bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant growth on a low calcium status solodic soil in a subtropical environment. II. Soil cation anisotrophy and plant cation balance
Authors: Russell JS
Published: November 2004

Pot and field experiments were carried out on solodic soils from southern Queensland showing marked soil cation anisotropy and increasing sodium absorption ratio with depth. The growth and cation composition of Phaseolus lathyroides and Cenchrus ciliaris were compared in a pot experiment with the surface and subsurface horizons of a solodic soil from site 1. Significant yield responses were obtained on the subsurface soil to each of five different calcium compounds. Applied calcium was associated with decreased plant sodium percentages. Effects were small on the surface soil. The effects of cation pair and cation ratio and various rates of calcium carbonate and magnesium carbonate on the yield and cation content of P. lathyroides were also measured for the surface soil. The calcium content was greatly reduced by high levels of applied magnesium. Under these conditions the relative constancy of the total plant cation content was disturbed. Field data on the chemical composition of grasses and legumes grown on solodic soils showed species differences in relation to cation content. Chloris gayana and Avena sativa contained high percentages of sodium. Panicum coloraturn contained moderate sodium percentages but levels in C, cdiaris were low. Temperate legumes, particularly annual Medicago spp., contained moderate sodium percentages. Sodium levels of all tropicaLlegumes grown were low but magnesium percentages were high. The experimental results suggest that the low calcium level and relatively high sodium and magnesium levels may affect the growth of certain species on solodic soils in southern Queensland. The cation status of these soils may influence ion selectivity mechanisms, cation balance, and root integrity. In some aspects of plant nutrition these solodic soils are analogous to serpentine soils.
Nutrient cycling in grazed pastures. III. Studies on labelling of the grazed pasture system by solid [35S]gypsum and aqueous Mg35S04
Authors: Till AR , May PF
Published: November 2004

35S was applied to eight paddocks either onto strips that comprised 1/30 of the area of the paddock or uniformly over the paddock. It was applied as solid [35S]gypsum or aqueous Mg35SO4 at sulphur levels of either 130 mg/ha or 7.8 kg/ha. The specific radioactivity of wool grown by sheep grazing the paddocks showed that strip and uniform labelling gave similar results, that there was no retention of the applied sulphur in forms that were not eventually available to plants, and that after about 260 days the effective specific radioactivity of the cycling sulphur had approached a steady state. There were significant differences between the specific radioactivities of sulphur in phalaris and clover. The differences in the sulphur application levels produced plant materials having slightly different sulphur contents but the major changes in sulphur content were due to the natural sulphur cycle.
Inheritance of the necrotic and mosaic reactions in sorghum infected with a 'Johnson grass' strain of sugarcane mosaic virus
Authors: Teakle DS , Moore RF , George DL , Byth DE
Published: November 2004

When 30 sorghum inbred lines were inoculated with a 'Johnson grass' strain of sugarcane mosaic virus, seven reacted with systemic necrosis whereas 23 developed systemic mosaic symptoms. Nine F1 populations, 11 F2 populations, and 17 F3 populations derived from one F2 were tested for reaction to the virus. The results are consistent with the hypothesis that inheritance of the type of reaction is controlled by a single gene. The gene does not appear to have been reported previously, and the alleles are designated N, n. Presence of the dominant allele results in systemic necrosis, whereas presence of the homozygous recessive results in systemic mosaic symptoms. Colour of the necrosis, i.e. whether red or tan, is controlled by another single gene, probably the factor for purple (P) or tan (p) plant colour. The N and P genes do not appear to be linked.
Meiosis and embryo sac development in Urochloa mosambicenisis and three Paspalum species
Authors: Pritchard AJ
Published: November 2004

Paspalum commersonii is tetraploid and sexual. Urochloa mosambicensis, Paspalum plicatulum, and P. guenoarum are all tetraploid aposporous apomicts. The aposporous embryo sac is four-nucleate in U. mosambicensis and eight-nucleate in the Paspalum spp. Irregularities in chromosome pairing occurred at meiosis in all species except P. commersonii.
Responses of five pasture species to phosphorus, lime, and nitrogen on an infertile acid soil with a high phosphate sorption capacity
Authors: Helyar KR , Anderson AJ
Published: November 2004

The growth responses of Lolium pevenne L. cv. Clunes, Phalavis tubevosa L. cv. Australian Commercial, Trifolium subterraneurn L. cv. Mount Barker, Trifolium vepens L. cv. Victorian, and Medicago sativa L. cv. Hunter River to lime, superphosphate, and nitrogen were compared in a field experiment on a soil with a pH of 4.9-5.4 (115 soil/water ratio) and with the cation exchange capacity 25-50% saturated by aluminium. The soil had a high phosphorus requirement. The effects of superphosphate and lime on the sodium bicarbonate extractable phosphorus levels and on the soil pH are discussed. Lucerne was one of the least productive species at most harvests. It required more superphosphate than subterranean clover, perennial ryegrass, or white clover to attain any given percentage of maximum yield. The visual symptoms of the plants and the yield interactions showed little evidence of effects of high aluminium, which indicated that the superphosphate was needed to correct phosphorus deficiency rather than to counteract any aluminium toxicity. The initial soil pH was somewhat higher than the levels previously found to be associated with aluminium toxicity on the soil in pots. Phalaris growth was increased to the highest superphosphate level, but growth at lower levels improved with time. Subterranean clover growth was depressed by the highest superphosphate level early in the season. The other species were not affected in this way. More lime was needed for lucerne than for white clover, which in turn needed more lime than subterranean clover. Nitrogen decreased the response of clover to lime, and the evidence indicates that the response of the legumes to lime was due mainly to the effect of lime in improving nodulation and nitrogen fixation. The lime-treated subterranean clover responded to nitrogen, especially in the first few months after sowing. The grasses responded markedly to nitrogen, while lime had a small effect on their growth and response to nitrogen. In no case did lime decrease the requirement for superphosphate.
Nutritional status and intake regulation in sheep. VI. Evidence for variation in setting of an intake regulatory mechanism relating to the digesta content of the reticulorumen
Authors: Egan AR
Published: November 2004

In each of four experiments, individually penned sheep were fed on a range of diets ad libitum, consuming the feed over 24 hr each day. In preliminary feeding periods each experimental animal became stabilized to a feeding pattern giving low standard deviations between days for the amount of feed consumed at a meal when the animal began and left off feeding at will. The amounts of digesta in the reticulorumen at the end of a specific meal (the first meal after presentation of a new allowance of feed) or before the commencement of the next (second) meal were then measured directly by emptying the reticulorumen or indirectly by estimates based upon a polyethylene glycol (PEG) dilution technique. The amount of digesta present in the reticulorumen at the end of the first meal was significantly greater when animals were fed on chopped lucerne hay (1.8 % nitrogen, 68% digestibility) than on either chopped oaten hay (1.2% nitrogen, 62% digestibility) or chopped wheaten straw (0.8 % nitrogen, 56 % digestibility). The quantity of digesta present in the reticulorumen increased as intake per day, or per meal, increased. For each diet, however, the weight of digesta held at the end of the meal was found to be repeatable between separate observations to within 800 g, which indicated a possible regulatory relationship between 'fill' and the termination of that meal, and the order of precision of the regulation. The intake of chopped wheaten straw was less than that of chopped oaten hay or chopped lucerne hay, both per day and in the second meal, even though the amount of digesta present in the reticulorumen immediately before the second meal was substantially lower for sheep given chopped wheaten straw. Though the amount of digesta in the reticulorumen of sheep given a pelleted, ground lucerne hay-barley mixture was also relatively low before the second meal, intakes were very much greater than when animals were given chopped wheaten straw. When casein was given in the diet or per duodenum, the intakes of oaten chaff (0.9 % nitrogen, 59% digestibility) were increased, and the amount of digesta held in the reticulorumen at the end of the first meal increased. Results support the hypothesis that, while for each diet the intake may be regulated to give a relatively constant level of fill of the reticulorumen at the end of a voluntarily terminated meal, this level of fill is not a constant between diets but is influenced by other, presumably nutritional, factors. One such factor is the protein nutrition of the animal.
The effect of early superphosphate toxicity on the subsequent growth of wheat
Authors: Bhatti AS , Loneragan JF
Published: November 2004

The effects of 19 days' treatment with three rates of superphosphate and four rates of ammonium nitrate application on the growth of wheat in a siliceous sand have been studied both during and after treatment. Severe necrosis of leaf tips developed after 7 days at high superphosphate and no ammonium nitrate. Plant tops with symptoms had high concentrations of phosphorus. Decreasing superphosphate or increasing ammonium nitrate gave lower phosphorus concentrations and fewer symptoms in plant tops. Ammonium nitrate depressed phosphorus concentrations by promoting top growth relative to root growth. Symptoms were ascribed to phosphorus toxicity. When plants with severe symptoms of phosphorus toxicity were transplanted to siliceous sand and watered with complete nutrient solution containing adequate phosphate, tillering was delayed and dry weights of tops, roots, and grains were depressed about 30%. Plants with symptoms of only moderate intensity recovered and grew as well as plants which initially had mild or no symptoms. The results suggest that the intensity of phosphorus toxicity reported to occur in cereal crops in the field is not likely to depress yields seriously.
Duration of susceptibility of apricot pruning wounds to infection by Eutypa armeniacae
Authors: Carter MV , Moller WJ
Published: November 2004

The duration of susceptibility to infection by Eutypa armeniacae has been studied in field experiments involving inoculation of pruning wounds on apricot trees within and outside a rainproof shelter, thereby enabling susceptibility to be assessed in the absence of natural infection. The susceptibility of wounds made in early winter on sheltered trees declined from 100% on the day of pruning to c. 30% 4 weeks later. On unsheltered trees exposed to natural infection, inoculation of 2-week-old wounds did not increase the proportion infected above that occurring in non-inoculated wounds. An hypothesis is advanced to explain the decline in susceptibility with age of wound.
Factors affecting uredospore liberation in Puccinia antirrhini
Authors: Carter MV , Yap ASJ , Pady SM
Published: November 2004

Air sampling within an annular field plot of rusted snapdragons, and in a wind tunnel, has shown that uredospores of Puccinia antirrhini are readily liberated by wind shear at speeds = 2 m/sec. At constant temperature and wind speed, most uredospores are liberated in the light, mainly in the morning. Liberation in dry air is related logarithmically to wind speed; it is increased by the onset of rainfall or overhead sprinkling, and by bombarding sori with water droplets in the wind tunnel.
Response to selection in Australian Merino sheep. III. Single character selection for high and low values of wool weight and its components
Authors: Turner HN , Brooker MG , Dolling CHS
Published: November 2004

Direct and correlated responses are reported for 10 traits in eight pairs of lines under selection for high and low values of single characteristics : clean wool weight per head, clean wool weight per unit skin area (measured only in the groups under selection for it), body weight, wrinkle score, fibre number per unit skin area (adjusted for body weight), fibre diameter, staple length, and percentage clean yield. All groups showed overall divergence in the character under selection, though response was not always symmetrical, and in two cases (long staple and low fibre number) there was no continuing response after the initial response to extreme selection of the base parents. In all except one case, whenever previous estimates of genetic correlation were at the level of 0.2 or higher, correlated responses were in the predicted direction, though not always symmetrical in magnitude. The exception was a previously reported negative correlation between fibre number and staple length, which was not exhibited under selection for either character. Where two characters of a pair were under selection, reciprocal responses agreed in sign; magnitude will be examined in a later paper. Wool per unit area was shown to have a greater influence on clean wool weight than that of surface area, with staple length on this occasion being the most important component of wool per unit area. Reasons for an apparent decrease in the relative importance of fibre number are discussed. Three other points of importance in sheep breeding are again emphasized by these results : 1. Crimp in several pairs of groups was a poor indicator of fibre diameter. 2. Increases in clean wool weight were associated with falls in crimp number, even though fibre diameter actually became finer; diameter, not crimp, should therefore be used as a guide to wool quality. 3. The absence of genetic correlations DL and NL indicates that selection can be for high N (fibre number) with high L (staple length) and low D (fibre diameter) -in other words, a desirable fleece -with no impeding genetic correlations.
Studies of grain production in Sorghum vulgare. II. Sites responsible for grain dry matter production during the post-anthesis period
Authors: Fischer KS , Wilson GL
Published: November 2004

The relative contributions of different photosynthetic sites to the filling of the grain in grain sorghum (Sorghum vulgare cv. Brolga) were estimated by measuring the 14C in the grain after exposing various leaves and the head to radioactive carbon dioxide. Methods for preventing photosynthesis were also used. Of the grain yield, 93% was due to assimilation by the head and upper four leaves. The head contribution of 18 % was due equally to direct assimilation of atmospheric carbon dioxide and to reassimilation of carbon dioxide released within the grain by respiration of material translocated from the leaves. The remaining 75 % was equally assimilated by the upper four leaves, the flag leaf being the most efficient contributor per unit area and the third uppermost leaf the least efficient. The percentage contributions to the grain by the flag leaf and fourth leaf, estimated from the decrease in grain yield when they were shaded, agreed closely with the estimates obtained by using 14CO2.
The relation between lucerne shoot growth and temperature
Authors: Leach GJ
Published: November 2004

Two lucerne cultivars were grown in glasshouses maintained at temperatures of 15, 21, 27, and 33�C to study the influence of temperature on regrowth after cutting; and especially to determine whether temperature affected the response from retaining basal leaves after cutting, and also the relation between the number of shoots remaining on plants and the size to which shoots grew. In one experiment plants were cut at 5 cm above crown level, and basal leaf was either removed or retained. In cv. Totana the total weight of shoots 7 days after cutting increased with each temperature increment, but by 21 days after cutting was maximal at 27�C. Cv. Rhizoma was less responsive to temperature; maximum weights appeared to be obtained at 27' on both days. Removing basal leaves decreased shoot weight in both cultivars at all temperatures, and there was no significant interaction of cultivars or temperatures or both with defoliation. The relative effect of removing leaves was greater at lower temperatures, and greater for Rhizoma than for Totana. In two other experiments with Totana, either all shoots were permitted to regrow after cutting or only a predetermined number. When all shoots regrew, the weight attained by individual shoots was generally independent of the number of shoots, but at 33�C the weight attained by shoots observed shortly after cutting decreased as the number increased. Where only one, two, four, or eight shoots were permitted to grow on each plant, the weight attained by individual shoots was independent of the number present at 21�, but at 33� shoots were significantly larger when only one or two were retained than when four or eight were retained. These results support the concept that shoot growth is normally restricted by environmental rather than by plant factors, and that it is only when environment is conducive to high shoot growth rates immediately after cutting that there is inter-shoot competition for growth substrates.
Variations between and within breeds of cattle in resistance to field infestations of the cattle tick (Boophilus microplus)
Authors: Seifert GW
Published: November 2004

Maturing female ticks were counted in herds of Brahman x British, Africander x British, and British breed (Shorthorn x Hereford) cattle run together. About 3000 counts were made on over 1000 cattle. The Zebu crossbreds on average carried two-fifths the number of ticks carried by the British cattle, though in some herds the difference was greater, and it tended to be greater in females than in males, in summer than in winter, and in F2 than in F3 animals. Brahman cross and Africander cross cattle did not differ significantly in resistance. Male cattle carried significantly more ticks than females, and the resistance of lactating British breed cows, but not Zebu crossbreds, was lower than that of dry cows. Repeatability of counts was higher in females than in males, and higher in Zebu crossbreds than in British cattle. Expression of inherent resistance in the British cattle was variable according to circumstances which are only partly defined. Heritability estimates were up to 48%, but in some cases much lower. In the Zebu crossbreds there was little heritable variation in F, cattle, but in subsequent generations heritability was estimated as 82%. The needs for selection for resistance, and the control of error and the prospects of success, are discussed.
Early-flowering mutants of Medicago ploymorpha var. Polymorpha
Authors: Brock RD , Andrew WD , Kirchner R , Crawford EJ
Published: November 2004

Treatment of dry seeds of Medicago polymorpha L. var. polynzovpha with 20 krad gamma rays resulted in a large increase in variation for flowering time. Selection among spaced plants in the M2 and M3 generations, primarily for early flowering and secondarily for plant vigour and fertility, resulted in the isolation of mutant lines which flowered from 2 to 3 weeks earlier than the unirradiated controls and which were comparable in vigour with the unirradiated controls. This method of generating variability for plant improvement programmes proved to be simple, relatively quick, and economical (c. 1000 plants x 4 generations). It is recommended for more extensive use with self-fertilizing annual species where the primary selection criteria are clear cut and simply measured.
The effect of defoliation on the persistence of Atriplex vesicaria
Authors: Leigh JH , Mulham WE
Published: November 2004

To determine the response of the perennial shrub Atriplex vesicaria Hew. ex Benth. (bladder saltbush) to grazing, bushes were grazed by Merino sheep to two levels of defoliation, severe and complete. Ungrazed bushes were used as controls. Separate groups of plots were defoliated in October and February and two levels of soil moisture were imposed. Results showed that the more heavily the bushes were grazed the less likely they were to regenerate. Completely defoliated bushes did not regrow, irrespective of soil moisture status or season. It is hypothesized that the inability of A, vesicaria to persist after complete or severe grazing is due to the removal, by grazing, of potential growth sites which apparently occur only along the young stems.
Heterotic performance and combining ability in a diallel cross among spring wheats (Triticum aestivum L.)
Authors: Bhatt GM
Published: November 2004

Levels of hybrid vigour for earliness, plant height, four components of yield, and yield were examined in the F1 generation of a diallel cross of eight cultivars of spring wheat. Kernel weight and kernels per spike exhibited high levels of heterosis effects. The analysis for general combining ability indicated that a large part of the total genetic variation observed for six out of seven traits was associated with genes which were additive in their effects. The estimates for specific combining ability were highly significant for five out of seven traits. These estimates were lower than those of general combining ability for six out of seven traits. The combining ability analysis helped in classifying the parents in terms of their hybrid performance and in gaining greater understanding of the nature of quantitatively inherited traits. The importance of genetic diversity in relation to heterosis was also assessed.
Sulphur metabolism and excretion studies in ruminants. IV. Cystine and sulphate effects upon the flow of sulphur from the rumen and upon sulphur excretion by sheep
Authors: Bird PR , Hume ID
Published: November 2004

In a 4 x 4 Latin square design experiment, sheep were fed on a basal ration which supplied 0.61 g sulphur per day, or the basal ration supplemented with 1.4 g inorganic sulphate sulphur, or 1.4 g cystine sulphur, or 1.4 g sulphate sulphur plus 1.4 g cystine sulphur per day. All forms of sulphur supplements increased the daily flow of protein sulphur from the rumen to the omasum (P < 0.05) above basal. Only the cystine treatments increased the flow of sulphide (P < 0.005), ester sulphate (P < 0.005), soluble organic sulphur (P < 0.05), and cystine (P < 0.05), and increased the ruminal sulphide concentrations above basal (P < 0.005). From 7.0 to 12.6% of the added cystine was not degraded in the rumen. In three animals less than 3 % of the added sulphate, alone or in combination with cystine, passed unchanged to the omasum. The fourth animal (67) differed from the others (P < 0.05): the added sulphate was poorly reduced in the rumen, and 62% reached the omasum unchanged. The sulphur composition of the digesta collected from the omasum was: protein sulphur, 55-70%; soluble organic sulphur, 13-22%; inorganic sulphate sulphur (excluding sheep 67), 2.2-2.6 %; ester sulphate sulphur, 1.8-3.4 %; and sulphide, 0.4-28%. Excluding sheep 67, 36% of the dietary sulphur was absorbed from the rumen when the sulphur was added as sodium sulphate or as cystine, and 50 % when added in both forms together. There was a net addition of 0.45 g sulphur per day to the rumen on the basal diet. The influence of the amount and the form of the dietary sulphur on the excretion of faecal and urinary sulphur fractions is discussed.
The absorption of amino acids from the rumen of the sheep. I. The loss of amino acids from solutions placed in the washed rumen in vivo
Authors: Leibholz J
Published: November 2004

L-histidine, glycine, and L-amino acid mixtures were placed in the washed rumen of sheep in concentrations similar to those found under normal feeding conditions. The amounts of individual amino acids lost from the rumen over a 4 hr period ranged from virtually zero to 50% of the initial concentration of amino acids placed in the rumen. It was calculated that this could account for 6% of the total nitrogen absorption from the rumen. The amount of L-amino acids lost from the rumen depended on their initial concentration and on the concentration of other amino acids present. The branched chain amino acids showed the most rapid absorption.
Sulphur-nitrogen relationships in the tropical legume Stylosanthes humilis
Authors: Jones RK , Robinson PJ , Haydock KP , Megarrity RG
Published: November 2004

The effects of age and sulphur fertilization on various sulphur fractions in the legume Stylosanthes humilis were examined. Plant material was obtained in two consecutive seasons from nodulated plants growing in the field and from a glasshouse experiment. A very close relationship between the concentration of total nitrogen (Nt), that of total sulphur (St), and age was found. In young material Nt increased at first then reached a plateau with increases in St (brought about by additions of sulphur). As the plants aged, however, both Nt and St declined and the relation between them became more nearly linear. Nt and St were also closely related in seed from these plants but the St/Nt ratio was much lower than in the vegetative material. A moderate deficiency of sulphur had little effect on the ratio of alcohol-insoluble to total nitrogen. In contrast with published work on other species it was found that sulphur applications increased the ratio of sulphur to nitrogen in the alcohol-insoluble (protein) fraction.
Patterns of symbiotic behaviour in Trigonella L.
Authors: Brockwell J
Published: November 2004

The symbiotic behaviour of five species of Trigonella in combination with 19 strains of Rhizobium melloti were examined in bacteriologically controlled culture. Nodule formation occurred in all but 10 of the symbiotic combinations and, on the basis of nodulation, there were three groups of host plants and three distinct types of Rhizobium. In respect of nitrogen fixation, which took place in 41 of 92 combinations, each species behaved differently and the rhizobial strains formed seven groups. Nitrogen fixation relationships fell into orderly patterns of increasing specificity. The data provide a basis for selection of suitable inoculants for Trigonella.
Effects of root temperature on growth of four lines of subterranean clover
Authors: Williams JD
Published: November 2004

One line of subterranean clover (CPI 14196) produced significantly more dry matter than three other lines (CPI 12621 — Israel, Dwalganup, and Mount Barker) at root temperatures suboptimal for shoot growth (10 and 15°C). These differences were associated with leaf area per plant and the size of individual leaves, and the greater growth was associated with partitioning of a greater part of the dry matter to leaves. The significance of the results is discussed in terms of limits to winter production of pastures based on subterranean clover.
Relationship between intake of silage and its chemical composition and in vitro digestibility
Authors: Brown DC , Radcliffe JC
Published: November 2004

Twenty experimental silages were made from seven pasture species at different stages of maturity. In vivo dry matter, organic matter, and energy ad libitum intakes and digestibilities of the silages were determined with standardized pairs of Merino wethers. The following chemical characteristics of the silages were measured: nitrogen, ammonia nitrogen, total titratable acids, acetic, propionic, butyric, and lactic acids, total volatiles lost during oven drying, lactic acid as a percentage of the total organic acids, pH, acid pepsin dry matter disappearance, dry matter content, and in vitro digestibility and rate of digestion. When all 20 silages were considered, energy intakes on a body weight basis were significantly related to silage pH (r = 0.55) and rate of in vitro digestion (r = 0.58). When the five legume silages were removed from the analysis and only the 15 grass-dominant silages were considered, dry matter intakes were significantly related to acetic (r = –0.57) and propionic acid (r = –0.55) concentrations. Multiple regression analyses did not significantly increase the accuracy of predicting intake. The results suggested that silage intake was negatively related to the degree of fermentation that occurred during the ensiling process.
Maintenance energy requirement of grazing sheep in relation to herbage availability. II.* Observations on grazing intake
Authors: Young BA , Corbett JL
Published: November 2004

Grazing pressure on three pastures was adjusted so that the mean liveweights (W) of three groups of 10 Merino wethers, initially uniform, were kept at nominally 45, 35, and 25 kg (groups H, M, and L respectively). Grazing intakes of each sheep were estimated over eight 7-day periods during 6 months. The organic matter (OM) content of the faeces decreased to less than 40% with dccreasing W, but concentrations of nitrogen (FN) and chromium sesquioxide (Cr2O3) in the OM increased. Sheep in groups M and L re-ingested with herbage, Cr2O3 they had previously excreted on their pastures. Faecal Cr2O3 concentrations were adjusted for this recycling, which otherwise would have resulted in underestimation of faecal OM outputs by up to 10% (group M) or 15% (group L). The digestibility in vitro was determined of herbage grazed from each pasture by a sheep with an oesophageal fistula. The values obtained for group H showed some differences, but not in a consistent manner, from those predicted from FN. For groups M and L, the in vitro digestibility values were consistently lower than those predicted from FN, on average by 12.5 percentage units with a maximum discrepancy of 18.5 units. It is shown that when sheep graze sparse pastures, as did groups M and L, the ingestion of large amounts of soil can lead to biased estimates of digestibility from FN, resulting in gross overestimation of digestible OM intakes. It is suggested that this bias may account for the apparently high maintenance feed intakes reported by other workers for sheep in these conditions, and that the calorimetric studies made on groups H, M, and L reported earlier gave more reliable estimates of maintenance requirements.

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*Part I, Aust. J. Agric. Res., 23: 57 (1972)
The calcium and pH components of lime responses in tropical legumes
Authors: Lee MT , Wilson GL
Published: November 2004

Pot experiments with nodulated tropical pasture legumes on a soil low in calcium and with a pH of 5.3 showed wide variation between species in response to lime applications. Further experiments with Lotononis bainesii which showed a small response to lime, and Glycine wightii which showed a large response, allowed the lime effects to be resolved into calcium and pH effects. This was done by supplying calcium in a number of forms, and by altering the soil pH with a variety of compounds. The yield of Lotononis was affected only by pH, in spite of large variation in the calcium content of the plant resulting from varying the calcium supply. Glycine responded to both calcium and pH. The pH effect did not involve molybdenum supply or the alleviation of manganese and aluminium toxicities. Yield responses to low levels of calcium nitrate could not be attributed solely to pH effects, and suggest that a nodular dependence on favourable pH may have been circumvented. A calcium content of only 0.2% in the shoot is apparently sufficient for Lotononis, and the soil used was able to supply this.
The relation of semen and vaginal mucus traits to fertility in the Australian Merino
Authors: Dunlop AA , Tallis GW , Brown GH , Gream BD
Published: November 2004

Data relating semen traits and vaginal mucus scores in 515 ram years and 4190 first inseminations to subsequent lambing performance of ewes were analysed by a range of statistical methods. The results showed there to be an important curvilinear effect of mucus score at insemination time and linear effects of scores for motility and consistency of semen in the ejaculates used. These effects operated both on fertility and on fecundity. There appeared also to be smaller linear effects of volume of semen inseminated per ewe and estimates of the proportion of abnormal spermatozoa in ejaculates collected before the insemination season on fecundity and probably on fertility. The effects of age of ewe on fecundity to a single insemination are in contrast with the usual effects of age on lambs born under natural mating. In our material two-tooth ewes produced 5–6% more lambs from a single insemination than did older ewes. It is suggested that, while older ewes are more sexually active and shed increased numbers of ova, the reproductive tract becomes a less favourable environment for initiation and completion of pregnancy with increasing age.
Response to selection in Australian Merino sheep. V.* Inheritance of abnormal staple crimp: Crimp abnormalities in groups of breeding ewes selected for high and low values of clean wool weight and its components
Authors: Chapman RE , Jackson N
Published: November 2004

Correlated responses in crimp abnormality in wool (i.e. irregularity of staple crimp frequency, to which the term "doggy" wool or "rough fleece" is applied when the crimp frequency is markedly reduced) are reported for two groups of Peppin Merino sheep selected for high clean wool weight, and for eight pairs of groups under selection for high and low values of the following single characters: clean wool weight per head, clean wool weight per unit area of skin, body weight, wrinkle score, fibre number per unit area of skin, fibre diameter, staple length, and percentage clean yield. In the first two groups the correlated responses in crimp abnormality were small and for practical purposes negligible. However. there appeared to be slight increases in crimp abnormality following changes in selection criteria, although this period coincided with adverse seasonal conditions. In the eight pairs of groups selected for single characters, correlated increases in crimp abnormality occurred in the groups selected for high clean wool weight per head, high and low fibre number per unit area of skin, high fibre diameter, and low percentage clean yield, and correlated decreases occurred in the groups selected for low clean wool weight per head, low fibre diameter, and high percentage clean yield. The responses were due mainly to the initial, intense selection of the foundation animals, and the responses to continuing selection were small. Environmental factors (year of fleece growth, maternal handicap, and lambing performance) did not have large effects on crimp abnormality. Crimp abnormality increased with age, and the rate of change was altered by selection in each of the single character groups in which correlated responses in crimp abnormality occurred, the responses being more pronounced at older ages.
Undernutrition in grazing sheep. I. Changes in the composition of the body, blood, and rumen contents
Authors: Farrell DJ , Leng RA , Corbett JL
Published: November 2004

Studies were made on three initially similar groups of adult Merino sheep at pasture; each group comprised eight animals of which four each had a rumen cannula. Group A was kept at about the initial mean liveweight of 35 kg; groups B and C were reduced in weight over 14 weeks by restriction of grazing and then held at about 26 and 23 kg respectively for 9 months. Measurements were made at intervals of 4-6 weeks of ruminal concentrations of volatile fatty acids (VFA) and ammonia, rumen volume and flow rate of digesta, tritiated water (TOH) space, and blood composition. Haemoglobin concentrations and haematocrit values decreased in the undernourished sheep, but there were no marked changes in blood β-hydroxybutyrate, or lactate, or plasma urea nitrogen. Estimates of body composition from TOH space indicated that sheep in groups B and C lost 51 and 58 Mcal respectively during the first 14 weeks; estimated fat contents were thereafter about 9 and 7% of liveweight. Metabolizable energy requirements for maintenance were calculated from estimated VFA production rates and changes in body energy content. During a 9 month period commencing shortly after shearing and extending into winter, requirements per unit liveweight were about 45% greater for the undernourished groups B and C than for group A.
Undernutrition in grazing sheep. II.* Calorimetric measurements on sheep taken from pasture
Authors: Farrell DJ , Leng RA , Corbett JL
Published: November 2004

The fasting heat production (kilocalories per kilogram liveweight) of sheep normally kept at pasture decreased during a period of 4 months when their liveweight was declining owing to low availability of pasture herbage, but increased considerably after shearing in autumn. It subsequently remained higher than for well-nourished sheep, which showed an effect of loss of fleece for only a few weeks. In thin animals critical temperature was higher after shearing, and their rate of increase in heat production as ambient temperature fell below critical was greater than in sheep in good body condition. Energy expenditure per unit of horizontal locomotion or vertical ascent (calories per metre per kilogram) did not vary significantly with body condition, but total daily expenditure at pasture was probably greater for the undernourished sheep. These results, and energy expenditures at pasture calculated from estimates of carbon dioxide entry rate, were consistent with observations on ruminal concentrations of volatile fatty acids and body energy content. The observations indicated that maintenance requirements (kilocalories per kilogram liveweight) of undernourished grazing sheep might be up to 45% greater than those of well-nourished sheep, particularly during inclement weather.

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*Part I, Aust. J. Agric. Res., 23: 483 (1972).
Undernutrition in grazing sheep. III.* Body composition and its estimation in vivo
Authors: Farrell DJ , Reardon TF
Published: November 2004

Twenty-four sheep, 12 fitted with rumen cannulae, were divided into three similar groups and kept at pasture. The grazing intake of group A was not restricted, but groups B and C were undernourished for a period of about 4 months and were then maintained in thin condition for a further 9 months, when all sheep were killed. The mean fat content was then 27, 9, and 5% of mean body weight in groups A, B, and C respectively. Undernourished sheep had a significantly higher (P < 0.01) water content in the fat-free empty body than well-nourished sheep. Multiple regression equations relating the fat, protein, and estimated energy contents of the body to tritiated water space and body weight differed between well-nourished and undernourished sheep. This was due to the larger amount of water in the rumell-reticulum of thin sheep and to the high water content of their fat-free body.

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*Part II, Aust. J. Agric. Res., 23: 499 (1972)
Ear branching as a means of increasing grain uniformity in wheat
Authors: Rawson HM , Ruwali KN
Published: November 2004

Grain growth was compared in two field-grown wheats, Kalyan Sona, a high-yielding, seinidwarf line with few spikelets per ear and many grains per spikelet, and a branched-eared cultivar with many spikelets, each with few grains. The basis of comparison was the spikelet in Kalyan Sona and the branch in the branched material. Within the central spikelets of the main ear in Kalyan Sona, grain growth rates for the greater part of filling were b > a = c > d > e; final weights per grain for these florets were 42, 40, 37,26, and 12 mg respectively. The gradation in growth rate for the eight grains along the branch in the branched-eared cultivar was relatively small with the consequence that all grains were similar in size at maturity (range 39–43 mg); peak growth rates for all positions were at least as high as for grains a, b, and c in Kalyan Sona. In another cultivar, Triple Dirk, increasing competition for assimilates by reducing the light intensity during grain filling had a differential effect on grains within the spikelet but scarcely on the pattern between spikelets. The relationship between all grains was unaffected by temperature changes. The results are discussed in relation to competition for assimilates between grains, and the suggestion made that a high number of grains per spikelet may not use the available assimilates most efficiently. Ear branching is proposed as a preferable alternative, as this also provides abundant grain sites to utilize assimilates to the potential of the photosynthetic system, yet ensures grain uniformity per ear, regardless of grain number, by having few grains in each spikelet.
Effects of time of day, moisture stress, and frosting on the alkaloid content of Phalaris tuberosa
Authors: Williams JD
Published: November 2004

Time of day had a slight effect on the level of N,N-dimethylated indolealkylamines in leaf tissue of plants of Phalaris tuberosa L. grown under controlled environmental conditions, and a somewhat larger effect on plants grown under field conditions. The alkaloid content was not affected significantly by moderate increases in moisture stress, but severe wilting caused an increase in the alkaloid content. The immediate regrowth from plants previously stressed had a higher alkaloid content than regrowth from unstressed plants. Severe moisture stress also caused an increase in certain related compounds, as yet unidentified. Frosting increased the alkaloid content more in plants receiving adequate nitrogen, and even more in plants grown at 21/16°C compared with plants grown at 15/10°. Changes in alkaloid content are discussed in relation to field observations and previous experimental results on the toxicity of P. tuberosa pastures to sheep.
The effect of withholding drinking water on wool growth and lamb production of grazing Merino sheep in a temperate climate
Authors: Lynch JJ , Brown GD , May PF , Donnelly JB
Published: November 2004

Drinking water was withheld from grazing pregnant and non-pregnant Merino ewes for a period of 12 months in an experiment carried out near Armidale, N.S.W., lat. 30° S., altitude 1000 m. There was no reduction in the wool production or liveweight of, or the number of lambs born to, ewes without drinking water as compared with ewes with water supplied. There was a significant reduction in the birth weight of the lambs of ewes without drinking water. Body water turnover rates were similar in sheep with and without water in the cooler months but a combination of climatic effects resulted in considerably lower water turnover rates of the sheep without water in early summer. Lactation, together with a low pasture water content and moderately high thermal loads in late December, resulted in a 25% mortality of the mated ewes without drinking water and the subsequent death of their lambs. Removal of the remaining ewes and lambs to green pasture immediately stopped the deaths although no drinking water was supplied. There were no deaths in the unmated ewes. The survival of most of the ewes when deprived of drinking water reflects in part the temperate climate of the Armidale area, where mean daily air temperatures during summer do not exceed 25°C and rain usually falls in each month of the year.
Effectiveness of mechanical mass selection in wheat (Triticum aestivum L.)
Authors: Derera NF , Bhatt GM
Published: November 2004

The efficiency of mechanical mass selection in wheat was tested on genetically heterogeneous and homogeneous populations. The populations were mechanically stratified according to seed size and field-tested for 2 years. Shifts in means and reductions in variances for kernel weight, grain weight per ear, and grain yield per plot were observed in the mass-selected populations of heterogeneous bulks. No such shift in means or reduction in variance was observed in stratified homogeneous populations. Populations selected for high seed size in heterogeneous bulks expressed themselves into higher grain yields per plot. Practical implications of these findings in formulating a wheat improvement program are discussed.
Metabolism of pyrrolizidine alkaloids in the ovine rumen. IV. Effects of chloral hydrate and halogenated methanes on rumen methanogenesis and alkaloid metabolism in fistulated sheep
Authors: Lanigan GW
Published: November 2004

Five halogenated methane analogues (bromoform, chloroform, iodoform, carbon tetrabromide, and carbon tetrachloride) have been shown to inhibit methane formation in the sheep's rumen as well as in rumen fluid in vitvo. On a molar basis the methane analogues were 100-200 times as effective as chloral hydrate in vitro, but in the rumen this difference was reduced by a factor of 10 with four of the compounds and to parity with chloral hydrate in the case of carbon tetrachloride. When rumen methanogenesis was inhibited by administration of chloral hydrate, bromoform, or iodoform, the time taken for metabolism of 2 g of Heliotropium europaeum alkaloids was reduced to 25-40% of that taken in animals not so treated. These results support the conclusion that inhibition of methanogenesis may be a useful protective measure for sheep ingesting plants which contain hepatotoxic pyrrolizidine alkaloids.
The effect of succinamic acid 2,2-dimethylhydrazide on shoot and fruit growth of Williams' Bon Chretien pear trees
Authors: Jerie PH
Published: November 2004

Whole-tree sprays of the growth retardant succinic acid 2,2-dimethylhydrazide (SADH) applied in autumn increased the fruit yield of Williams' Bon Chretien pears by 50-20%. Shoot number was reduced by 25-50 %. Delayed flower opening was not observed. The increase in fruiting did not result from the action of SADH in the flower bud during spring. Treatments combining shoot tipping and autumn SADH sprays indicated that competition from shoots resulted in abscission of fruitlets. It was concluded that autumn SADH treatments increased fruit number per tree at harvest by reducing to spurs a substantial number of potentially vigorous shoots. Label movement from single leaves fed with 14CO2 showed that during the 6 weeks following bloom, basal shoot leaves and spur leaves supplied both shoot tips and fruitlets. However, the results indicate that by 3 weeks after full bloom the observed shoot competition for assimilates was not the cause of fruitlet abscission.
Toxicity of malathion to California red scale, Aonidiella aurantii (Mask.) (Hemiptera: Diaspididae)
Authors: Abdelrahman I
Published: November 2004

The natural enemies of red scale, Aphytis melinus (Hymenoptera: Aphelinidae), Comperiella bifasciata (Hymenoptera: Encyrtidae), and Lindorus lophanthae (Coleoptera: Coccinellidae) were found to be much more susceptible to malathion than the female red scale in the second moult stage. It is concluded, therefore, that integration of malathion and biological control of red scale does not seem possible. Susceptibility of A. melinus to malathion was found to be a linear function of the duration of starvation prior to treatment. Individuals of A. melinus varied markedly in weight and this was found to be due to the number of parasites developed on one host and on the size of the host. A method based on wing length for estimating after treatment the pre-treatment weight of A. melinus is described, so that a correction for the weight of individuals may be applied. A circadian rhythm of susceptibility of A. melinus to malathion was found. It was shown that A. melinus possesses a mechanism for developing resistance to malathion. In eight generations of selection it had become 3.4 times more resistant and still had potential for further increase in resistance if selection were continued.