bluuebunny/crossref_metadata_2025 huggingface dataset:
The photosynthetic capacity of stubble leaves and their contribution to growth of the lucerne plant after low level cutting
Authors: Hodgkinson KC , Smith NG , Miles GE
Published: November 2004

The net carbon dioxide exchange rate (NCE) of lucerne (Medicago sativa cv. Hunter River) stubble leaves was found to be low (c. 55 ng CO2 cm-2 sec-1) immediately after removing shoots 15 cm above the stem base. However, within several days the NCE rose to a maximum of 130 ng CO2 cm-2 sec-1 on day 8. This peak rate was similar to that of recently expanded new leaves and held for about 3 days before declining. Leaves of similar age and position on uncut plants showed a steady decline in NCE. Leaf resistance, r'l, was low (c. 0.8 sec cm-1) and did not change as the NCE increased during the first 8 days. Mesophyll resistance, r'm, to carbon dioxide diffusion was initially high and declined from c. 9 to 2 sec cm-1 during this period. Comparison of dry weight changes of plant parts after stubble leaves were either retained or removed suggested that the tap-root benefited most by stubble leaf retention. The contribution to new shoots from stubble leaves appeared to be slight. However, when stubble leaves were exposed to 14CO2 on day 11, photosynthate was mainly exported into the shoot arising from the axil of the exposed leaf. This suggests that stubble leaves substitute, in part or completely, for the supply of carbohydrate to stubble shoots normally derived from reserves mobilized in the tap-root. The likely causes of rejuvenation in NCE of stubble leaves after partial shoot removal are discussed along with the significance of this photosynthetic contribution to regrowth of the lucerne plant.
Nodulation and frequencies of wild leguminous species in the northern Negev region of Israel
Authors: Hely FW , Ofer I
Published: November 2004

(1) The nodulation by Rhizobiurn of Old World leguminous range species occurring naturally under semi-desert conditions on soils of medium and lower fertility was assessed for reference to comparable areas in southern Australia and in connection with the development of ley farming practices in dry marginal wheat areas of the Middle East. (2) Nodules were present on all 33 legumes found on three soil associations in a transition zone between the Mediterranean and Irano-Turanian plant geographical territories. All species showed evidence of symbiotic nitrogen fixation; there was great variation between species in that some were uniformly well nodulated, but others were nodulated sparsely and at a low level of effectiveness. (3) In terms of amount and apparent effectiveness of nodulation per plant in spring, species of Lathyrus, Pisum, and Vicia were outstandingly good. A species each of Hymenocarpos and Lotus were well nodulated, and intermediate degrees of nodulation characterized species of Hedysarum, Hippocrepis, another Lotus, Medicago, Onobrychis, Scorpiurus, Trifolium, and Trigonella. Four species of Astragalus, one of Coronilla, and two of Ononis were poorly nodulated in the natural state on these lands. (4) Plants of Trigonella arabica Del. were present at greatest frequency over the three soil associations but species of Trifolium and Medicago were minor components. In terms of volume of active nodule tissue, however, Hymenocarpos circinnatus (L.) Savi was rated best over all soils; Onobrychis crista-galli(L.) Lam. was prominent in this respect in the most arid places.
Comparisons of body composition and energy utilization between Merino and fixed halfbred (Border Leicester × Merino) wethers
Authors: Searle TW , Graham NM
Published: November 2004

Merino and halfbred weaner sheep were fed ad libitum for 6 months and food intake recorded; some animals of each breed were given a roughage-concentrate mixture and others were given a wholly roughage diet. The chemical composition of the body was determined from time to time. The halfbred animals ate more of each diet and grew faster than the Mennos. The Merinos became progressively fatter, weight for weight, than the halfbreds; fatness was not affected by diet per se. There was no detectable difference between the breeds in energetic efficiency. Prediction of the energy content of the body from tritiated water space measured in vivo gave similar results to carcass analysis.
Nutritional status and intake regulation in sheep. VII.* Control of voluntary intake of three diets and the responses to intraruminal feeding
Authors: Egan AR
Published: November 2004

In six experiments, sheep were fed ad libitum on either chopped lucerne hay, chopped wheaten straw, or a ground, pelleted lucerne hay/barley diet. On each diet either the dietary material itself, a more highly digestible material, or sawdust was introduced per fistulam into the reticulorumen in amounts equal to c. 25% of the normal daily intake by weight. For each diet, with intraruminal additions on a single occasion only, the most accurate adjustments of oral intake on a weight or a digestible energy basis were observed when the diet itself was added. On the pellet diet, reduction of oral intake was most rapid and of greater magnitude when materials of high digestibility were introduced, though intake was also reduced when sawdust was introduced. On the chopped lucerne hay diet and on the chopped wheaten straw diet, oral intake was depressed more after the introduction of materials of lower digestibility. When pellets were introduced into animals fed on chopped wheaten straw, oral intake was at first reduced but subsequently increased, which indicated an interaction between the basal diet and the supplement. In longer-term experiments, daily introduction per fistularn of the dietary material at c. 25% of the mean daily intake resulted in a rapid decrease in oral intake of each diet. The decreases in intake, expressed as a percentage of the weight of diet added per fistulam (response index), were 95–115% (pellets), 60–80% (lucerne hay), and 76–104% (wheaten straw), and generally became greater with time. With the pellet diet, trends in intake with time showed an increasingly greater adjustment to materials of high digestibility, and an apparent accommodation or compensation for imposition of a load of indigestible material. Such compensation for indigestible material was not apparent on the two all-roughage diets. Introduction of lucerne/barley pellets into the rumen of sheep fed on chopped wheaten straw resulted in no change, or a slight increase, in straw consumption, and an overall increase in intake of digestible dry matter. In two further experiments a bladder, expanded with water to volumes of 1,2, or 3 litres, caused significant decreases in intake of both the pellet diet and the chopped wheaten straw diet, effects being more rapid and more drastic in the case of the wheaten straw diet. Although there was subsequently a partial recovery of oral intake with the pellet diet, no such apparent compensation occurred with the wheaten straw diet. The results indicate that sensitivity to indigestible material can limit the intake of roughage even though the digesta content of the reticulorumen is not at a maximum, and confirm that important relationships exist between the nutritive value of the diet or nutritional status of the animal and the ability to accommodate indigestible material.

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*Part VI, Aust. J. Agric. Res., 21: 735 (1970).
Effect of pre- and post- natal nutrition on the growth of beef cattle I. The effect of nutrition and parity of the dam on calf birth weight
Authors: Tudor GD
Published: November 2004

The influence of submaintenance (low plane) nutrition during the last trimester of pregnancy, and parity of the dam, on calf birth weight was studied in Hereford cows.The submaintenance ration (3.5 kg Rhodes grass hay per head per day) significantly (P < 0.01) reduced the mean calf birth weight by 6.8 kg to 24 1 kg, and the mean length of gestation by 5.4 days to 277.3 days, compared with an above-maintenance (high plane) ration (3.5 kg each of Rhodes grass hay and barley grain per head per day). Dam nutrition, however, did not influence the number of retained placentae, calf mortality, or the incidence of dystocias. Dam parity did not significantly influence calf birth weight or length of gestation, but significantly (P < 0.05) reduced the number of retained placentae of second parity cows. There were no significant differences between sexes in mean birth weight or mean gestation length. The regression of calf birth weight on dam weight just prior to calving was significant (P < 0.05) for high plane cows: y = 20.248 + 0.023x, r = 0.40. The regression of calf birth weight on length of gestation was significant for both high(P < 0.05) and low(P < 0.01) plane cows: y = –28.343 + 0.210x, r = 0.40, and y = -41.015 + 0.235x, r = 0.42 respectively.
Herbage reponse to tree and shrub thinning in Eucalyptus populnea shrub woodlands
Authors: Walker J , Moore RM , Robertson JA
Published: November 2004

Effects of tree and shrub densities on production of native grasses and herbs in woodlands dominated by Eucalyptus populnea were investigated in two experiments. Densities were controlled experimentally by selectively killing individual trees and shrubs with chemical compounds. In an experiment in which girdling or ring barking was compared with chemical treatment, the herbage response was more rapid and of greater magnitude on plots treated chemically. Throughout the experiment the herbage biomass was always highest on chemically treated and lowest on untreated plots. The highest dry weight of herbage from areas in which trees were chemically treated was 2600 kg/ha; comparable yields from ring barked and untreated areas were 1540 and 820 kg/ha respectively. In a second experiment, living trees and shrubs were reduced to several density levels by chemical thinning. Herbage biomass fluctuated with season and with rainfall, but the relationship between herbage weight and woody plant density consistently had the same form and closely fitted a transition sigmoid curve. Trees had a greater effect than shrubs on herbage production: limits for maximum herbage biomass were 2–6 and 360 per hectare respectively. Practical implications of the findings for the management of E. populnea woodlands are discussed.
The fertility of Merino ewes artificially inseminated with semen diluted in solutions based on skim milk, glucose or ribose
Authors: Lapwood KR , Martin ICA , Entwistle KW
Published: November 2004

The fertility of Merino ewes artificially inseminated with semen diluted tenfold in milk or buffered glucose solution was lower than that of a control group of ewes inseminated with the same number of spermatozoa in undiluted semen. By means of centrifugation, the concentration of spermatozoa in the insemination dose of diluted semen was raised to match that of the undiluted semen and then the effect of dilution on fertility was eliminated for the glucose-diluted semen, but not for the milk-diluted semen. Respective percentages of ewes not returning to oestrus and ewes lambing were, after insemination with undiluted semen, 60.5, 46.7; with milk-diluted semen, 55.9, 40.2 and after reconcentration 56.0, 38.0; with glucose-diluted semen, 48.2, 35.3, and after reconcentration 62.1, 46.1. In another experiment, the percentage of ewes lambing after insemination with undiluted semen, with semen diluted tenfold with glucose, and with semen diluted with a ribose mixture and chilled at 5°C for 24 hr were respectively 67.0, 58.0, and 26.1. Both diluents contained 6% (v/v) egg yolk and diluted semen samples were reconcentrated to the original sperm density of the semen immediately before insemination.
Variation in burr burial ability in subterranean clover
Authors: Francis CM , Quinlivan BJ , Nicol HI
Published: November 2004

A simple technique for the measurement of burr burial capacity in subterranean clover (Trifolium subterraneum) is described. The technique is based on the ability of the peduncles to penetrate and form burr below a standard polyethylene mesh.Highly significant variations in degree of penetration occurred between and within subspecies, with subsp. subterraneum > yanninicum > brachycalycinum. Cultivar differences were also strongly correlated with maturity grading, earlier-maturing cultivars showing a greater degree of penetration.
The effect of diet and heat stress on feed intake, growth, and nitrogen metabolism in Friesian, F1 Brahman × Friesian, and Brahman heifers
Authors: Colditz PJ , Kellaway RC
Published: November 2004

Four Friesian, four F1 Brahman x Friesian, and four Brahman heifers were fed on high and low quality diets in controlled environment rooms. Feed intake, growth, and nitrogen metabolism were assessed during four periods of 28 days when the animals were either subjected to heat stress (38°C) or maintained under cool ambient conditions (17°).Brahman x Friesian animals were the superior genotype only under heat stress. At 17°C the feed intake and growth rate of Friesians and Brahman x Friesians were similar. At 38° the Brahman x Friesians ate more and grew faster than the Friesians. Brahmans ate less than the Brahman x Friesians at both temperatures and grew more slowly than them at 38°. Water intake per kilogram dry matter intake was greater for the Friesians than for the other two genotypes at 17 and 38°C. Rectal temperatures and respiration rates increased between 17 and 38°C; the change was greatest for the Friesians and least for the Brahmans. These responses were not significantly correlated with feed intake or growth rate. On the high quality diet the digestibilities of dry matter and nitrogen were similar between genotypes. On the low quality diet they were higher for Friesians than for the other two genotypes, although this was confounded with differences in intake. The utilization of digested nitrogen differed between diets but was similar for the three genotypes within diets. The concentration of plasma creatinine was higher in Brahmans than in the other two genotypes. Creatinine excretion per unit of liveweight was greater at 38° than at 17°C for Friesians and Brahman x Friesians.
Clinically silent hypocuprosis and the effect of molybdenum loading on beef calves in Gippsland, Victoria
Authors: Bingley JB , Anderson N
Published: November 2004

Whole blood and liver copper concentrations of less than 0.5 µg per ml and 6 p.p.m. dry weight respectively were found in healthy beef calves from an acid soil region at Koonwarra in Victoria. Pasture samples collected each month for a year contained 2.4–6.7 p.p.m. dry weight of copper, 2.1–9.2 p.p.m, dry weight of molybdenum, and 0.07–0.47% dry weight of sulphate. The copper/molybdenum ratio was usually well below 2.0.Changes in the copper status of the cattle were related to seasonal fluctuations in the copper and molybdenum contents of the pastures. A macrocytic hypochromic anaemia was found in hypocuprotic calves. However, pallor of the mucous membranes was not observed and there was no relationship between coat colour and copper concentration of either hair or whole blood. The subcutaneous injection of 120 mg copper as glycinate raised the concentration of copper in the whole blood and liver of calves to c. 0.8 µg/ml and up to 50 p.p.m. dry weight respectively. Growth rates of calves given copper improved significantly and their carcass weights were 8.4% heavier than controls. In this environment the effects of a single treatment with copper glycinate lasted only 5 months. Although liver copper contents ranged from below 5 to above 70 p.p.m. dry weight, the copper contents of other tissues examined, such as kidney, spleen, heart, and bones, were similar whether the animals had received additional copper or molybdenum or neither. At the levels of molybdenum found in the pastures (2–9 p.p.m. dry weight) the synthesis of ceruloplasmin was readily decreased, whereas erythrocyte copper decreased more slowly. Therefore the estimation of ceruloplasmin oxidase activity in plasma is suggested as a reliable and convenient means of assessing bovine hypocuprosis. The regression analyses showed a strongly positive correlation (r = 0.97) of plasma copper with ceruloplasmin oxidase activity as determined with p-phenylenediamine as substrate at the optimal pH. Special molybdenum pellets given to the calves augmented the tissue levels of molybdenum tenfold, but copper depletion did not occur to the point where clinical signs of copper deficiency or of molybdenosis appeared. In contrast to calves with large copper reserves, the mitochondria1 fraction of liver cells from hypocuprotic calves was found to contain more and the microsomal fraction less of the total liver copper. Because of the complex relationships between soil, pasture, and animals, it is concluded that a general recommendation for the minimum copper requirement of grazing cattle cannot reasonably be made without reference to soil and pasture concentrations of copper, molybdenum, and sulphate.
The influence of rotation systems on long-term trends in wheat yield
Authors: Elliott BR , Jardine R
Published: November 2004

The wheat yield trends of six rotation systems were examined over the 29-year period 1940-1968. The multiple regression model used incorporated variables to minimize the effect of climatic fluctuations and trends. All the rotation systems examined showed positive, almost linear, yield increases over the first 19 years (1940-1958). Over the final 10 years (1959-1968) those systems including a pasture phase continued to show a linear yield increase; other three-course systems (fallow, wheat, stubble crop) showed a less than linear yield increase; while the two-course system (fallow, wheat) showed a 22% yield decline. Possible factors influencing the yield trends are briefly discussed.
A numerical classification of Cajanus cajan (L.) Millsp. accessions based on morphological and agronomic attributes
Authors: Akinola JO , Whiteman PC
Published: November 2004

Ninety-five accessions of Cajanus cajan from 11 countries were field-gown and studied throughout a year at Redland Bay, south-east Queensland. By using the MULTCLAS hierarchical program and the Euclidean system according to Burr (1970) the accessions were classified into 15 groups. Thirty-one attributes were used, including plant and leaf morphology, growth, flowering patterns, disease tolerance, and components of seed yield. Hardseededness and an unusual inflorescence formation pattern, not previously reported in pigeon peas, were recorded. Agronomically important attributes and their implications are discussed.
Liveweight and wool growth of sheep in response to the quantity and botanical composition of annual pasture induced by nitrogen fertilizer and stocking treatments
Authors: Davies HL , Greenwood EAN
Published: November 2004

For five years, three rates of ammonium sulphate (N0, N1, and N3: 0, 280, and 840 kg/ha/year) were applied as a split dressing to ,a pasture of Bromus mollis L. and Trifolium subterraneum L. which was continuously grazed by wethers set-stocked at 8.6 and 12.4 sheep/ha. The N0 treatment produced clover dominance, N1 a mixed sward, and N3 grass dominance. The higher stocking rate increased the proportion of clover in the mixed sward. These differences in botanical composition produced three significant effects on the relation between liveweight gain and quantity of green pasture on offer. An increase in the proportion of clover in the sward increased: (1) the quantity of herbage dry matter on offer required for liveweight maintenance; (2) the maximum rate of liveweight gain; (3) the quantity of dry matter on offer at the point of 90% maximum liveweight gain. Regressions of those three parameters on botanical composition accounted for over 90% of the variance. The effects of treatments on liveweight at other times of the year are also described. In the first year of grazing ammonium sulphate increased liveweight, apparently because of increased pasture on offer after emergence. In subsequent years the effect of ammonium sulphate was reversed: liveweight was reduced, and this was associated with lower nitrogen concentrations in, and lower quantities of, herbage produced. Wool elongation rates were greatest in spring and lowest prior to the germinating rains in autumn. Elongation rate was unaffected by stocking rate and only slightly affected by ammonium sulphate. From January to April, greatest elongation occurred on the grass-dominant N3 paddocks; from May to December greatest elongation occurred on the clover-dominant N0 paddocks. The implications of the role of nitrogen fertilizer in relation to sheep production in the winter rainfall regions of Australia are discussed.
Regrowth and flowering in sweet orange after pruning
Authors: Moss GI
Published: November 2004

Sweet orange trees, cv. Late Valencia, 6 m in height were moderately pruned in the spring of 1969, up to 8 % of the canopy being removed. Over 2 years, three or four growth cycles were completed. The amount of regrowth was correlated with the size of the first growth cycle flush after pruning, and this was correlated with the diameter of the pruned branch. No flowers were found on regrowths 1 year after pruning; only 75% of regrowths produced flowers 2 years after pruning, and only 50 % produced fruit. Small plants (rooted cuttings) were used to investigate pruning responses in the phytotron. Low temperatures (18/13�C) immediately after pruning for 8 weeks resulted in smaller first growth cycle flushes after pruning, and even after transfer to warm (27/22�) conditions the original height was not regained after three growth cycles. Plants that received cool conditions after the first or second growth cycles regained their original height after the third growth cycle. The amount of regrowth was correlated with the length of the first growth cycle flushes, which was correlated with the original height of the plants and the height after pruning. Flowers could not be induced on the old wood after pruning or on the first growth cycle flushes, and only few flowers were formed in the second growth cycle flushes. Many inflorescences were produced on third growth cycle flushes following inductive conditions (18/13�C) for 8 weeks. Light pruning of less vigorous plants did not inhibit subsequent flowering. The practical implications of this work are discussed. Moderate pruning will remove part of two crops, not one, because of the inability of regrowth flushes to flower until several growth cycles have formed. The tree relatively quickly replaces the growth removed, and this depends on the vigour of the first growth cycle flushes after pruning. Pruning in autumn or winter would be expected to result in less vigorous regrowth. Our lack of knowledge on the pruning responses of orange trees is emphasized, with suggestions for future practical investigations.
Effects of protein and energy intakes on the wool growth of Merino wethers
Authors: Black JL , Robards GE , Thomas R
Published: November 2004

The results of an experiment are presented which show that the supply of both protein and energy to the small intestine of adult sheep affects the rate of wool growth, and that the direction and magnitude of the response to energy absorption is dependent upon the particular level of protein given. Thirty fine-wool Merino wethers received their entire diets, which consisted of reconstituted spray-dried cow's milk, sodium caseinate, glucose, butterfat, and micronutrients, by direct abomasal infusion in an experiment consisting of two parts. In part I the effect of protein intake (20,40, 60, 80, or 100 g/day) at constant energy intake (5.02 MJ/day) was investigated, while in part II the effect of energy intake (3.01, 4.02, 5.02,7.53, or 10.04 MJ/day) at three levels of protein intake (20, 60, or 100 g/day) was studied. A nitrogen balance trial was conducted with selected animals during 7 days near the end of each part of the experiment. In part I, as the daily intake of protein was increased from 20 to 80 g, the wool growth rate increased almost linearly from 2.3 to 9.0 g/sheep/day. With a further rise in protein intake to 100 g/day the mean value fell to 8 .O g/sheep/day. The overall trend in wool growth with increasing protein intake was significantly quadratic. In part II, for sheep receiving 100 g protein/day, an increase in energy intake from 3.01 to 10.04 MJ/day caused a highly significant, linear rise in wool growth rate of 52 %. For animals receiving 60 g protein/day, wool growth rate tended to increase at first and then fell again as energy intake was raised from 3.01 to 10.04 MJ/day, but the differences were not significant. When sheep were given only 20 g protein/day, an increase in energy intake from 3.01 to 10.04 MJ/day resulted in a decline in wool growth rate of 45 %. The results suggest that there is an optimum ratio of protein to energy absorption required for maximum wool growth in sheep. If protein is limiting, an increase in protein absorption stimulates wool growth, but an increase in energy absorption reduces it. Conversely, if protein is in excess an increase in protein absorption reduces wool growth, but it is stimulated by an increase in energy absorption. The practical significance of the results is discussed.
The influence of aerial environment, nitrogen supply, and ontogenetical changes on the chemical composition and digestibility of Panicum maximum Jacq. var. trichoglume Eyles
Authors: Wilson JR
Published: November 2004

The effect of aerial environment and nitrogensupply on the chemical composition and in vitvo digestibility of a tropical grass was studied by comparing plants of Panicum maximum var. tvichoglume grown in pots either outdoors or in an humidified glasshouse. Plants from the two environments were similar in their percentage content of protein and cell wall materials. Young tissue from the outdoor plants was more digestible than material from the glasshouse, but the digestibility of this material was nevertheless very high in all plants. Thus, it appears that the unusually high nitrogen percentages and digestibilities which have been recorded for tropical grasses in laboratory studies by comparison with field-grown material may not be directly associated with differences in the aerial environment. This point remains to be conclusively tested under precisely controlled conditions. Increase in nitrogen supply from low to moderate levels increased digestibility by 3-5 percentage units, and had a small positive effect on the percentage of total soluble carbohydrates. Very high nitrogen supply lowered the soluble carbohydrate content of the plant tops. There was an inverse relation between tissue nitrogen concentration and the content of cell wall material. The amount of cell wall material increased progressively from the earlier- to the later-formed leaves on a tiller. When compared at a similar age, later-formed leaves tended to be less digestible. This influence of leaf position on nutritive quality is very interesting and warrants further investigation.
The control of slender thistle, Carduus pycnocephalus L. and C. tenuiflorus Curt. (Compositae), in pasture by grazing management
Authors: Bendall GM
Published: November 2004

The effect of grazing management on slender thistle populations and botanical composition of improved pasture was studied in two field trials in southern Tasmania. Deferring grazing until winter or spring reduced slender thistle populations in both trials. The reasons underlying these observations are discussed. Spring grazing favourably altered pasture botanical composition by increasing the frequency of perennial ryegrass and subterranean clover and reducing the frequency of weed grasses. These changes arc discussed in relation to thistle control. It is suggested that deferred autumn grazing may be incorporated into the farm programme as an economical method for the control of slender thistle in pasture.
Lucerne in wet soils — the effect of stage of regrowth, cultivar, air temperature and root temperature
Authors: Cameron DG
Published: November 2004

Hunter River lucerne grown in pots, was subjected to either 21°C or 33°C constant temperatures for the first 10 days of regrowth. At 33°C, flooding immediately after cutting killed 85% of the plants. Flooding 5 days after cutting killed 35% of the plants. Even when plants were not killed by flooding at 33°C they were severely checked, and made negligible regrowth during the next 30 days. At 21°C no plants were killed by flooding. Plants flooded immediately after cutting were severely checked but those flooded 5 days after cutting were similar to the unflooded controls. Hunter River lucerne flooded under all combinations of 20°C and 30°C air and root temperatures for the first 5 days after cutting was more severely affected at both root temperatures than Rhizoma and Lahontan lucernes. High root temperature during flooding had a severe effect on all cultivars, but high air temperatures did not affect flooding reaction. Possible mechanisms by which flooding damage occurs are discussed.
Factors influencing infection, colonization and symptom expression in barley by Rhynchosporium secalis
Authors: Ali SM
Published: November 2004

Germ tube growth and mycelium establishment of Rhynchosporium secalis, the causal agent of scald in barley, were studied in seven resistant and four susceptible barley hosts of known genotype. Although no visible symptoms were apparent, none of the resistant hosts were free from mycelium establishment in leaf tissue. The resistant hosts could be divided into two categories according to the rate of germ tube growth. The effect of host age, duration of incubation period, temperature, spore concentration, and pathogen age on symptom expression in the 11 genotypes was examined. Excluding the effects of temperature, the resistant genotypes could be grouped into (a) those expressing their resistance consistently, e.g. Psaknon, Atlas 46, Atlas 57, Hudson and Turk, and (b) those expressing their resistance inconsistently, e.g. West China and La Mesita. High temperature caused breakdown of resistance in Psaknon, Turk, Hudson and West China. The pathogenicity of one isolate (UWA307) was found to be impaired by high temperature. Implications of the above findings are discussed in relation to the disease situation in Western Australia.
The relative importance of sources of variation in fibre diameter for Australian Merino sheep
Authors: Dunlop AA , McMahon PR
Published: November 2004

Variation in fibre diameter was estimated in five Merino strains under the headings: between sheep; between sites over the body of the sheep; between fibres within sites; and between points along the fibre. The variation between fibres constitutes some two-thirds of the total, and that between sheep, on which the classer can operate, is about one-fifth. By means of correlations between crimps per inch and fibre diameter together with selection differentials, the differences in fibre diameter which a classer is likely to achieve in making clips into two and three lines respectively were estimated. These were less than 1 µm in all cases. Between-line variances computed on the basis of these between-line ' differences in fibre diameter will reduce the total variance within a resulting line by fractions that are always less than 2%. It is concluded that the elimination of crimp-based classing should not produce bulk wools that are unacceptable on the basis of variation in fibre diameter.
The effect of inoculation of seed with antagonists of Rhizoctonia solani on the growth of wheat
Authors: Merriman PR , Price RD , Baker KF
Published: November 2004

Biological control of Rhizoctonia solani on wheat by seed inoculation with microorganisms was investigated. Initially inoculants were selected from bacteria and actinomycetes isolated from two soils and screened for antagonism to R. solani on agar. Of 148 isolates tested on agar, 96 were antagonistic to R. solani and of these 42 were added to pasteurized soil sown with peppers and inoculated with the pathogen. Seven isolates which controlled disease were screened further as seed inoculants of wheat in pasteurized and field soils inoculated with R. solani. Four inoculants, viz. Streptomyces griseus 2-A24 and three Bacillus subtilis isolates 1-B80, 1-B77 and 1-B68, significantly reduced symptoms caused by R. solani and also increased grain yield and dry matter of wheat. S. griseus 2-A24 and B. subtilis 1-B80 increased grain yield by 30% over controls. The magnitude of these differences suggests that biological control and growth stimulation are involved in yield increases.
Effect of seed inoculation with Bacillus subtilis and Streptomyces griseus on the growth of cereals and carrots
Authors: Merriman PR , Price RD , Kollmorgen JF , Piggott T , Ridge EH
Published: November 2004

The effect of Bacillus subtilis A13 and Streptomyces griseus 2-A24 on the yield of cereals and carrots was studied. The organisms, both antagonistic to Rhizoctonia solani, were applied individually to barley, oats and wheat for sowing at three sites with a known incidence of R. solani. Root disease was not effectively controlled, yet the seed treatments increased grain yield and dry matter production at one site, advanced time of heading at another site and increased tiller number at two sites. Evidence was obtained that the organisms persisted on pericarps in soil for 5 weeks after sowing. In subsequent trials application of B. subtilis and S. griseus in combination with a pellet treatment increased marketable yields of carrots by 48% and 15% respectively over controls. Addition of the organisms to seed without pelleting increased yields by 17% over controls. These results indicate a non-specific effect of B. subtilis and S. griseus, since they increased growth of plants belonging to two different families, the Gramineae and Umbelliferae, in different soils.
Competitive interaction of grasses with contrasting temperature responses and water stress tolerances
Authors: Harris W , Lazenby A
Published: November 2004

Lolium perenne (cv. Kangaroo Valley ryegrass), L. perenne x multiforum (cv. 'Grasslands Manawa' short rotation ryegrass), Phalaris tuberosa (cv. Australian Commercial),Festuca arundinacea (cv. Demeter) and Paspalum dilatatum were grown for 2 years in monoculture and two-species mixtures, under dryland and irrigated treatments at Armidale, N.S.W. Competition effects were described, with the use of diallel analysis. Early aggressivities were in the order L. perenne × multiflorum > L. perenne > F. arundinacea = P. tuberosa > P. dilatatum in both water treatments; subsequently, the aggressiveness of F. arundinacea, P. tuberosa and P. dilatatum increased relative to the ryegrasses (especially L. perenne), P. tuberosa (more so in the dryland treatment) and P. dilatatum (particularly in summer and autumn). Specifically high aggressivities of P. tuberosa towards P. dilatatum and P. dilatatum towards L. perenne were shown. Under dryland conditions, the P. tuberosa monoculture produced the highest yield in both years, differing markedly from L. perenne × multiforum in response to limited water availability. Under irrigation overall gains of yield were obtained by mixing grasses in the second year, the gains being significant for ryegrass-P. dilatatum mixtures. This response is related to the different growth potentials of the species in different seasons with the proviso that conditions such as water stress or excess suppression do not limit the expression of these potentials. Although P. dilatatum was of lower digestibility than the ryegrass, the difference was not sufficiently large to cancel the gain from mixing when expressed as digestible organic matter (DOM). An unsatisfactory feature of these mixtures was the depressive effect on winter yield of dormant P. dilatatum. By comparison, winter yield stimulation by mixing P. tuberosa and L. perenne, occurring when digestibilities were high, contributed to a significant gain of DOM yield by this mixture. Marked dominance of L. perenne × multiforum under dryland conditions, although appearing to assist the survival of this species in mixture, was detrimental in that by suppressing P. tuberosa, F. arundinacea and P. dilatatum, it restricted the potential of these species to produce in dryland conditions. There was evidence that F. arundinacea depressed yield in mixture, especially when associated with L. perenne.
The yield and quality of phalaris seed harvested prior to maturity
Authors: McWilliam JR , Schroeder HE
Published: November 2004

Harvesting inflorescences of phalaris earlier than 27–30 days after the onset of anthesis results in lighter seed with reduced viability and inferior seedling performance. Delaying the harvest improves the quality of the seed but causes a marked reduction in yield due to seed shattering. These results suggest that the widespread practice of cutting and windrowing, or direct heading of phalaris seed crops prior to maturity to reduce the effects of seed shattering, is contributing to a reduction in the yield and quality of the seed, and is at least partly responsible for the poor record of establishment of this species. Spraying inflorescences with a quick-setting plastic lacquer just prior to seed maturity reduces shattering and represents a promising technique to improve both the yield and quality of harvested seed.
Studies on Fusarium species associated with a field planting of 'pathogen-tested' potatoes
Authors: Chambers SC , Millington JR
Published: November 2004

Bacillus subtilis (isolate 1-B80) and Streptomyces griseus (isolate 2-A24), both antagonistic to Fusarium species, were applied to 'pathogen-tested' cuttings of the potato cultivars Kennebec and Sequoia, and to their potting soil, before transplanting to the field. No data were obtained to indicate that either microorganism reduced Fusarium infection of tubers from these transplants. However, the Fusarium population was significantly less at 70 days in soil proximal to Sequoia transplants treated with either microorganism, and to Kennebec transplants treated with S. griseus. Tuber yields were significantly greater from Sequoia, but not from Kennebec when treated with either microorganism. Six Fusarium species were isolated from infected tubers, F. oxysporum being the commonest. In most instances, infection was confined to one tuber per plant. There was no correlation between tuber infection and stem injury, nor between tuber infection and soil population. In the laboratory, the addition of B. subtilis and S. griseus to soil from the experimental site significantly reduced estimates of the Fusarium population for 70 and 140 days respectively.
The effect of infestation by Lolium rigidum Gaud. (annual ryegrass) on the yield of wheat
Authors: Smith DF , Levick GRT
Published: November 2004

The effect of ryegrass infestation on the grain yield of wheat was examined and related to a yield analysis equation. Up to the two-leaf stage, apparently through competition for nitrogen, the presence of ryegrass at quite a low density (450 plants per m²) reduced the capacity of wheat plants to produce laterals. Neither the later removal of ryegrass nor the addition of nitrogen overcame this setback. In fact, the results suggest that nitrogen addition would result in a further loss in yield, and that this would increase with increasing density of ryegrass. However, the presence of ryegrass up to the two-leaf stage did not affect grain number per head or grain size: such effects were entirely dependent on the presence of ryegrass during the reproductive stage.
Phosphorus homeostasis in sheep. I. Effects of ligation of parotid salivary ducts
Authors: Tomas FM , Somers M
Published: November 2004

The effects of bilateral parotid duct ligation upon calcium and phosphorus concentrations in blood plasma and upon phosphorus excretion in urine and faeces have been examined. Five Merino wethers were used, of which three were given a phosphorus-deficient diet (0.304 g phosphorus/day) and two a phosphorus-sufficient diet (1.454 g phosphorus/day) for 32 days prior to ligation of the parotid ducts. Blood samples were taken every 6 hours for 2 days before and 4 days after parotid duct ligation followed by less frequent sampling for a further 3 days. Parotid duct ligation caused an increase in plasma inorganic phosphorus levels after the first day in the phosphorus-supplemented sheep and in one of the deficient animals. Plasma calcium concentrations tended to be inversely related to plasma phosphorus levels and showed marked variations on the fourth day following duct ligation, coinciding with a sudden fall in plasma phosphorus levels of 30-50 %. Urinary phosphorus excretion in the phosphorus-sufficient animals was increased 20 to 50-fold following ligation and reached a peak of about 600 mg/day on the fourth day, but there was no significant change in phosphorus balance. Marked alterations in the daily urinary output of phosphorus tended to be associated with a change in plasma phosphorus levels in the reverse direction. Four of the sheep were re-examined 22 months after duct ligation and the elevated urinary output of phosphorus was found to have persisted in three of the four animals. It appears that there is a relationship between the salivary secretion of phosphorus to the gut and the urinary phosphorus excretion which contributes towards maintenance of the phosphorus homeostasis in sheep.
Phosphorus homeostasis in sheep. III.* Relationship between the amount of salivary phosphorus secreted and the quantities of phosphorus excreted via the urine and faeces
Authors: Tomas FM
Published: November 2004

The interrelationships between the urinary and faecal pathways for phosphorus excretion in sheep have been examined under conditions allowing direct proportional control of the major portion of endogenous phosphorus secretion to the gut which is contributed by the parotid salivary glands. Two rumen-fistulated Merino wethers were fitted with permanent bilateral re-entrant parotid duct cannulas which allowed continuous collection and return of parotid saliva. During experimental periods, a proportion of the phosphorus secreted by the parotid glands during control periods was returned to the rumen in artificial saliva, and the remaining quantity not returned in this manner was infused intravenously over a corresponding time period. Diversion of the secreted parotid salivary phosphorus from the rumen to the blood led to an increase in urinary phosphorus excretion which was proportional to the fractional amount of secreted phosphorus withheld from the rumen. Phosphorus balance remained unaltered, which indicated a virtual substitution between the two excretory pathways. The increased urinary excretion of phosphorus is attributed partly to increased plasma phosphorus levels and partly to a reduced efficiency of renal tubular reabsorption of phosphorus. No direct evidence for any hormonal action could be seen. The data show that the pathway of excretion of phosphorus can be determined quantitatively by the rate of endogenous phosphorus secretion into the gut. This mechanism is of fundamental importance among factors contributing to phosphorus homeostasis in sheep.

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*Part II, Aust. J. Agric. Res., 25: 485 (1974).
Effect of body condition on the intake of food by mature sheep
Authors: Donnelly JR , Davidson JL , Freer M
Published: November 2004

Mature Merino wethers were changed in liveweight by grazing treatments or by feeding in pens and their intake of food over the next 5 weeks was then measured at two levels of pasture availability or in pens. Of nine groups of six sheep with mean initial fleece-free liveweight of 33 kg, three groups were increased to 37 kg (389 MJ energy) in 6 weeks by grazing abundant pasture, another three were reduced to 28 kg (220 MJ) on sparse pasture, and those remaining were reduced to 30 kg (268 MJ) by restricted feeding in pens. The three groups from each treatment were then moved to abundant pasture, to sparse pasture or to pens where food was offered ad lib. Energy status, within the range imposed here, had no effect on the intake of pasture or on the time spent grazing; both of these variables depended solely on the herbage currently available. Nor did energy status affect food intake when sheep were removed from pasture and compared in pens with a standard food. Sheep moved from sparse pasture to abundant pasture gained at least as much liveweight, but only 20% as much energy as sheep in better condition because more of their gain was water. These results suggest that short-term changes in the body condition of mature grazing sheep will have no effect on their intake of food and that their subsequent changes in fasted liveweight may give a misleading impression of changes in energy status.
Effects of autumn on the induction of dormancy in apple and peach seedlings and their subsequent regrowth in spring
Authors: Nichols DG , Jones DL , Thompson WK
Published: November 2004

Apple and peach seedlings were grown for 8 weeks under various regimes: two photoperiods (16 and 8 hr), two air temperatures (12.8° and 18.3°C) and three root temperatures (12.8°, 18.3° and 23.9°C). After the leaves were removed the seedlings were chilled in the dark at 5.6° for three periods (apples 750, 1500 and 2500 hr; peaches 750, 1500 and 2000 hr) and then grown in a glasshouse for 7 weeks during which bud break and extension growth were measured. Growth of apple seedlings (cv. Granny Smith) stopped in an air temperature of 12.8� irrespective of photoperiod and root temperature. At 18.3° growth continued, but was retarded by short days and a root temperature of 12.8°. Peach seedlings (cv. Elberta) did not grow after any of the treatments. Extension growth and bud break in both species increased with increased hours of chilling. Pre-dormancy factors had no effect on bud break in apples, but low air temperature and short days prior to chilling increased bud break in peaches, although the effects decreased as chilling increased. Low pre-dormancy air temperature increased the growth of both species after chilling. Photoperiod produced opposite effects in the two species. Thus short days increased the growth of peaches while long days were effective with apples. Apples grew best at a root temperature of 12.8°, and peaches grew better at this temperature than at 18.3° but not as well as at 23.9°.
Effect of salt water ingestion on pregnancy in the ewe and on lamb survival
Authors: Potter BJ , McIntosh GH
Published: November 2004

The addition ot sodium chloride, to provide concentrations of 1.0 and 1.3?, to the drinking water of pregnant ewes caused distress at parturition to some of the ewes and neonatal mortalities in their lambs. The effects were more evident in older sheep (aged 7 years) than in younger (3-year-old) animals and were associated, in general, with ewes which carried twin lambs. Progesterone levels in the blood plasma of sheep were higher in twin-bearing ewes than in ewes with single lambs, both for control ewes drinking fresh water and for ewes drinking saline. Drinking 1.3% saline augmented the increase in progesterone levels in older ewes bearing twins. Cortisol levels were normal in all ewes.Plasma levels of potassium and chloride were significantly higher and calcium and magnesium levels lower in pregnant ewes which received saline.It is suggested that the adverse effects of salt water ingestion in twin-bearing pregnant ewes could be due to an excessive retention of potassium and chloride, brought about by a disturbance of normal sodium homeostatic mechanisms associated with the pregnant state of the animals.