bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of subsoil acidity and phosphorus placement on growth, root development and phosphorus uptake by Stylosanthes humilis and Desmodium intortum
Authors: Pinkerton A , Simpson JR
Published: November 2004

The effects of differing levels of soil acidity and phosphorus (P) deficiency on root growth and P absorption by Stylosanthes hurnilis and Desmodiurn intorturn were studied in columns of an acutely P-deficient soil. Four rates of P were supplied in layers located 15-45 cm (dilute) or 20-25 cm (concentrated) below the soil surface. Calcium carbonate was added to some columns to raise the pH of the subsoil from 5.4 to 5.9 (in water). Yield and P uptake by D. intorturn without lime was always lower than yield and uptake by S. humilis, and there was little response to lime by either species at low P rates. At the highest P rate, however, there was a large interaction between lime and P placement for D. intortum. S. humilis produced finer roots and had a greater root density than D. intorturn in the fertilized layer; it also responded in root fineness to concentrated P and to lime. D. intortum did not respond in root fineness, but the highest rate of concentrated P with lime stimulated P absorption and transport as well as shoot growth. Efficiency of P uptake (i.e. per unit length of root) did not account for the differences between species. The success of S. hurnilis was due to its ability to exploit acidic soil layers under conditions of low P supply by forming dense masses of fine roots, rather than to an innate highly efficient P uptake.
Competition among weedy species: diallel experiments
Authors: Moore RM , Williams JD
Published: November 2004

Competition among some introduced species sown or volunteering in temperate woodlands of southern New South Wales was studied in three greenhouse experiments in which species were grown alone and in 1:1 binary combinations. In two experiments competition between species was studied at different levels of nutrients. Total yields of most two-species mixtures were not significantly different from average yields in monocultures. For the most part, species yielding highest in monocultures had a competitive advantage in mixtures. There were exceptions; the annual legume, Trifolium subterraneum, was not always the most competitive in mixtures when highest yielding in monocultures. Except in two instances, neither statistically significant, the order of yields in monocultures of four annuals, two grasses and two cruciferous weeds, did not change with levels of phosphorus, calcium, potassium or nitrogen, but competitive advantages in mixtures, notably of the two grasses, were influenced by combinations of levels of these nutrients. Competition among three weedy thistles and a widely sown pasture legume, T. subterraneum, was studied at three levels of calcium and nitrogen. Yields of species in monocultures differed significantly at only three of nine nutrient combinations, but competitive advantages in mixtures differed significantly in all but one nutrient state. The legume was the most competitive species at low calcium, and Carduus pycnocephalus was the most competitive at high calcium; the advantage of both species increased with levels of nitrogen.
Effect of particle size and delignification on the rate of digestion of hemicellulose and cellulose by cellulase in mature pangola grass stems
Authors: Ford CW
Published: November 2004

Stem cell walls of pangola grass (Digitaria decumbens) were ground to two particle sizes (c. 1 and 0.1 mm diameter), and incubated with cellulase (ex. Trichoderma viride) for varying times before and after delignification. Total cell walls finely ground (0.1 mm) with a Spex Shatterbox mill were initially degraded more rapidly (to 24 h) than delignified 1 mm particles. Thereafter the delignified material was solubilized to a greater extent. Subsequent specific determinations of cell wall polysaccharides indicated that delignification increased the rate of hemicellulose degradation to a greater extent than did particle size reduction, whereas the opposite was found for cellulose. The difference between delignified and Spex-ground residues, in terms of the amount of polysaccharide digested, was much greater for cellulose than hemicellulose. It is concluded that structural features play a more important role in limiting cellulase degradation of cellulose than does association with lignin, the reverse being so for hemicellulose.
The effect of field storage and laboratory conditions on germination of five Xanthium species
Authors: Martin RJ , Carnahan JA
Published: November 2004

Noogoora burr (Xanthium occidentale) and Bathurst burr (X. spinosum) are widely distributed in wool-growing areas of eastern Australia. Hunter burr (X. italicum), Californian burr (X. orientale) and South American burr (X. cavanillesii) have not shown the same ability to spread. After the burrs of these five Xanthium species had been recovered from field storage in three microenvironments at five sites in spring and autumn 1980, their germination responses were assessed in growth cabinets set at 25/15 and 35125�C (8/16 h) with a 12/12 h light/dark regimen. Two types of dormancy were recognized in Xanthium species, and these types showed different responses to field storage and season of recovery. In all species except Bathurst burr innate dormancy was observed in upper seeds and was overcome by high temperature and exposure to light. Storage in soil reduced levels of innate dormancy but season of recovery had no significant effect. Induced dormancy was observed in lower seeds following storage in soil over summer and this was overcome by storage in soil over winter. It could also be overcome in Noogoora burr, Californian burr, and Hunter burr by high temperature and exposure to light. Removal of seeds from the burr increased the rate of germination, but the expression of innate and induced dormancy did not appear to be affected. The responses of the other species were not evident in Bathurst burr. Seeds of Bathurst burr germinated rapidly but a large proportion of seeds remained dormant and responses to field storage and germination conditions were variable. Differences in burr morphology between Bathurst burr and other species indicated that germination responses of Bathurst burr might be modified by the burr. Innate and induced dormancy were expressed most strongly in the least widespread species, namely Hunter burr, Californian burr and South American burr. while Noogoora burr and Bathurst burr had the most rapid germination rate. It is suggested that the success of Noogoora and Bathurst burr as weeds might be due in part to their rapid germination rate coupled with a delay in imbibition caused by the burr.
Environmental effects on seed development and hardseededness in Stylosanthes hamata cv. Verano. I. Temperature
Authors: Argel PJ , Humphreys LR
Published: November 2004

The level of hardseededness in Stylosanthes hamata cv. Verano grown in the open at St Lucia was positively and linearly related to temperature during seed formation; this relationship was stronger in 1976 than in 1977 when warmer conditions occurred. In two other experiments Verano plants were grown under the same conditions until early flowering and then exposed to differing temperature regimens. Seed production was maximal at 31/24�C (day/night), and cool temperatures (20/16�C or 18�C constant) had negative effects on inflorescence differentiation, rate of floret blooming and seed setting. Hardseededness developed most strongly at the high temperatures (35/28, 31/24�C, or 27 and 24�C constant), and this was also allied with lower seed moisture contents at harvest and in varying storage conditions. These findings may explain the variation in hardseededness of seed lots of differing provenance, which also may bear on the climatic adaptation of this short-lived plant. A range of mechanisms promote continued seed dormancy and its progressive release. Verano exhibited a transitory and weakly developed embryo dormancy at maturity, strong pod and testa inhibition of germination which decreased after 120 days of storage, and hardseededness continuing after 180 days of storage; the last was greater in the upper than in the lower articulation or seed pod.
The cellular and metabolic organization of ovine subcutaneous adipose tissue
Authors: Thornton RF , Hood RL , Rowe RWD , Jones PN
Published: November 2004

The cellular organization and lipogenic capacity ([14C]acetate incorporation per l06 cells) of sections, parallel to the skin, of subcutaneous adipose tissue from the rump, shoulder and brisket regions of fat sheep were studied. Adipocytes from the brisket (134 �m in mean diameter; 1.35 nl in mean volume) were smaller than those from the shoulder (213 �m; 4.77 nl) or rump (202 �m; 4.69 nl). Furthermore, cells from the brisket incorporated significantly less [I4C]acetate than those from either the shoulder or rump, which were not significantly different in lipogenic capacity. The frequency distributions of diameters of cells from the rump and shoulder were predominantly normal, but those of brisket cells were positively skewed. Adipocytes were larger and lipogenesis was greater in sections closer to the skin than in sections closer to the muscle for each region. This gradient of cell size and lipogenic capacity indicates that ovine subcutaneous adipose tissue is not homogeneous but is organized in structure and metabolism.
A bacterial inhibition assay for corynetoxins from parasitized annual ryegrass
Authors: Stynes BA , Vogel P
Published: November 2004

A rapid and sensitive method is described to detect and measure corynetoxins in extracts of ryegrass seed galls colonized by Corynebacterium rathayi, as well as in crude extracts of pasture samples containing such galls. The assay is done in microtitre plates by incorporating a test organism, C. tntrci, with a series of dilutions of plant extracts. The presence of at least 125 ng ml-1 of toxin inhibits the growth of C. tritici, which can be detected by optical density measurements. There is evidence that growth inhibition is due to the presence of corynetoxins. It is likely the test could also be used to detect the closely related tunicamycin compounds.
Factors affecting egg shell colour in crosses between Australorp and Rhode Island Red chickens
Authors: Polkinghorne RW
Published: November 2004

The intensity of the brown colour of eggs from reciprocal crosses between Australorp and Rhode Island Red chickens decreased with age of the bird in a non-linear manner. There was no convincing evidence of sex-linked effects on shell colour in these two breeds. No relationship was observed between shell colour and egg number or egg size. Food intake was found to be associated with shell colour; the two crosses were significantly different in their response.
Differences between two grain sorghum genotypes in adaptation to drought stress. III. Physiological responses
Authors: Wright GC , Smith RCG , Morgan JM
Published: November 2004

A sorghum hybrid (E-57) giving a higher yield under rain-fed systems of production was studied to examine the physiological basis of this effect. A comparison was made with another hybrid (TX-671) with similar maturity. E-57 was able to maintain stomatal opening to a lower leaf water potential than TX-671 because of its greater capacity to osmoregulate. In E-57 osmotic potential declined due to active solute accumulation, thus maintaining turgor as leaf water potential declined to - 2.0 MPa. In contrast, TX- 671 could only maintain this adjustment to - 1.4 MPa. The differences in osmoregulation were associated with maintenance of leaf area, water extraction and possibly root growth by E-57. This indicated that osmoregulation enabled photosynthesis to continue and that a significant amount of the resultant assimilate may have been diverted to root growth.
The effect of defoliation on seed yield of two strains of subterranean clover grown in monocultures and in binary mixtures
Authors: Collins WJ , Rhodes I , Rossiter RC , Palmer MJ
Published: November 2004

The effect of defoliation on seed production was examined in swards of Seaton Park and Midland B grown in a de Wit replacement series in the field. The three defoliation treatments were: D0, uncut (control); D1, defoliated at weekly intervals until the beginning of flowering; and D3, as for D1 but with cutting continued until the end of flowering. Defoliation up to the commencement of flowering (D1) had no significant effect on seed yield in the monocultures of either strain. However, with severe defoliation (D3) seed yields were reduced in both strains, although more so in Midland B than in Seaton Park. This greater sensitivity of Midland B supports the results of earlier work. The most important finding from this study was that cutting influenced the competitive relations between the two strains. For both the D0 and D1 treatments there was competition for the same resources ('space' of de Wit); in D0 neither strain had a competitive advantage, whereas in D1 Midland B appeared to be the better competitor. By contrast, in the D3 treatment there was the relatively unusual case of competition for resources which were not entirely the same; and here Seaton Park was the better performer. Possible explanations for this response are suggested.
Investigations into the increased rust (Puccinia helianthi) intensity on some hybrid sunflower cultivars grown in Queensland
Authors: Goulter KC , Kochman JK , Brown JF
Published: November 2004

Sunflower rust intensity in crops of several hybrid cultivars in Queensland during the 1980, 1981 and 1982 seasons ranged from 30 to 60% of leaf area. In previous years, these cultivars had rust ratings of 2-5%. Rust was also found on some crops of usually immune hybrids grown during winter in central Queensland. A number of rust differential lines were inoculated with several isolates collected from throughout Queensland during 1981 and 1982, as well as with isolates stored in liquid nitrogen from the years 1976, 1978 and 1980. Because all isolates failed to infect the differentials possessing either the R1 or R2 genes for resistance, all collections were allocated to race 1. Comparisons of the temporal isolates revealed that no differences could be detected among the generation times, pustule number and pustule size produced by isolates on a range of sunflower rust differentials and hybrid cultivars. These data indicated that the composition of the pathogenic population had not altered. The application of higher inoculum densities shortened generation times and produced more pustules; both relationships were linear. The development of race 1 rust on seedlings of the immune hybrid Hysun 30 was induced by maintaining the plants under low light intensity or short photoperiods.
Growth and productivity of irrigated Sorghum bicolor (L. Moench) in Northern Australia. II. Low solar altitude as a possible constraint to productivity in the tropical dry season
Authors: Foale MA , Wilson GL , Coates DB , Haydock KP
Published: November 2004

A growth study was carried out during the dry season on irrigated grain sorghum cultivar NK 300F at latitude 16�S. in northern Australia. The apparent efficiency of the canopy in the photosynthetic conversion of solar radiation increased progressively in high density stands between June and September, while low density stands showed no change. An hypothesis is advanced that the rise in canopy efficiency was due to increasing solar altitude combining with a suitable canopy structure at high density to give increased light penetration into the canopy. A parameter named weighted mean solar altitude (WMSA) is used in conjunction with noon solar altitude (NSA) to assist in the interpretation of published models of light penetration. This solar altitude effect, if verified by further work, would lower the expectations, based on mean daily solar radiation, for dry season yield of irrigated sorghum and possibly other cereals in the semi-arid tropics.
Comparison of the internal and external requirements of wheat, oats and barley for copper
Authors: Snowball K , Robson AD
Published: November 2004

Wheat, oats and barley were grown with several levels of copper application on a copper-deficient soil. Differences among cereals in growth responses to applied copper appeared to be due to differences in copper uptake rather than to differences in internal copper requirements. Critical concentrations of copper in the youngest fully emerged leaf were approximately 1.3 �g g-1 for all three species.
Sulfur nutrition of temperate pasture species. I. Effects of nitrogen supply on the external and internal sulfur requirements of subterranean clover and ryegrass
Authors: Gilbert MA , Robson AD
Published: November 2004

The effects of nitrogen supply on the external and internal sulfur requirements of subterranean clover (Trifolium subterraneum cv. Trikkala) and ryegrass (Lolium rigidum cv. Wimmera) were examined in a glasshouse experiment. Plants were grown for 28 and 42 days on a sulfur-deficient soil supplied with varying rates of sulfur. Nitrogen application increased the external requirement for sulfur of ryegrass by greatly stimulating growth and, to a lesser extent, sulfur content. Hence nitrogen application decreased sulfur concentrations in ryegrass. In subterranean clover there was relatively little effect of nitrogen application on the external requirement for sulfur because nitrogen did not greatly increase the sulfur content. Nitrogen application did not affect the external requirement for sulfur by changing the distribution of sulfur either between root and shoot or within shoots. The internal sulfur requirements, based either on sulfur concentrations or nitrogen to sulfur ratios, in the young leaves of both species were unaffected by nitrogen supply.
Fleece rot in Merino sheep. 1. The heritability of fleece rot in unselected flocks of medium-wool Peppin Merinos
Authors: McGuirk BJ , Atkins KD
Published: November 2004

Fleece rot was observed on hogget ewes and rams in unselected medium-wool Peppin Merino flocks over a 15-year period at Trangie Agricultural Research Centre, N.S.W. Each sheep was given a score of from 0 (no fleece rot) to 5 (very severe fleece rot) following a subjective visual assessment along the backline prior to shearing. Data were analysed as two measures of susceptibility to fleece rot: a score as defined above; and incidence, where fleece rot was treated as an all-or-none trait. The average incidence of fleece rot over 23 flock x year combinations was 36%, but this varied widely, from 8 to 90%. Other environmental factors (sex, birth type and age of dam) generally had small and non-significant effects on fleece rot. After adjusting for significant environmental effects, the half-sib heritability estimates for sires:with at least three progeny were 0.36 (�0.07) for score and 0.23 (�0.07) for incidence. Separate anaiyses were conducted for flock x year data sets of low, intermediate and high incidences. The highest heritability estimate for incidence was, as expectedly theoretically, obtained in the data set of intermediate incidence. Offspring-dam heritability estimates ( � s.e.) for fleece rot score and incidence were respectively 0.21 (� 0 0 5 ) and 0.14(�0.04). Corresponding offspring-sire estimates for score and incidence were 0.20 (�0.06) and 0.17 (�0.05). It is concluded that a realistic estimate of the heritability of the underlying liability to fleece rat is of the order of 40%.
The effectiveness of chewing during eating on particle size reduction of roughages by cattle
Authors: Lee JA , Pearce GR
Published: November 2004

The physical disintegration of five mature, chaffed roughages (barley straw, oat straw, pea straw, ryegrass hay and lucerne hay) in chewing during eating was examined using four oesophageal-fistulated steers. Measurements were made of intake, chemical composition, modulus of fineness and grinding energy of the feeds, and of particle size distribution, modulus of fineness and the proportion of particles greater than 1 mm in the oesophageal extrusa. Significant differences between steers and between feeds occurred in modulus of fineness and the proportion of particles greater than 1 mm. Between steers, there were decreases, with chewing, of 30-40% in the mean proportion of particles greater than 1 mm. The order of proportionate particle size reduction for the different roughages was as follows: pea straw <: oat straw < ryegrass hay < lucerne hay < barley straw. Expressed in terms of the modulus of fineness, the mean decreases in particle size ranged from 46 to 52% for the different roughages. Some interactions occurred between the different roughages and individual steers. The critical characteristics responsible for the variation that occurred have not been defined either in the roughages or in the steers.
Variation in virulence and pathogenic specialization of Colletotrichum gloeosporioides isolates from Stylosanthes scabra cvv. Fitzroy and Seca
Authors: Davis RD , Irwin JAG , Cameron DF
Published: November 2004

A survey of anthracnose of Stylosanthes scabra cvv. Fitzroy and Seca, caused by Colletotrichurn gloeosponoides, at 31 sites in Queensland found a wide range of disease severity. Disease was present at each of the 26 sites surveyed for Fitzroy, and inoculation experiments with an isolate from each site indicated that the isolates varied markedly in their virulence on Fitzroy. Some of the variation in disease severity between sites could be explained by differences In virulence of the isolates. Disease was observed In only one of the five fields of Seca surveyed. When nine of the isolates from Fitzroy were tested on SIX genotypes of S. scabra, there was no evidence of pathogenic specialization, and all isolates were avirulent on Seca. The isolate from Seca, when tested on the same genotypes, was moderately virulent on Seca and highly virulent on Fitzroy, indicating further pathogenic specialization within the Type A forms of C. gloeosporioides in Australia. There was a direct relationship between mean linear growth rate of isolates from Fitzroy in pure culture, and virulence on Fitzroy. The recovery of highly virulent Isolates from pods of a Fitzroy seed crop is discussed in relation to the rapid spread of highly virulent physiologic races.
Factors affecting diet selection by sheep. 4. Level of feeding
Authors: Kenney PA , Black JL
Published: November 2004

The effects of level of feeding on the potential intake rate and preference shown by sheep for dried forages varying widely in nutritive value was investigated. Intake rate of the forages ranged from 5 to 21.4 g/min when offered for short periods to sheep given 0.8 kg/day of a pelleted ration consisting of 60% lucerne hay and 40% oat grain. When sheep were fed on 0.2 kg/day of pellets, the intake rate of most forages fell slightly, but when feeding level was raised to 1.4 kg/day, the intake rate of all forages declined. The latter depression was only c. 10% for forages that were eaten at a rate of more than 15 g/min by sheep given 0.8 kg/day; but the intake rate of wheaten straw, which was previously eaten at 5 g/min, was depressed by 96%. Level of feeding did not affect the relative preference by sheep for forages which were eaten at rates exceeding 15 g/min. However, calculations indicated that preference for forages with an intake rate of less than 15 g/min would decline as feed intake was raised to the highest level. The results suggest that, for predicting diet selection by sheep, a standardized level of feeding should be adopted when the intake rates of forages are measured.
Growth of seedlings of prairie grass and tall fescue in small swards of kikuyu at different temperatures
Authors: Hill MJ , Pearson CJ , Campbell LC
Published: November 2004

Seeds of prairie grass (Bromus catharticus Vahl) and tall fescue (Festuca arundinacea Schreb.) were planted in established small swards of kikuyu (Pennisetum clandestinum Hochst ex Chiov.). Growth of the temperate seedlings and the subtropical grass sward was measured over a period of 59 days under four temperature regimes from 14/6 to 23/20�C (12/12 h). The capacity of the seedlings of the oversown temperate perennial grasses to establish in the sward of the subtropical kikuyu depended on temperature. At low temperature (mean daily temperature < 1l�C) the seedlings grew faster than the kikuyu and became successfully established. At moderate temperatures (11-19�C) the relative growth rates of seedlings were comparable with the relative growth rates of kikuyu tillers, but the latter dominated due to a greater absolute growth rate. Stature was an important component in the inter-species competition, and the taller prairie grass grew much better in competition with kikuyu than did fescue. Temperatures above 20�C exceeded the optimum of the seedlings of the temperate species but not that of kikuyu, so that the sown species were at a disadvantage and kikuyu dominated the mixture. It is concluded that prairie grass and tall fescue can be established successfully only in swards of kikuyu when day temperatures are below 21 and 15�C respectively, unless kikuyu is suppressed for a long period. A herbicide may be an economical means of doing this.
Establishment and expression of soybean symbiosis in a soil previously free of Rhizobium japonicum
Authors: Brockwell J , Gault RR , Chase DL , Turner GL , Bergersen FJ
Published: November 2004

An irrigated crop of Chaffey soybeans [Glycine max (L.) Merrill] was grown at Leeton, N.S.W., on a soil that was initially free of Rhizobium japonicum, with six rates of seed bed inoculation, three plant spacing treatments (4.5, 9.0, 18 cm), and two soil pretreatments (cropped, fallow). Rhizosphere populations were larger, nodulation throughout growth was better, and increases in amount of N in the plants between 78 and 114 days were greater on previously cropped than on previously fallow land because there was more plant-available soil N in the fallow than in the previously cropped treatments. Especially in the previously cropped treatments, there were h~ghly significant correlations, In sequence, between rate of inoculation, number of R. japonicum in the rhizosphere, extent of early nodulation, and progressive increase in nodulation. Lower, but still significant, correlations were found between extent of nodulation, shoot N, seed yield, and seed N. Plants compensated for wider spacing by increased growth. However, plants grown 18 cm apart were unable to compensate fully and yielded less seed and less seed N per hectare than plants grown at 4.5 and 9.0 cm. Plant spacing had little effect on the sequential development of the symbiosis. Rate of inoculation and seed yield were highly correlated and the correlation coefficients were higher in previously cropped treatments than treatments on previously fallow land. The amount of seed N in the treatments on previously cropped land with the highest rate of inoculation was 207 kg N ha-1, whereas shoot N in that treatment 47 days before final harvest was 355 kg N ha-1. This substantial quantity of N taken up by the well-nodulated soybeans in response to high levels of inoculation was greatly in excess of the requirements for seed production and might contribute to the nitrogen nutrition of subsequent crops.
Mixed model procedures for the Australian beef industry. 1. Multiple-trait model for estimation of breeding values for 200-day and final weights of cattle
Authors: Graser H-U , Hammond K
Published: November 2004

A multiple-trait mixed model is defined for regular use in the Australian beef industry for the estimation of breeding values for continuous traits of sires used non-randomly across a number of herds and/or years. Maternal grandsires, the numerator relationship matrix, appropriate fixed effects, and the capacity to partition direct and maternal effects are incorporated in this parent model. The model was fitted to the National Beef Recording Scheme's data bank for three growth traits of the Australian Simental breed, viz 200-, 365- and 550-day weights. Estimates are obtained for the effects of sex, dam age, grade of dam, age of calf and breed of base dam. The range in estimated breeding value is reported for each trait, with 200-day weight being partitioned into 'calves' and 'daughters' calves', for the Simmental sires commonly used in Australia. Estimates of the fixed effects were large, and dam age, grade of dam and breed of base dam had an important influence on growth to 365 days of age. The faster growth of higher percentage Simmental calves to 200 days continued to 550 days. Estimates of genetic variance for the traits were lower than reported for overseas populations of Simmental cattle, and the genetic covariance between direct and maternal effects for 200-day weight was slightly positive.
Comparative response to salinity of the growth and nodulation of Macroptilium atropurpureum cv. Siratro and Neonotonia wightii cv. Cooper seedlings
Authors: Wilson JR
Published: November 2004

Seedlings of two tropical legumes, Macroptilium atropurpureum cv. Siratro (siratro) and Neonotonia wightii cv. Cooper (glycine), were grown in nitrogen-free sand culture, and 12 days from germination were exposed to 14 days of salt treatment by addition of 0, 18, 36,72 or 144 mM NaCl to the base culture solution. Cowpea Rhizobium CB756 was applied either at germination (early inoculated) or at the start of salt treatment (late inoculated). Plants were sampled during salt exposure and during a 21-day recovery period in the absence of salt. Siratro was more tolerant of salt than glycine. Both species had similarly high chloride concentrations in their tops, up to 8-9% of dry weight of the leaf tissue. Siratro tolerated this high chloride with less injury and fewer plant deaths than glycine. Sodium was effectively excluded from leaves except in glycine at 72 and 144 mM NaCl. Chloride concentration of the leaves was more closely related to plant growth rate during recovery than was sodium concentration. Late-inoculated plants despite their small size and nitrogen deficiency were not more sensitive to salt than the early-inoculated plants. It is suggested that sodium and chloride accumulation in the late-inoculated plants may have been somewhat restricted by nitrogen deficiency, thereby limiting tissue injury in these small, slow-growing seedlings. Nodulation occurred during salt exposure, but was minimal at 144 mM NaCl. Rhizobia, however, survived this concentration and nodulation occurred during the recovery phase. Nitrogen fixation per unit nodule weight was not greatly restricted by salt, except where injury to the host was severe. Concentrations of salt ions in the nodules were generally low compared with those for the plant tops.
Relationship between scald (Rhynchosporium secalis) and losses in grain yield of barley in Western Australia
Authors: Khan TN , D'Antuono MF
Published: November 2004

The three commonly used techniques, viz. critical point model, area under the curve and multiple linear regression, were applied to study the relationship between scald infection and grain yield in field experiments conducted during 1979-1983 in Western Australia. In the preliminary analysis leaf three from the top and the mean of the top three leaves were found to be best correlated with yield. The three models did not dilfer greatly, presumably owing to the high correlations between scald at the milky ripe stage and at the earlier growth stages. The critical point model was chosen because of its simplicity. Percentage yield loss in combined data from all experiments showed a significant correlation (P < 0.001) with scald at the milky ripe stage and defined percentage yield loss in cultivars Clipper and Stirling to be about one-third of the mean scald damage on leaves 1 (flag), 2 and 3 at g.s. 75. Due to the range of trials in this analysis, it was suggested that this relationship may be applied to estimate yield loss from survey data in other parts of southern Australia, where scald is endemic.
A field comparison of sunflower (Helianthus annuus) and sorghum (Sorghum bicolor) in a long drying cycle. I. Water extraction
Authors: Bremner PM , Preston GK , St Groth CFde , Fazekas de St Groth C
Published: November 2004

This paper describes the extraction of water by field crops of sunflower and sorghum from deep podzolic profiles during a drying cycle encompassing most of the growth period. The work was done to evaluate sunflower as a prospective dryland crop for southern Australia, and data are presented for two contrasting years. Sunflower extracted water more rapidly from all levels of the measured profile (0-2 m). Both species drew similar amounts from the top 1 m, but sunflower took two to three times more than sorghum from 1-2 m, the difference being greater in the year of greater evaporative load. Sunflower exhausted the soil of available water to 150-175 cm, sorghum only to 50 cm, taking progressively less from each successive layer down the profile. Extraction of available water from 0-2 m by sunflower was estimated to be 92%, and by sorghum 64%. In the absence of rainfall during its growth period, dryland sunflower is strongly dependent on the presence of water at depth - for example, at 50% flowering the crop was already drawing two-thirds of its water from below 1 m. This dependence limits the frequency with which the crop may be grown in southern Australia and regions similarly characterised by low effective summer rainfall, high evaporative load, and uncertainty in the time needed for a recharge of the profile sufficient to grow sunflower again. In such environments, sunflower may better be regarded as an opportunity crop than as one featuring regularly in farm rotations.
Leaf acid phosphatase isozymes in the diagnosis of phosphorus status in field-grown wheat
Authors: McLachlan KD , Elliot DE , Marco DGde , Garran JH , De Marco DG
Published: November 2004

This study examined the inorganic and total phosphorus in wheat plant tops, along with the phosphatase activity and the phosphatase isozymes occurring in the youngest fully expanded leaves, from two field experiments done in 1983 and I984 at two sites in South Australia. Twelve levels of phosphorus were used in the first year, and split plots in the second year allowed the effects of current and/or residual phosphorus treatments to be determined.The inorganic or total phosphorus concentration, or content per plant, could be related to plant and grain yield, but values relative to phosphorus deficiency varied between different stages of growth and between sites. Relationships with inorganic phosphorus were no better than those with total phosphorus.Leaf acid phosphatase assays were a better measure, providing similar values relative to plant deficiency between sites, between seasons and irrespective of whether current or residual phosphorus was the source, but the values varied with plant age.The phosphatase zymograms identified an isozyme which appeared when plants were deficient in phosphorus. It did not appear when they were adequately supplied. The isozyme appeared at all stages of growth to anthesis, and from late tillering through to heading was related to grain yield at both sites, in both seasons and whether freshly applied or residual phosphorus was the source of supply. For diagnostic purposes, specific sets of standards would be required for the phosphorus and phosphatase assays. They would not be required for the phosphatase zymograms.
Assessment of drought resistance in pearl millet [Pennisetum americanum (L.) Leeke]. I. Factors affecting yields under stress
Authors: Bidinger FR , Mahalakshmi V , Rao GDP
Published: November 2004

Yield trials of advanced lines of pearl millet were grown under midseason (panicle initiation to flowering) and terminal (flowering to maturity) drought stresses in the dry seasons of 1981, 1982, and 1983. Grain yield and its components were severely reduced by the terminal stress, but were little affected by the midseason drought, as there was compensation by later tillers for yield lost on the earlier shoots. The major factor determining grain yield of a genotype in both stress treatments was its time to flowering. Because of this, yield-yield component relationships under stress were a result of yield component-phenology relationships. Yield potential (measured in an irrigated treatment in the same field) was generally positively related to yield under stress, but accounted for a much smaller fraction of yield variation than time to flowering. These two factors together accounted for more than 50% of the total variation in grain yield under stress, suggesting that genotype drought response (drought resistance/susceptibility) was a secondary rather than a primary factor in differences in yield under stress among the genotypes tested.
Effects of time of urea application on combine-sown Calrose rice in south-east Australia. I. Crop response and N uptake
Authors: Humphreys E , Muirhead WA , Melhuish FM , White RJG
Published: November 2004

Urea (50 kg N ha-1) was applied at one of four times (before the first flush, before permanent flood, after permanent flood and at panicle initiation) to Calrose rice growing on an alkaline grey clay soil. Plant N uptake was highly correlated with dry matter production (r2=0.90) and with grain yield (r2 = 0.95). Efficiency of fertilisation and grain yield were highest when urea was applied either before permanent flood (56 kg grain (kg N) -1, 6.4 t ha-1) or at panicle initiation (47 kg grain (kg N)-1, 6.0 t ha-1), and these efficiencies are among the highest that have been recorded in rice. Significantly lower yields were obtained when the fertiliser was applied at sowing or after permanent flood, largely due to lower panicle densities. Fertilisation at sowing did not produce significantly more grain than the control, despite an early vegetative response. This is in contrast with previous findings on a more fertile acid red-brown earth, and suggests that soil properties may be an important consideration in predicting optimum fertilisation strategies.
Effect of frequency of defoliation of 40 Stylosanthes guianensis genotypes on field reaction to anthracnose caused by Colletotrichum gloeosporioides
Authors: Miles JW , Lenne JM
Published: November 2004

Four different defoliation frequency treatments (uncut, or cut to approx, 10 cm every 4, 8, or 12 weeks) were imposed over 40 weeks on 40 S. guianensis genotypes to determine whether defoliation frequency can reliably be used to alter reproductive stage (as measured by visual score of flowering abundance) of the host plant and to determine the degree of association between anthracnose severity and reproductive stage. Flowering was more abundant and anthracnose more severe with less frequent defoliation. Flowering abundance was closely related with weeks of uninterrupted regrowth. Anthracnose severity was not closely associated either with weeks of uninterrupted regrowth nor with flowering abundance. The genotype-defoliation frequency interaction effect on anthracnose severity was very small compared to the main effects. Thus defoliation frequency of field trials should not affect reliability of estimation of relative genetic resistance to anthracnose. Flowering abundance was positively correlated with anthracnose susceptibility across genotypes, but the correlation was generally of only moderate magnitude.
Leaf emergence rates of wheat in a mediterranean environment
Authors: Kirby EJM , Perry MW
Published: November 2004

Rates of leaf appearance on the main stem were measured for various wheat varieties for five to ten sowing dates in three field experiments in Western Australia.Rate of leaf appearance was constant in relation to thermal time for any given variety and sowing date, and ranged from 0.0064 to 0.0132 leaves (�C day)-1. Most of this variation could be accounted for as a response to sowing date or rate of change of daylength, although the response was complicated by interactions with variety and year.Because successive measurements were made on the same plants, it was possible to estimate directly the effects of temperature on the rate of leaf emergence. In the three years, mean rates of leaf emergence were 0.008, 0.008 and 0.011 leaves day-1 �C-1 with base temperatures (temperatures at zero rate) of 0.08, -1.2 and 0.4�C respectively. Contrary to expectation, rate of leaf emergence decreased as temperatures increased in late sowings due probably to depression of leaf emergence as daytime temperatures exceeded 25�C.For Gamenya, the only variety common to the three years, the rate of leaf emergence (RLE) on the main stem was related to the rate of change of daylength (-DL, min day-1 negative when daylength shortening) by the equationRLE = 0.00949 + 0.000988 (-DL).For crops emerging in late June (-DL approximately zero) in southern Australia, this implies a constant thermal time for leaf appearance of 105�C day leaf-1.
The digestion of wheat starch in broiler chickens
Authors: Rogel AM , Annison EF , Bryden WL , Balnave D
Published: November 2004

Apparent metabolizable energy (AME) of wheat for 6-week-old male broiler chickens was highly correlated with starch digestibility when pelleted diets containing 820 g wheat per kg were fed. Starch isolated from low-AME wheats was hydrolysed in vitro by chicken pancreatic amylase as rapidly as starch from high-AME wheats. When included in semi-purified diets the isolated starches were completely digestible. Digestibility of starch was poor and highly variable when 3-week-old chickens were fed unpelleted wheat diets, but improved with age. Oat hulls improved the digestibility of starch in young chickens fed unpelleted diets.
Factors affecting the hydrogen cyanide potential of white clover (Trifolium repens L.)
Authors: Vickery PJ , Wheeler JL , Mulcahy C
Published: November 2004

Pot experiments were used to determine the effects of age, light, temperature, mineral nutrition and wilting on the HCN potential (HCNp ) of white clover (Trifolium repens L.). HCNp, adjusted for pre-expenmental HCNp, was reduced by higher light intensity (505 v. 220 mg HCN kg-1 DM), by increased temperature (408 v. 317 mg HCN kg-1 DM) and by phosphorus application (382 v. 343 mg HCN kg-1 DM). These effects were largely explained by the hypothesis that HCNp diminished as the size and vigour of the plant increased, and the use of dry matter production as a covariate on HCNp removed the significant effects of light, temperature and phosphorus. In two experiments wilting plants prior to harvest increased HCNp by 15 and 24%, and reduced dry matter yield by 9 and 13%. HCNp declined curvilinearly as the white clover aged. The conditions shown to favour high HCNp, namely, immaturity, moisture stress, low light intensity, cool temperature, and inadequate P supply, are those which occur periodically in the late autumn and early spring of temperate climates. Sheep in late pregnancy at this time, could, if white clover comprises a substantial proportion of their diet, experience thiocyanate absorption as a consequence of HCN detoxication and hence increase the risk of goitri to the lamb.
Production of corynetoxins in vitro by Corynebacterium sp. isolated from annual ryegrass seedheads
Authors: Payne AL , Cockrum PA
Published: November 2004

Corynetoxin complex is the family of tunicamycin-like antibiotics isolated from annual ryegrass (Lolium rigidum) seedheads infected with a plant pathogenic Corynebacterium and identified as the causative toxins for annual ryegrass toxicity (ARGT) in Australia. Only trace amounts of corynetoxins have been reported to be produced in vitro. Enhanced in vitro production of corynetoxins by Corynebacterium sp. has now been demonstrated. The important conditions required were growth on an agar surface, absence of light, low incubation temperature and strain of the organism. Strains of the Corynebaterium sp. grown under conditions not supporting corynetoxin production failed to produce corynetoxins when subsequently grown under more favourable conditions. Even when maintained under the most favourable conditions, toxigenicity of strains declined on repeated subculturing. While levels of toxin typically produced in vitro were only about 5% of those found in infected ryegrass seedheads, they were high enough to be a useful source of corynetoxins for experimental purposes.
Cattle handling at abattoirs. II. The effects of rest in transit and duration of the resting period before slaughter on carcass weight, bruising and muscle properties
Authors: Wythes JR , Arthur RJ , Dodt RM , Shorthose WR
Published: November 2004

In two experiments, we examined the effects on carcass weight, bruising and muscle properties of resting cattle during a long rail journey and for various periods at an abattoir before slaughter. In experiment 1, 170 Shorthorn bullocks (mean liveweight 556 kg) were transported 90 km by road and 650 km by rail, with three groups (34 per group) going directly to an abattoir and two groups resting once for one day midway during the rail journey. The resting periods at this abattoir were 2, 3, 4,2 and 3 days, respectively. In experiment 2, 240 cows (mean liveweight 424 kg) were transported 190 km by road and 965 km by rail, with three groups (40 per group) going directly to another abattoir, two groups resting once for one day and one group twice for one day during the rail journey. The resting periods at this second abattoir were 1.5, 2.5, 3.5, 1, 2 and 1 day(s), respectively. All cattle had access to feed and water during resting periods and to water until slaughter. As the total resting period after the start of the rail journey and before slaughter increased, the percentage of carcasses with high pH values for M. longissimus dorsi decreased (P < 0.05); correlations for pH 24 h post mortem and ultimate pH were -0.97 and -0.71, respectively. The correlation between total resting period and shear values (initial yield and peak force) were c. -0.5. A resting period during the rail journey was as effective as that time spent resting at the abattoir. Cattle transported directly by rail to the abattoir had a greater bruise score than those rested en route, although cows rested twice were as bruised as those going direct. Treatment had no significant effect on carcass weight or systematic effect on cooking loss. Very high incidences of high ultimate pH values in one group of bullocks (29.4%) and another of cows (20.5%) occurred following periods of stress when slaughtering was interrupted by unavoidable stoppages.