bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between the diet selected by grazing sheep and the herbage on offer
Authors: Hamilton BA , Hutchinson KJ , Annis PC , Donnelly JB
Published: November 2004

Oesophageal extrusa samples were collected from sheep grazing monospecific swards of four temperate perennial grasses. The in vitro digestibility and the proportion of green plant material in the extrusa samples were related exponentially to the yield of herbage on offer. The digestibility of ingesta was highly correlated with the yield of green herbage. When the yield of green herbage exceeded c. 550 kg/ha the sheep selected a diet more digestible than the mean of the green plant material on offer, and when there were low amounts of green herbage available the ingesta was less digestible than the green plant material on offer because of the low proportion of green plant material eaten. A relationship between the proportion of green plant material in extrusa samples and the green herbage yield was determined for each species, and no significant difference in regressions between species was found. It is suggested that the pooled relationship obtained in this study may be used to predict the proportion of green plant material in the ingesta of sheep over a range of grass species and yields.
Assessing photosynthetic limitation to grain yield in a field crop
Authors: Gifford RM , Bremner PM , Jones DB
Published: November 2004

A method is proposed for assessing the degree to which the availability of photosynthate during grain filling limits the yield of a cereal ('source limitation'). The technique uses shading and carbon dioxide enrichment to alter photosynthesis after anthesis, and may be applied in the field. From only final dry weight determinations, the degree of source limitation of grain yield is quantified on a 0 to 1 scale by relating differences in grain weight to differences in plant weight. For a crop of barley (cv. Resibee) on which the method was tried, the degree of source limitation was about one-half, which suggested that for this particular crop neither the source nor the sink presented an overriding limitation to grain yield. This was so for four stands of the cultivar produced by different levels of shading and carbon dioxide enrichment before anthesis. A yield component analysis indicated that kernel weight was the major component changed by post-anthesis treatments. Pre-anthesis treatments, which also affected grain yield, mainly influenced the numbers of ears produced.
Effect of aluminium on the growth chemical composition of some tropical and temperate pasture legumes
Authors: Andrew CS , Johnson AD , Sandland RL
Published: November 2004

The effects of aluminium (0, 0.5, 1.0, 2.0 p.p.m.) on the dry matter production (tops and roots) and chemical composition of five tropical and six temperate pasture legumes grown in a cultu1.e solution containing 2 p.p.m. phosphorus were ascertained. The tolerances of the tropical species to aluminium were in the order Desmodiunz uncinatum = Macroptilium latlzyyuoides = Lotonis bainesii = Stylosanthes humilis = Glycine wightii > Medicago sativa, and temperate species in the order Trifolium rueppellianum= Trifolium sernipilosum > Trifolium repens = Medicago scutellata = Medicago truncatula = Medicago sativa. In the tolerant species the yield of plant material from the 0.5 p.p.m. aluminium treatment was greater than from the control. The top/root weight ratios of the tolerant species were unaffected by treatment; the ratios of the sensitive species were reduced. The effect of aluminium treatment on aluminium, nitrogen, phosphorus, potassium, calcium, magnesium, and sodium concentrations in the plants are given. The principal nutrients to be affected were calcium and phosphorus. Aluminium treatment reduced the calcium concentrations in the tops of all species and there were reciprocal relationships between calcium, magnesium, and potassium concentrations. In the sensitive species aluminium treatment reduced phosphorus in the plant tops and roots; in some of the tolerant species the intermediate aluminium treatment increased the phosphorus concentration in the plant tops; however, the high aluminium treatment reduced the phosphorus concentration.
The influence of aluminium on phosphate sorption by whole plants and excised roots of some pasture legumes
Authors: Andrew CS , Berg PJVanden
Published: November 2004

The effects of aluminium (0, 0.5, 1.0, and 2.0 p.p.m.) on dry matter production and subsequent short-term uptake and translocation of phosphorus in whole plants, and on the uptake of phosphorus by excised roots, of six tropical pasture legumes were ascertained. Macroptilium lathyroides, Desrnodiurn uncinaturn, Lotononis bainesii, and Stylosanthes hurnilis were tolerant species in terms of effects on dry matter production. Glycine wightii was a sensitive species and Medicago sativa a very sensitive one. In the whole plant study, plants were grown in Solution culture with a phosphorus concentration of 2 p.p.m., under the above aluminium treatments. Aluminium increased the subsequent uptake of phosphorus (tops+roots) in all species (phosphorus substrate concentration 1 x 10-5M labelled with 32P, 1 and 3 hr uptake periods). Phosphorus uptake in the tops of the four tolerant species was increased by aluminium treatment, and in the two sensitive species it uas reduced. In both the absence and presence of applied aluminium, L. bainesii was the most efficient species per unit weight of root tissue in sorbing total phosphorus, and in addition had the highest efficiency of translocation of phosphorus from roots to tops. S. humilis was also an efficient species. In the excised root study, addition of aluminium to the solution enhanced the sorption of phosphorus by all species. The enhancement was greater in a relatively strong phosphorus solution (2 x 10-4 M) than in a dilute solution (1 x 10-4). The sorption of phosphorus by excised roots of S. humilis from dilute and relatively strong phosphorus substrates was greater than that of other species, both in the absence and presence of added aluminium. L. bainesii was omitted from the excised root experiments.
Comparison of various methods of selecting parents for hybridization in common bread wheat (Triticum aestivum L.)
Authors: Bhatt GM
Published: November 2004

A study was conducted with the objective of rationalizing the method of choosing parents for hybridization in a wheat breeding programme aimed at yield improvement. The various systems of selecting parents included (a) conventional method, (b) random method, (c) multivariate analysis method, and (d) according to ecogeographic diversity. The relative merits of these systems was measured by (i) F2 hybrid bulk yield, (ii) means and variances of yield of F5 lines, and (iii) the number of useful transgressive segregates for yield detected in F5. The application of multivariate analysis method of selecting parents and effecting crosses between the parents representing high intergenotypic divergence appeared to be more efficient than the method of selecting parents according to ecogeographic diversity. The conventional and random methods were relatively less efficient.
Four strains of sugarcane mosaic virus infecting cereals and other grasses in Australia
Authors: Teakle DS , Grylls NE
Published: November 2004

Viruses of the sugar-cane mosaic virus (SCMV)-type were isolated from 23 naturally infected species of Gramineae in Queensland, New South Wales, or the Northern Territory. The virus isolates were placed in four groups or strains on the basis of host reactions. Each strain was named after an important perennial host, viz. (1) Johnson grass (Sorgltum halepense), (2) sugar-cane (Saccharum officinaruin), (3) sabi grass (Urochloa mosambicensis), and (4) Queensland blue couch grass (Digitaria didactyla). The strains could be distinguished on the basis of mosaic or necrotic reactions in Yates NK220Y and Atlas sorghums, on abi!ity to cause systemic infection of Johnson grass or sugar-cane, or local infection of French bean (Phaseolus vulgaris cv. Bountiful). This ability of the sabi grass strain to infect a dicotyledonous host is previously unreported for any strain of SCMV . All four virus strains had a normal particle length of 736�17 nm, but the variability in particle length was greater for the sugar-cane and Queensland blue couch grass strains than for the other two. The Johnson grass strain was only distantly serologicaliy related to the sugar-cane, sabi grass, and Queensland blue couch strains, but the latter three were very closely related amongst themselves. Five aphid species, Aphis craccivora, A. gossypii, Macrosiphum euphorbiae, Rhopalosiphum maidis, and R. padi mere shown to transmit at least one strain of SCMV. A. craccicora and R. maidis were each able to transit all four strains. The Johnson grass strain of SCMV is the major strain infecting maize and sorghum crops in Australia. It was probably the cause of the maize ringspot mottle disease first observed in 1948 and of the mosaic and necrotic diseases of Sorghum almum first observed in 1960. These early records and its distinctive host reactions and serological properties make it unlikely that it is z recent introduction to Australia.
Trichostrongylid infections of sheep in a winter rainfall region. II. Epizootiological studies in the western district of Victoria, 1967-68
Authors: Anderson N
Published: November 2004

Mean counts of O. circumcincta and Trichostrongylus spp. from groups of 'tracer' sheep ranged between 220 and 2150 per fortnight between June and October and were less than 100 per fortnight from November to February inclusive. O. circumcincta was more numerous than Trichostrongylus spp. The relatively low numbers of available larvae were attributed to the dry weather conditions in autumn which did not favour development and survival of the free-living stages. Between May and December 1967, worm numbers increased linearly in weaner sheep to reach mean levels of 14,000 without any detectable resistance to reinfection or significant decrease in liveweight gain or wool production. Correlations between mean plasma pepsinogen concentrations from weaner and adult sheep and 'tracer' worm burdens were significantly different; r = 0.37 and 0.47 for weaners and r = 0.8 for adult sheep. Thus the relationship between larval intake and abomasal damage as reflected by plasma pepsinogen concentrations is not a simple one. Mucosal damage is probably preceded by a hypersensitive state. Anthelmintic treatment, given in October and January, reduced the worm egg output of treated sheep to one-tenth that of untreated sheep for a period of 18 weeks between October and March.
The performance of calves given concentrate diets treated with formaldehyde
Authors: Faichney GJ , Davies HL
Published: November 2004

Five groups of Friesian bull calves were given concentrate diets containing 70 % barley in which low (12 %), medium (15 %), and high (19%) protein levels were obtained by varying the amount of peanut meal included. The effects of protein level and of formaldehyde treatment of the complete diet at the low and medium protein levels were studied in terms of liveweight gain, voluntary food consumption, digestibility of the diet, ammonia nitrogen in rumen fluid, and urea and a-amino nitrogen in blood plasma. Observations were begun when the calves reached 70 kg liveweight and continued until they reached 130 kg liveweight. The calves given the low protein diets grew more slowly than those given the higher protein diets. The calves given the high protein diet grew no better than those given the medium protein diets. Formaldehyde treatment was associated with an increase in the rate of liveweight gain of 9% (P = 0.11) at the low protein level but had practically no effect at the medium protein level. The treatment did not adversely affect voluntary food consumption but was associated with decreases in the digestibility of nitrogen and in rumen ammonia levels and small increases in plasma urea levels.
Heat tolerance of Brahman cross, buffalo, Banteng and Shorthorn steers during exposure to sun and as a result of exercise
Authors: Moran JB
Published: November 2004

Rectal temperatures, respiration rates, cutaneous evaporation rates, and skin temperatures were measured in Brahman cross, buffalo, Banteng, and Shorthorn steers exposed to sun at 31-32�C dry bulb and 40-46�C globe thermometer temperatures during April and September. The animals were also subjected to forced exercise lasting 45 minutes. The buffaloes were judged to be least heat tolerant in both stationary and exercise trials with the Shorthorns showing the second highest rectal temperatures as a result of the imposed heat stresses. The heat tolerance of Brahman crossbreds and Bantengs differed little in the stationary trials, but the latter species were more stressed by forced exercise. Cutaneous evaporation rates were higher in Bantengs than Brahman crosses, suggesting possible differences between these two species in their methods of heat dissipation. The buffaloes appeared to be least capable of increasing their cutaneous evaporation when under heat stress. The results are discussed in the light of existing knowledge about the differences between species with respect to heat dissipation, heat production, and resistance to heat uptake.
Effect of irrigation and defoliation on the herbage production and water use efficiency of four temperate pasture species
Authors: Johns GG , Lazenby A
Published: November 2004

Measurements were made over a 12-month period of the herbage production of both dryland and irrigated monoculture swards of four temperate pasture species under two defoliation regimes. By relating herbage production to the previously reported water use results for these swards, water use efficiencies (WUE) have been computed. Dryland clover produced 2000 kg/ha less herbage than did the dryland grasses, although it used a similar quantity of water. Consequently, the WUE of dryland clover was substantially less than that of the dryland grasses. Under dryland conditions, fescue not only produced more herbage, but also used water more efficiently than did the other species. Similar amounts of irrigation enabled the clover to yield an extra 6000 kg/ha of herbage compared with a mean grass response of 1760 kg/ha. The irrigated clover swards generally used water much more efficiently than the dryland clover swards. In contrast, the grasses generally used water with similar efficiency under both irrigated and dryland conditions. Under both irrigated and dryland conditions the frequently defoliated swards usually outyielded those cut infrequently as well as making more efficient use of water. The response of pastures to irrigation is discussed in terms of the effects of irrigation on the water status of the plants and the availability of nutrients in the rhizosphere.
The relationship between apparent retention time in the rumen, voluntary intake, and apparent digestibility of legume and grass diets in sheep
Authors: Thornton RF , Minson DJ
Published: November 2004

Eight grasses and six legumes were fed ad libitum at hourly intervals to wethers fitted with large rumen fistulas to determine voluntary intake, apparent digestibility, and the apparent retention time of organic matter in the rumen, as well as the quantity of rumen digesta and the organic matter content of the rumen digesta. The voluntary intake of legumes was 28% higher than that of equally digestible grasses. This difference was caused by a shorter retention time (17%) and a higher amount of organic matter (14%) in the rumen digesta from legume diets than from grass diets. The weight of wet digesta in the rumen of sheep fed on legumes was 7% lower than from those fed on grass. Neither the quantity of digesta nor the quantity of organic matter in the rumen was related to the voluntary intake, digestibility, or retention time of organic matter in the rumen. Number of jaw movements each day and rate of cotton thread digestion were not related to the retention time of the diets either. Daily intake of digestible organic matter (DOMI, g/day) was closely correlated with retention time (RTOM, hr) for the feeds in this study (r = –0.93) and the same relation applied to both temperate and tropical feeds, viz.
DOMI = 1276–50.7 RTOM (r=0.96)
Differences in voluntary intake between grasses and legumes were attributed to differences in retention time and the density to which the food was packed in the rumen.
Formaldehyde as a silage additive. II. The chemical composition and nutritive value of lucerne hay, lucerne silage, and formaldehyde and formic acid-treated lucerne silages
Authors: Valentine SC , Brown DC
Published: November 2004

Formaldehyde-treated silage, formic acid-treated silage, formaldehyde-formic acid-treated silage, untreated silage, and lucerne hay were made from a lucerne sward and offered to Merino wethers. The formaldehyde was applied at a rate of 0.9 % of the weight of the dry matter and formic acid at 0.5 % of the fresh weight of the lucerne. Formaldehyde-treated silage and formaldehyde-formic acid-treated silage had significantly lower concentrations of ammonia nitrogen and total and individual organic acids than untreated silage. Formic acid-treated silage had a similar degree of fermentation to untreated silage, but more acetic acid and less lactic acid were produced than in untreated silage. However, when formic acid was applied in combination with formaldehyde, the ensiling fermentation was inhibited more than when formaldehyde was applied alone. There was some apparent protection of protein by the formaldehyde treatment. Treatment with formic acid significantly increased the in vivo digestibility of both nitrogen and dry matter, but did not increase ad libitum intake or wool growth by sheep offered this silage. Compared to untreated silage, treatment with formaldehyde significantly reduced the in vivo digestibility of nitrogen, produced a non-significant increase in intake, and significantly increased wool growth. The treatment of lucerne with both formaldehyde and formic acid significantly increased in vivo digestibility of dry matter, ad libitum intake, and wool growth compared with untreated silage. The treatment of lucerne with a mixture of formaldehyde (0.9% of the dry matter) and formic acid (0.5% of the fresh weight) was a suitable method of controlling the ensiling fermentation in order to increase the ad libitum intake of lucerne silage by sheep and their subsequent wool production. However, the intake and wool production of sheep offered such silage was still significantly less than that of sheep offered lucerne hay.
Association of bacteria with sporangium formation and breakdown of sporangia in Phytophthora spp
Authors: Broadbent P , Baker KF
Published: November 2004

Leachates from different soils extracted at similar moisture potentials varied in their ability to induce sporangium formation, zoospore release and sporangium breakdown in Phytophthora spp. Sporangium production by P. cinnamomi did not occur in soil leachates heated at 40–50°C for 10 min or in soils treated with steam-air at 60° for 30 min. No evidence was obtained that Pseudomonas or Chromobacterium spp. were involved in the induction of sporangium formation. Chemotaxis of bacteria to sporangia occurred at zoospore release. Where sporangial breakdown occurred, the chemotaxis persisted for a longer period as the cytoplasm was withdrawn from the sporangial wall to be released eventually, without zoospore formation, through the papilla. The bacteria were oriented at right angles to the sporangial wall. Electron micrographs showed that in the vicinity of a bacterium, the outer, thin, electron-dense layer of the sporangial wall had disappeared and the cytoplasm of the sporangium had withdrawn from the cell wall.
The flow of calcium and phosphorus in the digestive tract of the sheep
Authors: Leibholz J
Published: November 2004

The flow of calcium and phosphorus to the proximal duodenum was measured over 22 24-hr periods in sheep fitted with re-entrant duodenal cannulae. The sheep were offered one of six diets in a ground and pelleted form supplying 1.4–30 g of nitrogen per day from three different protein sources. The estimated metabolizable energy content of the diets was 1.9 or 1.3 Mcal/kg. The diets supplied 2.0–5.8 g of calcium per day and 2.2–3.3 g of phosphorus per day. Between 49.9% and 61.2% of the dietary calcium intake appeared at the duodenum in the sheep given all diets except the one supplying 1.4 g of nitrogen per day, where the value was 98.5%. There were highly significant correlations between the daily calcium intake and the flow of calcium to the duodenum, the excretion of calcium in the faeces, the retention of calcium and the calcium content of the rumen. Between 85.0 and 119.1% of the daily phosphorus intake appeared at the duodenum in the sheep given all six diets. The flow of phosphorus was correlated with the dietary phosphorus intake. There were significant correlations between the flow of calcium and phosphorus to the duodenum and, also, their retention.
An ecological study of an attempt at biological control of Noogoora burr (Xanthium strumarium)
Authors: Wapshere AJ
Published: November 2004

The recent introduction of two cerambycids, Mecas saturnina and Nupserha vexator, for the biological control of Noogoora burr, Xanthium strumarium, a weed of sheep pastures in subtropical eastern Australia, has led to the development of a verbal model of the effect of these introductions on the populations of the weed. The model takes into account the dependence of X. strumarium on late spring and summer rainfall, the overwinter survival and germinability of the burrs, and the effect of plant density and growth conditions oil the number of stems and burr production per plant. The fact that only one cerambycid survives in each rootstock, no matter how many stems are attacked, and the small estimated reduction in burrs per plant produced by an individual cerambycid larva (15 for N. vexator, 35 for M. saturnina), indicated that successful biocontrol depended on high cerambycid populations. On taking into account the egg production of each cerambycid, it was concluded that, although high beetle populations could develop in dense, strongly growing X. strumarium stands in coastal and subcoastal regions, they would cause only minor reductions in plant density. They would be more effective against poorly growing stands and at sites with low overwinter burr survival, provided that stands occur consistently each year. These conclusions are dependent on the adaptability of the cerambycids to the climates of the Noogoora burr-infested region. a factor not considered.
The effect of sodium on potassium nutrition and ionic relations in Rhodes grass
Authors: Smith FW
Published: November 2004

The effects of sodium on the response of Rhodes grass (Chloris gayana) to potassium have been studied in pot trials. The amount of potassium required to achieve maximum growth was progressively reduced as the level of sodium application was increased from 0 to 400 mg per pot. The concentration of potassium in the tops of plants growing at 95% of maximum yield was also progressively reduced from 2.7% in plants not fertilized with sodium to 0.5% in plants receiving 400 mg sodium per pot. It is concluded that such interactions between the levels of major elements preclude the use of a 'critical potassium level' for diagnosing potassium deficiency in Rhodes grass. An alternative diagnostic scheme which takes account of interactions between some of the major elements is suggested. This scheme requires that plants would be adequately supplied with potassium if two criteria were met simultaneously: the potassium concentration was above the minimum specifically required (0.5% of the dry matter for Rhodes grass) and the cation-anion balance was above a minimum level characteristic for that particular species (800 m-equiv./kg dry weight for Rhodes grass).
Effects of temperature and day length on cytoplasmic male sterility in cotton (Gossypium)
Authors: Marshall DR , Thompson NJ , Nicholls GH , Patrick CM
Published: November 2004

Temperature and day length were shown to affect, to a major and minor degree respectively, the expression of male sterility in G. hirsutum stocks carrying G. anomalum or G. arboreum cytoplasms. Generally, sterility increased with increasing temperature and day length. Day temperatures above 33°C were required for the consistent expression of male sterility in the sterile A lines tested, while the maintainer, or B, lines became completely sterile at day temperatures above 36�. It was concluded that while the production of hybrid cotton seed by means of the sterile A lines currently available may be feasible in some tropical areas of Australia, it would be desirable to develop genotypes in which the cytoplasmic male sterile character is stable under a much wider set of temperature regimes.
The effect of formaldehyde treatment of a casein supplement on urea excretion and on digesta composition in sheep
Authors: Faichney GJ
Published: November 2004

The urinary excretion of urea, the fate of an intravenous dose of urea, overall nitrogen metabolism and the composition of rurnen and abomasal samples were studied in crossbred sheep given a basal roughage diet to which supplements of starch, casein or formaldehyde-treated casein were added. Urea excretion was closely related to plasma urea level (r = 0.935) and to the filtered load of urea (r = 0.957). The amount of urea reabsorbed by the kidney increased as'the amount filtered increased; the relationship was improved when values obtained at urine flow rates less than 1 rnl/rnin were omitted. When sheep were given the starch and treated casein diets, the rate at which they cleared a small dose of urea from their plasma was greater than the renal clearance rate; only 75% of a large dose was recovered in the urine. The capacity to dispose of exogenous urea by extra-renal pathways was apparent only when rumen ammonia nitrogen levels were less than about 200 mg/l. Formaldehyde treatment reduced nitrogen digestibility but reduced urine nitrogen excretion to a greater extent so that nitrogen retention increased. Treatment was associated with reduced plasma urea levels, reduced rumen and abomasal ammonia levels, reduced total VFA levels, increased proportions of acetic acid and decreased proportions of isobutyric, isovaleric and n-valeric acids, and more protein in abomasal contents.
Studies on frost injury to wheat. IV.* Freezing of ears after emergence from the leaf sheath
Authors: Single WV , Marcellos H
Published: November 2004

Internal and external factors which may influence the survival of emerged wheat ears during radiation frost were examined by a number of experiments in a freezing chamber. Hardening, stage of ear development, supercooling and cultivar were the internal factors studied in ears protected from external ice nucleation by enclosure within polyethylene bags. Neither hardening nor stage of ear development had any effect on freeze resistance. Spikelet survival was unaffected by supercooling. Variation in internal ear resistance was revealed among 16 cultivars frozen at –3.9°C. Removal of the cuticular wax coating over the unprotected ear reduced its ability to survive at –3°C in an atmosphere abundant in ice nuclei. This supports the proposal that hydrophobic wax coatings may be important in the field in protecting floral parts from external ice nucleation. The implications of these findings with respect to frost resistance in the field are discussed.

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*Part III, Aust. J. Agric. Res., 17: 601 (1966).
Effects of temperature on spikelet number of wheat
Authors: Halse NJ , Weir RN
Published: November 2004

The number of spikelets on the primary inflorescence of wheat was shown to vary with temperature per se in addition to any vernalization effects. Temperature affected spikelet number principally by influencing the rate and duration of appearance of primordia after floral initiation. However, in the absence of seed vernalization in cultivars responsive to vernalization, temperature also affected the number of spikelets arising from primordia already present on the apex at initiation. Maximum spikelet number resulted from intermediate temperatures which varied in 13.5-hr photoperiods from 10/5°C for Sunset to 22/17° for Mexico 120. There was an interaction with day length: most cultivars reached maximum spikelet number at lower temperatures in short days than in longer days. When the total amount of illumination was increased by providing a longer period of fluorescent light, spikelet number was increased with little interaction with other factors. The rate of appearance of primordia on the primary apex increased at the time of floral initiation.
Morphophysiological determinants of yield in rapeseed (Brassica campestris and Brassica napus). I. Growth and morphological characters
Authors: Thurling N
Published: November 2004

Variation in sowing date was found to have a marked effect on the seed yield and different morphological and growth characteristics of spring cultivars of the oilseed rape species Brassica campestris and Brassica napus. The two species differed appreciably, however, in their responses to successive delays in sowing date. In B. napus, there was a significant and continuous decline in seed yield with later sowings. This decline in seed yield was associated primarily with a reduction in the total dry weight of the plant at the final harvest which, in turn, was most closely correlated with the duration of the vegetative phase of growth. The total dry weight of the plant and the seed yield were greatest in the first sowing where flowering was substantially later than in either of the later sowings. Since earlier-flowering cultivars of B. napus would be better adapted to Western Australian conditions, where there is a rapid decline in soil moisture reserves during the spring, significant improvements in seed yield could depend largely on increasing the rate of pre-anthesis growth. In this experiment, however, no significant variation in the relative rate of growth prior to flowering was observed because of the marked negative association between net assimilation rate and leaf area ratio. Further studies of the variation in growth amongst a far wider range of genotypes will, nevertheless, be necessary to properly assess the feasibility of increasing relative growth rates by selection. The seed yield of B. campestris was substantially greater in the second sowing than in either the first or third sowings. Although seed yield was significantly correlated with both total dry weight of the plant at final harvest and the harvest index, the latter appeared to be the most important determinant of seed yield in this species. By contrast with B. napus, most of the dry weight of the plant at the final harvest was accumulated during the post-anthesis phase of growth. Accordingly, the character leaf area duration between anthesis and final harvest was found to be the most significant determinant of the total dry weight of the plant in B. campestris. The leaf weight ratio of the plant at anthesis also contributed significantly to total dry weight at the final harvest; this indicates that the pattern of dry matter distribution in the plant during the vegetative phase could prove a useful criterion for selecting potentially high-yielding strains of this species.
Response of soya beans to planting date in south-eastern Queensland. II.* Vegetative and reproductive development
Authors: Lawn RJ , Byth DE
Published: November 2004

Vegetative and reproductive development of a range of soya bean cultivars was studied over a series of planting dates in both hill plots and row culture at Redland Bay, Qld. Responses in the extent of vegetative and reproductive development were related to changes in the phasic developmental patterns. The duration and extent of vegetative development for the various cultivar-planting date combinations were closely associated with the length of the period from planting to the cessation of flowering. Thus, vegetative growth was greatest for those planting dates which resulted in a delay in flowering and/or extended the flowering phase. Similarly, genetic lateness of maturity among cultivars was associated with more extensive vegetative development. Seed yield per unit area increased within each cultivar as the length of the growing period was extended until sufficient vegetative growth occurred to allow the formation of closed canopies under the particular agronomic conditions imposed. Further increases in the length of the period of vegetative growth failed to increase seed yield, and in some cases seed yields were actually reduced. Biological efficiency of seed production (BE) was negatively correlated with the length of the vegetative growth period. Differences in BE among cultivar-planting date combinations were large. It is suggested that maximization of seed yield will necessitate an optimum compromise between the degree of vegetative development and BE. Optimum plant arrangement will therefore vary, depending on the particular cultivar-planting date combination.

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\*Part I, Aust. J. Agric. Res., 24: 67 (1973).
Oil and protein content of the seeds of some pasture legumes
Authors: Tonnet ML , Snudden PM
Published: November 2004

Trifolium species contained 3.5–19.4% oil and 28.8–46.7% protein. The degree of unsaturation of the oil differed between the species, but T. subterraneum was found to have both a high oil content and a high degree of unsaturation (74%). Differences between cultivars of T. subterraneum in oil composition were small and an average of 51% linoleic acid was found. The oil resembles that of cottonseed and T. subterraneum could have worth-while potential as an edible oil seed crop. Nine Medicago species had oil contents of 3.3–15.9% and protein contents of 30.6–48.9%. Thirteen Onobrychis species had oil and protein contents in the ranges 6.5–17.7% and 35.5–40.0% respectively. The oil from these 22 species differed in both fatty acid composition and degree of unsaturation, with large proportions of linolenic acid in most species. Trigonella coelesyriaca contained 5.2% oil and 30.0% protein. Ornithopus compressus contained 37.7% protein and 13.3% oil with low linolenic acid but 6% erucic acid.
The regions of infestation of wool by Noogoora burr (Xanthium strumarium), their climates and the biological control of the weed
Authors: Wapshere AJ
Published: November 2004

The distribution in Australia of a vegetable fault in wool caused by Noogoora burr, Xanthium stumarium, is outlined. The climates of the region in Australia where the burr produces maximum contamination of wool and where it is of the greatest economic importance are compared with the climates of North America (Texas) and the Indian subcontinent (New Delhi) from where the cerambycids, Mecas saturnina and Nupserha vexator, have been introduced respectively as biological control agents for the weed. The comparisons suggest that neither agent is climatically pre-adapted to the region in Australia where Noogoora burr has the greatest economic importance. On the other hand, a pyralid moth, Oeobia vevbascalis, from Pakistan is well adapted to the climates of the regions affected.
Changes in wool growth and the skin of Merino sheep following administration of cyclophosphamide
Authors: Reis PJ , Chapman RE
Published: November 2004

Two Merino sheep were dosed orally, and two intravenously, with cyclophosphamide at the rate of 30 mg/kg body weight; the effects on wool growth were measured, and changes in the histology of skin and of wool follicles were studied. All sheep were readily defleeced following treatment. This effect was associated with a complete cessation of wool growth for a period of about 2 weeks with oral dosing and 2½ weeks with intravenous dosing. There was considerable variation in the time taken for new fibres to commence growth. Length growth rates during the period 28–36 days after dosing were consistently greater than pre-treatment rates. Post-treatment fibre diameters were variable compared with the pretreatment values. The extent to which the enhanced length growth after dosing would compensate for the loss of wool growth requires further investigation. Degenerative changes were observed in some wool follicles 1 hr after dosing, and proliferation of cells of the fibre and inner root sheath appeared to have ceased at 1 day. Fibre growth ceased prior to 4 days. Regeneration of most follicles commenced prior to 14 days after dosing, and regrowth of wool was apparent above the skin by 21 days. A small proportion of follicles was still inactive after 36 days. Changes were observed in the sebaceous and sweat glands, epidermis and dermis following dosing. Even 36 days after dosing, sebaceous glands were considerably enlarged and excess stratum corneum remained on the epidermis. Infiltration of the dermis by lymphocytes was observed as early as 1 hr after dosing and was intense by 28 days.
Population control in the Australian sheep blowfly, Lucilia cuprina, by the release of female-borne chemosterilant. II.* Sterilization under field cage conditions
Authors: Beattie GAC , McDonald FJD , Whitten MJ
Published: November 2004

Females of the Australian sheep blowfly, Lucilia cuprina (Wiedemann), topically treated with the chemosterilant N,N'-hexamethylene-bis(1-aziridinecarboxamide), were liberated into large field cages containing untreated flies to determine if sterilizing doses of chemosterilant were transferred to untreated flies. Full sterility was induced in cages carrying equal numbers of untreated males, untreated females and females treated with 300 or 600 µg of chemosterilant. In other cages, one female treated with 600 µg of chemosterilant for every five untreated flies of each sex had a similar effect but lower levels of sterility were obtained with higher ratios of untreated to treated flies. Transfer of chemosterilant appeared to occur through contact during mating, attempted matings, and between flies of both sexes at the oviposition site.

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*Part I, Aust. J. Agric. Res., 25: 995 (1974).
Agronomic studies on Pigeon pea (Cajanus cajan (L) Millsp.) II.* Responses to sowing density
Authors: Akinola JO , Whiteman PC
Published: November 2004

Vegetative and seed yield in Cajanus cajan accession UQ1 were investigated over nine sowing densities ranging from 6727 to 215,278 plants per hectare. Dry matter yield per plant declined asymptotically with increasing density, while the yield per hectare v. density relationship was described by a parabolic curve. The highest yield per hectare (22,950 kg) was produced at the 0.305 by 0.305 m spacing (107,639 plants ha-1). Maximum seed yield (2774 kg ha-1) was attained at a relatively low density at a spacing 0.914 by 0.610 m (17,940 plants ha-1). At higher densities, increased stand mortality and reduced numbers of pods per plant resulted in severe yield reductions. Reduced pod number per plant was related to significant reductions in the number of pod-producing branches and the inflorescence-bearing stem length, with little change in seed size or seeds per pod. Interactions of yield components, leaf area index, and other plant parameters are discussed.

*Part I, Aust. J. Agric. Res., 26: 43 (1975).
Juvenile lodging in barley: a yield-depressing phenomenon
Authors: Gardener CJ , Rathjen AJ
Published: November 2004

A field experiment was conducted in South Australia to examine the relationship between juvenile lodging (lodging prior to stem elongation) and ear production in barley. Two levels of nitrogen application and six treatments were used either to prevent or increase juvenile lodging in two cultivars. Applications of 2-chloroethyltrimethylammonium chloride (CCC) at the fourth and sixth leaf stages shortened both pseudostems and leaves, prevented juvenile lodging, and increased the number of ears and the grain yield. CCC did not reduce the mature plant height, but did increase the incidence of Rhynchosporium secalis in one cultivar. Ear numbers were marginally increased by supporting the crop with a wire grid or by defoliating the crop to 20 cm at the fifth leaf stage, but this advantage was nullified by a compensating decrease in the other yield components. Removing up to 4 units of leaf area index at this stage did not reduce the yield. Deliberately lodging the crop before stem elongation had little effect since most of the controls lodged naturally. All treatments became erect during stem elongation, and the plants did not lodge again before maturity. It is concluded that short pseudostems, a maximum leaf length under 30 cm, fewer leaves per culm and a shorter period prior to stem elongation are characters which will reduce the juvenile lodging in barley which occurs when the crop is sown early at high plant densities or is grown at high fertility levels.
Mechanisms regulating germination in seeds of Stylosanthes
Authors: Gardener CJ
Published: November 2004

Seed coat impermeability, embryo dormancy, decline in embryo vigour and the effect of adhering pods on germination were measured monthly on 15 lines of Stylosanthes which had weathered on the soil surface. The effect of pod and seed coat on imbibition was investigated in S. humilis over a range of soil water contents. The level of impermeability of newly harvested seed was initially high for all lines, but the rates of loss varied both between and within species, which indicated the possibility of screening for residual hard seed. The lines also differed in their ability to maintain impermeability over a 14-day germination period. The initial level of embryo dormancy varied between species but the protection afforded against germination was short lived. Decline in embryo vigour appeared to be partly caused by the testa restricting the radicle mechanically. The presence of pods enclosing the seed reduced germination by a mean of 15.4%, but this ranged from 1% in a line of S. guyanensis with thin papery pods to 42% in a line of S. viscosa with thick strong pods. There was no evidence of germination inhibitors in either pods or seed coats, but both restricted the entry of water into the seed. Imbibed seed could be dehydrated without damage provided the radicle had not emerged from the seed coat. This occurred when the water content of the seed reached 90%.
Studies of weaner sheep during and after a period of weight stasis. I. Energy and nitrogen utilization
Authors: Graham NMcC , Searle TW
Published: November 2004

Wether sheep (4 months old) were held at 20 kg liveweight for either 4 or 6 months by restricting their food intake, and then fed ad libitum to recover weight for age. Voluntary food intake during recovery was recorded for several months in 20 penned animals. Basal metabolic rate was estimated in eight other sheep at intervals during weight stasis and once after a month of recovery. Complete balances of energy, carbon and nitrogen were measured continuously in the latter sheep during the first month of recovery and in immediately preceding and succeeding short periods at 'maintenance'. Control data were derived from an earlier experiment. Voluntary food intake was greater during rehabilitation than in controls of the same weight. Basal metabolic rate per kg¾ tended to fall during the period of weight stasis. It rose in the first month of recovery but by a smaller amount than predicted for controls growing at the same rate. Net energetic efficiency was probably higher than normal, and maintenance requirement lower, in the first week of recovery, but otherwise was the same as for the controls. Hence, apart from this first week, gross efficiency was unusually high solely because voluntary food intake was high relative to maintenance requirement. Nitrogen utilization was also more efficient in the first week or two of compensation than predicted for control sheep of the particular body weights and energy intakes.
Characterization of Stylosanthes introductions by using seed protein patterns
Authors: Robinson PJ , Megarrity RG
Published: November 2004

Seed protein patterns of 182 Stylosanthes accessions, representing 16 species and two hybrids, were obtained by polyacrylamide gel electrophoresis of crude extracts. All species could be recognized by examination of photographs and densitometer traces of the gels. Within the species capitata, guyanensis, hamata and viscosa considerable variation occurred, whilst the variation in humilis, scabra and fruticosa was not as great. Data from the densitometer traces were analysed by various methods of pattern analysis and the resulting classifications compared. A variance-standardized Euclidean distance coefficient was found to be the similarity measure of choice, whilst selection of fusion strategy was not as critical.Species relationships obtained by using the chemical data were not in agreement with the accepted taxonomic division of the genus into the sections Styposanthes and Stylosanthes. A classification based on the complete data set was compared with a working classification based on morphological and agronomic data, which is used in the agronomic assessment of the genus. Only within S. scabra did the two classifications conform. Morphological–agronomic (M–A) types within the species hamata and subsericea could be distinguished by the examination of the fine structure of the densitometer traces, whilst groups based on protein data in the species ahumilis, guyanensis, fruticosa and viscosa did not correspond with M–A groups. The application of seed protein patterns as a rapid and inexpensive means of identifying introductions of the genus at the species level, as well as characterizing types within certain species, is proposed.
The effect of heat stress on growth and nitrogen metabolism in Friesian and F1 Brahman × Friesian heifers
Authors: Kellaway RC , Colditz PJ
Published: November 2004

Friesian and Brahman × Friesian (F1) heifers were kept in controlled environment rooms and given a high quality diet. Feed intake, growth and nitrogen metabolism were assessed during three periods of 21 days when the animals were maintained at 20, 30 or 38°C (68, 52 and 46% relative humidity respectively). The F1 animals were superior only under heat stress. Feed intakes and growth rates of Friesians and F1 animals were similar at 20°C. With each successive increase in temperature the feed intake and liveweight gain of Friesians were significantly reduced. With F1 animals the reductions were much smaller. Respiration rates and rectal temperatures of Friesians were higher than those for F1 animals at 30 and 38°C. Although the water intakes of Friesians were much higher than those of F1 animals under heat stress, the calculated evaporative water losses were similar. The efficiency of digestion in the two genotypes was similar at all temperatures. Friesians responded to increasing heat stress by increasing the nitrogen lost in urine and by decreasing nitrogen retention in relation to nitrogen intake. Similar trends for the F1 animals were much smaller. The reduction in nitrogen retention in Friesians was associated with a decrease in RNA concentration in muscle tissue and an increase in the excretion rate of creatinine.
Effect of high intakes of sodium chloride on the utilization of a protein concentrate by sheep. I. Wool growth
Authors: Hemsley JA
Published: November 2004

Both the water intakes and wool growth rates of sheep fed on a high protein diet (37% crude protein), consisting mainly of linseed meal, were significantly increased when salt (c. 130 g sodium chloride per day) was given in both the food and drinking water. Offering the food once a day resulted in a higher wool growth response to salt (22%) as compared with offering the food at 3-hr intervals (14%). It is suggested that the effects of salt were due to reduced ruminal degradation of protein, which remained in the rumen for a shorter time than usual when salt was given.