bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrigendum - Photosynthesis of wheat under field conditions. II. Effect of defoliation on the carbon dioxide uptake of the community
Authors: Puckridge DW
Published: November 2004

A field assimilation chamber was used to measure the carbon dioxide uptake of wheat plants in the field before and after defoliation or ear removal. At anthesis and 10 days later only the top three leaves were effective in photosynthesis. Removal of the two leaves below the flag leaf reduced photosynthesis of the community by 25–28% and further removal of the flag leaf reduced the community photosynthesis by an additional 24–30%. The estimated contribution of the ears depended on the technique of measurement and varied from 7 to 15%. After removal of the leaf laminae and ears, the stems and leaf sheaths assimilated carbon dioxide at a rate of 44% of that of the whole community. For defoliated plants, photosynthesis of the ears and stems increased with increasing elevation of the sun, which indicated a greater efficiency of photosynthesis with an increased horizontal component of radiation. This was opposite to the response of the undefoliated community. The techniques of estimating the contribution of individual organs to total photosynthesis of the wheat plant are discussed in relation to variability of results and the effects of compensation.
Changes in nitrate and nitrate reductase levels on restoration of molybdenum to molybdenum-deficient plants
Authors: Randall PJ
Published: November 2004

The effect of molybdenum on nitrate reductase was assessed by incubating wheat leaf fragments with potassium nitrate, with or without molybdenum, under lights supplying 2000 f.c. Enzyme activity was then estimated by measuring the nitrite produced by the fragments and released into the solution during 1 hr in total darkness. Light stimulated the induction of nitrate-reducing activity while darkness was essential to obtain accumulation of nitrite. Molybdenum deficiency in wheat depressed nitrate reductase activity and dry matter yield. Molybdenum caused a rapid increase in nitrate reductase in tissue from deficient plants but had no such effect on tissue from non-deficient plants. The difference in response patterns between deficient and non-deficient plants, induced by molybdenum treatment could form the basis for a plant test for molybdenum deficiency.
Competition between effective and ineffective strains of Rhizobium trifolii in the nodulation of Trifolium subterraneum
Authors: Robinson AC
Published: November 2004

The competitive ability of effective and ineffective strains of Rhizobium trifolii to form nodules on two cultivars of Trifolium subterraneum was examined under bacteriologically controlled conditions in tube culture. Seedlings were inoculated with mixtures of known numbers each of effective and of ineffective strains and the strains forming the nodules subsequently determined. In all instances, the effective strains formed a much greater proportion of nodules than would be expected from the relative numbers of each strain in the inoculum. Moreover, a reduction in the numbers of an effective strain relative to the numbers of an ineffective strain failed to result in a corresponding increase in the proportion of nodules formed by an ineffective strain. Instead, the ratio of ineffective to effective strains had to be of the order of 108/104 or wider (c. 10,000/1) before there was a substantial reduction in the number of nodules formed by the effective strains. Even when this ratio was of the order of 108/102, the effective strains still produced some of the nodules. A parallel study of the rates of nodulation of seedlings inoculated with mixtures of strains showed that these rates were characteristic of the proportions of nodules being formed by each strain. Subsequently seedlings were inoculated with mixtures of effective and ineffective strains, and after 66, 90, and 114 hr the roots were surface-sterilized and their contents isolated and identified. Independently of the mixture of strains used, most of the bacterial cells were identified as the effective strains. Because the strains of effective and ineffective bacteria used produce nodules freely when inoculated separately onto these hosts, it is postulated that the hosts distinguished between effective and ineffective strains, and that this recognition is related to compatibility in association with the host. The significance of the results in relation to studies of the root-nodule bacteria is discussed.
Studies of zinc nutrition in sheep. II*. The influence of zinc deficiency in ram lambs upon the digestibility of the dry matter and the utilization of the nitrogen and sulphur of the diet
Authors: Somers M , Underwood EJ
Published: November 2004

Dry matter digestibilities and nitrogen and sulphur balances were compared in ram iambs fed on a zinc-deficient diet containing 2.4 p.p.m. zinc and showing clinical signs of zinc deficiency and in pair-fed ram lambs consuming the same basal diet supplemented with 30 p.p.m. zinc. Dry matter digestibility was similar for the two treatments but both nitrogen retention and sulphur retention were significantly lower in the zinc-deficient animals, although they were consuming and digesting the same amounts of food. Faecal excretion of nitrogen and sulphur was similar in the two groups but the urinary excretion of both these elements was significantly elevated in the zinc-deficient animals. These findings provide further evidence that protein utilization is impaired in zinc deficiency in sheep.

*Part I, Aust. J. agric. Res., 1969, 20, 889.
Influence of fertilizer treatment on apple fruit composition and physiology. II. Influence on respiration rate and contents of nitrogen, phosphorus, and titratable acidity
Authors: Letham DS
Published: November 2004

The respiration rates and tissue contents of nitrogen, phosphorus, and titratable acidity were determined for apple fruit from trees receiving differential fertilizer treatments U, N, P, NP, and NPK (U, no fertilizer; N, 2 lb ammonium sulphate; P, 4 1b superphosphate; and K, 1 Ib potassium sulphate, per tree per year). The results obtained (expressed on a dry weight basis) are summarized as follows: Respiration rate: N > NP = NPK = U > P.
Total nitrogen content: NPK > NP = N > U = P.
Ethanol-insoluble nitrogen content: NPK = NP = N > U = P.
Ethanol-soluble nitrogen content: NPK > NP = N > U = P.
Phosphorus content : P > NP = NPK > U > N.
Titratable acidity content: NPK > N > NP = U > P. The incidence of internal breakdown in stored fruit from these treatments has positively correlated with respiration rate per cell and negatively correlated with phosphorus content. Phosphorus content was negatively correlated with cell volume and respiration rate. Mechanisms by which phosphorus content might regulate the incidence of internal breakdown are discussed.
Interaction between leaf pruning and fruiting of pot-grown Valencia orange cuttings
Authors: Maggs DH , McEAlexander A
Published: November 2004

The effects of leaf pruning on plants with and without fruit were studied in a 4-month pot trial. Pruning levels were (a) leaves intact, (b) leaves halved, and (c) leaves quartered. Leaves were pruned when they attained full size. Fruiting had no effect on total dry weight increment whereas leaf pruning reduced it. For fruiting trees, however, leaf pruning affected mainly fruit weight, the vegetative increments differing by only 10.7% of their mean. Fruiting had no significant effect on the proportions of leaf, stem, or root but leaf pruning increased the proportion of leaf at the expense of root. The proportion of fruit in the total increment decreased with increasing severity of leaf pruning. The intact defruited plant continued to produce flowers throughout the experiment. The total number of leaves produced was approximately halved by fruiting. The net assimilation rate of intact defruited plants was at least 30% less than that of all other treatments. It is concluded that fruit does not compete successfully for metabolites against a stimulated leaf production.
Liveweight gain, food intake, and eating rate in Brahman, Africander, and Shorthorn X Hereford cattle
Authors: Frisch JE , Vercoe JE
Published: November 2004

Food intake, liveweight gain, and eating rate were measured over 3 years on nine Brahman, nine Africander, and nine Shorthorn x Hereford male cattle offered lucerne hay ad libitum for 53–76 days. When intakes were adjusted for differences in liveweight, the Brahmans ate significantly less feed than the Africanders and Shorthorn x Herefords. Gain was correlated with intake but not with liveweight. When gains were adjusted for differences in intakes the Brahmans gained significantly more than Africanders or Shorthorn x Herefords. The greater gain of the Brahmans is apparently related to a lower maintenance requirement. The eating rate of animals was highly repeatable, and significantly correlated withvoluntary food intake (r = 0.61, P < 0.01) and liveweight gain (r = 0.63, P < 0.01)
The comparative rates of phosphate absorption by eight annual pasture species
Authors: Keay J , Biddiscombe EF , Ozanne PG
Published: November 2004

Phosphate flux into roots from soil increased with increase in applied phosphate in eight annual pasture species, except in lupins at higher levels of application, where toxicity was pronounced. The rate of uptake decreased with time, the decrease being least in the clovers. The relationship between rate of uptake and level of applied phosphate was sigmoid for the legumes, less so for erodium and cape-weed, and non-sigmoid for the grasses. Marked differences among species were found in the distribution of absorbed phosphate. It is suggested that the observed differences among species in response to applied phosphate depend on physiological and anatomical characteristics, although the evidence from phosphate fluxes suggest that lupin had an ability to remove phosphate not possessed by other species.
A numbrical analysis of variation patterns in Australian introductions of Glycine wightii (G. javanica)
Authors: Edye LA , Williams WT , Pritchard AJ
Published: November 2004

Numerical methods of classification were used to separate varietal types among 51 introductions of the polymorphic species G. wightii from Africa, India, and South America. Thirty-one morphological and agronomic attributes were used in the classification by the programme MULTBET on the Control Data 3600 computer at Canberra. Preliminary assessment gave four homogeneous groups and two 'nonconformist groups'. The 11 introductions in the latter groups were individually assessed and in some cases reallocated. Finally, six varietal groups were obtained and their interrelationships examined. The morphological and agronomic characteristics of each group are described and related to Bogdan's varietal types. Chromosome counts on 48 of the introductions classified confirmed, with few exceptions, the homogeneity of the diploid (2n = 22) and tetraploid (2n = 44) varietal groups and these bore some relationship to country of origin. A total of 124 introductions were counted of which 54 were diploid, 62 tetraploid, and 8 mixed. The highest proportion of diploids was in Tanzania, Kenya, and Rhodesia. Tetraploids were more common in countries at greater altitudes such as Malawi and Uganda, or in higher latitudes such as South Africa. Numerical methods of varietal classification appear to be a valuable technique for integrating morphological and agronomic data from a number of experiments to evaluate large numbers of introductions of polymorphic pasture species. This aids in the understanding of the relative agronomic performance of introductions and their taxonomic affinities and should lead to more effective collection, introduction, and evaluation of further introductions of the species.
Distribution in the sheep of selenium derived from 75Se-labelled ruminal pellets
Authors: Handreck KA , Godwin KO
Published: November 2004

Dense pellets consisting of elemental iron and selenium (9:1 by weight) labelled with 75Se were introduced into the rumen of two groups of sheep for 1 month prior to slaughter. One group was considered to be in normal selenium status, the other had grazed low selenium pastures for 2 years prior to the experiment and were shown, by analysis of blood selenium levels, to be in low selenium status. During the experimental period the pellets released 0.5-1.3 mg selenium each day; of this, about 30% was excreted in the urine and about 1 % in the expired air. Blood selenium levels rose rapidly during the first week, then more slowly, and finally leveled out at 0.18-0.34 �g/ml. Concentrations of selenium derived from the pellets were determined in various body tissues and organs at slaughter. In the course of the experiments no toxic effects were observed, and the examination of a wide variety of tissues at autopsy indicated that in no case was there excessive accumulation of selenium. The results of these experiments are discussed in relation to the use of these pellets commercially.
Fertilization, sperm transport, and early embryonic loss in ewes grazed on cultivars of subterranean clover. (T. subterraneum)
Authors: Kaltenbach cC , Davies HL
Published: November 2004

The causes of infertility due to phyto-oestrogens were investigated in ewes which had grazed Dwalganup, Yarloop, Geraldton, Woogenellup, and Mount Barker cultivars of subterranean clover (T. subterraneum L.) for 5 years. At laparotomy, sperm transport was investigated by making counts of spermatozoa in the oviduct 22-26 hr post coitum; fertilization rates were checked 72 hr post coitum and embryonic survival at 27-31 days. A larger proportion of ewes on high oestrogen cultivars Dwalganup, Yarloop, and Geraldton) had low oviducal spermatozoa counts and the fertilization rate was significantly lower (P < 0.05) than in ewes grazed on low oestrogen cultivars (Woogenellup and Mount Barker) (44% v. 63 %). There was no statistically significant difference in embryonic survival between these groups. Merino ewes had fewer oviducal spermatozoa and a lower (P < 0.05) fertilization rate than Border Leicester x Merino ewes. Impaired sperm transport is considered to be the reason for reproductive failure in the ewes that had grazed the high oestrogen cultivars of subterranean clover.
Synthesis of microbial protein in the rumen. III.The effect of dietary protein
Authors: Hume ID
Published: November 2004

Protein production in the rumen of sheep fed on a virtually protein-free diet supplemented with urea and higher volatile fatty acids (VFA) and yielding 600 g digestible organic matter per day amounted to 90 g/day. When gelatin was substituted for the higher VFA and 50% of the urea nitrogen, microbial protein production remained at a similar level (91 g/day); with casein, production increased to 101 g/day, and with zein to 104 g/day. Nitrogen balances increased from 4.1 g/day in sheep fed on the casein diet to 5.5 g/day in those fed on the zein diet (P < 0.05). These values were both significantly higher than those for the urea/VFA or gelatin-containing diets, reflecting the different levels of microbial protein production on the respective diets. In addition, 44 g un-degraded zein left the rumen daily, accounting for the increase in nitrogen balance on this diet above that on the casein diet. Negligible amounts of nitrogen were recycled on the urea/VFA, gelatin, and casein treatments, but at least 7.5 g recycled nitrogen was utilized in the rumen daily on the zein diet. This is equivalent to 47 g protein, sufficient in itself to satisfy the maintenance requirement of the sheep for protein. The yields of protein from ruminal fermentation on the three protein treatments suggest that the maximum possible yield may exceed 20 g/100 g organic matter digested in the rumen.
Nodulation and growth of Medicago truncatula on acid soils. I. Effect of calcium carbonate and inoculation level on the nodulation of Medicago truncatula on a moderately acid soil
Authors: Robson AD , Loneragan JF
Published: November 2004

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.
Effects of temperature and photoperiod on growth and reproductive development in Hyparrhenia hirta
Authors: McWilliam JR , Shanker K , Knox RB
Published: November 2004

Hyparrhenia hirta occurs naturally in the Mediterranean region and in the winter rainfall areas of South Africa, in association with temperate festucoid grasses. However, the temperature response curves, flowering behaviour, and widespread apomixis found in this species are more typical of other tropical members of the Andropogoneae. This residual tropical adaptation provides an explanation for the sensitivity of H. hirta to low temperature (below 15�C) during seed germination, and especially during the seedling stage, which makes autumn establishment difficult in temperate climates. Also, the low seed yield is attributable to the high proportion (c. 50%) of male florets in the inflorescence, and the breakdown of both sexual and apomictic embryo sacs during development. A possible genetic approach to the improvement of both these characters, utilizing facultative apomixis, is discussed.
Calcium stimulation of phosphate absorption by annual legumes
Authors: Robson AD , Edwards DG , Loneragan JF
Published: November 2004

At calcium and phosphate concentrations within ranges commonly encountered in soil solutions, increasing calcium concentration in flowing culture solutions markedly increased phosphate absorption by several annual legumes. Calcium increased phosphate uptake relatively more at low than at high phosphate concentration. The effect of calcium was greater for two Medicago species than for two cultivars of Trifolium subterraneum and is suggested as at least a partial explanation for the greater sensitivity of Medicago to soil acidity and its greater tolerance to soil alkalinity than Trifolium subterraneum. Pretreatment at different calcium levels had no effect on phosphate absorption, while transfer to solutions of different calcium levels caused an immediate response in phosphate uptake. These results indicate that calcium had a direct effect on phosphate absorption, rather than an indirect effect through root morphology or anatomy. It is suggested that calcium increased phosphate absorption by screening electronegative charges on the roots, thus increasing the accessibility of absorption sites to phosphate.
Fertility following synchronization of oestrus in the sheep with intravaginal sponges. I. Effects of vaginal douche, supplementary steroids, time of insemination, and numbers and dilution of spermatozoa
Authors: Robinson TJ , Moore NW , Lindsay DR , Fletcher IC , Salamon S
Published: November 2004

A number of treatments were used in association with Cronolone (Searl)- impregnated intravaginal spones in ewes which were artificially inseminated. Five factorial tests were conducted, involving 4880 ewes. Supplementary oestrogen (25 � oestradiol benzoate) or androgen (1 mg testosterone) given at the time of withdrawal of sponges after 16 days' insertion was of no benefit. Few extra ewes exhibited oestrus and fertility was lowered. Flushing the vagina with a mild disinfectant at the time of withdrawal of sponges had no advantage. Ewes came into oestrus earlier, but fertility was not improved. Factors in the tests which did affect fertility were: (a) amount of Cronolone absorbed, (b) time of onset in ewes inseminated on detection of oestrus, (c) time of insemination relative to time of withdrawal of the sponge in ewes inseminated on a fixed time basis, and (d) number of spermatozoa used in the inseminate. There also was an interaction between dilution of semen and number of spermatozoa in that high fertility was associated with maximum number and minimum volume (maximum density and number). Insemination once with 600 x l06 spermatozoa in 0.2 ml inseminate at fixed times of 36, 42, or 48 hr after withdrawal of sponges resulted in lambing in 50 % of ewes (60 of 120).
Urinary sediments in sheep feeding on oestrogenic clover. I. Preliminary observations on changes in certain urinary constituents
Authors: Parr WJ , Steele P , Gabbedy B , Nottle MC
Published: November 2004

In recent years a series of widespread outbreaks of acute urinary obstruction has occurred in spring in Merino wethers. Animals involved have been grazing oestrogenic strains of subterranean clover at a time when isoflavone concentrations can be expected to be high. Studies have been made on one property on the relationships between these outbreaks, the pasture isoflavone content, and the urinary excretion of phenolic and other constituents by wethers. A trial group of animals was grazed on a dominant sward of the highly oestrogenic Trifolium subterraneum cv. Dinninup during winter and spring. Isoflavone concentrations in the clover reached a peak in early August. However, since the pasture became highly clover-dominant in September and early October the maximum daily intake of isoflavones probably occurred during this period, which also coincided with the occurrence of maximum concentration and maximum daily excretion of total phenols and acid-precipitable material (APM) in the urine. It is suggested that the sediments causing clinical obstructions at this time of the year may be a direct result of increased excretion of phenols. APM showed a highly significant direct relationship with total phenols but its excretion increased at a greater rate than did that of phenols. Urinary calcium excretion also increased at the same time.
Glucose tolerance of sheep as related to post-mortem muscle characteristics
Authors: Shorthose WR
Published: November 2004

The glucose tolerance, expressed as T 1/2, of sheep unaccustomed to blood sampling procedures was negatively correlated with the muscle glycogen concentration of the M. semitendinosus (ST) immediately after death and the extent of glycolysis. T 1/2 was positively correlated with the pH of the ST 24 hr after death. It was suggested that the rate of decline of plasma glucose concentration in a tolerance test was influenced by the animal's response to venipuncture and handling during the test. The extent of the animal's response to this stress was considered to be related to the animal's response to pre-slaughter stress and to account for the correlations between T 1/2 and post-mortem muscle properties.
Some components of reproductive performance of sheep in Victoria
Authors: Mullaney PD , Brown GH
Published: November 2004

Estimates are given of the relative contribution of each component of reproductive performance - the relative number of ewes having no, one, or two lambs - in the effect of age on the number of lambs born per ewe joined for Merino and Corriedale sheep in Victoria. For Merinos, the proportion of ewes giving birth to more than one lamb increased by 0.05 from ages 3 to 6, followed by a decline of 0.02 at age 8. For Corriedales, this proportion increased by 0.06 from age 3 to age 6. The proportion of ewes having no lamb was greater at the maiden lambing (age 3, Merinos; age 2, Corriedales) than at any other age. Estimates of the effect of age on these components are used to assess the reproductive performance of flocks of different age structures.
Follicle characteristics in a group on Merino sheep selected up and down for fleece weight
Authors: Nay T
Published: November 2004

It was found that the animals in a group selected for high fleece weight had straight follicles and the animals in a group selected for low fleece weight had predominantly bent follicles. These shifts in the follicle bending index in opposite directions, brought about by selection, indicate a genetic correlation between weight and percentage bending. The negative correlation between clean fleece weight and number of crimps per inch can be explained in anatomical terms.
Some factors affecting the relative importance of hosts in the survival of Ophiobolus graminis
Authors: Chambers SC
Published: November 2004

Saprophytic survival of Ophiobolus graininis was studied in artificially infected straws and sods of wheat, oat, and barley. The estimated relative importance of these cereals in the survival of O. graminis varied with the method of assessment. Estimates based on sods also varied with plant density, time of inoculation, and the time interval between inoculation and inversion of sod. In artificially infected sods of grass species, O. graminis survived better on Bromus gussonii and Hordeum hystrix than on Phalnris minor, Avenue sterilis, and Ehrharta erecta; and on Lolium perenne, Bromus mollis, and B. sterilis than on Avena fntue and Vulpin myuros when inoculated at seeding and inverted 8 weeks later.
The effects of temperature and light energy on dry weight and leaf area changes in seedling plants of Lolium perenne L
Authors: Silsbury JH
Published: November 2004

Nine identical seedling populations of Lolium perenne cv. Grasslands Ruanui were grown at different times in a controlled environment cabinet under 22, 38, and 117 watts m-2Visible radiation (16 hr day length) and at 10, 20, and 30�C for 32 days. The proportion of the total dry matter present as roots and that of the shoot dry weight present as leaf laminae were only slightly affected by the environment. Shoot growth was dominated by leaf growth; responses to the environment of the average relative growth rate (El,) and the average leaf area growth rate RA) were similar. RW and RA were maximal at 20�C at each light flux density and increased toward a maximum with increased radiation at each temperature. Maximum RW for seedling plants of L. perenne was about 25% per day. The net assimilation rate increased approximately linearly with increase in light flux and was scarcely affected by temperature. The leaf area ratio was greatly affected by changes in light energy, mainly owing to change in the specific leaf area. The rate of leaf appearance was accelerated by a temperature increase from 10 to 20�C. Total tiller number was maximal at 20�C and increased with light flux. When related to leaf number, tillering was reduced only by high temperature at low light energy. The relative changes in net assimilation rate induced by variation in light flux at 20�C were the same as those in the net photosynthesis of a single leaf lamina. The growth of seedling ryegrass plants in the field in winter is considered to be strongly dependent on temperature and much less restricted by low light energy.
Pathogenic effects of Heterodera avenae and Rhizoctonia solani and their interaction on wheat
Authors: Meagher JW , Chambers SC
Published: November 2004

The effects of the cereal cyst nematode Heterodera arenae and the fungus Rhizoctonin solani on the growth of wheat seedlings were examined under glasshouse conditions. In combination, the pathogens caused significantly greater reduction in tillering, plant height, fresh weight, and root number and length than that caused by either pathogen when acting alone. Reduction in plant height, root number, and root length were the result of interaction. Nematode-fungus interaction may be the cause of disease in the field usually attributed to only one of these pathogens.
Variation in growth and nodulation of Glycine wightii under controlled environment
Authors: Nicholas DB , Haydock KP
Published: November 2004

The growth and nodulation of Glycine wightii (formerly G. javanica L.) were studied in two experiments with several effective strains of Rhizobim under controlled environment, with the aim of producing lines with improved nodulation and nitrogenfixing ability. Significant differences were found between the accessions in their ability to nodulate and also between the strains in their symbiotic effectiveness. Variation within lines for dry weight per nodule and time to nodule appearance was large. The results indicated that total nodule weight per plant is a suitable character for selection in a breeding programme to improve noddation in G. wightii.
Pattern analysis of a grazing experiment
Authors: Williams WT , Gillard P
Published: November 2004

The complementary functions of pattern analysis and statistical analysis are discussed, with particular reference to the analysis of agricultural experiments. It is suggested that pattern analysis, in addition to its usual function of simplification of complex data, may contribute to the analysis of grazing experiments in the special case in which there is reason to suspect the existence of an external non-random environmental factor. Such a case is analysed completely; it is shown that the existence of such a factor can be established by intrinsic classification of entire liveweight sequences. The factor can then be partitioned out by principal coordinate analysis; its spatial configuration can be elucidated, and the extent of its contribution to the overall results assessed. Its optimum correlation with parallel botanical data can be established by canonical coordinate analysis. It is then possible to formulate causative hypotheses as to the nature of the factor; in the present case the most plausible hypothesis was that a small systematic change in tree density caused a progressive reduction in quantity and quality of herbage as we passed from the centre of the area to the periphery. This hypothesis could be used for further experiment and statistical test. Standard programmes for the entire analysis exist on the Control Data 3600 computer at Canberra.
The effect of temperature on characteristics of semen of rams
Authors: Smith JF
Published: November 2004

The effect on a number of semen characteristics of exposure to four periods (4, 6, 9, and 13.5 hr) of high temperature (41�C) was studied in nine rams. Individual rams varied in their susceptibility to seminal degeneration, and repeatability within rains at successive heat treatments was low. There were significant linear effects of duration of heat treatment on volume, density, number of spermatozoa per ejaculate, percentage of abnormal spermatozoa, motility, fructose concentration, and reaction time. There was a significant effect of week of collection after treatment on all characteristics. The major component of this effect was quadratic, showing a degeneration and recovery pattern. Evidence of degeneration appeared at approximately the 12th day and reached its maximum at the 19th day, after which recovery was shown up to the 30th day. This pattern was observed in most of the characteristics studied. There was a significant negative correlation (r = -0.593 ; P < 0.01) between a mean semen composite score and the maximum subcutaneous scrotal temperature recorded during the corresponding heat treatment period. Correlations between mean semen composite score and the increase in scrotal temperature (r = -0.22) and the minimum difference between body and scrotal temperature (r = +0.33) were not significant. Thus, the maximum subcutaneous scrotal temperature appears the important factor involved in seminal degeneration following exposure to high temperature.
Embryo dormancy in subterranean clover seeds. I. Environmental control
Authors: Quinlivan BJ , Nicol HI
Published: November 2004

Embryo dormancy in seeds of subterranean clover (Trifolium subterraneum) is at a maximum at field maturity in the spring. High summer temperatures are the causative agent in the subsequent breakdown of embryo dormancy, the germination inhibitors in the seeds apparently being susceptible to heat. There is no evidence for germination inhibitors in the pod and burr material, nor is there any evidence to support the hypothesis of an environmentally imposed dormancy, for germination is relatively fast at 15 ? 25�C, a temperature regime equivalent to the daily temperature change of summer moist soil. There are differences between cultivars in the initial level of embryo dormancy and in the subsequent rate of breakdown.
Promoting flowering in sweet orange
Authors: Moss GI
Published: November 2004

Two substances reported to stimulate flowering in citrus, Alar (N-dimethylamino-succinamic acid) at 3000 p.p.m. and Hyvar-X (5-bromo-6-n1ethyl-3-s-butyluracil) at 783 p.p.m., when applied twice to sweet orange plants under marginally flower-inducing conditions (24/19�C day/night temperature) resulted in fewer flowers being formed than in the controls. These substances had no significant effect on the numbers of flowers formed by either fruit-bearing or non-fruiting plants under flower-inducing conditions (18/13�C day/night temperature). In the field, Alar (3000 p.p.m.) applied twice or girdling of branches, about the time of flower formation, did not promote flowering on either fruit-bearing or non-fruiting branches.
Leucaena leucocephala as a feed for dairy cows. Direct effect on reproduction and residual effect on the calf and lactation
Authors: Hamilton RI , Donaldson LE , Lambourne LJ
Published: November 2004

Leucaena 1ericocc.phala was given for periods of 30 days to 14 months to nonlactating dairy cows in all stages of the reproductive cycle. Similar cows were fed on lucerne for comparison. Leucaena did not affect oestrous cycle length, conception rate, or gestation length. Feeding leucaena to heifers pre partum did not affect the mean yield and composition of milk over the first 9 weeks of lactation when a normal milking ration was used post part~lm, but the shape of the lactation curve was slightly flattened. Some mild incoordination and nervous symptoms occurred briefly during gestation in some cows on leucaena. Mild depilation was seen in several cows and quite extensive depilation in one. Calves from cows fed on leucaena had a significantly lower mean birth weight (19.6 kg) than control calves (25.8 kg) and one cow fed on leucaena had a still-born calf. Calf thyroid glands were enlarged and plasma protein-bound iodine levels elevated, but thyroid gland histology was normal. Basal metabolic rates and growth rates of the calves were the same in the two groups.
Heterosis and combining ability of American and African cotton cultivars in a low latitude under high-yeild conditions
Authors: Thomson NJ
Published: November 2004

A diallel cross of nine cultivars of Gossypium hirsutum L. (race latifolium), grouped on a basis of origin and staple characteristics into African uplands and American high quality and ordinary quality uplands, was used to examine heterosis and combining ability effects. Heterosis associated with the African cultivars, in combination either with the American cultivars or with each other, at an average of 22 % was approximately double that associated with either American group of cultivars. A number of hybrids significantly outyielded the standard commercial cultivar of the region, Stoneville 7A. The best hybrid yielded 271 kg lint/ha more than Stoneville's yield of 1622 kg lint/ha. This increase was brought about by heterosis in the three yield components: number of bolls, boll weight, and lint percentage. Heterosis was also marked for early height with all groups but was absent or only slight for mature height. No significant heterotic effects were demonstrated for micronaire value or Pressley strength index. Variation due to general combining ability predominated in all traits, particularly for lint yield, number of bolls, boll weight, and mature height. Even when significant, the specific combining ability component of variance was much less than the general combining ability component. All three African cultivars and the ordinary quality American type Stoneville 7A had high general combining ability for lint yield and number of bolls and should be valuable parents for use in a breeding programme. Lint yield in the F1 population was strongly genetically correlated with number of bolls but negatively correlated with boll weight, not associated with lint percentage, and slightly negatively associated with micronaire value and Pressley strength index.
Ecto- and endoparasitic effects on the growth rates of Zebu crossbred and British cattle in the field
Authors: Seifert GW
Published: November 2004

The effect of natural infestations of internal parasites (Cooperia species, Haemonchuspbcei, Oesophagostomum radiatum, and Trichostrongylus axei) and the cattle tick Boophilus microplus on the growth rate from weaning to 21 months of age of 93 F3 Africander x Hereford and Shorthorn (AX), Brahman x Hereford and Shorthorn (BX), and Hereford x Shorthorn (British) was studied. All animals were weighed, ticks counted, faeces sampled, and the animals treated at fortnightly intervals. Faecal egg counts were used as an index of internal parasite burdens, and tick infestations assessed according to the number of females between 0.45 and 0.8 cm in length on one complete side of the animal. Breed differences for the internal parasitic burdens were small and were only significant (P<. 0.05) for O. radiatum. The BX cattle carried the highest burdens. The BX cattle were significantly more resistant to tick infestations than the AX group, which in turn were significantly more resistant than the British group. Males carried significantly more ticks than females. Parasites had little or no effect on gains while the animals were gaining weight rapidly, and it was only after a cessation of gains due to deteriorating pasture conditions that significant treatment effects became evident. Treatment had the largest effect on the British and very little effect on the BX group. Regressions of gains on parasitic burdens within treatments were all negative. The repeatabilities of a series of egg counts for the species were significant, Haemonchus egg counts having the highest repeatabilities. Correlations between egg counts of Cooperia spp and 0. radiatum, and H. placei and T. axei were significant (r = 0.82, P < 0.001; and r = 0.23, P < 0.05). Internal parasites significantly depressed packed red cell volume, haemoglobin concentration, and plasma protein levels. There were significant negative correlations of egg counts of O. radiatum with haemoglobin concentration and packed cell volume of the Zebu crossbreds (r = 0.46 and v = 0.47, P < 0.01).
Effect of recent red leaf virus infection on the distribution of 65Zn, 45Ca, and 54Mn in subterranean clover
Authors: Millikan CR , Kellock AW , Woodcock T
Published: November 2004

Subterranean clover (Trifolium subterraneurn L. cv. Yarloop) was grown in nutrient solutions which were supplied with 45Ca, 65Zn, or 54Mn either before (series A) or at the same time as (series B) the plants \+ere inoculated with subterranean clover red leaf virus (SCRLV) by means of the aphid vector Acyrthosiphon solani Kltb. SCRLV infection affected the distribution of each isotope, but less in series A than in series B plants. In both series, movement of the isotopes from the petiole (P) into the lamina (L) was retarded. In series B this resulted in a significant decrease in the concentration of 45Ca, 65Zn, or 54Mn in the lamina. The L/P ratios of concentration and the total contents of 65Zn and 54Mn in the leaves of SCRLV-infected plants from both series were also reduced. In addition SCRLV infection reduced the 54Mn concentration in the distal third more than in the remainder of the lamina. SCRLV infection increased the dry weight of the lamina and/or the LIP ratio of dry weight of the younger leaves of the series B plants.
Botanical and chemcial composition of a Townsville stylo-spear grass pasture in relation to conception rate of cows
Authors: Ritson JB , Edye LA , Robinson PJ
Published: November 2004

A previously described experiment designed to study the effect of stocking rate, superphosphate, and conservation of hay on the fertility of cows had shown that only superphosphate significantly increased the conception rate. The present paper discusses the nutritional adequacy of the pastures for breeding cows. All experimental factors significantly influenced yield and botanical composition. Pastures at the lower of two stocking rates remained dominated by perennial grasses while those at the higher rate became dominated by Townsville stylo and annual grasses. Conservation of hay increased annual species, and superphosphate increased Townsville stylo in lightly grazed pastures. Pasture yield was adequate at the lower stocking rate but became limiting at the higher rate. Superphosphate increased pasture yields during the third and fourth year. Superphosphate increased the phosphorus and sulphur contents of the three major components —Townsville stylo, perennial grasses, and annual grasses, the nitrogen content of Townsville stylo, and the sodium content of perennial and annual grasses. Stocking rate affected chemical composition in the third and fourth year: the high stocking rate increased the nitrogen contents of the three major components, the phosphorus and sulphur contents of Townsville stylo and perennial grasses, and the sodium contents of perennial and annual grasses. Cow conception rate was significantly and positively correlated with the phosphorus contents of the three major components, the sulphur content of Townsville stylo, and three yield attributes of annual grasses (dry matter, phosphorus, and nitrogen yield). The phosphorus content of all three components was less than 0.15% for much of the year at the two lower rates of superphosphate; only at the highest rate did the pastures approach an adequate phosphorus content for pregnant and lactating cows. Phosphorus and sulphur deficiency could have limited the utilization of Townsville stylo protein by cattle on unfertilized pastures. Superphosphate at a rate of 126 kg/ha a year was adequate for maintaining Townsville stylo above the critical plant value for phosphorus, but inadequate to satisfy the phosphorus requirements of pregnant and lactating cows.
Fruit splitting in grapes: Determination of the critical turgor pressure
Authors: Considine JA , Kriedemann PE
Published: November 2004

A technique was devised to measure the internal turgor pressure required for fruit rupture in order to assess resistance to splitting objectively rather than rely solely on field observation. In the laboratory, fruit of uniform maturity and known osmotic potential were immersed in a range of osmotica to create a known turgor pressure at equilibrium. "Critical turgor", the pressure which resulted in 50% of the berries splitting, was approximately 15 atm in grape cultivars prone to splitting and 40 atm in resistant cultivars. Cultural treatments with growth regulators subsequently affected fruit resilience. p-Chlorophenoxyacetic acid lowered critical turgor, while gibberellic acid caused an increase. These laboratory-based observations coincided with field experience. Additional factors in fruit splitting, including berry morphology and anatomy, are discussed.
The utilization of spear grass (Heteropogon contortus). I. Factors limiting intake and utilization by cattle and sheep
Authors: Siebert BD , Kennedy PM
Published: November 2004

The addition of 13.6% lucerne to a diet of spear grass increased the total intake of digestible organic matter of cattle by nearly 30%. Further additions (24.5 and 44.9%) increased the total organic matter intake, but decreased the spear grass intake. In cattle, the digestibility of the spear grass portion of the diet appeared to decrease as lucerne was added to the diet. Sheep consumed and digested spear grass poorly, although an addition of 14.4% legume increased both digestibility and intake. Further additions of legume slightly decreased the digestibility of the spear grass. The addition of urea alone did not influence digestion or feed intake by either cattle or sheep. When cattle were fed on spear grass, urea, and minerals, the quantity of organic matter digested was not significantly different from that with a diet of spear grass and 20% lucerne. The digestibility of the spear grass was not influenced by urea and minerals, whereas it decreased with the addition of lucerne. Increased feed consumption was maintained when various components of the mineral supplement were withdrawn, excepting nitrogen and sulphur. The energy derived from diets of spear grass and lucerne or spear grass and minerals appears to be above the maintenance requirements of cattle, but below those of sheep.
The effects of undernutrition on libido and semen quality in adult Merino rams
Authors: Parker GV , Thwaites CJ
Published: November 2004

Groups of mature Merino rams were fed at maintenance, or at 75 or 50% of maintenance, for a 15-week experimental period, during which the treated groups lost on average 12.5 and 20.6% of their respective initial body weights. Libido and semen quality were assessed at weekly intervals on a series of eight ejaculates collected from each ram at 20-min intervals. Libido, as assessed by reaction time, number of mounts per ejaculate, frequency of failure to ejaculate, and vigour of the ejaculatory thrust, was progressively and markedly depressed in both treated groups during the last third of the experiment. Semen quality (volume, density, and motility of ejaculate, and methylene blue reduction time) was significantly greater in the first than in the eighth ejaculate collected each week, and the quality of the first but not the eighth ejaculate was significantly depressed during the last month of the experiment in both treated groups.
Efficiency of conversion of food to wool in selected and unselected Merino types
Authors: Saville DG , Robards GE
Published: November 2004

Comparisons were made between Collinsville, Bungaree, and Peppin Merino ewes in efficiency of conversion of food to wool. The effect of selection for some characters on efficiency of conversion within the Peppin Merino was also investigated. The Collinsville ewes grew 14% more wool and had an 8% lower food intake at maintenance than did the Peppins. Differences in wool growth between the Peppin and Collinsville types fed ad lib. were mainly due to efficiency and body weight differences. Efficiency, intake, and body weight each had a similar influence on wool growth differences between Peppins and Bungarees. Peppin ewes selected for wool production, either alone or together with crimp frequency, had a higher gross efficiency than unselected sheep fed below maintenance (13 and 8%) or ad lib. (14 and 13%). The efficiency difference between selected and unselected sheep increased, then decreased, with increasing intake. The decrease in efficiency differences at higher intakes did not appear to influence the ranking of selected or unselected sheep. The response to selection for clean fleece weight was shown to develop a plateau after about one generation of selection. Selection had resulted in the elimination of a relationship between efficiency and wool growth. The present results indicate that further progress in fleece weight is unlikely to be made either by selecting for fleece weight with some control on fibre diameter or by selecting for increased surface area.