bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative digestibility and anatomy of some sympatric C3 and C4 arid zone grasses
Authors: Wilson JR , Hacker JB
Published: November 2004

The importance of C4 (panicoid) and C3 (festucoid) leaf anatomy to differences in in vitro dry matter digestibility (DMD) of grasses was assessed using two Australian summer-growing arid zone C4 grasses, Cymbopogon obtectus and Digitaria brownii, and two C3 grasses, Thyridolepis mitcheiliana and Monochather paradoxa. Seed of these sympatric species was collected from a 400 m2 area near Charleville, Qld. Thus the usual problem of confounding C4 and C3 type with species of different environmental adaptation was avoided in this study. Proportions of tissue types in leaf cross sections and DMD were measured for plants grown in a glasshouse under summer (� water stress) or winter ( - stress) conditions. Differences in tissue proportions due to C4 and C3 leaf anatomy were greater than those induced by growth conditions. C4 leaves consistently had less mesophyll and more of the less-digestible epidermis, bundle sheath, sclerenchyma and vascular tissues. Water-stress resulted in leaves with an increased proportion of mesophyll, but differences in tissue proportions between summer- and winter-grown leaves were small. Species were divided into fast (D. brownii and 7, mitchelliana) and slow (C. obtectus and M. paradoxa) leaf development groups for comparison of DMD. Within each group the C3 species consistently had the highest leaf DMD, but across groups the difference of 18-27 days in time to develop a new leaf sometimes overrode the advantage to DMD of the C3 anatomy. Stem DMD did not differ consistently between C4 and C3 species. The DMD was highest for water-stressed material, and higher in winter- than summer-grown plants. The anatomy associated with either C4 tropical or C3 temperate grass genera clearly contributes to difference in DMD between leaves, but variation in DMD associated with leaf age or environment was only in part attributable to differences in tissue proporxions.
Competition between Chondrilla juncea and Trifolium subterraneum: the influence of canopy areas and heights
Authors: Nicholls AO , Williams JD , Moore RM
Published: November 2004

Growth in the field of Chondrilla juncea and Trijolium subterraneum at different nitrogen levels was compared during late vegetative and early reproductive phases in monocultures and mixed stands. Observed differences between the species in terms of relative growth rates and net assimilation rates in monocultures were not reflected in the performance of the species in competitive mixtures. A major factor contributing to this anomaly was the different leaf distribution of the two species in mixtures.The annual T. subterraneum produced a larger area of leaf at a higher level in the canopy than did the perennial C. juncea.The crowding coefficient of C. juncea with respect to T. subterraneum was significantly less than 1, indicating that T. subterraneum was more competitive than C. juncea.Applications of nitrogen at a late stage of growth did not change the competitive ability of the species.Some limitations of the experimental procedure and of the de Wit competition analysis are discussed.
Root length density and water uptake in cereals and grain legumes: how well are they correlated
Authors: Hamblin AP , Tennant D
Published: November 2004

Total root length per unit ground area (La) is often considered to be directly related to the amount and rate of water uptake. Experiments were conducted to compare the water use of spring wheat, barley, lupin (L. angustifolius) and field pea on four differing soil types in drought-stressed conditions. The La values of cereals were consistently five to ten times as large as those of grain legumes, whereas the aboveground biomass was sim~iar and never greater than twice that of the grain legumes. Growing-season water loss (WL) from the soil profile was very similar for wheat and lupins, despite this big difference in root length. Soil evaporation may have been greater under lupins, but when crop water uptake was compared for the period when leaf area was greatest, rates of change in soil water content within the root zone were still similar and were not well correlated with La. Specific root water uptake (Ur) was consistently greater for lupin than wheat. Maximum rooting depth was better correlated with WL than was La in all cases. Higher Ur values in lupin and pea may be related to their large and abundant metaxylem vessels, which give much lower axial resistance than in cereals. These results provide strong evidence for genotypic variation in root morphology, density and root extension between dicotyledenous and monocotyledenous species. They also indicate that La is not necessarily the root morphological characteristic most responsible for efficiency of water uptake in drought-stressed environments.
Multi-allelic nature of the locus controlling leaf marking in subterranean clover
Authors: Tan BH , Collins WJ
Published: November 2004

The inheritance of leaf markings in subterranean clover (Trifolium subterraneum ssp. subterraneurn) was studied in diallel cross involving a parental genotype without a leaf marking and eleven others, each with a distinctive marking. The results indicate Mendelian inheritance, and each marking appeared to be controlled by a different allele at a single locus. An alternative interpretation of the segregation data might be that the leaf mark locus is complex and comprises many tightly linked genes. Four types of dominance were manifest in the heterozygous combinations, including one that has not previously been described. With the exception of a completely dominant allele, the dominance relationships among the other alleles could not be predicted. In one cross, the expression of one of the leaf mark alleles was partially modified, and this could be attributed to an independent recessive gene. Mutation appears to be the sole genetic mechanism by which new alleles arise. Their origin and evolution in subterranean clover is discussed with reference to Fisher's theory on the evolution of dominance.
The etiology of head rot disease of broccoli
Authors: Wimalajeewa DLS , Hallam ND , Hayward AC , Price TV
Published: November 2004

Transmission and scanning electron microscope studies of broccoli florets affected by head rot, at various stages of disease development, strongly indicated a bacterial etiology for the disease. Nevertheless, the different species of bacteria isolated from diseased heads, using standard techniques, failed to reproduce symptoms in pathogenicity tests conducted in the glasshouse and in the field. However, a modified isolation technique, using broccoli heads showing incipient watersoaking symptoms, yielded a fluorescent pseudomonad which reproduced disease symptoms readily in glasshouse and field tests. On the basis of physiological and biochemical characters, the pathogenic bacterium was identified as a highly pectolytic pathovar of Pseudomonas marginalis. The bacterium also caused the rotting of potato, tomato and swede turnip slices, and also of intact and detached tomato fruit. However, it was not pathogenic on lettuce, parsnip or lucerne, and also failed to rot carrot slices.
Overwintering of Tranzchelia discolor in prune orchards in New South Wales
Authors: Ellison PJ , McFadyen L , Kable PF
Published: November 2004

There are several ways in which Tranzschelia discolor may overwinter in prune orchards in the Murrumbidgee Irrigation Areas of New South Wales. The aecial state, cross-infection from peach and almond, twig cankers, and urediniospores on living leaves persisting through winter were considered, but were thought to be unlikely. The ability of urediniospores to survive on infected leaf litter, either on the ground under trees or lodged within the framework of trees, was studied over two winters. Urediniospore viability declined with time, but in both seasons a proportion were capable of germination in the spring. Spores exposed within the tree framework survived better than those exposed on the ground, with about 20% and less than 5% respectively remaining viable by spring. In both winters spores from litter which overwintered within the framework of the tree were able to infect prune leaves in the spring. The infectivity of spores exposed on the ground was tested in the spring of one year and infections resulted on inoculated plants. The implications of these findings for the control of the rust in prunes are discussed.
Growth and carcass characteristics of crossbred and straightbred Hereford steers. III. Post-weaning growth in seven environments in New South Wales
Authors: Darnell RE , Hearnshaw H , Barlow R
Published: November 2004

Post-weaning growth, liveweight and body condition at slaughter were examined in 289 steers comprised of straightbred Hereford and first cross Brahman x Hereford, Simmental x Hereford and Friesian x Hereford. The steers were grown from weaning in seven environments throughout New South Wales. All steers were slaughtered when the average fat cover of the Herefords was in the range of 6-10 mm at the 12/13th rib. Brahman crossbreds were in similar body condition to Herefords at slaughter, which in turn were generally in better condition than both Simmental and Friesian crossbreds. Crossbred steers were heavier than Herefords at slaughter. Simmental crosses and Friesian crosses were 53 kg (12%) heavier on average over all environments, and Brahman crosses 41 kg (10%) and 83 kg (16%) heavier in inland and coastal environments respectively. Mean average daily gain (ADG) of the crossbred steers was always greater than that of the Hereford steers. There was a trend for ADG to be greater among the Brahman crosses earlier in the post-weaning period, but for the Simmental and Friesian crosses to grow faster later in the post-weaning period. Simmental crosses maintained a constant ADG advantage relative to Friesian crosses throughout the post-weaning period in environments where growth was favoured. Significant genotype x environment interactions occurred. Relative to Herefords, Simmental and Friesian crossbreds responded more to improved conditions, while Brahman crossbreds maintained a constant growth advantage regardless of environmental conditions. Bos taurus crosses grew faster than Brahman crosses, and Simmental crosses faster than Friesian crosses, only when environments were highly favourable.
Factors affecting the growth of kikuyu. I. Potential growth and nitrogen supply
Authors: Murtagh GJ
Published: November 2004

The potential growth of kikuyu (Pennisetum clandestinum) with ample supplies of water and fertilizer, and the effect of varying nitrogen supply, were estimated from field measurements of growth rate. A model, incorporating the effects of light interception, temperature and nitrogen supply, was used to account for variation in canopy development and temperature under field conditions. The model predicted a peak growth rate of 234 kg DM ha-1 day-1 by a well-fertilized kikuyu sward with a yield of 3590 kg DM ha-1 (LAI = 5.4), and grown at maximum/minimum temperatures of 32.0/23.9�C. Growth was not limited by the nitrogen supply, provided that the nitrogen concentration of recently grown foliage exceeded 3.5%. However, at lower concentrations, assimilation (net growth plus an allowance for maintenance respiration) declined by 36% per unit decline in nitrogen concentration.
The effect of changes of assimilate supply around flowering on grain sink size and yield of maize (Zea mays L.) cultivars of tropical and temperate adaptation
Authors: Aluko GK , Fischer KS
Published: November 2004

Two maize (Zea mays L.) cultivars of temperate and one of tropical adaptation were grown in a subtropical (27�s.) environment under favourable conditions of plant population density, water and nutrient supply. The radiation incident to the plant during the period from flag leaf to 10 days after flowering was varied from the control by either shading or temporarily restraining leaves of neighbouring plants. The effects of these changes in assimilate supply, and of the presence of the male inflorescence, on the immediate dry weight of various plant parts and grain sink size, and consequential on dry matter production and grain yield was investigated. The radiation treatments effected small but significant changes in crop growth rate. Shading reduced the dry weight of the ear, and husk of the female inflorescence and male inflorescence (tassel). There were increases due to enhanced radiation. While removal of tassels also enhanced the dry weight of the female inflorescence, there was no evidence that the male inflorescence was a preferred sink for assimilates during this stage of growth.In the temperate cultivars, grain number m-2 was associated with ear dry weight at 10 days after anthesis (r = 0.95**). However, only in the tropical cultivar did the larger grain sink result in an increase in grain yield. Shading reduced grain yield in all cultivars probably because of a reduction in the supply of labile assimilates for grain filling.
Effects of moisture stress on the oil and protein components of soybean seeds
Authors: Rose IA
Published: November 2004

Over a five year period, early-maturing indeterminate soybean lines were evaluated in parallel dryland and fully irrigated field experiments. Moisture stress effects on yield, seed weight, and oil and protein content of seeds were evaluated by comparing genotype x moisture regime means. Both the amount and distribution of rainfall varied among seasons, resulting in dryland yields from 6% to 84% of the fully irrigated experiments. Seed weight also responded to seasonal rainfall patterns with reductions owing to moisture stress contributing from 29% to 54% of the yield response. Between 57% and 68% of the seed weight loss was attributed to changes in weight per seed of oil and protein. An index relating response to stress to irrigated performance was calculated for each trait. Regression equations showed significant (P > 0.05) relationships between the effect of stress on seed weight and the resultant oil and protein responses to stress. When compared to the irrigated treatments, oil and protein percentages of dryland seed varied, depending on the balance between reduction in seed weight and response of these constituents to the pattern of stress. In one season when severe stress occurred very early in podfill, the result was reduced protein and increased oil percentages. In three other years the protein percentage of dryland seed increased, and was accompanied by a decrease in oil percentage. In a high rainfall season, non-significant (P > 0.05) increases in both oil and protein percentage were obtained. Sowing early-maturing genotypes into soils with more than 150 mm available soil moisture will usually avoid moisture stress until after podfill commences. Stress will usually increase during podfill, which will most often result in higher protein and lower oil content of dryland produced soybean seed.
The long-short day requirement for flowering in Stylosanthes guianensis
Authors: Trongkongsin K , Humphreys LR
Published: November 2004

Five 'tardio' selections of Stylosanthes guianensis ssp. guiunensis var. pauciflora and S. guiunensis var. guianensis cv. Cook were grown in a glasshouse where natural daylength was shortencd, or extended by incandescent lamps. They did not flower or flowered weakly in 152 cycles of 10 h short days (SD), but flowered more rapidly and prolifically if exposed to 30, 60 or 90 16 h long days (LD) followed by 30 10 h cycles than under natural daylength conditions at 27' 30' S. Increasing the previous exposure to LD reduced the number of 10 h cycles to floral initiation. Similar behaviour was exhibited by cv. Bandeirante which did not flower in 131 cycles of 11 h, but which flowered when SD induction followed 45 to 65 cycles of 14 h. Spike density was positively related to number of LD, which favoured first flower appearance on the terminal apices of lateral rather than of main shoots. CIAT 1283 and cv. Cook grown in controlled environment cabinets at 30�/23� (day/night) did not flower in 140 cycles of 10 h SD, but flowered if LD were interposed before SD induction. Cook had a greater LD requirement of 50 cycles of 14 or 15.5 h for floral initiation, whilst CIAT 1283 had a lesser LD requirement and flowered after 20 cycles of 14 or 15.5 h or after 50 cycles of 12.5 h. These data indicate a qualitative long-short day flowering response. This has implications which favour the higher latitudes for seed production and the early summer sowing of seed crops when plants would receive maximum LD exposure before SD induction occurs.
The effect of stocking rate on the population dynamics of siratro in siratro (Macroptilium atropurpureum)-setaria (Setaria sphacelata) pastures in south-east Queensland. I. Survival of plants and stolons
Authors: Jones RM , Bunch GA
Published: November 2004

The persistence of plants and stolons of the tropical forage legume Siratro (Macroptilium utropurpureurn) was measured in Siratro-setaria (Seluriu sphacelala) pastures at Samford, south-east Queensland. The pastures were sown in 1968. Three pastures were set stocked and continuously grazed from 1969 to 1985 at 1.1, 1.7, and 2.3 heifers ha-1. A fourth pasture was stocked at 3.0 heifers ha-1 from 1969 to 1973 and at 2.0 heifers ha-1 thereafter. In 1972 the density of Siratro crowns was similar in the four pastures, although crowns were smaller and stolon density was considerably less at the highest stocking rate. Persistence of plants at a moderate stocking rate (1.7 heifers ha-1) and a heavy stocking rate (3.0/2.0 heifers ha-1) was followed in fixed quadrats from 1971 to 1986. Stocking rate had a marked effect on the recruitment of new crowns and on crown survival. Total numbers gradually declined at the heavy stocking rate and no plants were recorded after 1982. This decline was associated with poor survival of plants (half life of only 6 months) and with reduced input of new plants, particularly after 1980. In contrast, Siratro density at 1.7 heifers ha-1 remained constant from 1971 to 1978. and then increased to 1982. This was associated with a longer half life of plants (c. 20 months) and sustained input of new crowns. However, there was a drastic decline in Siratro density from 1982 to 1985. Siratro was clearly unable to persist under heavy grazing, but there was no single reason why it suddenly declined in a moderately grazed pasture where it had persisted for 14 years. However, the advent of Siratro rust, together with a run of years with below average summer rainfall, are likely major contributory factors. Both these factors increased the grazing pressure on Siratro under the set-stocking and continuous grazing that was imposed.
Toxic tunicaminyluracil antibiotics identified in water-damaged wheat responsible for the death of pigs
Authors: Cockrum PA , Culvenor CCJ , Edgar JA , Jago MV , Payne AL , Bourke CA
Published: November 2004

A unique mixture of toxic tunicaininyluracil antibiotics, closely related to the corynetoxins which causc annual ryegrass toxicity and to the tunicamycins, has been identified in rain-damaged, stored wheat implicated in a fatal intoxication of pigs. The toxins, present at a level of approximately 4.5 mg per kg, were isolated by preparative t.1.c. They displayed specific inhibition of uridine diphospho-N-acetylglucosamine : dolichol-phosphate N-acetylglucosamine-1-phosphate transferase and bacterial inhibition consistent with this type of antibiotic, and produced symptoms in rats identical with those associated with the tunicamycin and corynetoxin complexes. Chemical identification, based on t.l.c., h.p.l.c., co-chromatography with authentic toxins and catalytic hydrogenation, was confirmed by fast atom bombardment mass spectrometry. The origin of these toxins is unknown, but the unique mixture of components detected suggests a previously unreported tunicaminyluracil antibiotic-producing microbial source.
Agronomic potential of native grass species on the Northern Tablelands of New South Wales. II. Nutritive value
Authors: Archer KA , Robinson GG
Published: November 2004

The quality of three year-long green and three summer-growing, frost-susceptible perennial native grasses was compared with that of two introduced temperate perennial grasses and white clover (Trifolium repens L. cv. Haifa). Digestibility of white clover generally exceeded that of all grasses, except for the green leaves of the two introduced species, Festuca arundinacea Screb. cv. Demeter and Phalaris aquatica L. cv. Sirosa, during winter. The digestibility of the green leaves of most winter-green species increased during winter and decreased in summer, the extent of this being greater for the introduced grasses.The digestibility of fescue and phalaris was generally similar throughout the study and was mostly higher than that of the native grasses, but the quality of the green leaves of two year-long green native species, Danthonra linkii Kunth and Microlaena stipoides (Labill.) R.Br., approached that of the two introduced grasses. The quality of the summer perennial species was poor during winter owing to the presence of only dead leaves, but the green leaves of Bothriochloa macra (Steud) S. T. Blake retained high levels of digestibility during summer. Considerable variation in digestibility exists between individual plants of Poaseiberana Spreng, indicating that opportunities may exist for selection of highly productive lines from some native species.In pen-feeding studies, voluntary intake of most of the year-long green native grasses was similar to that of the introduced grasses, but intake of the summer perennial species tended to be lower.Results from this study indicate that the quality of native pastures and their potential for animal production will vary considerably according to species composition, season and the presence of white clover.
Partition of organic matter, fibre and protein digestion in ewes fed at a constant rate throughout gestation
Authors: Faichney GJ , White GA
Published: November 2004

The digestion of dietary organic matter, fibre constituents and protein in the stomach and intestines of multiparous Corriedale ewes was studied at different stages of gestation. As gestation progressed, the digestion of organic matter and cell wall organic matter in the rumen decreased. Digestibility in the whole tract declined to a small extent. The degradation of dietary protein was reduced from 72% In non-pregnant ewes to 37% at day 139 of gestation. Protein digestion distal to the stomach increased by 20%. Microbial protein synthesis in the rumen decreased, and it is suggested that the unexpected decrease in the efficiency of microbial synthesis may have been due to reduced rumen osmolalities as a result of the polydipsia exhibited in this experiment in late gestation. Rumen ammonia levels were related to the degradation of dietary N compounds, and caecal ammonia levels increased as protein digestion in the intestines increased. Plasma glucose levels remained normal, and D-3-OH-butyric acid levels remained low until the gravid uterus reached about 4.5 kg (equivalent to about day 120 in single- and day 90 in twin-bearing ewes). Thereafter glucose levels fell and D-3-OH-butyrate levels rose. The latter rise was associated with an increase in the urinary excretion of ammonia N. Plasma urea levels declined to day 90, then rose to day 139, and plasma amino acid N levels rose in late gestation; these increases may reflect tissue mobilization and increased fetal use of amino acids as an energy source.
Variable responses of stomatal conductance, growth, and yield to fulvic acid applications to wheat
Authors: Dunstone RL , Richards RA , Rawson HM
Published: November 2004

Studies in China have shown that fulvic acid (FA), applied after maximum leaf area is achieved, substantially increases the yield of wheat over a wide range of yield levels. The effects were greatest when there was a sustained drought and hot, dry winds. Yield increases appeared to result from the effect that FA had on stomatal conductance and leaf senescence. We report here the responses of predominantly Australian wheat genotypes to FA applied in both glasshouse and field. FA, extracted from coal in Australia or China, was applied to the leaves of wheat plants as a 0.05 or 0.1% spray. Although it reduced stomatal conductance by as much as 55% in particular studies and stimulated the growth of seedlings in other studies, the results were neither consistent nor predictable. We were unable to define a set of conditions under which the maximum effect could always be obtained. In the field studies, three slightly droughted crops were sprayed between late-boot stage and ear emergence. The effects of FA on stomatal conductance were variable amongst treatments 4 h after application, and had virtually disappeared one week later. Grain yield and harvest index were unchanged by FA. Similarly, in glasshouse studies, FA applied to plants at the onset of drought at four stages of development commencing at flag-leaf-emergence had no effect on grain yield or water use. It is concluded that, while FA does appear to have some effects in wheat, we were unable to identify the conditions required for it to influence grain yield and water use. We therefore recommend caution in its use as a foliar spray until these conditions can be defined.
Pollination and fertilization in crops of Vicia faba
Authors: Marcellos H , Perryman T
Published: November 2004

Crops of faba beans (Vicia faba cv. Fiord) were surveyed for the frequencies of pollination of stigmas, and fertilization of ovules, based on the detection of pollen tubes by fluroescence of aniline blue fluorochrome. The frequency of pollination ranged from 89.8 to 99.6% over crops, with an overall mean of 96.8%. Pistil fertilization varied from 88.4 to 99.1% about a mean of 95.5%; overall, 82.2% of all ovules examined were fertilized. There was no significant main effect of flower position in the raceme, although there were significant crop x floral position effects on fertilization. Mean ovule fertilization rate declined from a mean 91.6% for ovule 1 closest to the stigma to 56.7% for the fourth. Pollination was the controlling factor in the steps toward fertilization, there being a 99% likelihood that pistil fertilization would occur following pollination. It was concluded that neither pollination nor fertilization were limiting seed yield in these crops. There was also no evidence that measurable postfertilization abortion of ovules occurred, but that reductions in potential yield occurred owing to pod abortion.
A tiller inhibitor gene in wheat and its effect on plant growth
Authors: Richards RA
Published: November 2004

A recessive gene that inhibits tillering was identified in a wheat (Triticum aestivum L.) from Israel. The locus for tiller inhibition, designated Tin, is linked to the locus for hairy glume (10 � 3 map units apart) and black awns, and hence is presumed to be on the distal end of chromosome IAS. Such a gene has been proposed as desirable for wheat in both low and high input environments. Serial sowings were made every 21 days between autumn and spring in buckets outdoors with lines differing in tillering. At a harvest at the 4.5 leaf stage, tillering was less in the low tillering lines than in the conventional lines in all sowings, but leaf area and weight per plant were unexpectedly higher. Stunting, which is a characteristic of low tillering lines when temperatures are low and daylength long, became apparent in one of the low tillering lines in sowings made in late winter and spring at a time when daylength was 11.5 h and increasing. In four populations segregating for the tillering trait, low tiller number was associated with a higher harvest index, reduced height, an increased duration of the flag leaf life and of grain filling, a lower leaf to stem weight ratio at maturity, higher specific leaf weight, higher stem density and a higher kernel number per unit stem weight. Traits likely to severely limit crop yield other than stunting were not found.
Genetic diversity in Old Subterranean Clover (Trifolium subterraneum L.) Populations in Western Australia. II. Pastures sown initially to the Mt Barker strain
Authors: Rossiter RC , Collins WJ
Published: November 2004

Subterranean clover burrs were collected during the summer period from 20 pastures, all of which had been sown to the Mt Barker strain before 1951. These population samples were surveyed for variation in morphological characters and isozyme diversity as in Part I. The old Mt Barker populations, on average, contained about 50% of a few known strains - mostly Mt Barker and/or Woogenellup - and 50% of numerous variant genotypes. The large amount of genetic diversity probably arose from infrequent outcrossing between Mt Barker and Woogenellnp or Mt Barker and Dwalganup. The population genetic structure in T. subterraneum populations is grouped into four types. Type 1 consists of a single commercial strain and type II of a few such strains. In type III about half of the population consists of very few known strains and the remaining half very many variant genotypes. In type IV the original strains have been completely (or almost completely) replaced by numerous variant genotypes. These findings are significant in defining procedures for seed certification in clover. We suggest that substantial genetic diversity may be important (if not essential) for long-term success of this species. This implies that potential cultivars should be evaluated in admixture with a number of already adapted genotypes.
Factors affecting mature size and dry-season weight loss in Bos indicus cross cows in northern Queensland
Authors: Fordyce G , Saithanoo S , Goddard ME
Published: November 2004

Mature size and dry season weight loss affect the feed requirements, mortality rate and fertility of cows in the dry tropics. The aim of the work reported here was to study the effects of genotype and selection for growth rate on these parameters. The data consisted of: growth rate to 18 months; weight, height and condition score of cows over 5 years old; the change in these parameters during the dry season; and the past fertility of these cows. The cows were + or + bred Brahman of Sahiwal crosses. The Brahman crosses had the same growth rate but a higher mature weight than the Sahiwal crosses. The +-breds lost less weight during the dry season than the +-breds, implying a lower maintenance requirement. Growth rate to 18 monthswas correlated with adult height (r = 0.54) and weight (r = 0.58-0.68). Growth rate was correlated with dry season weight loss (r = 0.36), but only because weight loss was correlated with weight at the start of the dry season. After correcting for this starting weight, growth rate was not correlated with weight loss, and in fact growth rate was positively correlated with condition score late in the dry season (r = 0.17). Adult height was weekly correlated with dry season weight loss (r = 0.13). Past fertility was correlated with current fertility and with ability to maintain condition during the dry season.
Effects of soil nitrogen status and rate of inoculation on the establishment of populations of Bradyrhizobium japonicum and on the nodulation of soybeans
Authors: Brockwell J , Gault RR , Morthorpe LJ , Peoples MB , Turner GL , Bergersen FJ
Published: November 2004

Soybeans (Glycine max [L.] Merrill cv. Forrest) were grown under irrigation on a well-structured grey clay soil, previously free of Bradyrhizobium japonicum and containing relatively high levels of mineral N, at Trangie, N.S.W. There were two soil pretreatments, pre-cropped (which had the effect of reducing the level of mineral nitrogen in the soil) and pre-fallowed, and four rates of inoculation (B. japonicum CB 1809 - nil, 0.01 X, 1.OX [=normal] and 100X).Mineral nitrogen (0-10 cm) initially was higher in pre-fallowed soil than in pre-cropped soil (37.6 v. 18.5 mg N per kg). Depletion of mineral nitrogen occurred more rapidly in pre-fallowed treatments, so that, 7 days after harvest, mineral-N in pre-cropped soil was significantly higher than in pre-fallowed soil (14.4 v. 10.6 mg per kg).With high levels of soil mineral nitrogen, colonization of seedling rhizospheres by rhizobia and plant nodulation were diminished. These effects were ameliorated but not eliminated by increased rates of inoculation. The development of the symbiosis was also impeded by lower rates of inoculation (0.01 X, 1.OX).
The effect of copper supply on vegetative and seed yield of pasture legumes and the field calibration of a tissue test for detecting copper deficiency. I. Subterranean clover (Trifolium subterraneum and Trifolium yanninicum)
Authors: McFarlane JD
Published: November 2004

Three cultivars of subterranean clover (Trifolium subterraneum L. cvv. Woogenellup, Nungarin; Trifolium yanninicum cv. Trikkala) were grown on three copper-deficient soil types at seven rates of copper, applied at sowing, to determine their vegetative and seed yield response to copper fertilizer.On two soil types, symptoms of copper deficiency were apparent where no copper was supplied. On the third, symptoms appeared only in one season, after the site was waterlogged. On the three soil types, the symptoms disappeared when 0.125 kg Cu/ha was applied at sowing. although at this rate vegetative and seed yields were reduced by as much as 44% and 59% respectively.The proposed critical concentration range in youngest open leaf tissue for both diagnosing maximum vegetative dry matter and predicting maximum seed yield is 3.0-4.5 mg Cu/kg for Woogenellup and Nungarin subterranean clover. Trikkala subterranean clover had higher critical concentration ranges for diagnosing maximum vegetative dry matter (4.0-6.0 mg Culkg) and predicting maximum seed yield (4.5-7.0 mg Cu/kg). It was not clear whether this difference was due to a higher internal requirement for copper of Trikkala or overlying environmental conditions affecting the external copper supply at the time of sampling.For whole top tissue (WT), there was no difference in the critical concentration range between the three cultivars for diagnosing maximum vegetative yield (3.0-4.0 mg Cu/kg). However, the critical concentration in WT for predicting maximum seed yield was higher for Trikkala (5.0-6.0 mg Cu/kg) than Woogenellup and Nungarin (3.5-4.5 mg Cu/kg). In the pasture situation, a critical concentration of 5.0-6.0 mg Cu/kg in the WT should be adopted when animal requirement is considered.Seed copper concentration for predicting maximum seed or vegetative yield was not a reliable indicator of copper status of subterranean clover.
An epidemic of celery mosaic virus in South Australian celery
Authors: Alberts E , Francki RIB , Dietzgen RG
Published: November 2004

A virus isolated from celery (Apium graveolens L.) around Adelaide was identified as celery mosaic virus (CeMV) by its host range, symptom expression, particle morphology, and cytopathic effects. The virus was shown to be serologically related to CeMV in Great Britain, New Zcaland and the United States, and to a virus described as celery yellow mosaic virus in Brazil. Disease incidence was most prominent in the cultivar Tendercrisp, but the virus was also isolated from other cultivars, including Summit, Green Giant and Baulderstone. Incidence of the disease reached 70% in some crops and many of the infected plants were unfit for marketing. It is suggested that control of the disease may be achieved by introducing a celery-free period to break the cycle of virus transmission between successive crops.
Genetic and environmental effects on the fertility of beef cattle in a tropical environment.
Authors: Mackinnon MJ , Hetzel DJS , Taylor JF
Published: November 2004

Calving data recorded over a 28-year period were analysed for the effects of breed, filial generation,
lactational status, cow liveweight at mating and year of mating. The herd comprised six distinct
breeding lines ('breeds') and analysis was performed both within and across breeds. The least fertile
breeds were the high grade (314-718) Africander (A) and high grade (718-purebred) Brahman (B) cows
which had average calving rates of 56% and 55%, respectively. Crossing these with a Hereford-
Shorthorn line, which had an average calving rate of 6O%, resulted in 19% heterosis (in absolute calving
percentage units) in the F1 Africander-cross (AX) and 16% heterosis in the F1 Brahman-cross (BX). In
subsequent generations, 13% residual heterosis remained in the AX, while in the BX only 1%
remained. Reciprocal crossing of the AX and BX lines generated 6% heterosis in the Fl AXBX, and all
of this was maintained in subsequent generations. In the F2 et seq. generations of the AXBX, the line of
animals carrying the Bos indicus Y chromosome was similarly fertile (P> 0.05) to the line carrying the
Bos taurus Y chromosome.
Lactating mature (3 5-year-old) cows were on average 15% less fertile than non-lactating cows.
This lactation effect was larger in younger cows. There was a curvilinear response in fertility to
increasing liveweight at mating which was most pronounced in 2-year-old heifers. Breed appeared to
react differently to the effects of environmental stress where the AX and HS cows were limited more by
liveweight, and the BX and AXBX were more limited by lactation effects per se.
Lactating cows that also lactated in the previous year were 6% more fertile than lactating cows that
were dry the previous year, suggesting that calving records are moderately repeatable and therefore
that permanent differences in fertility could be established by phenotypic selection.
Net photosynthesis, water use efficiency, leaf water potential and leaf rolling as affected by water deficit in tropical upland rice
Authors: Dingkuhn M , Cruz RT , O'Toole JC , D÷rffling K
Published: November 2004

Growth and production of tropical upland rice is often impeded by drought. Little is known on varietal response of CO2 assimilation to water deficit under tropical field conditions. A drought-susceptible semidwarf (IR20) and a drought-resistant traditional (Azucena) rice were grown in a dryland field experiment with sprinkler irrigation during the dry season in the Philippines. Differential irrigation was imposed for 11 days during vegetative growth using a line source sprinkler. Net photosynthesis, leaf conductance, transpiration, leaf rolling and leaf water potential were determined during the stress cycle at pre-noon and afternoon, with all measurements on the same leaf. No varietal differences in maximum photosynthetic rate and in the relationship between photosynthesis and leaf conductance were observed. In both rices, partial stomatal closure and nonstomatal inhibition reduced assimilation rates in the afternoon. Leaf water deficits restricted gas exchange through at least three apparently independent mechanisms: leaf rolling, reduced stomatal conductance and non-stomata1 inhibition which became evident only at severe degrees of stress. Stomata1 closure and leaf rolling were more sensitive to water deficit in Azucena which maintained higher leaf water potential throughout the stress cycle. Both stomatal closure and leaf rolling improved water use efficiency at moderate stress while nonstomatal inhibition of photosynthesis reduced water use efficiency.
Effect of phosphorus on three perennial Stylosanthes species in tropical Australia. II. Phosphorus and nitrogen within the plant and implications for grazing animals
Authors: Gilbert MA , Edwards DG , Shaw KA , Jones RK
Published: November 2004

This paper describes the effect of phosphorus application on concentrations and distribution of phosphorus (P) and nitrogen (N) in three Stylosanthm specics (S. scabra cv. Scca, S. guiunensis cv. Schofield and S. viscosa CPI 34904) grown in the field on a soil of low acid-extractable (0.005 M H2SO4) P status (4 mg/kg). Over a two-year period (May 1978 to September 1979), regular measurements were made of P and N in whole plant shoots, leaves, stems, inflorescence, seed and litter.Phosphorus application increased P concentrations in all three legumes, but did not affect its pattern of seasonal change throughout the year. The P (and N) concentrations in most plant parts decreased through the wet season to reach minima in the late dry season. However, with seed there was little seasonal variation. In the second year, Seca was more efficient at taking up P and utilizing it for growth under low soil P conditions than Schofield. CPI 34904 was less efficient than Seca at taking up P, but also used P efficiently for growth. The efficient utilization of P in the leaves and stems of Seca and CPI 34904 meant that P levels were often below the level (0.12%) considered adequate for growth of grazing cattle. Dry season P concentrations in all legumes were inadequate. When P was applied, P concentrations in leaf and green stem of all species were higher than 0.12% during the wet season, but green stem of Seca and CPI 34904 fell below this level during the dry season.Applied P slightly increased N concentrations in leaves, green stems and whole plants of all species. Nitrogen concentrations were adequate (> 1.1% N) for maintenance of cattle weight at most times. Only in the late dry season did green stem of Seca contain insufficient N.Phosphorus application had little effect on the distribution of P and N within the plants. All species held a large percentage (20-50%) of these nutrients in green stems, but CPI 34904 was exceptional in directing up to 60% of the P and N to inflorescence and seed at the expense of leaf and stem.
Corrigendum - The influence of pasture and animal factors on the consumption of pasture by grazing sheep
Authors: Birrell HA
Published: November 2004

Interrelations of animal and pasture factors to account for variance in (i) the time spent grazing (GT, H/day) and (ii) the rate of eating (IR, OM/h) in data collected over 2.5 years on Corriedale sheep (adult castrated males) grazing pasture of mixed perennial/annual species in south-western Victoria were examined by sequentially adding factors and analysing in nonlinear regression relationships. Three plant and two animal factors accounted for almost 80% of the variance (100R2) in the GT of sheep grazing on green pasture in the period from March to November (n = 176). Five factors, including a stress factor related to environmental conditions, accounted for 82.5% of the variance in IR of sheep grazing through the green pasture period from March to December (n = 192). Pasture factors associated with organic matter digestibility were also examined. Total pasture mass (H, t DM/ha) and the green proportion of the pasture (G, %DM) accounted for 74.6% of the variance in D (n = 232). The implications of these relationships for developing an understanding of the biological basis for intake control and compensatory growth of animals are discussed.
Trapping of larvae of the cattle tick Boophilus microplus by Stylosanthes scabra under grazing conditions
Authors: Wilson LJ , Sutherst RW , Kerr JD
Published: November 2004

Several varieties of the leguminous genus Stylosanthes have the capacity to trap larvae of the tick Boophilus microplus. This capacity was assessed for S. scabra plants collected from grazed fields at two locations, Brian Pastures Research Station and 'The Springs' in central Queensland. Morphological attributes which may affect the capacity of plants to trap tick larvae were recorded. In laboratory tests, plants collected from Brian Pastures trapped 27% of larvae in summer and 12% in winter, whilst plants from 'The Springs' trapped an average of 12%, with no seasonal pattern discernible. The percentage of branches which were sticky was the major determinant of a plant's capacity to trap ticks. Variation in stickiness per se was less important. Frost and burning temporarily reduced tick-trapping capacity, but after four months, burnt plants trapped a higher percentage of larvae than unburnt plants due to the production of sticky regrowth. The implication of the results for the use of S. scabra in tick control programs is discussed.
Variation in, and inheritance of seedling and adult-plant resistance in subterranean clover (Trifolium subterraneum L.) to leaf scorch (Kabatiella caulivora) (Kirch.) Karak
Authors: Chandrashekar M , Halloran GM
Published: November 2004

The disease reaction of seedlings (2 weeks old) from a field collection of subterranean clover (Trifolium subterraneum) to clover scorch (Kabatiella caulivora (Kirch.) Karak), revealed 89 immune plants out of a total of 1530. However, with adult plants (15-16 weeks old) only one plant remained immune. In the F2 population of the cross of the cultivars (Daliak X Woogenellup (D X W), seedling resistance was conditioned by a single dominant gene and in the cross (Enfield X Woogenellup) (EX W) by a single recessive gene. However, with adult plants, resistance in the (D X W) F2 was conditioned by a single recessive gene and that in the (EX W) F2 by two recessive genes. The effect of increasing age in reducing the proportion of plants resistant to clover scorch in both studies indicates that caution is needed in evaluating resistance to clover scorch in epidemiological, breeding and genetic studies.
Fleece rot and body strike in Merino sheep. IV. Experimental evaluation of traits related to greasy wool colour for indirect selection against fleece rot
Authors: Raadsma HW , Wilkinson BR
Published: November 2004

The potential for using indicators of greasy wool colour as indirect criteria for selection of sheep genetically resistant to fleece rot and body strike was examined. Nine traits based on the subjective grading of wool samples (1 trait), objective reflectance (6 traits) and colour development during incubation (2 traits) were evaluated for their genetic potential, ease and reliability of measurement, and relationship with other major production characteristics. The colour of wool was assessed in 949 Merino ewe hoggets representing the progeny of 134 sires before the induction of fleece rot. All colour traits were moderately heritable, ranging from 0.25 � 0.13 for subjective colour score to 0.40 � 0.14 (h2�.s.e.) for an objective reflectance index. Based on the combined estimate of the heritability of the indicator trait and its genetic correlation with fleece rot, indices based on the objective measurement of colour reflectance and colour development following incubation showed the highest genetic potential for indirect selection. Objective measurement of colour reflectance also showed a high genetic potential for indirect selection against body strike. Subjective colour assessment prior to the induction of fleece rot showed the lowest potential for indirect selection against both fleece rot and body strike. The cost of objective measurement of colour was less than that of colour development during incubation, and the former was found to be the most reliable indirect selection criterion in this experiment. A consequence of selecting solely for decreased greasy wool colour on other production characters is likely to result in decreased fibre diameter, increased wool yield, with a potentially small decrease in greasy fleece weight. Further evaluation of colour indicators as additional selection criteria should first focus on the likely role of fleece rot and body strike resistance as part of (national) breeding objectives. Only then can the full impact of using colour variables on the overall breeding aggregate be established.