.
The rhizosphere bacteria in grass-clover associations
Authors: Rovira AD , Stern WR
Published: November 2004

A quantitative and qualitative assessment was made of the rhizosphere populations of grass and of clover, growing together in soil, at different levels of nitrogen. The quantitative analysis showed less variation when the results were expressed as numbers of bacteria per gram of root than if they were expressed on a soil weight basis. On a root weight basis grass supported more bacteria than clover, and on a soil weight basis the converse held. The rhizosphere populations of clover and grass increased with increasing nitrogen supply. In the high nitrogen treatments the increase in numbers on grass was due to more vigorous growth, but the high number on the shaded clover plant was probably due to bacteria growing on decomposing root tissue. The qualitative analysis was made on bacterial isolates from the various rhizospheres and showed an abundance of branching bacteria. Only small differences were found between the isolates from clover and grass roots growing under the different conditions.
The copper status of some helminth parasites, with particular reference to host-helminth relationships in the gastro-intestinal tract of cattle
Authors: Bremner KC
Published: November 2004

The copper content was determined in samples of 12 nematode, four cestode, and two trematode species collected from a variety of hosts infected either naturally or experimentally. Copper concentrations varied considerably from species to species, the lowest value recorded being 2 p.p.m. copper (dry weight basis) in the cestode Moniezia benedeni and the highest 604 p.p.m. in the nematode Haemonchus placei, both from cattle. Both the total content and the concentration of copper varied among mature individuals of the same population of the liver fluke, Fasciola hepatica, collected from cattle. Copper levels varied greatly in samples of H. placei and Oesophagostomum radiatum from cattle drawn from different host individuals, whereas values for Bunostomum phlebotomum and M. benedeni also from cattle varied little from host to host. Copper concentrations in samples of H. placei and O. radiatum, recovered from the abomasum and large intestine respectively of experimentally infected calves supplemented daily with copper sulphate, were considerably higher than those in samples from unsupplemented calves. With both species, the increases in worm copper levels were associated with increases in concentrations of soluble copper in the environment. It is suggested that soluble copper in environmental fluids can be absorbed through the cuticle of these helminths. Copper supplementation of the host's diet, on the other hand, had no effect on the copper content of B. phlebotomum Furthermore, the concentration of copper in solution in the contents of the duodenum and jejunum was not elevated significantly by the supplementatlon. The hypothesis that the intestinal helminths of bovines compete with the host for copper was examined, and it is concluded that in dairy calves in southeastern Queensland parasitic gastro-enteritis has a far greater significance as a disease entity in itself than as a factor contributing to the expression of a clinical state of copper deficiency.
Social behaviour studies on domestic animals. I. Hens in laying cages
Authors: James JW , Foenander F
Published: November 2004

The social ranks of neighbouring birds in a laying cage plant were determined by paired encounters. It was found that a definite social structure existed in the cages. Three strains of birds originating from the same population were used in the experiment, and found to differ in social rank as well as production. Social rank affects early egg production by delaying the onset of sexual maturity, but does not appear to affect intensity of lay, the social effect apparently occurring only when birds are first housed. The effect of social rank is not only on the mean but also on the variance, low-ranked birds being slower to mature and also more variable in the age at which they begin to lay. The applications of these results to strain testing and cage design are discussed.
Tetraploid and hexaploid chromosome races of Phalaris arundinacea L.
Authors: McWilliam JR , Neal-Smith CA
Published: November 2004

Chromosome counts of a wide range of Phalaris arundinacea introductions have revealed the existence of two chromosome races, one tetraploid (2n = 28) and the other hexaploid (2n = 42). The majority of the introductions, including those from the Soviet Union, northern and central Europe, and North America, belong to the tetraploid race, whereas those from Portugal, Spain, Oregon, U.S.A., and two Botanic Garden collections in central Europe belong to the hexaploid race. Both races have regular meiosis and a stable chromosome number, and are fully fertile. The hexaploid hybridizes freely with the tetraploid Ph. Arundinacea and also with Ph. Tuberosa, but is effectively isolated from both owing to the sterility of the hybrids. The hexaploid differs from the tetraploid in a number of characteristics, and in particular in its growth rhythm. Under Australian conditions it has a longer growing season, and is more productive in the autumn and winter. In this and in other respects the hexaploid is intermediate between the tetraploid form of Ph. Arundinacea and Ph. Tuberosa, and is considered to have arisen through hybridization and subsequent introgression between these two species along the junction of their respective distributions in southern Europe.
Studies on the carbohydrate metabolism of sheep. XIV. The adrenal response to psychological stress
Authors: Reid RL , Mills SC
Published: November 2004

The effect of change in environment on plasma cortisol and blood glucose levels in sheep has been studied in the following situations: movement from grazing paddock to small enclosed yards, movement from grazing paddock to indoor animal quarters, and short periods of transport. Consistent large increases in plasma cortisol values were recorded in previously grazing animals, but the degree of elevation during road transport was usually less in "trained" animals housed indoors. Previous undernourishment or fasting increased the changes in plasma cortisol level in response to stress. Individual variation in plasma cortisol response between animals was considerable. Pronounced, but variable, increases in blood glucose occurred in all experiments except those in which exercise (walking) was associated with the brief stressful situation created by moving animals from the paddock into an enclosed yard. It is concluded that movement to an unfamiliar environment is an emotionally stressful situation, but that there are important differences in the quantitative adrenal cortical response between the grazing animal and experimental animals housed indoors and already subjected to a series of novel environmental changes. It is further suggested that exercise during a short period of stress may modify or prevent the normal hyperglycaemic response to adrenaline release. These experiments provide further support for the conclusion that the elevated plasma cortisol levels observed in the "stress syndrome" of pregnancy toxaemia are primarily a response to physical or emotional stress, rather than to the nutritional stress of fasting or severe undernutrition.
The effect of a Mediterranean summer environment on the permeability of hard seeds of subterranean clover
Authors: Quinlivan BJ , Millington AJ
Published: November 2004

Burr samples of nine strains of subterranean clover (Trifolium subterraneum L.) were collected from field sward trials at monthly intervals during the summer and autumn months and tested for hard seed content. Similar tests were carried out on burrs exposed to an artificial environment in a laboratory oven, which simulated the temperature conditions on a bare soil surface during the hot summer months in the agricultural districts of Western Australia. The maximum level of hard-seededness for all strains was achieved in the late spring or early summer soon after field maturity. There was significant variation in the maximum hard seed content of the different strains. Over the summer and autumn months the hard seed content of all strains declined in the samples from the field and the laboratory. There was considerable variability among strains in the rate and pattern of decline in hard seed content, and in the percentage of hard seed remaining in the autumn. The agronomic significance of the strain variability and the possibility of its inclusion in a breeding and selection programme are discussed.
Effects of Gibberellic acid on pasture and animal production in winter
Authors: Biddiscombe EF , Arnold GW , Scurfield G
Published: November 2004

Results are given of a series of field experiments in which Phalaris tuberosa subterranean clover pastures were sprayed with gibberellic acid during winter. The growth of Phalaris was initially stimulated to a marked degree. At considerable expense per acre, this increase in dry matter produced a temporary advantage in liveweight in both weaner sheep and pregnant ewes at a time of the year when the supply of normal pasture was low. Further effects on animal production are discussed in relation to food demands and the sequence of plant reactions to spraying treatment; these effects were adverse in the case of lambing ewes because pasture growth temporarily declined after the period of stimulation. Effects of gibberellic acid on the nutritive value and botanical composition of the pasture are also reported.
Partition of excreted nitrogen, sulphur, and phosphorus between the faeces and urine of sheep being fed pasture
Authors: Barrow NJ , Lambourne LJ
Published: November 2004

Merino wethers in metabolism cages were fed a range of pasture samples at a level sufficient to maintain body weight nearly constant. The quantities of food eaten and of faeces and urine produced were recorded. The nitrogen, sulphur, and phosphorus contents of the feed and of the faeces and urine were determined. The phosphorus content of the faeces was further fractionated into organic and inorganic forms. Faecal excretion of nitrogen, sulphur, and organic phosphorus per unit of feed eaten was not significantly affected by the nitrogen, sulphur, or phosphorus content (respectively) of the feed eaten, nor by the level of feed intake. Average values were 0.835 g of nitrogen, 0.114 g of sulphur, and 0.059 g of organic phosphorus per 100 g of dry matter eaten. The remainder of the nitrogen and sulphur was excreted in the urine, and hence the proportion excreted in the urine depended on the nitrogen or sulphur content (respectively) of the feed. Most of the remainder of the phosphorus was excreted in the inorganic form in the faeces, and hence the proportion of the faecal phosphorus in inorganic form depended on the phosphorus content of the feed. However, these proportions also depended on the level of feed intake, especially if this was so low that the animal was in negative balance. Because the nitrogen / sulphur ratio of faeces (and also of wool) was smaller than that of the feed, the nitrogen/sulphur ratio of the urine tended to be larger than that of the feed. The sulphur and phosphorus contents of faeces, although correlated with digestibility, were inferior to nitrogen as an indicator of digestibility and were too highly correlated with nitrogen to be of much value as additional measures.
Studies on the reactions of animals to infestation with ticks. VI. Resistance of cattle to infestation with the tick Boophilus microplus (Canestrini)
Authors: Riek RF
Published: November 2004

The resistance of Bos taurus and B. indicus cattle and of their crosses to infestation with the tick Boophilus microplus was assessed by repeated experimental infestation. The assessment was based on the yield of engorged female ticks, the weight of the engorged female, the weight of the eggs laid, and the duration of the parasitic life cycle. Two types of resistance were observed: an acquired resistance which became evident after repeated exposure, and an innate resistance which was present in some animals, never previously exposed, on their first infestation. Acquired resistance was least apparent in purebred B. taurus, but considerable variation in the degree of resistance was observed between individuals within the respective breed groups. When a group of purebred B. taurus (Shorthorns) and a group of B. taurus (Shorthorn) x B. indicus (Zebu) were exposed to natural infestations, the crossbreds were significantly more resistant. Acquired resistance was shown to be associated primarily with the development of a hypersensitivity to the salivary secretion of the tick and was manifested by serous exudation, usually accompanied by a papular reaction, at the site of attachment of the tick. Histological changes in the skin following attachment of the various instars are described. Lesions indicative of an allergic reaction were found only in animals with soma degree of resistance, and consisted of cellular invasion, predominantly eosinophilic, which extended deep into the dermis. In highly resistant cattle, blood histamine concentration reached a peak 48 hr after infestation with larvae and subsided to normal levels 7–8 days later. In susceptible cattle, there was little or no variation in histamine levels during the parasitic life cycle of the tick. In animals with varying degrees of resistance, temporary increases occurred following the larval and nymphal moults. No correlation could be found between skin thickness or sweat gland or sebaceous gland concentrations and the degree of resistance. Some evidence was obtained that it may be possible to induce the hypersensitive state, with consequent reduction in tick burden, by repeated daily subcutaneous injections of 0.5 ml of a 1 in 10 dilution of larval extract. Innate resistance was observed in some B. indicus. The mechanism appeared to persist in subsequent exposures, but its significance was difficult to assess, as some animals manifesting this type of resistance also became hypersensitive.
The bacteriology and histopathology of footrot in sheep
Authors: Thomas JH
Published: November 2004

Fusiformis nodosus was shown to cause severe footrot in sheep without the intervention of either, or both, of the other bacteria usually present in natural cases, namely, Treponema penortha and a motile fusiform bacillus. The progress of experimental infections in the sheep's foot with pure cultures of F. nodosus has been related to the histopathological changes observed. The organism was shown to invade the stratum lucidum of the hoof but did not penetrate beyond the granular layer. The epithelial cells of the stratum lucidum became detached and disintegrated. The horn became separated from the underlying tissues in this region. Penetration into the stratum corneum was accompanied by sinus formation and degeneration of the horn.
Studies on ensilage. II. Plant maturity effects in the ensilage of ryegrass and clover under laboratory conditions
Authors: Lanigan GW , Catchpoole VR
Published: November 2004

Laboratory silages made from pure crops of three varieties of ryegrass (Lolium multiflorum, Lolium perenne, and Lolium sp., N.Z. H1 strain) differed according to maturity at harvest. When ensiled at a stage of development characterized by first appearance of heads, all varieties tested sustained an initial lactic fermentation which ensured an adequate degree of stability during prolonged storage. Earlier harvesting tended to give less satisfactory results. Species effects, if present, could not be distinguished from possible effects of seasonal factors in this investigation. Experiments conducted with known mixtures of short rotation ryegrass (N.Z. HI strain) and white clover (Trifolium repens) showed that the proportion of the legume which could be added without appreciable ill-effect increased with later harvesting. Major adverse effects of clover additions appeared as increased losses of dry matter in the effluent and a greater tendency to instability in the silage, the latter being demonstrated by destruction of part of the lactic acid accumulated earlier, with consequent rise in pH level during storage.
Studies on the use of mutagenic agents in plant breeding. I. The effect of seed moisture content on sensitivity to X-ray in Lupinus angustifolius
Authors: Francis CM , Gladstones JS
Published: November 2004

Seeds of Lupinus angustifolius were subjected to X-ray doses of 2.5, 5, 10, and 20 kr at each of 12 moisture contents ranging from 6.1 to 18.1% (fresh weight basis). X1 plant damage was measured in terms of reduction in height at 110 days from sowing, delay in flowering, and reduction in mean seed yield per plant. The three measures were found to be highly correlated. Survival was not significantly affected within the range of treatments used. Sensitivity increased progressively with decreasing moisture contents below 11.6%, seeds with 6.1–7.6% being four to five times as sensitive as those with 11.6–16% moisture content. The latter range represented a "plateau" of minimum sensitivity. Between 16.0 and 18.1% moisture, sensitivity again increased.
Effects of different levels of zinc and phosphorus on the growth of subterranean clover (Trifolium subterraneum L.)
Authors: Millikan CR
Published: November 2004

Four water culture experiments are described in which the effects of the addition of all combinations of graduated amounts of phosphorus and zinc on the growth of subterranean clover were studied.In the first experiment, the variety Dwalganup was used, and in the other experiments the varieties Clare and Edenhope. Varietal differences in the symptoms of zinc deficiency are described. Phosphorus toxicity symptoms occurred in the variety Clare but not in Edenhope. The effects of increases in zinc or phosphorus level, or both, on growth of top + root (T + R) and on percentage top are described. A highly significant variety x phosphorus interaction effect on T + R was recorded at adequate zinc levels, which indicated that the phosphorus requirement of Edenhope was considerably greater than that of Clare. By contrast, tolerance to high levels of zinc in the substrate was greater in Clare than in Edenhope. In the presence of added phosphate, the initial T + R response to small, but still insufficient, additions of zinc to the substrate occurred in root growth more than in top growth, whereas when a level of zinc adequate for normal growth was supplied, top growth of the plants benefited more than root growth. Highly significant zinc x phosphorus interaction effects on T + R occurred. No relationship existed between zinc concentration and the occurrence of zinc deficiency symptoms. The critical zinc level was not a point of narrow range, but included a wide range of values, depending on the age of the plants and the phosphate level. The depression in T + R induced by high phosphate when the zinc level was insufficient was not due to a decrease in zinc concentration resulting from the high phosphate treatment, but such plants gave a high value for the phosphorus/zinc ratio. The results suggest that zinc is essential to phosphate utilization by the plant. Evidence of redistribution of phosphorus from tops to roots, and of decreases in the total amount of phosphorus in phosphorus-deficient plants, was obtained in one experiment between days 27 and 60.
Defoliation as a factor in the growth of varieties of subterranean clover (Trifolium subterraneum L) when grown in pure and mixed swards
Authors: Black JN
Published: November 2004

This paper describes two experiments analysing the recovery from defoliation of subterranean clover varieties grown in swards in large seed boxes at the Waite Agricultural Research Institute, Adelaide. The first experiment examined the way in which the six common commercial varieties recovered from a single severe defoliation, and showed that under these conditions they can be placed in three groups: Yarloop and Clare are tall, high-yielding varieties with few, large leaves, recovering slowly from defoliation; Tallarook and Dwalganup are prostrate varieties, lower-yielding, with many small leaves, recovering rapidly after defoliation; Bacchus Marsh and Mount Barker are intermediate in all respects. In the second experiment mixed swards of equal numbers of Yarloop and Tallarook plants were grown under three treatments: A, no defoliation; B, defoliated twice at a height which removed the higher Yarloop canopy but left the lower Tallarook plants untouched; C, defoliated twice at a height which removed the canopies of both varieties. Measurement of dry weight on four occasions after each defoliation showed that in the undefoliated treatment, all Tallarook plants died by the end of the experiment. In the defoliated treatments, the removal of the Yarloop canopy resulted in only a temporary improvement in the illuniination in which the Tallarook plants grew, and their dry weight and plant numbers progressively declined. Dry weight changes in the Tallarook component were shown to be dependent on the light energy available to it, which was in turn determined by the light-absorbing capacity of the superior Yarloop canopy. In mixed swards, the ability of Yarloop to re-establish quickly a leaf canopy above that of Tallarook appeared to explain its success when defoliated.
Acquired systemic resistance to tobacco mosaic virus in Nicotiana tabacum evoked by stem injection with Peronospora tabacina Adam
Authors: Mandryk M
Published: November 2004

Resistance to tobacco mosaic virus (TMV) was induced in leaves of Nicotiana tabacum L. (cv. Xanthi and cv. Havana 423) by injecting spore suspensions of Peronospora tabacina Adam into the stems of plants. TMV lesions that developed on the leaves of stem-injected plants were 62% smaller and 32% fewer in number than their counterparts in control plants. While the difference in numbers of lesions on the leaves between injected and control plants decreased from the bottom to the top of the plant, the difference in the size of lesions was maintained at all leaf levels.
Effect of local advection on evaporation rate and plant water status
Authors: Millar BD
Published: November 2004

The effects of local advection on the evaporation rate (E) and the relative turgidity (RT) of Ladino clover grown in lysimeters were measured at four distances down wind from the leading edge of a small irrigated field adjoining a drier area. Both E and RT decreased with increasing distance down wind from the leading edge, and were directly proportional to powers of the down-wind dimension (x). Presumably plant growth rate may also depend on the distance down wind.Plants near the leading edge showed early afternoon wilt during a mild day in autumn, although soil moisture content was very high. This is in keeping with the concept of a "ceiling absorption rate". Some agronomic implications of these advective effects are discussed.
Variation in hair characters over the body in Sahiwal Zebu and Jersey cattle
Authors: Pan YS
Published: November 2004

In both Sahiwals and Jerseys, mean hair length and diameter increased posteriorly. The length/diameter ratio, and diameters of non-medullated hairs, of medullated hairs, and of the medulla itself also varied between positions, as did the percentage of medullated hairs. Jerseys had greater hair length than Sahiwals at all positions (average + 80%) though in the majority of positions Sahiwals had a greater hair diameter than Jerseys (average + 12%). Coefficients of variation in hair length were similar for the two breeds. In general, variation of hair diameter within positions was slightly greater in Sahiwals, but differences between positions in the variability of hair diameter were small. In all positions, Jerseys had greater hair length/diameter ratios than Sahiwals (average + 90%). In the majority of positions, Jerseys had a greater percentage of medullated hairs than Sahiwals. The mean percentage of medullated hairs for Jerseys was 88% and for Sahiwals 85%, whilst the mean diameters of both medulla and medullated hairs were greater in Sahiwals (39.4 and 62 1 µ) than in Jerseys (26.7 and 54.2 µ). Diameters of non-medullated hairs differed little between the two breeds, being 44.40 µ for Sahiwals and 40.82 µ for Jerseys. Only differences between the two breeds in hair length, hair length/diameter ratio, and medulla diameter were statistically significant. The percentage of medullated fibres was the only character for which the commonly used midside sample provided estimates which were within 10% of the mean over all positions for each breed. Estimates of means and coefficients of variation for other characters are likely to be misleading if based on a single sample from this region. Positions providing better estimates for other traits are: mean hair length in Sahiwals, position 2; C.V. of mean hair length in Jerseys, position 12; mean hair diameter in Sahiwals, position 4; C.V. of mean hair diameter in Jerseys, position 4; mean hair length/diameter ratio in Sahiwals, position 8.
Some effects of soil waterlogging on the cobalt and copper status of pasture plants grown in pots
Authors: Adams SN , Honeysett JL
Published: November 2004

Glass-house experiments were made to measure the effect of soil waterlogging on the cobalt and copper status of subterranean clover and ryegrass. The cobalt content of the plants was much increased by soil waterlogging. Very high plant cobalt contents were obtained when soil was waterlogged for 2 months at room temperature, or for shorter periods at higher temperatures, before planting; or when it was waterlogged while the plants were growing rapidly. The effect of waterlogging on the cobalt content persisted when soils were stored air-dry. Soil waterlogging raised the copper content of the plants much less than it did the cobalt. The copper content was significantly increased only when plants had been severely stunted by waterlogging. Waterlogging raised the plant cobalt content more than it reduced the yield. Thus the total uptake of cobalt, but not of copper, from the soil was increased by waterlogging.
Yield depression due to phosphate fertilizer in sugar-cane
Authors: Yates RA
Published: November 2004

A large series of trials involving phosphate fertilizer showed that yields of cane could be reduced by the application of superphosphate at rates of up to 2 cwt/acre in four distinct areas. In these areas, the yield response to phosphate was dependent on the rate of nitrogen fertilization; yield depression only occurred where the nitrogen supply was adequate; phosphate could increase yields at low nitrogen. In most cases, the yield depression was associated with a low calcium/ magnesium (Ca/Mg) ratio in the soil (a ratio of less than 3.0 in terms of milliequivalents). On soils with high Ca/Mg ratios, regressions of yield response on soil or leaf phosphate indicated critical levels similar to those accepted elsewhere. Significant regressions could not be obtained from soils with low Ca/Mg ratios. A few trials testing a phosphate x trace element interaction indicated that the phosphate yield depression in at least one area was due to an induced deficiency of some trace element. The trace element effect is independent of the Ca/Mg ratio effect.
Some anatomical and chemical effects of "flat-limb" virus on apple var. Gravenstein
Authors: Scurfield G , Reinganum C
Published: November 2004

Anatomical investigations were made of lateral branches of 3-year-old healthy and "flat-limb"-infected nursery trees, and of the main stem of 5-year-old healthy and 10-year-old flat-limb-infected orchard trees of apple var. Gravenstein. Anatomical abnormality as a result of virus infection occurred in the late autumn of the first year of growth (7–8 months after infection in the nursery tree), spread laterally in spring of the second year, was overcome somewhat in summer, and spread more widely again in the autumn. In the nursery tree, anatomical studies indicated that there was a dilution of virus effects (including lessening of surface depressions in the stem) or lag in their appearance in passing up from the original point of infection to the top of the tree and to the tips of its lateral branches. Both wood and phloem structure were abnormal in the virus-infected trees. Fibres, tracheids, and vessels in the wood, and fibre-sclereids and sieve-tube elements in the phloem, failed to differentiate. The wood consisted of parenchymatous cells, often much enlarged and distorted, with lignified and thickened walls and lumina packed with starch grains, and the phloem of a disordered array of loosely packed parenchymatous cells containing tannins and crystals. Schizogenous intercellular spaces developed in abnormal wood. The cambium was scarcely distinguishable from the phloem in the 10-year-old virus-infected orchard tree. Despite this there were indications that it had not lost its power to divide and provide derivatives differentiating as normal fibres when partial recovery from infection occurred. Deposition of starch and tannin in the pith was enhanced by virus infection. The fact that sections of infected stems gave deep yellow solutions in water while those from healthy wood gave pale yellow solutions led to chemical analysis for quantitative and qualitative differences in methanol extractives between healthy and infected wood. Qualitative differences in the extractives from healthy and diseased 2- year-old wood were established. Enhanced starch and extractives contents as a result of virus infection were interpreted as effects of disrupted translocation.
Properties and serological relationships of Australian and Californian soil-borne viruses of the grapevine and arabis mosaic virus
Authors: Taylor RH , Hewitt WB
Published: November 2004

Grapevines infected with soil-borne viruses were collected in Australia and California, and transmissions made from them to a range of herbaceous hosts. Positive transmissions were obtained more readily in the winter than in the summer, and Chenopodiurn quinoa was found to be the most sensitive test plant at all times. An increased transmission rate was obtained if leaves from infected vines were first homogenized in 5% nicotine base, and the virus concentrated by ultracentrifugation. Each of seven isolates differed in the symptoms produced on herbaceous hosts. The reactions of Gomphrena globosa to four Australian isolates were studied in detail. In cross-protection experiments one of the Australian isolates protected G. globosa plants from invasion by two of the others, and partially protected it from invasion by the third. Arabis mosaic virus, however, did not protect this host from infection by one of the Australian grapevine isolates. Three Australian and three Californian grapevine isolates and two English isolates of arabis mosaic virus were purified, and antisera prepared against them. The grapevine isolates were serologically identical, and all distantly related to arabis mosaic virus, as determined by immunodiffusion tests. The purified viruses were transmitted back to Mission grapevine seedlings and cuttings. The symptoms produced after 4 months were characteristic of the isolate, but were all of the fanleaf type.
Domestic dogs as hosts of the cattle tick, Boophilus microplus
Authors: Hoyte HMD
Published: November 2004

Larval B. microplus were placed on 36 domestic dogs, about half of which were adults and half were puppies. Ticks matured on the adults only. The yield of adult female ticks was very low and variable (average for all dogs, 0.01%); more time was needed to mature than on cattle, and size and egg production were reduced. Most of the resulting larvae matured successfully when placed on cattle. No ticks matured on the small number of young foxes and dingoes which were tested. It is suggested that the unconsidered presence of dogs represents some risk to the success of campaigns to eradicate this tick.
Apple fruit cell numbers in relation to cropping alternation and certain treatments
Authors: Martin D , Lewis TL , Cerny J
Published: November 2004

Fruit cell numbers in a block of Jonathan apple trees with an alternate cropping rhythm were studied over the period 1955–1962. The number of cells per fruit showed a rhythm in phase with the crop level, while the percentage dry matter showed a rhythm counter to this. Seed numbers per fruit showed no rhythm. The rhythm in cell numbers proved very persistent, continuing for some years under severe thinning treatments. Against this background four types of treatment designed to affect cell numbers were imposed over the period 1957–1962: (1) Decreasing competition between fruits, by thinning by hand, by DNOC, and by NAA. (2) Attempts to increase competition, by delaying abscission with 2,4-D. (3) Attempts to stimulate cell division by kinetin plus synergistic compounds. (4) Attempts to supplement nutrition which forms the background to cell division. No significant effects resulted from the 2,4-D, kinetin, or nutritive supplements, but reducing competition by thinning, either by hand or by DNOC, resulted in an increase in cell numbers which was cumulative over several years. Thinning with NAA did not increase cell numbers. The implications of these results are discussed.
The rumen as a water store in sheep
Authors: Hecker JF , Budtz-Olsen OE , Ostwald M
Published: November 2004

The rumen fluid volume in sheep was measured by the method of phenol red dilution. Serial determinations made in 22 sheep deprived of food and water for up to 8 days showed that the greatest decrease in rumen fluid volume occurred during the first 2–3 days, the magnitude of the decrease depending on the initial volume. After the third day, the rate of loss of rumen fluid became slower as the rumen fluid volume became depleted. Sheep deprived of food only gave similar results to those deprived of both food and water. This absorption of rumen fluid during the first 2–3 days of food and water deprivation may account for the expansion of plasma volume which has been recorded on the third day. In a group of eight sheep deprived of food and water for 4 days, the mean rumen volume loss for the period amounted to about half the body weight loss. These results support the view that in the sheep, the water balance of the body proper is kept virtually unaltered by fluid drawn from the alimentary tract during the first days of water deprivation. The animal does not become dehydrated, in the physiological sense, until this reserve is depleted. For this reason, the rumen may be regarded as a water "store" in sheep.
The effect of sucrose on the utilization of straw plus urea diets by sheep
Authors: Faichney GJ
Published: November 2004

An experiment was carried out on sheep to investigate the effect of supplementary energy, in the form of sucrose, on the intake and utilization of a diet of oat straw supplemented with urea. The sucrose supplement had no significant effect on the dry matter intake, although there was a tendency for the intake of straw to decline with an increase in the sucrose supplement. There was no significant effect on the digestibility of dry matter or crude fibre, but the digestibility of crude fibre tended to decrease when the sucrose supplements were fed. This may explain an increase in faecal nitrogen excretion, which was reflected in a significant (P < 0.05) decrease in the apparent digestibility of nitrogen on the diets supplemented with sucrose. There were no significant differences between the diets in rate of passage, rate of cellulose digestion in the rumen, nitrogen balance, body weight gain, rumen pH, or concentrations of volatile fatty acids and ammonia nitrogen in the rumen. It was concluded that the lack of a supplement of readily available energy was not a limiting factor in the sheep's utilization of the diets used.
Pigmentation of sheep. I. Inheritance of pigmented wool in the Merino
Authors: Brooker MG , Dolling CHS
Published: November 2004

The results of a series of matings are presented which demonstrate that the presence of black or grey wool in a group of medium-wool Merinos, except in sheep with a certain pattern of pigmentation, is due to the action of a single recessive gene, w. The allele, W, for white wool appears to be a complete dominant. The exceptional phenotype is that of animals with a small discrete area of black or grey wool in an otherwise white fleece. Possible genotypes of this class of pigmented sheep are discussed.
Laboratory ensilage of Setaria sphacelata (Nandi) and Chloris gayana (C.P.I. 16144)
Authors: Catchpoole VR
Published: November 2004

The ensilage of two harvests of Setaria sphacelata (Nandi) and Chloris gayana (C.P.I. 16144) with and without added sucrose has been examined in laboratory silos. Without added sucrose, second harvest S. sphacelata and both harvests of C. gayana produced "acetic acid" silage. With added sucrose, and in spite of rapid initial acidification to pH c. 3.8, material from these harvests tended to produce "butyric acid" silage. First harvest S. sphacelata, both with and without sucrose, produced wellpreserved silage. The reasons for this are not obvious, but may hold the key to successful ensilage of this grass.
Some effects of cultivation and waterlogging on the availability of phosphorus in pasture soils
Authors: Williams CH , Simpson JR
Published: November 2004

Compared with growth on undisturbed soil, uniform mixing of the surface 4 in. of pasture soils caused a decrease in the yield of subterranean clover grown in pot culture. This was shown to be due to lowered availability of the soil phosphorus and was probably brought about by sorption of the available phosphorus, which had accumulated at the soil surface, by the unsaturated subsurface soil. Short periods of waterlogging (1–2 days) also brought about lowered availability of soil phosphorus. This occurred both with undisturbed soil cores and with mixed soils, but was much more severe when the soil was mixed. The effect appeared to be due to the conversion of phosphate to non-available forms during the short period of anaerobic conditions. The phosphate sorption capacity of the soil was increased by the waterlogging treatment but decreased to its original value when the soil was air-dried.