bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of vernalization, photoperiod, and temperature on phenological development and spikelet number of Australian wheat
Authors: Halse NJ , Weir RN
Published: November 2004

Sixteen Australian wheat cultivars grown in controlled environment cabinets demonstrated a range of responses to seed vernalization varying from little or no promotion of floral initiation in Darkan, Kondut, Falcon, and Sunset to about 3 weeks in Festiguay, Claymore, and Mexico 120. Under short days (10 hr photoperiod v. 14 hr) or cold temperatures (12/7�C day/night v. 18/13�) the response to seed vernalization was reduced. None of the cultivars responsive to vernalization achieved floral initiation earlier under cold temperatures than under warm temperatures, even in the absence of seed vernalization. All cultivars achieved floral initiation earlier in long days but the magnitude of the response varied considerably among them. Long days similarly accelerated development from initiation to anthesis. Higher temperatures accelerated development to initiation and anthesis in all cultivars, with only minor differences in magnitude of response. Selected treatments in the cabinets gave rates of development to initiation which closely paralleled results for the same cultivars in field experiments. The number of spikelets per head varied considerably with cultivar, day length, and vernalization treatment. Within the range of conditions of the experiments, temperature did not affect spikelet number other than through vernalization. At either temperature, the spikelet number was closely and positively related to the number of days to floral initiation.
Variation among strains of Phalaris tuberosa L. in nutritive value during summer
Authors: Clements RJ , Oram RN , Scowcroft WR
Published: November 2004

Several plant characters related to the quality and yield of summer herbage were investigated in 21 Phalaris tuberosa strains and three P. arundinacea strains or hybrids grown as undefoliated spaced plants in the field. Significant variation existed amongst the strains in in vitro digestibility and protein content at the completion of the head emergence and seed ripening stages. Considerably more variation, of the order of four- to eightfold, existed in yield during the first winter, spring, and summer. Some strains were superior to the Australian cultivar in each of these characters, but no strain possessed high levels of all characters. By considering the range of variation exhibited by the plant characters, and their phenotypic correlations with other traits it was concluded that selection may be applied to the best advantage for higher yields of leaf lamina and higher digestibility and nitrogen content of stem and sheath after senescence, and for higher herbage production during summer. These changes would probably be accompanied by a delay in heading time and a reduction in stem yield. Direct assessment of the selected characters would be necessary, because none of them is closely correlated with other characters which could be measured more easily or at an earlier developmental stage.
The determinants of herbage intake by grazing sheep: The interrelationship of factors influencing herbage intake and availability
Authors: Allden WG , McDWhittaker IA
Published: November 2004

The interrelationship of characters of the pasture (herbage yield, height of sward) and of the animal (size of animal, rate of intake, rate of biting, size of bite, and time spent grazing) which influence the consumption of herbage by the grazing sheep was examined in three short-term experiments. In one study the high correlation usually observed between herbage yield per unit of land area and plant height was disturbed by manipulating the spatial relations of the sward; it was observed that the rate of intake of pasture by grazing animals was closely associated with plant height (estimated from tiller length) there being little relation between herbage yield and intake. Size of bite increased almost linearly with changing tiller length, whereas after a small initial increase the rate of biting decreased. These differences produced a sevenfold change in the rate of herbage consumption between sheep grazing pastures of 3.7 cm tiller length (1.0 g dry matter/min) and 7.7 cm (7.1 g/min). At greater tiller lengths the size of bite and rate of biting varied inversely to maintain a constant rate of intake. When accessibility of herbage imposed limitations on the rate at which the animal was able to prehend its feed, it was shown that the sheep was able partially to compensate for the reduced amount of herbage present by an increase in grazing time (from 6 to 13 hr/day). However, as the animal extended its period of grazing the compensation became progressively more incomplete. Under sparse pasture conditions lambs were able to consume feed at a significantly greater rate than yearlings but as pasture availability increased the situation was reversed. The role of short-term grazing studies in relation to problems of grazing management is discussed.
The effect of pregnant mare serum gonadotrophin and human chorionic gonadotrophin on ovulation and on fertility in the ewe
Authors: Killeen ID , Moore NW
Published: November 2004

An experiment involving 300 cyclic Merino ewes and designed to study the effects of pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) on ovulation and subsequent fertility is described. PMSG (750 i.u.) was given on the 12th day of the oestrous cycle and HCG (400 and 800 i.u.) was injected intravenously within 3 hr of the onset of oestrus. PMSG induced multiple ovulation and hastened the time of ovulation in relation to the onset of oestrus by 2-3 hr, but did not enhance the precision of the time of ovulation. HCG had no effect upon the time of ovulation but did increase the proportion of follicles which ruptured. Neither PMSG nor HCG, alone or in combination, adversely affected fertility. In fact, HCG increased the proportion of ewes which lambed. Both PMSG and HCG increased the incidence of multiple births. The effect of PMSG on the incidence of multiple births was a direct reflection of its ability to induce multiple ovulation. HCG given alone, or after PMSG increased the incidence of multiple births but its effect was less marked than that of PMSG, and unlike that of PMSG the effect of HCG did not appear to be solely due to an increase in the number of ovulations.
Corrigendum - Factors affecting uredospore production and dispersal in Tranzschelia discolor
Authors: Carter MV , Moller WJ , Pady SM
Published: November 2004

Uredosori of Tranzschelia discolor mature on infected twigs of susceptible peach varieties in July and uredospores are produced at a diminishing rate throughout most of the following growing season. Dry liberation of uredospores from sori on leaves occurs at a rate which increases logarithmically with the wind speed. The onset of heavy rain, or irrigation from overhead sprinklers, may cause a temporary 10-fold increase in the concentration of airborne uredospores within an orchard. In wind tunnel tests, bombardment of sori by water droplets caused liberation of uredospores at wind speeds below those normally required to release detectable quantities. The results emphasize the importance of directing control measures at prevention of the overwintering phases of the rust, which in peaches occur on twigs, and in almonds on rusted leaves retained throughout the short dormant period.
Photosynthesis of wheat under field conditions. III. Seasonal trends in carbon dioxide uptake of crop communities
Authors: Puckridge DW
Published: November 2004

Photosynthesis of two wheat cultivars grown in the field was examined during three seasons by use of a portable field assimilation chamber. There were large differences in dry weight, leaf area, and carbon dioxide uptake between seasons. Variations in carbon dioxide uptake by the community were related mainly to changes in leaf area index (LAI). There were changes in carbon dioxide uptake per unit LAI with time, and between the two cultivars in the first season, but the effects of these changes were small compared with the effects of LAI. Differences in grain yield were correlated with LAI and carbon dioxide uptake in the period after anthesis.
Photosynthesis of wheat under field conditions. IV. The influence of density and leaf area index on the response to radiation
Authors: Puckridge DW , Ratkowsky DA
Published: November 2004

The photosynthesis of two cultivars of wheat at three densities of sowing was measured during the growing season of 1968. When the data were plotted as carbon dioxide uptake versus leaf area index (LAI) (leaf laminae and green stem) for a fixed value of solar radiation, it was found that all of the data could be fitted by a single curve, irrespective of variety, sowing density, or time of season when the measurements were made. Since the curve was of continuously decreasing slope, the carbon dioxide uptake per unit LAI was highest for the low values of LAI and was reduced with the increased light interception at high LAI. For a solar radiation of 0.6 cal/cm2/min the approximate maximum net photosynthesis was 4.5 g CO2/m2/hr for an LAI of 6. A mathematical model for photosynthesis was found to give good prediction of carbon dioxide uptake versus solar radiation for most of the period of measurement. For each plot, a rectangular hyperbola was fitted to the data. When the parameters of the model were subsequently plotted as a function of LAI, then within a given variety, it was found that lines of common slope but differing intercepts could be drawn through the points for different sowing densities. From these fitted lines together with the measured values of LAI and respiration, carbon dioxide uptake was then predicted as a function of solar radiation by employing the rectangular hyperbola model. Good agreement between predicted and measured values of photosynthesis was obtained.
Quantitative inheritance studies in sugar-cane. I. Estimation of variance components
Authors: Hogarth DM
Published: November 2004

Two experiments in quantitative genetics were conducted, one based on a nested design in lattice squares and the other on a factorial design in a balanced lattice. Lattice designs were found to be suitable for genetic experiments if a large number of crosses was involved, but posed some problems in partitioning the sum of squares for treatments. The factorial design was considered preferable to the nested design, although neither design permitted estimation of epistatic variances which, therefore, were assumed to be negligible. Additive genetic variance was found to be more important than dominance genetic variance for most characters. However, most estimates of genetic variance lacked precision in spite of the use of large, precise experiments, which illustrated the difficulty in obtaining estimates of variance components with adequate precision. The validity of assumptions made for these analyses is discussed. The effect of competition was studied and estimates of heritability and degree of genetic determination were determined.
Soil fertilizer levels and protein quality of wheat grains
Authors: Abrol YP , Uprety DC , Ahuja VP , Naik MS
Published: November 2004

Studies with two dwarf wheat strains, HD(M)1592 and HD(M)1620A, show that the enhanced protein content observed following increased fertilizer application is mainly accounted for by an increase in gluten content. Bran and shorts have a higher percentage of protein than the flour. However, accumulation at high fertility takes place in the flour only. Protein fractionation studies reveal that there is an increase in the relative proportion of prolamin and glutelin while cytoplasmic proteins show little change. Amino acids like glutamic acid, phenylalanine, proline, and leucine increase at high fertility levels while the reverse is true for lysine, valine, threonine, isoleucine, and tyrosine.
Effects of calcium carbonate and ammonium sulphate on manganese toxicity in an acid soil
Authors: Siman A , Crodock FW , Nicholls PJ , Kirton HC
Published: November 2004

The effects of increasing rates of lime and ammonium sulphate on French beans were studied on an acid red basaltic soil (pH 4.5-4.8), rich in manganese, on the north coast of New South Wales. Addition of lime resulted in an increased plant yield, a higher soil pH, and a marked reduction in available soil manganese and plant manganese. Applications of 2 or more tons lime per acre corrected manganese toxicity. Ammonium sulphate applications acidified the soil, increased manganese levels in both soil and plant tissue, and increased the frequency of manganese toxicity symptoms at less than 2 tons lime per acre. At pH 4.7-4.8, exchangeable and water-soluble manganese levels were sensitive to slight changes in reaction. Changes in pH between 5.2 and 6.0 caused only slight alterations in manganese levels in soil and plants. Two tons lime per acre reduced the level of manganese in the soil to about half that in the untreated soil, whereas 3 tons lime was necessary to halve the level of manganese in plants. Close linear relationships were found between rates of lime application and pH, between exchangeable and water-soluble manganese, and between both water-soluble and exchangeable soil manganese and plant manganese. Hyperbolic relationships were found between lime and manganese in soil and plants and also between pH and manganese fractions. Toxic levels of manganese in soil and leaves varied seasonally and yearly, and symptoms usually appeared when the manganese content of the first mature leaves was greater than 600 p.p.m. in the winter crop. Symptoms were more closely related to high levels of plant manganese than to soil manganese. The results of this trial indicate that soil and plant analyses are useful for predicting manganese toxicity in acid soils.
Epidemiology of lettuce necrotic yellows virus in South Australia. II. Distribution of virus, host plants, and vectors
Authors: Randles JW , Carver M
Published: November 2004

A survey has shown that both lettuce necrotic yellows virus (LNYV) and its vector Hyperomyzus lactucae are commonly associated with the widely distributed host plant, Sonchus oleraceus. Three newly discovered naturally infected host plant species, Reichardia tingitana, Sonchus hydrophilus, and Embergeria megalocarpa, have a restricted distribution, yet their ability to support colonies of the vector shows that they are potential sources of LNYV. Both S. hydrophilus and E. megalocarpa appear to be endemic to Australasia, and the possibility that either could be the original source of LNYV is discussed. Serological relationships have been demonstrated between some isolates of LNYV. A simple and rapid method for concentrating LNYV from sap extracts for serological testing is described. Hyperomyzus carduellinus has been shown to transmit LNYV, and the distinguishing morphological characteristics of this species are described. Its geographical distribution is limited, and it was found most commonly on R. tingitana.
Effect of droughting and chilling on maturation and chemical composition of Townsville Stylo (Stylosanthes humilis)
Authors: Gates CT , Williams WT , Court RD
Published: November 2004

The effects of droughting and chilling on maturing Townsville stylo plants was assessed in terms of growth, seed and leaf shed, nitrogen, phosphorus, and amino acid composition. The major effect was due to droughting. Temperature participated as a small temperature-droughting interaction, in that cold reduced growth and increased proline under moist, but not under dry conditions. With droughting under warm conditions seed and leaf shed were increased and the nutrient content of seed was raised, which resulted in more of the plant's nitrogen and phosphorus being lost in these fractions. Droughting increased soluble nitrogen at the expense of protein nitrogen, but the amino acids fell as a proportion of the soluble nitrogen. The interrelations of nine amino acids were examined by multivariate techniques and it was shown that proline and aspartic acid behaved atypically, and that while other amino acids fell, proline increased some 10-fold under drought or cold stress. These effects indicate that soluble nitrogenous components may both increase and change in composition in the maturing plant as a result of stress, so rendering the plant more susceptible under field conditions to leaching or breakdown caused by dew or by slight showers of rain.
Estimation of heterosis in Merino × Corriedale crosses with sheep
Authors: Iwan LG , Jeffries BC , Turner HN
Published: November 2004

Reproduction rate data (lambs born, lamb survival rate, and lamb body weight) are presented for purebred Merino and Corriedale ewes and their reciprocal crosses. The four breeds were born in each of two years (1961 and 1962) and mated in each of two years (1963 and 1964, 1964 and 1966) to Dorset Horn rams. Heterosis was estimated as the superiority of the mean of the crossbreds over the mean of the purebreds, expressed as a percentage of the latter. The heterotic effect for lambs born per ewe joined was 1.9 % in 2-year-old ewes and 5.3 % in adults, the corresponding figures for lamb survival being 3.5 and 1.4 % for single-born, 17.2 and 12.0% for twin-born lambs. For mean age-corrected lamb body weight, 2-year-old ewes showed a heterotic effect of 3.7 % and adult ewes 2.0 %, while for pounds of lamb weaned per ewe joined the figures were 11.3 and 10.2%. Although some heterosis was exhibited, the mean of the crossbreds seldom exceeded that of the superior parent (the Corriedale), and there were sometimes differences between the reciprocal crosses, the Corriedale x Merino cross being superior in performance to the other. The potential for exploiting this degree of heterosis in reproduction rate cannot be assessed until the corresponding wool data have been analysed. In reproduction rate, the Corriedale was superior to the Merino, but again a final conclusion about their merits must await results on wool data.
Red-leaf virus - a newly recognized virus disease of subterranean clover (Trifolium subterraneum L.)
Authors: Kellock AW
Published: November 2004

A previously undescribed virus disease, for which the name subterranean clover red-leaf virus (SCRLV) is proposed, affects subterranean clover (Trifolium subterraneum L.) in the northern and southern pasture belts of Victoria. The leaves of infected plants are red and the plants may collapse and die. The virus was transmitted by the aphid Acyrthosiphon solani (Kltb.), but not by the aphids Myzus persicae (Sulz.), Aphis cracciuora Koch, or A. gossjpii Glover. The virus was not sap-transmissible nor was there any evidence of transmission through subterranean clover seed. A. solani transmitted the virus to 45 cultivars of subterranean clover, and also to white clover (T. repens L.), red clover (T. pratense L.), strawberry clover (T. fragiferum L.), strand medic (Medicago littoralis L.), and barrel medic (M. trunculata L.). The virus was not transmitted to several other indicator species. The virus persisted in the vector after a moult and thus the mode of transmission is of the circulative type. The acquisition, transmission, and availability thresholds were 6 hr, 20 min, and 4 days respectively. After an acquisition feed, the virus had a latent period of about 12 hr in the vector. SCRLV resembles other members of the leaf-roll group of persistent aphid-borne viruses. The present cryptogram for the virus is */* : */* : */* : S/Ap.
Salt tolerance in the wild relatives of the cultivated tomato: Responses of Lycopersicon esculentum, L. peruvianum, and L. esculentum Minor to sodium chloride solution
Authors: Tal M
Published: November 2004

The species used in this study were the cultivated tomato Lycopersicon esculentum, the wild species L. peruvianum, and plants originating from the wild species L, esculentum minor. The three plant types were compared in control and sodium chloride solutions for stability of fruit size, growth, dry weight, leaf relative water content and succulence, and chloride, sodium, and potassium contents. Fruit size decreased under salinity in the cultivated species but remained unchanged in the wild plants. It was also found that plant growth, shoot/root dry weight ratio, relative water content, and potassium concentration decreased under salinity in cultivated and wild plants. In all instances, except for potassium, the decrease was smaller in the wild plants. However, chloride and sodium concentrations and leaf succulence increased in all three plant types. Increases in chloride, sodium, and leaf succulence were greater in the wild plants. The differences in response to salinity between the cultivated and the wild plants and their significance are discussed.
The utilization of spear grass (Heteropogon contortus). II. The influence of sulphur on energy intake and rumen and blood parameters in cattle and sheep
Authors: Kennedy PM , Siebert BD
Published: November 2004

Sheep and cattle were used to study the influence of nitrogen and sulphur on the consumption and digestion of spear grass. With sheep, additions of sulphur to the diet increased the digestibility and intake of the feed. The relatively high levels of plasma urea which were found in sheep fed on spear grass alone, decreased with sulphur intake. In cattle, sulphur supplementation did not increase the digestibility of feed. The levels of plasma urea were comparable with those of sheep receiving additional sulphur, which suggested that sufficient sulphur was returned to the bovine rumen to maintain digestion. As previously shown, feed intake was further raised in cattle receiving supplements of nitrogen and sulphur. With the addition of sulphur to the diet of spear grass and urea, the concentration of rumen ammonia was reduced and more nitrogen was retained. The levels of serum sulphate in groups of heifers fed in yards or at pasture demonstrated that sulphur may be limiting for the optimum utilization of spear grass in particular situations.
Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.). X.* Isoflavone formation and carbohydrate metabolism
Authors: Rossiter RC
Published: November 2004

The relationships between isoflavone formation and carbohydrate metabolism were studied in a controlled-environment experiment at low (4700 lux) and high (31,200 lux) light intensities. During expansion of the first trifoliate leaf, isoflavone contents per cell were much lower at low light supply than at high. These low isoflavone contents were associated with low contents of sugars and starch. Protein and cell walls were less affected by low light than were sugars and starch and, presumably, competed strongly with isoflavones for carbon substrates. From the results of this and earlier controlled-environment experiments a close curvilinear relationship was obtained between isoflavones and soluble sugars per cell at the stage of full leaf expansion (when isoflavone synthesis normally ceases). Thus soluble sugar content provided a good index of the level of carbon substrates used for isoflavone synthesis. Some instances where isoflavones increase after full leaf expansion are also discussed.

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*Part IX, Aust. J. Agric. Res., 23: 411 (1972).
Grapevine yellow speckle — a newly recognized graft-transmissible disease of Vitis
Authors: Taylor RH , Woodham RC
Published: November 2004

Evidence is presented to show that many grapevines showing leaf symptoms which, particularly when intense, cannot be distinguished from those caused by strains of grapevine fanleaf virus (GFV) or tomato ringspot virus (TRSV) are infected with a previously undescribed disease for which the name grapevine yellow speckle (GYS) is proposed. The causal agent of the disease has not been isolated, but it is graft-transmissible from infected to healthy grapevines. It has not been transmitted by sap inoculation to herbaceous plants. The disease has been detected in some grapevine cultivars grown in Australia for many years, and also in several other cultivars and rootstocks imported from California over the past 10 years. There is no evidence of natural spread or of seed transmission. Attempts to eliminate GYS from plants by heat therapy and propagation of tip cuttings have been unsuccessful. Mataro and LN33, the best indicators for GYS at present, are not entirely satisfactory and there is a need to find an indicator which will detect GYS in a wide range of environments. The disease has not been previously detected, probably because of its similarity to GFV and TRSV and its peculiarity in expressing symptoms only in some environments.
Some aspects of the water balance of sheep at pasture when deprived of drinking water
Authors: Brown GD , Lynch JJ
Published: November 2004

In an experiment carried out near Armidale, N.S.W. (lat. 30°S., altitude 1000 m), measurements of water intake and water expenditure of grazing, lactating Merino ewes from which drinking water had been withheld for 22 months were compared with those of ewes with water supplied, in order to produce a table of water balance for each group. Estimates of the intake of water from the pasture, and of the free water available on the pasture from dew and guttation were obtained. Water intakes of the ewes supplied with water were measured directly. Estimates of water expenditure were obtained from measures of faecal and urinary water loss and daily milk production. These estimates of water intake and expenditure were compared with measurements of water turnover rates of ewes both with and without drinking water ("plus-water" and "minus-water" groups). There were large differences in turnover rates between plus- and minus-water sheep. The greatest discrepancies in water balance were between water intake and water turnover, which indicates that the contribution of water from dew and guttation has been underestimated. The sheep without water were observed to lick the dew from the pasture and fences in the early morning while the sheep with water grazed normally. There was a tendency for more grazing activity during the night and pre-dawn period by the minus-mater sheep than by the plus-water sheep. There were large differences in faecal and urinary water loss and in urine osmolality between plus- and minus-water sheep. At the lower stocking rate there was no difference in daily milk production. There was a reduction in body weight in the lactating minus-water ewes which had not been previously seen in unmated or pregnant sheep. This was probably due to the marked decrease in the feed intake of the minus-water sheep which presumably reflected the gradual reduction in the water content of the pasture as the experiment progressed into the summer months.
The effect of 2,4-dichlorophenoxyacetic acid on the formononetin content of Dwalganup subterranean clover
Authors: Rossiter RC , Barrett DW , Klein L
Published: November 2004

Two pot culture experiments were done, the first in an open-sided glasshouse and the second in a controlled environment cabinet. The sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D) was applied as a spray, at sublethal levels, to young clover plants. Increasing levels of 2,4-D led to a progressive decrease in the formononetin concentration (percentage of dry matter) in the clover leaves. At the highest 2,4-D levels of 112 48 mg/m2 (1 12 mg/m2 = 1 lb/acre), formononetin concentrations fell to one-half to one-third of the untreated control values. In the first experiment plant dry weights and leaf numbers were decreased by almost 50 % at high 2,4-D levels. In the second experiment-of much briefer duration-the rate of leaf production was also strongly decreased. Practical implications of the results are discussed briefly, and it is suggested that 2,4-D influences isoflavone synthesis by some means other than via carbohydrate metabolism.
The occurrence of bacterial leaf blight in wild and cultivated rice in northern Australia
Authors: Aldrick SJ , Buddenhagen IW , Reddy APK
Published: November 2004

Bacterial leaf blight (Xanthomonas oryzae) of rice is reported for the first time in Australia, where it occurred on cultivated rice and also on the indigenous wild rice species Oryza rufipogon and O. australiensis in the Northern Territory. The pathogen was isolated, characterized, and tested in Hawaii on a differential set of rice cultivars. All Australian isolates of X. oryzae had a lower average virulence, and a distinct pattern of virulence, in comparison with about 200 isolates from 10 Asian countries. The Australian isolates may represent a separate pathotype of X. oryzae, which suggests that the pathogen is indigenous and not recently introduced into northern Australia.
The efficiency of utilization of forage oats in relation to the quantity initially available
Authors: Hedges DA , Wheeler JL , Williams WT
Published: November 2004

Two experiments on the efficiency of utilization of oats by Merino sheep are reported. In the first experiment eight plots with a range from 2730 to 4850 kg dry matter per ha were stocked at c. one sheep per 40 kg of forage. In the second, five plots with approximately equal quantities of forage oats were stocked at c. one sheep per 18, 29, 38, 44, and 50 kg of forage. The data were analysed by regression, ordination, and canonical analysis. Over the range of availabilities examined in experiment I there was no indication that increased dry matter availability reduced the efficiency of utilization. In experiment II, however, increased grazing pressure was associated with an increase in the total liveweight gain and metabolizable energy harvested from a constant quantity of forage; this implied lower efficiency at the lower stocking pressures. The higher digestibility of the forage on some plots in the first experiment was associated with an increased rate of dry matter intake and a reduction in wastage; this effect appeared to be independent of the original planned comparison. It was concluded that within the range of availability studied, forage digestibility and stocking pressure were probably more important determinants of the efficiency of utilization of oats than was the quantity of forage available.
Influence of saline drinking water on mineral balances in sheep
Authors: Tomas FM , Jones GB , Potter BJ , Langsford GL
Published: November 2004

The influence of sodium chloride ingestion via the drinking water upon the mineral balance in sheep has been examined. Four Merino ewes were offered rainwater containing zero, 0.8, or 1.3 % sodium chloride as the only source of drinking water. After correction for variations in mineral intake, the data showed that the urinary excretion of calcium, magnesium, potassium, phosphorus, sodium, and chloride was increased by saline water ingestion. The faecal excretion of calcium, magnesium, and phosphorus was not affected by the inclusion of sodium chloride in the drinking water, but faecal potassium was decreased and sodium and chloride increased. The drinking of saline water by the sheep resulted in a decline in the calcium, phosphorus, and potassium balances, an increase in the sodium and chloride balances, and no change in the magnesium balance. The sodium balance was negative for the rainwater treatment, but all other balances were positive. Saline water ingestion also caused an increase in the glomerular filtration rate, a decline in plasma magnesium levels, and an increase in plasma potassium levels. It is concluded that saline water ingestion causes alterations in the pathways of excretion of minerals and the mineral balances in sheep, but the changes would appear to be of insufficient consequence to have detrimental effects.
Heavy metal toxicities: levels of nickel, cobalt and chromium in the soil and plants associated with visual symptoms and variation in growth of an oat crop
Authors: Anderson AJ , Meyer DR , Mayer FK
Published: November 2004

A study was made of toxicity in a field crop of oats on a soil developed in an area where ultrabasic rocks occur. An area selected for sampling showed a range of toxicity from the border where plants were normal to the centre where plants were most affected. The total nickel, cobalt, and chromium contents of the soil increased to high levels at the centre of the area. The concentration of the elements in soil solutions extracted with a centrfuge from soils at field capacity were in the order nickel > cobalt > chromium, the order in which they are found in natural waters. In the soil solutions nickel ranged from 0.13 to 3.25 p.p.m., cobalt from 0.03 to 0.14p.p.m., and chromium from 0.01 to 0.02p.p.m. The concentrations found in the soil solutions were compared with concentrations known to induce toxicities in oats grown in frequently renewed solution cultures. These comparisons indicated that the nickel ranged up to levels which were definitely toxic. At its highest level cobalt was present at less than one-tenth of the level needed to induce toxicity, while chromium was present at only one-hundredth of the minimum level for toxicity. Analyses of the toys of plants from the centre of the area indicated values of chromium which would be considered toxic, but because of the very low concentrations of chromium in the soil solutions it was considered more likely that the chromium detected was in soil material which the acid detergent washing procedure failed to remove. Evidence presented indicates the particular importance of contamination in the case of chromium. Nickel was present in much higher quantities at toxic levels. Cobalt was below toxic levels. The symptoms observed in the field and symptoms induced by the application of nickel to oats in pot cultures are described. A feature of these symptoms was a regular succession of chlorotic bands. The evidence suggested that the banding pattern, which is best developed in clear weather, relates to the changing conditions which influence the actively growing tissue as the leaf is emerging. The symptom provided us with a means of identifying nickel toxicity in the field. Degrees of toxicity were related to levels of elements in soil extracts and in the plants.
Effects of varying nitrogen supply at different stages of the reproductive phase on spikelet and grain production and on grain nitrogen in wheat
Authors: Langer RHM , Liew FKY
Published: November 2004

Plants of wheat cv. Arawa confined to the main shoot were grown in solution culture in a glasshouse. Nitrogen supply was either high (150 p.p.111.) or low (15 p.p.m.) at three stages of development: between the double-ridge stage and floret initiation, between then and ear emergence, or after ear emergence, giving eight treatment combinations. Spikelet numbers were increased only by raising nitrogen supply at the doubleridge stage. Number of grains per spikelet also responded to treatment during the same period, but was greatest when high nitrogen was given until ear emergence. This response depended on the position of the spikelet within the ear, and the basal and terminal spikelets contributed least when nitrogen supply was low. Individual grain weight responded less to treatment than grain numbers. Nitrogen application had a large effect on leaf area duration, but the grain/leaf ratio (G) was depressed. Since their appeared to be no nitrogen effects on photosynthesis per unit flag leaf area, it is suggested that grain yield was controlled mainly by the capacity of the ear to accept carbohydrate, depending on the number of sites available for grain filling. Percentage grain nitrogen increased with lateness of nitrogen application. However, raising nitrogen supply before ear emergence and then decreasing it again also affected grain nitrogen in the ear, which suggests redistribution during grain filling
The effect of plant structure on the intake of tropical pastures. I. Variation in the bite size of grazing cattle
Authors: Stobbs TH
Published: November 2004

To determine the effect of sward canopy structure on bite size a technique was developed for measuring the size of bite prehended by grazing cattle. Almost complete recovery (a mean of 95%) of ingested material was achieved by inserting a foam rubber plug in the lower oesophagus of oesophageal-fistulated animals, whilst the number of bites taken during grazing was automatically recorded. Theoretical calculations showed that a mean bite size of less than 0.30 g OM/bite can seriously limit daily intake of herbage by grazing cattle. Four experiments were conducted to measure the variation in bite size prehended by Jersey cows when grazing tropical pasture swards of varying canopy structure. Bite size on a nitrogen fertilized Setaria anceps cv. Kazungula sward averaged 0.39 g OM/ bite, whereas an adjacent sparse unfertilized sward averaged 0.13 g OM/bite. Mean size of bite of cows grazing 5-week-old regrowths of the trailing legume (Macroptilium atropurpureum cv. Siratro) was 0.24 g OM/bite, compared with 0.34 and 0.38 g OM/bite for nitrogen fertilized Digitaria decumbens and Setaria anceps pasture respectively. Growth regulators, gibberellic acid (GA) and 2-chloroethyl-trimethylammonium chloride (CCC), were successfully used to alter the sward canopy structure of Digitaria decumbens (pangola) and Chloris gayana (rhodes) grass pastures. GA increased herbage yield, and sward height, and produced erect stemmy plants with long internodes, whereas CCC reduced plant height and internode length, and resulted in a denser sward which was higher in nitrogen and in vitro digestibility due to a higher leaf content. Measurement of bite size prior to any changes in sward structure being manifest showed that bite size was unaffected by the growth regulators per se. However, bite size on the CCC treated pastures sampled after 6 weeks was larger (0.52 g OM/bite) than from the same cows grazing pastures treated with GA (0.40 g OM/bite). It was concluded that the size of bite prehended by cattle grazing some tropical pasture swards can limit intake of herbage, and that sward bulk density, a low stem content, and a high leaf/height ratio have a major influence upon the size of bite taken by cows grazing these pastures.
The voluntary intake, digestibility, and retention time by sheep of leaf and stem fractions of five grasses
Authors: Laredo MA , Minson DJ
Published: November 2004

Chloris gayana, Digitaria decumbens, Panicum maximum, Pennisetum clandestinum, and Setaria splendida were each cut at three stages of growth, dried, chaffed, and separated into "leaf" and "stem" fractions using a gravity separator. The mean purity of the leaf and stem fractions were 78 and 93%. Each fraction was fed to eight sheep to determine voluntary intake and dry matter digestibility. Mean voluntary intake of leaf was 46% higher than that of stem (57.7 v. 39.6 g/kg0.75), despite a slightly lower dry matter digestibility of the leaf fraction (52.6 v. 55.8%). The higher intake of the leaf fraction was associated (r =0.74, P< 0.01) with a shorter retention time of dry matter in the reticulo-rumen (mean 23.8 v. 31.8 hr), which appeared to be caused by the large surface of the leaf fraction initially available to bacterial degradation (mean 128 v. 41 sq cm/g). Ground leaf and stem samples showed no difference in rate of digestion in vitro since structural differences had been destroyed. The energy required to grind 1 g sample in a laboratory mill was less for leaf than stem (mean 234 v. 411 J/g) with a significant correlation between voluntary intake and grinding energy (r = –0.81). In the past a high voluntary intake has been attributed to a high bulk density, but in this study bulk density of the stem fraction was three times that of the leaf fraction and negatively correlated with voluntary intake (r = –0.70, P< 0,001). It was concluded that different plant fractions may be eaten in different quantities, despite similar dry matter digestibilities, and that in any study of the voluntary intake of roughages it is necessary to determine physical properties of the feed in addition to chemical composition.
Responses to selection for seed weight and seedling vigour in Phalaris
Authors: Clements RJ , Latter BDH
Published: November 2004

Significant responses were obtained to three cycles of directional selection for seed weight, seedling weight, leaf size, and rate of leaf appearance in a broadly based P. tuberosa population. The responses were linear in both the high and low directions, and the realized heritabilities of the characters were 0.35, 0.12, 0.61, and 0.38 respectively. Leaf size was positively correlated with seedling weight and negatively correlated with rate of leaf appearance. Selection for high seed weight resulted in marked correlated increases in seedling weight and leaf size, but selection for heavy seedlings or large leaves did not significantly increase seed weight. Selection for light seedling or small leaves, on the other hand, led to a correlated decrease in seed weight. A hybrid population obtained by crossing the parents of the high leaf size line with those of the high rate of leaf appearance line had seedlings nearly as heavy as those of the high seedling weight line and significantly heavier than the mean of the two parent lines. This effect, together with other evidence of the effect of inbreeding on all characters, indicated some degree of directional dominance, particularly for leaf size. Plants in the high seed weight line matured earlier and had fewer heads. However, because they had heavier seeds and more seeds per head, there was no apparent decrease in seed yield per plant in this line, compared with the control population. Areas of the spikelets and leaf sheaths were greater in the high seed weight line, but areas of the flag and penultimate leaves were unchanged, and there was no evidence that increases in seed weight were accompanied by increases in the amount of photosynthetic area available to each developing seed. It was concluded that selection for large leaves is a relatively efficient means of increasing seedling weight, but results in a reduced rate of leaf appearance and possibly a slower rate of tillering. Selection for seed weight, though inefficient, exploits a source of variation largely untapped by direct selection for seedling weight.
Genotype × environment interactions and environmental adaptation. I. Pattern analysis — application to soya bean populations
Authors: Mungomery VE , Shorter R , Byth DE
Published: November 2004

The application of numerical classificatory and ordination procedures to the analysis of adaptation of populations, cultivars, or lines is discussed. Examples given are seed yield and seed protein percentage for a population of soya bean lines evaluated across environments in south-eastern Queensland. For each line, p attributes (mean performance in each of p environments) were defined, and were considered to represent a p-dimensional space. The performance of the lines defined their position in this space, and the attributes were used to classify the lines into groups which differed in the magnitude and/or direction of their environmental responses. Within groups, lines exhibited variations across environments which were similar in both direction and magnitude. The relative proximity of lines in the space was obtained by ordination, and this reflected the degree of similarity of their performance across environments. The actual environmental responses of a large number of lines may be examined by these methods, both individually and as members of groups of lines having similar responses. Unlike other analyses of adaptation, these methods require no prior assumption regarding the distribution and suitability of a particular environmental response. Consequently, the analysis is designed to allow hypothesis generation. If desired, a 'suitable' or 'ideal' response surface may be defined, but this occurs subsequent to, and may be independent of, the identification of the actual responses of the lines and groups of lines.
The proportion of dietary protein escaping degradation in the rumen of sheep fed on various protein concentrates
Authors: Hume ID
Published: November 2004

The 35S content of ruminal microbial protein following intraruminal infusions of Na235SO4 was used to estimate the relative proportions of microbial and dietary protein in the duodenal digesta of sheep, and hence the proportion of the dietary protein which escaped microbial proteolysis in the rumen. When sheep were given a protein-free diet, the mean ratio of the specific activities of the sulphuramino acids in the duodenal microbial fraction (M) and the unfractionated duodenal digesta (D) was 0.97 ? 0.08 and 1.00 ? 0.06 in two separate experiments. When zein was included in the diet the ratio M/D increased to 2.35 ? 0.14, which indicated that 44 ? 3.4% of nitrogen in the duodenum was microbial. When casein was offered, the ratio M/D was 1.12 ? 0.05, which indicated that 91 ? 6.7% of duodenal nitrogen was microbial. When sheep were offered a partially purified diet containing fish meal, lupin meal, peanut meal or soya bean meal, the ratio MID indicated that 29, 65, 63 and 39% of the fish meal, lupin meal, peanut meal and soya bean meal, respectively, was degraded in the rumen; rumen ammonia levels (mg nitrogen/100 ml fluid) were 8.3, 20.9, 16.0 and 6.5, and nitrogen balances were 5.0, 2.4, 2.9 and 5.4 g/day respectively. The 35S-incorporation technique appears to provide realistic estimates of the proportions of dietary proteins which escape degradation in the rumen.
Carcass and meat quality of Friesian steers fed on either pasture or barley
Authors: Purchas RW , Davies HL
Published: November 2004

Friesian steers were slaughtered as individual animals reached a fasted liveweight of c. 457 kg, after being on either a predominantly cereal diet (12 animals) or a predominantly pasture diet (13 animals) for at least 160 days. Those on the cereal diet grew 31% faster than the animals on pasture so that the latter group was an average of 69 days older. The carcasses of the cereal group were significantly fatter especially with regard to omental fat (+ 54%), intramuscular fat (+ 34% for M. semitendinosus) and dissectable fat from the 9–10–11 rib cut (+ 27%). These differences in composition may have been caused by either differences in growth rate or specific dietary effects. Measurements of tenderness all favoured the cereal group, the largest effect being on cold-shortened M. semitendinosus where the mean shear value was 50% greater for the pasture group. The greater age, lower percentage of intramuscular fat and greater susceptibility to cold-shortening may all be involved in these differences. The groups did not differ in ultimate muscle pH, muscle collagen content or adrenal cortical activity. A laboratory taste panel consisting of 15 members indicated that the flavour of topside roasts from the animals fed on the cereal was more acceptable.
Nodulating competitiveness amongst strains of Rhizobium meliloti and R. trifolii
Authors: Marques Pinto C , Yao PY , Vincent JM
Published: November 2004

The relative nodulating success of strains of Rhizobium meliloti, with Medicago sativa and M. truncatula, and R. trifolii, with Trifolium repens, T. glomeratum and T. subterraneum, has been determined with inocula of paired competitors, supplied in various proportions. Host plants were raised from surface-sterilized seed, grown on agar in enclosed tubes, and populations and strain ratios were determined on the root surface as well as in the supplied inoculum. The use of heavy inoculum did not prevent all growth, and strain representation on the root surface could differ from that of the inoculum, because of either different adherence or the narrowing of extreme ratios with time. The ratios of strains obtained from nodules when related to those on the root surface yielded a 'competitive index', defined as the ratio of nodules due to each strain under conditions of equal representation on the root. In the five available cases inferior nitrogen-fixing effectiveness of a strain with a particular host was reflected in poor nodulating competitiveness, but similar differences were found in six comparisons between equally effective pairs, and with the one ineffective pair. Competitiveness did not correlate with the relative speed with which the strains produced nodules when used as a single culture or with the number of nodules they produced. Cases of mixed infections were encountered throughout the study; they generally accounted for less than 10% of the nodules typed, but in some combinations of host and strains the figure exceeded 25%.