bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between herbicides, time of application and genotype of wild oats (Avena fatua L.)
Authors: Paterson JG
Published: November 2004

A glasshouse experiment was conducted on three groups of genotypes of Avena fatua L. representing those from the north, central and southern regions of the temperate area of Western Australia with a winter growing season. The interaction between genotype groups, three herbicides (barban, difenzoquat and flamprop-methyl) and six times of application was investigated. The results showed that all genotypes did not react similarly to the herbicides tested. Barban, in particular, was very susceptible to the genotype x time of application interaction. Reasons for this are suggested. These include the effect of climatic parameters on the evolution of predominant genotypes in various areas, together with micromorphological variability developed in response to environmental pressure. It is also suggested that the number of days after seedling emergence is as reliable a guide as leaf number for optimum application of barban and that mature wild oat seed-head counts may not adequately reflect important competitive attributes such as dry matter production. The possible erroneous extrapolation to subspecies level from data collected on a species basis is emphasized, as is the possibility of differentially specific herbicides contributing to population shifts towards greater herbicide resistance, and not only in wild oats. Lines of future research are indicated.
The effect of shade upon seedling growth in groundsel bush (Baccharis halimifolia L.)
Authors: Panetta FD
Published: November 2004

Analysis of seedling growth of groundsel bush (Baccharis halimifolia L.) under different glasshouse light conditions indicated that seedlings growing in light shade (24% daylight) maintained relative growth rates equal to those of seedlings grown unshaded (57% daylight) for up to 11 weeks after germination. Compensation for reduced light was effected through increased leaf area rather than through increased photosynthetic efficiency. Although markedly less than in unshaded or light shade treatments, growth was maintained throughout the experimental period under the lowest radiant flux employed (17% daylight). Root systems developed more slowly and were smaller in shaded than in unshaded seedlings. Increased stem allocation (height growth) followed a peak in root allocation, and did not occur until 11 weeks after germination in any treatment. Comparisons of seed weight and seedling relative growth rate with associated pasture species indicate that groundsel is at a disadvantage in terms of both parameters. It appears that the success of this woody weed is due largely to a combination of high reproductive output and effective dispersal, which enables it to colonize relatively open microsites which occur in cultivated as well as natural field situations.
Continued studies on the effect of grain or pasture on the carcass composition and meat quality of Friesian steers
Authors: Davies HL
Published: November 2004

Twenty-one Friesian steers were grown to a final fasted liveweight of 469 kg. Seven of the steers grazed irrigated ryegrass-white clover pastures, seven steers were fed on a high energy ration ad libitum, and seven were given a ration of the same composition as the second group but at a restricted amount such that the growth rate was similar to that of the grazing steers. There were no significant differences in carcass weight between the three groups. The dressing percentage of the grain ad libitum group was 58%, the restricted grain group 57% and the pasture group 55%. The dressing percentage was significantly lower (P < 0.05) in the pasture group. The grain ad libitum group had 51.5% more (P < 0.05) oaental fat than the pasture group, and the restricted group 28.9% more (P < 0.05) than the pasture group. In dissections of the 9th, 10th and 11th ribs the grain ad lib. group had 35.4% fat, the restricted grain group 32.8% and the pasture group 26.5%, the proportion of fat being significantly (P < 0.05) lower in the pasture group than in the grain ad lib. group. No significant differences were found in either tenderness, juiciness or flavour between the three groups.
Ascospore liberation, germination and attachment to host surface by Pseudopeziza medicaginis
Authors: Morgan WC , Parbery DG
Published: November 2004

Apothecia require a period (16–20 hr) of free water or a relatively longer period (at least 24 hr) in conditions of high relative humidity (RH) before ascospore discharge occurs. Provided the RH remains high (97–99%) ascospore discharge continues from individual apothecia for 7–14 days. The process of discharge of spores from individual asci in water is described. Germination of ascospores took 24–36 hr and infection of the host a further 24 hr. Thus 3½ days of high RH were required before infection occurred. This is suggested as the reason why lucerne rarely becomes infected with P. medicaginis in southern Australia during the summer months. Ascospores of P. medicaginis discharged naturally were liberated in pairs. Each spore pair was enveloped in a common membrane. It is believed that single spores are liberated only when the spore pair membrane ruptures during discharge. Single spores lack the membrane. The spore pair membrane is believed to serve two functions. Firstly, it adheres to and becomes more or less contiguous with the host cuticle. This attachment appears necessary for penetration of the host. Secondly, spores in pairs germinated more readily on host surfaces than single spores, and infections were noted only in association with spore pairs.
Water requirements of avocado in Israel. I. Tree and soil parameters
Authors: Kalmar D , Lahav E
Published: November 2004

The effect of different irrigation intervals on the avocado tree was tested during the years 1968–1974 in the northern coastal plain of Israel. The objectives of this experiment were: (a) to make measurements of soil and plant parameters to help understand mechanisms of response to irrigation; and (b) to establish the most suitable irrigation schedule for highest yields of export quality fruit. The trial consisted of four irrigation treatments, at intervals of 7, 14, 21 and 28 days; the respective average annual water applications were 8890, 7450, 6680, and 5940 m3/ha. The cultivars Ettinger, Fuerte and Hass were tested in five replications in randomized blocks. Soil moisture consumption was estimated by using a neutron probe and tensiometers. Most of the water consumption was from the upper 60-cm soil layer. With the 7-day interval, the calculated daily loss from the soil profile was greater throughout the whole irrigation season than with the other intervals. The least salt accumulation occurred under the long interval treatments since the large amounts of water supplied at each irrigation leached the salts continuously. Reduced intervals between irrigations resulted in increased trunk growth and increased tree size. It is concluded that with a 21-day interval the vegetative growth of producing trees was restricted and therefore relatively smaller trees with easier fruit picking and delayed orchard thinning were obtained.
Utilization of amino acids by preruminant lambs. II.* The effects of independent alterations in total nitrogen and total essential amino acid intake
Authors: Dove H , Pearce GR , Tribe DE
Published: November 2004

Male crossbred lambs weighing 12.5 kg were infusedper abomasum with milk-based diets containing 259, 209 or 175 g crude protein (CP)/kg dry matter. The proportion of crude protein supplied as essential amino acids (EAA) was also varied, to provide diets containing 414, 512 or 613 g EAA/kg CP. This allowed an estimation of the effects of independent alterations in total EAA intake and total nitrogen intake on rates of liveweight gain, and on daily nitrogen balance and metabolizable energy intake. At a given proportion of EAA in crude protein, reductions in the EAA intake reduced the rate of liveweight gain, especially when diets contained 414 or 613 g EAA/kg CP. At constant EAA intake, rates of liveweight gain were reduced when the nitrogen intake was such that the dietary proportion of EAA departed from 512 g/kg CP. Responses in nitrogen balance were similar to those in liveweight gain except that, at constant EAA intake, increases in nitrogen intake improved nitrogen balance. All nitrogen balance responses were less pronounced than liveweight gain responses. Lambs given diets containing 414 or 613 g EAA/kg CP had lower metabolizable energy intakes. This was not due to reduced metabolizability of apparently digested energy, but to differences in apparently digested energy intake. The relative effects of nitrogen intake and the proportion of crude protein supplied as EAA, on liveweight gain and nitrogen balance are assessed by using three-dimensional representations of the responses.
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Part I,Aust. J. Agric. Res., 28: 917 (1977).
A comparison of continuous grazing and deferred autumn grazing of Merino ewes and lambs at 13 stocking rates
Authors: Brown TH
Published: November 2004

The performance of Merino ewes and their lambs was measured when the sheep were either continuously grazed or autumn-deferred on annual pastures. The two management systems were compared at a series of 13 stocking rates from 4.9 to 19.8 ewes ha-1 for 5 years from 1970 to 1974 at the Kybybolite Research Centre, South Australia. The deferred sheep were fed in yards on a mixture of oat grain and hay at 6.8 kg per head per week during the 6-week deferment period. It was found that the continuously grazed ewes required very little hand-feeding up to a stocking rate of 17.3 ewes ha-1. Grazing management had little or no effect on wool production in ewes or lambs, on the number of lambs born and weaned, or on lamb growth rates. Although the incidence of pregnancy toxaemia was very low (1%) it was higher in the deferred treatments. Autumn deferment resulted in extra pasture during the winter months of June and July. However, the continuously grazed pastures reached the same level of availability as the deferred pastures in late winter and early spring. Total yearly pasture production tended to be greater on the continuously grazed pastures and increased as the stocking rate increased. It is concluded that there is little merit in adopting an autumn deferment system of grazing management for Merino ewes and lambs. A relationship between lamb growth rate and both available pasture and pasture height is presented. It would appear that pasture height measurements are no better predictors of Iamb growth rates than pasture yield measurements.
In vivo prediction with tritiated water of chemical and dissectible components of the dressed carcass of sheep growing at different rates
Authors: Searle TW , Hilmi M
Published: November 2004

Two groups of Border Leicester x Merino wether weaner sheep were given a concentrate ration either ad libitum or at 60% ad libitum. Mean growth rates were 255 and 136 g/day respectively. Animals were slaughtered at predetermined liveweights over the range 20–45 kg after a 30 hr fast, during which tritiated water (TOH) space was measured. The right half-carcass was dissected into fat, muscle and bone, and the left half-carcass was minced and analysed for chemical components (fat, protein, ash, water and energy). The relationships between the weight of carcass components and carcass weight were examined by regression analysis and were similar for both groups. Relationships between the weight of dissected fat, muscle and bone and chemical fat, protein and ash respectively were also determined. The chemical and dissected composition of the carcass could be predicted accurately from fleecefree fasted liveweight. The addition of TOH space to the regression equation improved the prediction of dissected and chemical fat and energy. The most accurate equation for bone included liveweight and age. It is suggested that tritiated water has only limited application in the prediction of dressed carcass composition in vivo.
Milk replacers for preruminant lambs: protein and carbohydrate interactions
Authors: Gibney MJ , Walker DM
Published: November 2004

Twenty-one male crossbred lambs, aged 2–5 days at the start of the experiments, were used. Experiment I. Groups of three lambs were each given one of three low protein diets (0.10 of the total energy as protein) based on isolated soybean protein. Carbohydrate was omitted from one diet, but in the other two it was added at the expense of fat to provide 0.10 or 0.25 of the total dietary energy. In lambs given the carbohydrate-free diet there was a significant reduction in nitrogen balance, in the retention of the apparently digested nitrogen, in liveweight gain and in plasma glucose levels, but a significant increase in plasma urea nitrogen and in the urinary excretion of nitrogen, urea, ammonia, sodium and potassium. The dry matter content of the faeces of lambs given the diet containing 0.10 carbohydrate (0.450) was significantly higher than that of lambs given the 0.25 carbohydrate diet (0.294). There were no other significant differences in performance between these two groups. Experiment 2. Twelve lambs were given diets based on casein, supplemented with DL-methionine, in which protein supplied 0.100, 0–175 or 0.250 of the total gross energy and, at each protein level, carbohydrate supplied 0.025,0.050, 0.100 or 0.200. There was a significant linear increase in liveweight gain, nitrogen balance and apparently digested nitrogen retained as the carbohydrate concentration at each protein level was increased, and a highly significant effect of the level of dietary protein on all parameters measured. It was concluded that the beneficial effect of carbohydrate on nitrogen balance and liveweight gain is of sufficient consequence to warrant the highest inclusion of carbohydrate in milk replacers for lambs that is compatible with the absence of diarrhoea.
Effects of environmental and plant factors on foliar freezing resistance in tropical grasses. I. Precondition factors and conditions during freezing
Authors: Ivory DA , Whiteman PC
Published: November 2004

The foliar freezing resistance of Setaria anceps cv. Narok and Panicum maximum var. trichoglume cv. Petrie was studied under controlled freezing in the laboratory. Maximum foliar hardening in both species was achieved in 8 days at a night temperature of 10°C or less. A reduction in relative humidity from 100 to 79 % during freezing at –5°C caused 80 and 88 % decreases in foliar damage (as measured by percentage foliage death) in P. maximum and S. anceps respectively. Reducing the cooling rate during a freezing cycle significantly increased the amount of foliar damage to both species but there was no significant effect of reheating rate. An increase in freezing duration from 0.5 to 4 hr increased foliar damage by 35 and 58 % at –2.5° and by 45 and 36 % at –3.5° in S. anceps and P. maximum respectively. Phosphorus and potassium applications had no effect on frost damage, but increased nitrogen application rates and nitrogen concentrations in the tissues were related to greater frost damage. A decrease in plant water status prior to frosting caused a significant decrease in foliar frost damage in P. maximum. Except for atmospheric humidity, a decrease in the minimum freezing temperature by 2° had a larger effect on foliar damage than had other plant or environmental factors. S. anceps demonstrated a greater frost tolerance than P. maximum in all experiments.
Effects of environment and plant factors on foliar freezing resistance in tropical grasses. II.* Comparison of frost resistance between cultivars of Cenchrus ciliaris, Chloris gayana and Setaria anceps
Authors: Ivory DA , Whiteman PC
Published: November 2004

The variability in foliar freezing resistance within and between five Cenchrus ciliaris, four Setaria anceps and six Chloris gayana ecotypes was examined in the laboratory over a sequence of freezing temperatures between –1.0° and –6.25°C. C. gayana and S. anceps ecotypes were generally more frost-resistant than C. ciliaris ecotypes. No significant differences in frost susceptibility were found in C. ciliaris, whilst S. anceps exhibited the greatest variability and C. gayana showed an intermediate degree of variability. The range of freezing temperatures which caused 50% foliage death (LT50) in C. ciliaris was –1.8° to –2.1°, in C. gayana –2.6° to –3.5° and in S. anceps –2.1° to –4.3°.

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* Part I, Aust. J. Agric. Res., 29: 243 (1978).
Two diseases in Stylosanthes spp. caused by Colletotrichum gloeosporioides in Australia, and pathogenic specialization within one of the causal organisms
Authors: Irwin JAG , Cameron DF
Published: November 2004

Two anthracnose diseases caused by Colletotrichum gloeosporioides have been found in Stylosanthes spp. in northern Australia. The two diseases can be readily distinguished by their symptoms and their pure-culture characteristics. The disease classified as type A was widespread, but the other, type B, was found at only two localities. In spray-inoculation tests under controlled conditions, S. guianensis cv. Endeavour was highly susceptible to type B isolates, and some lines of S. fruticosa, S. humilis, S. scabra and S. viscosa were highly susceptible to the type A isolates. Two pathogenic races of type A were recognized from the reaction of S. viscosa 33941 towards them. The importance of these diseases is discussed, together with aspects of disease dissemination and future control strategies.
Improvement in milk production of first calf heifers by multiple suckling
Authors: Fulkerson WJ , Hooley RD , Findlay JK
Published: November 2004

Thirty Friesian heifers were alternately allocated to two groups as they calved at 2½–3 years of age. Calves were left with the heifers for 36 hr after calving, then machine-milked twice daily (group 1) or machine-milked at 0600 hours and suckled at 1500 hours (group 2) by an average of 1½ calves for the first 8 weeks of lactation. Heifers were restricted in a race while suckling. Heifers in group 2 (suckled) produced 16% more milk during the 300 day lactation than group 1 (milked) heifers. The difference in milk production was in excess of that removed by the calves whilst suckling. Suckling appears to promote a more complete milk 'let-down' in early lactation, thus preventing milk accumulation in the udder. Milk accumulation at this critical stage is believed to adversely affect subsequent milk production by damaging secretory tissue. The concentration of prolactin in peripheral blood was lower during suckling than during milking, and the degree of udder infection (mastitis) in the two groups did not differ significantly. Multiple suckling of cows in early lactation appears to be a worth-while practice, particularly with animals showing a nervous disposition. It also provides a convenient calf-rearing system, as milk is provided at an optimal temperature to the calf and with minimum chances of contamination.
Determination of spikelet number in wheat. III.* Effect of varying temperature on ear development
Authors: Rahman MS , Wilson JH
Published: November 2004

The effects on rate of development and spikelet number per ear in eight wheat cultivars grown at various temperatures (16/9, 23/16, and 30/23°C for 8/16 hr) throughout or transferred from one temperature to another at floral initiation were studied under normal (12.5–14.0 hr) and 24 hr photoperiods. Under a 24 hr photoperiod, the durations of the vegetative, spikelet and elongation phases, and spikelet number per ear decreased as the temperature increased from 16/9 to 30/23°C in all cultivars. The rate of spikelet initiation increased as temperature increased from 16/9 to 23/16° in most cultivars, but further increase in temperature caused a variable response. Under a normal photoperiod, increasing the temperature from 16/9 to 23/16°C changed spikelet number little, but further increase in temperature decreased it in most cultivars. The rate of initiation increased, but the durations of the vegetative, spikelet and elongation phases, and the apex length at floral initiation decreased in all cultivars as the temperature increased from 16/9 to 23/16°; with further increase in temperature, the rate of initiation, apex length and duration of the elongation phase decreased in most cultivars, but the durations of the vegetative and spikelet phases either increased or changed little. Variation in the number of spikelets per ear in relation to variation in the factors considered to be its possible determinants is discussed with a view to understanding the control of spikelet number.

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*Part II, Aust. J. Agric. Res., 28: 575 (1977).
Variation between and within species of rapeseed (Brassica campestris and B. napus) in response to drought stress. II.* Growth and development under natural drought stresses
Authors: Richards RA , Thurling N
Published: November 2004

Two rapeseed species and cultivars within each of these species differed significantly with respect to the influence of variation in sowing date on growth, development and yield on two different soil types. Soil moisture stress, particularly after anthesis, was the major environmental factor affecting these processes. Grain yield declined markedly with later sowings in both species, and B. napus, despite its later maturity, was more tolerant of severe soil moisture deficits since its grain yield was consistently higher than B. campestris in the more stressed environments. The major distinguishing feature between species contributing most to this difference in yield was the pattern of dry matter accumulation. In B. campestris most of the dry weight of the plant was accumulated after anthesis when drought was most severe, whereas in B. napus dry weight accumulation occurred before anthesis. This resulted in a greater contribution of reserves accumulated by anthesis to grain-filling in B. napus. Most of the variation in seed yield resulted from differences in sowing dates and soil types. When these environmental effects were excluded, the main determinants of genotypic variation in yield were the numbers of pods and branches and harvest index in both species, growth rate in the post-anthesis phase in B. campestris, and plant weight and root/shoot ratio at anthesis in B. napus. Selection strategies for yield improvement in rapeseed growing in drought-stressed environments are discussed.
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*Part I, Aust. J. Agric. Res., 29: 469 (1978).
Response to selection in Australian Merino sheep. VIII.* Further results on selection for high clean wool weight with attention to quality
Authors: Turner HN , Jackson N
Published: November 2004

Results of selection for high clean wool weight per head with control of quality are reported for two selection groups over the period 1966–74. Results for the same experiment for the periods 1950–1959 and 1961–64 were reported earlier. Both groups were selected for high clean wool weight, one (S) with a ceiling on fibre diameter and degree of skin wrinkle, and the other (MS) with a lower limit on staple crimp frequency and a ceiling on skin wrinkle. Genetic progress in clean wool weight was greater in S than in MS over the 1966–74 period (0.12–0.15 lb/annum, compared with 0.06–0.09). This was to be expected from genetic correlations of clean wool weight with fibre diameter (low positive) and staple crimp frequency (high negative). The result supports the previous recommendation that staple crimp frequency is an inefficient way of controlling wool quality while attempting to improve quantity by selection, because its use severely restricts the likely progress in quantity. The actual rate of progress in the S group was similar to that in the period 1950–59, which was followed by a fall in superiority of the selected over the control group animals born during 1961–64. The recovery of response in the 1966–74 period negates the suggestion that the loss of response during the 1961-64 period was due to a 'plateau'. The most likely explanation is that a genotype x environment interaction occurred, such that the genetic gain made in the 1950-59 period could not be expressed in the poorer environments of 1960–65, but reappeared gradually under the improving environment of the 1966–74 period. Attempts to remove this interaction by regression of response on the mean clean wool weight of the unselected control group (as an index of the level of the environment) for each year, were not successful. The interaction is, therefore, not simply a case of all selection groups being equal when the environment is poor.

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*Part VII, Aust. J. Agric. Res., 26: 937 (1975).
Rapeseed adaptation in northern New South Wales. I. Phenological responses to vernalization, temperature and photoperiod by annual and biennial cultivars of Brassica campestris L., Brassica napus L. and wheat cv. Timgalen
Authors: Hodgson AS
Published: November 2004

Two experiments were conducted to investigate the developmental responses of annual and biennial B. campestris and B. napus cultivars and one annual wheat cultivar to vernalization, temperature and photoperiod at Tamworth, N.S.W.In the first experiment, mean daily temperature and photoperiod in the field varied within the ranges 6–26°C and 11–15 hr respectively. Serial plantings between April and September, the use of low intensity supplemental illumination, and vernalization treatment of young seedlings provided additional environmental variation. Wheat was insensitive to vernalization, and annual rapeseed cultivars showed significant facultative responses to vernalization, but the variation in phase duration of all annual cultivars was largely accounted for by correlation with temperature and photoperiod. The phenological responses of biennial cultivars to temperature and photoperiod were confounded by their unsatisfied vernalization requirements, because the response to vernalization treatment was incomplete. In the second experiment, the influence of plant age on the vernalization requirements of four cultivars of rapeseed was investigated in a glasshouse. There was a small response to vernalization in annual cultivars, but their planting date would not be dictated by obligate requirements for winter chilling. Biennial cultivars could not be effectively vernalized as seeds, but as green plants were shown to require 15–19 weeks of chilling at l°C to enable them to flower. With insufficient chilling, some biennial plants remained vegetative; flowering occurred in others, but tended to be delayed and variable. Planting dates of biennials would therefore be strongly influenced by their vernalization requirements, and planting should be sufficiently early to allow seedling growth before the stimulus is received during winter. The prediction of phenological pattern and the breeding of cultivars better adapted to local conditions are discussed.
Nitrogen response of seedlings of Aristida ramosa R.Br. and Danthonia DC. Spp
Authors: Harradine AR , Whalley RDB
Published: November 2004

Aristida ramosa R.Br., Danthonia linkii Kunth, and D. richardsonii Cashmore, common components of the native pastures on the North-western Slopes of New South Wales, differed markedly in their responses to applied nitrogen in the seedling stage in pot trials. Growth of A. ramosa was depressed and at higher levels seedlings were killed by nitrogen applied as a variety of sources, viz, ammonium nitrate, sodium nitrate, ammonium chloride and urea, especially when application occurred immediately prior to, or soon after seedling emergence. A significant nitrogen-phosphorus interaction was recorded, the negative effect of nitrogen being greatest at low soil phosphorus levels. Applied nitrogen enhanced growth of Danthonia seedlings. A dosage-mortality relationship was calculated with an application of 200 ppm nitrogen resulting in kills of 100 and 87% of A. ramosa seedlings at phosphorus levels of 0 and 50 ppm respectively; at the same nitrogen level the growth of D. linkii was enhanced at the higher phosphorus level and not affected at the lower level. An increase in the soil nitrogen level in a pasture containing these species could markedly affect the botanical composition.
Relationships between flowering and honey production of red ironbark, Eucalyptus sideroxylon (A. Cunn.) Benth., and climate in the Bendigo district of Victoria
Authors: Porter JW
Published: November 2004

Records of growth, flowering and honey production of red ironbark (Eucalyptus sideroxylon (A. Cunn.) Benth.) forests in the Bendigo district of Victoria are analysed. The sequence in which stems and flowers develop is described. Annual growth is bimodal and occurs during autumn and spring. Growth requires a threshold temperature of 16–17°C and a monthly rainfall of 45–60 mm. The rate at which flower buds develop in exposed umbels is related to the temperature and rainfall during the spring growing season. Flowering starts in January, reaches a maximum in July and ends in September. Honey production depends on flowering abundance, the number of hives at a site, the length of the harvesting time, and rainfall and temperature during and before harvest.
Agricultural climatology of the Upper Murrumbidgee River Valley, New South Wales
Authors: Edwards K , Johnston WH
Published: November 2004

Monthly and annual rainfall data for 63 recording stations in and adjacent to the upper Murrumbidgee River valley catchment area are analysed. A pattern analysis of median monthly rainfalls is compared with an isohyet map, and relationships between altitude and rainfall zones are described. An hierarchical agglomerative classificatory program was used to carry out the pattern analysis. A technique for estimating temperature has been devised, and tank evaporation and monthly temperatures calculated for each station. A simple moisture balance and growth index is used to assess the effect of rainfall and evaporation on soil moisture availability and that of temperature on plant growth at each centre. These results are also classified by means of the pattern analysis program. The integration of elements and the use of pattern analysis gives an objective and easily interpreted classification of the agricultural climatology of the area.
The nutrition of ruminants grazing native and improved pastures. II.* Responses of grazing cattle to molasses and urea supplementation
Authors: Langlands JP , Donald GE
Published: November 2004

Hereford heifers grazing native and fertilized phalaris pastures were supplemented with ureamolasses mixtures for 2 years. The liveweight of heifers grazing phalaris pastures did not respond to supplementation, but the liveweight gain of heifers grazing native pasture increased significantly by 6 g/day/g nitrogen consumed as urea during July, August and September and by 0.16 g/day/g digestible organic matter consumed as molasses at other times of year. Supplement consumption varied between animals, with a coefficient of variation of ±37%. Urea–molasses supplementation increased the rumen ammonia nitrogen levels of cattle grazing native pasture from 6.7 to 16.1 mg/100 ml. The application of superphosphate and introduction of white clover increased rumen ammonia nitrogen to 15.7 mg/100 ml. The effects of supplementation on liveweight gain were small relative to the changes which could be induced by pasture improvement. There was a curvilinear relationship between the digestibility of the diet and liveweight gain when pasture availability was not limiting intake. It was calculated from this relationship that the annual liveweight gains of cattle grazing native pasture, native pasture dressed with superphosphate and oversown with white clover, and two phalaris pastures were 223 498, 726 and 763 g/day respectively when forage was available ad libitum.

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*Part I, Aust. J. Agric. Res., 29: 863 (1978).
Resistance to Boophilus microplus (Canestrini) in different breeds of cattle
Authors: Utech KBW , Wharton RH , Kerr JD
Published: November 2004

Resistance to the cattle tick Boophilus microplus was assessed in heifer herds of various breeds of beef and dairy cattle in spring and summer in Queensland. All cattle had had tick experience before assessment. Resistance levels were determined as the percentage of larval ticks that failed to survive to maturity following infestations with c. 20,000 larvae. Bos indicus Brahman beef cattle were the most resistant (99%), followed by B. indicus × B. taurus (95–97%) and B. taurus British cattle (85%). In the dairy breeds, B. taurus Jersey cattle (98%) were more resistant than Guernsey (93%), Australian Illawarra Shorthorn (89%), and Friesian (85%), but not significantly different from B. indicus × B. taurus Australian Milking Zebu (96%). Cattle were classified as having high (> 98%), moderate (95–98%), low (90–95%), or very low (< 90%) resistance. The frequency distributions of resistance in B. indicus × B. taurus cattle showed that 80% had moderate to high resistance and that culling of 20% of the cattle would about halve the mean tick population. Of B. taurus cattle, 80% had low to very low resistance. Supplementary information on sibling bull herds showed that their resistance levels and frequency distributions of resistance were similar to those of the heifer herds.
The effects of copper and nitrogen supply on the retranslocation of copper in four cultivars of wheat
Authors: Hill J , Robson AD , Loneragan JF
Published: November 2004

The retranslocation of copper and nitrogen was studied in four cultivars of wheat grown in pots of a copper-deficient sand from Lancelin, W.A. Plants were grown at two levels of nitrogen and three levels of copper, and harvested three times during growth and at maturity. Plants grown at low copper were severely copper-deficient and yielded no grain. At low nitrogen, plants at marginal copper gave similar grain yields to plants at high copper. Application of high nitrogen at marginal copper either had little effect or depressed grain yield. Application of high nitrogen at high copper gave a strong positive interaction producing maximal grain yield in each cultivar. Low copper supply delayed yellowing and the decline in copper and nitrogen content of the oldest leaf of each cultivar. Application of high nitrogen further delayed yellowing of the oldest leaf and loss of its copper and nitrogen. Probably the copper content of the oldest leaf does not decline until the leaf begins to senesce. Senesced leaves retain low concentrations of copper and nitrogen. It is suggested that at marginal copper, copper retention by senesced vegetation limits the retranslocation of copper from vegetation to grain. Susceptibility to copper deficiency differed markedly with stage of growth and with cultivar. At marginal copper and high nitrogen, copper deficiency almost eliminated the grain yield of Argentine IX, but had relatively small effects on Gamenya, Olympic, and Petit Rojo. The higher susceptibility of grain production in Argentine IX to copper deficiency was not related to its copper content in whole tops or to its grain protein concentration. The susceptibility may have resulted from the ability of this cultivar to form large numbers of tillers which competed with the developing grain for retranslocated copper.
Seed-borne Fusarium species on subterranean clover and other pasture legumes
Authors: Kellock AW , Stubbs LL , Parbery DG
Published: November 2004

Fusarium avenaceum (Corda ex. Fr.) Sacc. was detected for the first time on seed of strand medic (M. littoralis Rhode), lucerne (M. sativa L.), white clover (T. repens L.) and strawberry clover (T. fragiferum L.). The percentage of seed infected was 24% on medic seed, 2–3% on strawberry clover, 2–6% on white clover, and 10–14% on lucerne, compared with 1–42% on subterranean clover seed. The majority of infected seed lines were grown in the main seed-producing areas of Victoria. F. arthrosporioides Sherb., F. equiseti (Corda) Sacc., F, acuminatum Ellis & Everhart and F. culmorum (W. G. Sm.) Sacc. were isolated from subterranean clover seed for the first time, comprising between 1 and 8% of Fusarium spp. isolates, while F. oxysporum (Schlecht) and F. avenaceum comprised the remaining 55% and 35% of isolates respectively. In laboratory tests, isolates of F. avenaceum from each seed host were all strongly pathogenic on roots of subterranean clover, but there was no evidence of pathogenicity by other Fusarium spp. F. oxysporum had no effect on the severity of root rot disease either alone or in combination with F. avenaceum.
A modified model for evaluating residual phosphate in soil
Authors: Barrow NJ , Carter ED
Published: November 2004

A model described by J. S. Russell for evaluating the residual effects of nutrients was modified and applied to the residual effects of phosphate as measured over 6 years in a field trial. Losses of phosphate, and phosphate converted to organic forms, were modelled by using a curvilinear relation such that the proportion lost or converted was greatest at low levels of application. Because of this, the effectiveness of fertilizer in years subsequent to its application declined relatively faster at low levels of application and responses became increasingly sigmoid. A function derived by Russell to describe the transfer of phosphate from available to unavailable forms was inadequate when this transfer was studied in isolated systems. For the field results, it was not possible to distinguish between Russell's function and two other functions and, provided the model was confined to the period to which it was fitted, it was immaterial which function was used. It is argued, however, that if the model were to be extrapolated it would be preferable to use component functions which can be separately justified.
Selection for high and low ratio and high and low primary density in Merino sheep
Authors: Rendel JM , Nay T
Published: November 2004

The result of selecting sheep up and down for secondary to primary follicle ratio (S/P) and up and down for the number of primary follicles to the square millimetre is examined from the point of view of Fraser's theory of competition between follicles. The possibility of finding other characters in which variation will cause variation in fleece weight has also been investigated. It is concluded that selection which increased the S/P ratio and primary density did not increase fleece weight; follicle depth is possibly one skin character which, when changed, causes changes in fleece weight but this requires confirmation.
Influence of temperature on oil content and composition of sunflower seed
Authors: Harris HC , McWilliam JR , Mason WK
Published: November 2004

The influence of temperature on the oil content and composition of sunflower was studied on plants grown under field conditions and in a range of controlled environments. Traces of oil were detectable in cypsela (seed) almost immediately after pollination. Much of this appeared to be present in the hull (pericarp), which is well developed at this stage. Significant production of oil commenced with the development of the embryo about 150 day-degrees after pollination, and the oil content reached a maximum value just prior to physiological maturity of the seed. Linoleic acid constituted the major component of the oil at all stages of seed development, and under favourable temperature conditions increased from c. 50% soon after pollination to over 70% at physiological maturity. High temperature during the development of the seed was associated with a reduction in total oil yield. However, under field conditions this effect was variable owing to confounding with other environmental factors such as moisture stress, which also influence the yield of oil through their effects on growth and development of seed. Elevated temperatures, and in particularly high night temperatures, caused a marked reduction in the percentage of linoleic acid, apparently due to the effect of temperature on the activity of the desaturase enzymes which are responsible for the conversion of oleic to linoleic acid.These results support the hypothesis that reduced yields and altered composition of sunflower oil from crops matured under high temperature conditions in midsummer are due to the effects of heat stress on the biosynthesis of fatty acids.
Genotype × environment interactions and evaluation of cotton cultivars*
Authors: Thomson NJ , Cunningham RB
Published: November 2004

Stoneville 7A and Deltapine Smooth Leaf, bred in the Mississippi delta, were the highest yielders among a small group of medium-staple United States cultivars compared over three seasons and three sites in the Ord River valley (15° 39´S.), north-western Australia. Significant cultivar x year interactions existed for lint yield, lint percentage, boll weight, micronaire and Pressley strength, and significant cultivar x site x year interactions occurred for lint yield, lint percentage and staple length. Significant cultivar x site interactions occurred only for lint yield and Pressley strength. From the expected standard errors of cultivar means an evaluation procedure involving sampling for seed cotton yield over 3 years at each of six sites and two replications, but sampling for other agronomic and fibre quality attributes only at one site, was suggested. This procedure should result in standard errors of 5% or less of the mean values for all attributes. Consistency and stability of cultivar behaviour was assessed by simple rank methods, and Finlay and Wilkinson's joint regression method. The consistency of performance was such that a high probability of choosing the top yielders successfully would have attended early selection.

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* The field work reported in this paper was carried out by the senior author when he was a member of the Division of Land Use Research, CSIRO.
Genotype × environmental interactions for wheat yields and selection for widely adapted wheat genotypes
Authors: Brennan PS , Byth DE
Published: November 2004

Large genotype x environment (g x e) interaction variances for yield relative to those for genotypes have been recognized for wheat cultivars in Queensland. The utility of a linear model to explain these interactions was examined by yield-testing 100 different wheat cultivars at nine different environments, including four locations and three years, in south-eastern Queensland. The linear model was found to explain less than 40% of the total g x e interaction and to give only a general indication of cultivar responses to different environments. Selection strategies to identify widely adapted cultivar involving several parameters (mean cultivar yield over all environments, the g x e interaction for each cultivar and the regression coefficient for each cultivar), singly and in combination, were evaluated. Greater selection differentials were found in most environments when selection was practiced for high mean yield across all environments when the yield of each cultivar in each environment was expressed as a percentage of the environment mean yield.
Growth, leaf physiology and fruit development in salt-stressed guavas
Authors: Walker RR , Kriedemann PE , Maggs DH
Published: November 2004

Two cultivars of guava (Psidium guajava L.) were grown in a porous medium irrigated with dilute nutrient solution containing 0, 25, 50 and 75 mM sodium chloride. The distribution of sodium and chloride between leaves, stems, roots and fruit of the two cultivars is described. Total biomass (and especially fruit fresh weight) was reduced by all salt treatments; however, fruit maturation was accelerated. Symptoms associated with high chloride concentrations developed only on leaves of plants treated with 25 mM sodium chloride. Different symptoms, associated with high sodium concentrations, developed on leaves of plants from the 50 and 75 mM treatments. Transpiration and photosynthesis were reduced in leaves of plants from the 50 and 75 mM treatments. Increased stomatal resistance and a reduction in apparent photochemical efficiency were largely responsible for the reduction in photosynthesis.
Factors limiting the intake of feed by sheep. IX.* Further studies of the roughage requirement of the ruminant lamb fed on concentrate diets based on wheat
Authors: Weston RH
Published: November 2004

The voluntary feed consumption (VFC) and body weight gain of lambs initially weighing 22 kg were measured when pelleted diets based on ground wheat grain and varying in content of ground straw were offered. VFC increased progressively as the straw content of the diet was increased from 2% through 8% to 14%. Lambs fed on the diets with 8 and 14% straw performed similarly, whereas those with 2% straw had lower rates of body weight gain (– 11%) and intakes of digestible organic matter (– 4%). Increase in straw content from 2 to 14% was accompanied by a decrease in diet digestibility and increases in (i) the rates of flow from the rumen of digesta, sodium and potassium, (ii) the pH of ruminal contents, and (iii) the time spent ruminating. Lambs initially weighing 37 kg were offered 'roughage-free' concentrate diets based on wheat in which the wheat was presented either as whole grain or in ground and pelleted form. With whole grain, values for VFC, digestible organic matter intake and body weight gain were respectively 17, 17 and 29% higher than with ground grain. The feeding of whole grain instead of ground grain increased the time spent daily in ruminating from 0.3 to 2.2 h. It was concluded that the roughage requirement of the ruminant lamb fed on concentrate diets based on wheat was higher when the wheat was in ground form than when whole grain was used. The requirement with ground wheat diets was tentatively assessed as in the range of 2–8 g ground straw per 100 g diet. Lambs were slow in adapting to a chopped roughage diet following prolonged feeding with wheat-based diets. VFC data suggested that the slow adaptation was associated with changes in rumen function.

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*Part VIII, Aust. J. Agric. Res., 25, 349 (1974).
Temperature effects on lignin, hemicellulose and cellulose in tropical and temperate grasses
Authors: Ford CW , Morrison IM , Wilson JR
Published: November 2004

Thirteen tropical and 11 temperate grasses were grown in controlled environment under day/night temperatures of 21/13, 27/19 and 32/24°C. Neutral detergent fibre (NDF) was prepared from the fifth leaf on the main stem of each plant, 2 days after it had reached maximum length. Panicum maximum var. trichoglume (tropical) and Lolium perenne cv. S24 (temperate) were also harvested at 4,8, and 12 days after this stage of development. For the tropical grasses NDF values, corrected for starch and protein, decreased with increasing growth temperature, whereas in the temperate species they increased. In the tropical group the decrease in NDF was due to a lower cellulose content, whereas hemicellulose and lignin levels generally tended to increase slightly with increasing temperature. In the temperate grasses, lignin, hemicellulose and cellulose levels all showed a consistent increase with growth temperature. At each growth temperature the lignin content of the species in the tropical group had a significant negative correlation with in vitro digestibility, and lignin appeared to be more closely associated with hemicellulose than with cellulose. In contrast, at each temperature, variation in digestibility between species of the temperate group was not correlated with lignin. Levels of cell wall components in the later-harvested material from Lolium varied in a similar manner to that of the younger growth stage, whereas older Panicum cell wall constituents showed more variability.