bluuebunny/crossref_metadata_2025 huggingface dataset:
Citrus polyploidy - origins and potential for cultivar improvement
Authors: Lee LS
Published: November 2004

Euploidy in Citrus is represented by monoploids, diploids, triploids, tetraploids, pentaploids and octoploids. Such plants offer considerable potential for cultivar improvement through expliotation of their horticulturally useful characteristics and as parents in breeding programmes. Further, they may also facilitate investigation of Citrus genetics. Their diversity of origins (sexual and apomictic, natural and artificial) allows flexibility in their exploitation. The development of seedless triploid varieties has already proven practical with the release of commercial cultivars, and the potential of somatic tetraploids as dwarfing rootstocks warrants thorough investigation. The advent of modern biotechnology holds promise for the exploitation of monoloids in breeding. This review examines the various origins of Citrus polyploidy and considers the potential for exploitation of certain polyploids.
Phosphorus efficiency in pasture species. II. Differences in the utilization of P between major chemical fractions
Authors: Chisholm RH , Blair GJ
Published: November 2004

A solution culture experiment was conducted over a range of initial solution P concentrations (1-16 8M P) to investigate differences in P utilization of a tropical and temperate pasture legume. The species used were white clover (Trifolium repens cv. 'Ladino') and Caribbean stylo (Stylosanthes hamata cv. 'Verano'). Incorporation of solution 31P and a pulse of 32P into the soluble (inorganic, ester P), lipid and residue (phytin RNA, DNA, phosphoproteins) fractions of roots and tops was monitored over five harvests. At low P concentrations the major finding was that clover reduced its incorporation of 31P and 32P into root phospholipids at the final harvest. The reduction in P concentration in phospholipids coincided with reductions in relative growth rate of the whole plant by the final harvest, which were discussed in the first paper of this series.At high P concentrations, dry weight accumulation was related to the extent to which absorbed P was incorporated from the soluble to the lipid and residue fractions. While clover had higher dry weights and a greater incorporation capacity at high P.Correlation coefficients between dry weight and biochemical parameters showed that the best correlations between dry weight and any biochemical parameter was for the relationship between dry weight and residues P or lipid plus residue P content. A relationship between P uptake rate and root soluble P concentration indicated that root soluble P may have a feedback effect on P uptake. The negative feedback effect was greatest in stylo at high solution P concentration.
Lucerne (Medicago sativa L.) selected for vigor in a nonsaline environment maintained growth under salt stress
Authors: Kapulnik Y , Teuber LR , Phillips DA
Published: November 2004

Lucerne populations HP32 and M69-33 (Medicago sativa L.), which were developed from Hairy Peruvian (HP) and Moapa 69 (M69) by selection for increased growth and N assimilation in nonsaline conditions, also produced more forage at 20% bloom than the original cultivars when moderate salt stress was applied after germination. During the first 45 days of seedling development, the improved populations produced as much total dry matter in the presence of 150 mM NaCl as the original cultivars did in the absence of NaCl. When plants were grown to 20% bloom with 200 mM NaCl, HP32 produced 70% more forage than HP (P=0.01), while M69-33 yielded 26% more forage than M69 (P=0.05). Because all tests were conducted in the absence of combined N, growth of the improved populations was accompanied by increased N2 fixation. Superior growth of HP32 under saline conditions was associated with greater exclusion of Na (P=0.05) and Cl (P=0.08) from the leaves. These results show that selecting for increased growth and N assimilation without salt stress in two populations of lucerne provided potential agronomic benefits in both saline and nonsaline environments.
The effect of nutrition on testicular growth in the Merino ram
Authors: Murray PJ , Rowe JB , Pethick DW , Adams NR
Published: November 2004

Fifteen rams were used in a series of three experiments in which different nutritional treatments were allocated to groups of 5 individually housed animals (3 treatments per experiment). In all experiments one group received only the basal ration (1 kg/day of a pelleted diet) and a second group was fed this ration plus 750 g/day of lupins. The remaining three treatments were: (1) the basal ration plus an intra-abomasal infusion of casein (200 g/day) and glucose (1 12 g/day); (2) a pelleted diet consisting of the basal ration plus oil (60 g/day) and VFA salts (255 g/day), together with an intra-abomasal infusion of casein (200 g/day) and glucose (112 g/day), and (3) the basal ration plus 800 g/day of barley. Experiments were carried out over a period of 42-49 days and measurements were made of testicular size, wool growth, liveweight and digestibility of the diets. The results of this study were compared with those of a number of published and unpublished experiments. Testicular growth was highly correlated (r= 0.86) with liveweight change in a curvilinear relationship. Change in liveweight and respiration rate were highly correlated with digestible energy intake (r=0.79 and r=0.94 respectively). Wool growth was highly correlated (r=0.97) with crude protein intake and nitrogen balance, with digestible energy having only a marginal influence. There was also a high correlation (r= 0.85) between digestible energy intake and testicular growth, with dietary protein having only a marginal influence. Comparison of these data with published data on testicular growth in rams confirmed the above relationships. It was concluded that testicular growth in rams responds more to digestible energy intake and liveweight change than to crude protein availability.
Variability in grain protein in Australian hexaploid wheats
Authors: Stoddard FL , Marshall DR
Published: November 2004

Grain protein content and grain yield data were collected from 11 Interstate Wheat Variety Trials (IWVT) and other sources. The level of variation in grain protein content beyond that attributable to covariation in environment and yield was estimated using a generalized linear model. A range of almost 4% in corrected protein content was found among 204 lines tested in IWVT. The Western Australian cv. Tincurrin was approx1% lower in grain protein content than any other line, while Shortim, Sun 43A, QT2200-20, QT2612-1 and Sun 92A were all 1.4-1.7% higher than the pooled mean of 4 control cultivars (Cook, Eagle, Halberd and Oxley). Accessions did not vary significantly in protein content with change in yield. Results from a range of other independent trials confirmed those from IWVT. Wheats genetically capable of producing a higher concentration of protein in their grain at a given yield level came principally from the Sydney University and Queensland breeding programmes, and those producing a lower concentration principally from Victoria and Western Australia. Grain hardness was independent of grain protein content and many low protein hard wheats entering the IWVT fell well outside current international market requirements.
The growth and yield of uniculm and tillered barley over a range of sowing rates
Authors: McDonald GK
Published: November 2004

The growth and yield of two lines of uniculm barley, WID-103 and WID-105, were compared over a range of sowing rates (50-400 kg/ha) with the commercial varieties Galleon and Schooner. The experiments were conducted at Strathalbyn, S.A., in 1986, 1987 and 1988 and at the Waite Agricultural Research Institute in 1987. A third tillered variety, Clipper, was included in the comparison in 1988. Over the three years plant populations measured early in the season ranged from 39/m2 to 709/m2, and grain yields from 97 to 41 1 g/m2. Dry matter production at ear emergence increased with greater plant density, and both the tillered varieties and the uniculm lines showed similar responses to higher sowing rates. At maturity, dry matter production of the tillered barleys was greater than or equal to that of the uniculms and the harvest indices (HIs) of the two types were similar. Consequently, grain yields of the tillered types were greater than or equal to the yields of the uniculms. Over the four experiments the tillered varieties had a 6% higher yield. The number of ears/m2 was the yield component most affected by plant density in both the tillered and uniculm barleys. The uniculm lines had more spikelets/ear, but tended to set fewer grains/spikelet and produce smaller kernels. The experiments failed to demonstrate any advantage of the uniculm habit to the grain yield of barley. These results differ from previous experiments that showed that a uniculm line, WID-101, had a higher yield than the tillered variety Clipper. It is suggested that the uniculm habit per se was not the cause of this higher yield, but its higher HI resulted in it outyielding Clipper. Current varieties, however, have HIs similar to the uniculm lines and yield equally to or more than the uniculm barleys examined. To further improve the grain yield of uniculm barley, greater dry matter production is necessary as the HIs of these lines are already high.
Responses of finishing broilers at high temperatures to dietary methionine source and supplementation levels
Authors: Balnave D , Oliva A
Published: November 2004

The methionine requirements of 3-6-week-old broilers kept at a constant 30�C or at diurnally cycling temperatures of 25-35�C were reduced compared with broilers kept at 21�C. The methionine requirements varied from 0.29 g/MJ of metabolizable energy (ME) at 2 1�C to 0.26 g/MJ of ME at 25-35�C to 0.22 g/MJ of ME at 30�C with total sulfur amino acid requirements of between 0.51 and 0.55 g/MJ of ME. The estimate at 21�C is similar to recommendations made by others for moderate temperatures. Differences in response to DL-methionine and methionine hydroxy analogue free acid were small.
Triticum tauschii: a novel source of resistance to cereal cyst nematode (Heterodera avenae)
Authors: Eastwood RF , Lagudah ES , Appels R , Hannah M , Kollmorgen JF
Published: November 2004

Four hundred and twenty accessions of Triticum tauschii (genome DD) were assessed for resistance to cereal cyst nematode (Heterodera avenae Woll.) and 13 were found to be resistant (P = 0.05). Synthetic allohexaploid wheats produced from different Triticum turgidurn var. durum (genome AABB) lines and H. avenae resistant accessions of T tauschii maintained the level of resistance expressed in the diploids. This is the first report of resistance to H. avenae in T. tauschii, and in synthesized allohexaploid wheat. Since the resistance is in the D genome it is likely to be novel. Resistance was most common in T. tauschii ssp. eusquarrosa var. meyeri, and its derivatives which are confined to the Pahlavi region of Iran.
The effect of inoculum distribution and sowing depth on Pleiochaeta root rot of lupins
Authors: Sweetingham MW
Published: November 2004

In paddocks with a history of previous lupin cultivation, propagules of the fungus Pleiochaeta setosa are most concentrated in the top 2 cm of soil and rapidly decline to zero at the base of the tillage layer (10-14 cm). The severity of Pleiochaeta root rot is greatly reduced as sowing depth increases, due to avoidance of the concentrated surface soil borne inoculum. Hypocotyls are not infected by P. setosa, enabling disease escape. In four field trials over three seasons, optimum establishment and grain yield occurred at sowing depths close to 5 cm, deeper than previously recommended for lupins in Western Australia.
Seasonal metabolic factors may be responsible for deaths in sheep exported by sea
Authors: Richards RB , Hyder MW , Fry J , Costa ND , Norris RT , Higgs ARB
Published: November 2004

Metabolic responses to persistent inappetance were studied in sheep transported by sea from Australia to the Arabian Gulf in May and August. In the May voyage inappetant sheep successfully mobilised fat and generated ketones to supply energy and few died (0.83%). However, in August, inappetant sheep failed to mobilise fat for more than a few days and the death rate was much higher (3.27%). The causes of death were similar in both voyages; approximately 65% of the deaths were due to inanition. We postulated that in May, sheep coming from dry pastures were nearing the end of a cycle of liveweight loss and were metabolically adjusted to using adipose reserves for energy. However, in August, sheep had entered a period of liveweight gain on green pastures and were consequently unable to sustain lipolysis for energy supply when inappetant.
Relationship between Phoma black stem severity and herbage and seed yield and coumestrol content in three Medicago polymorpha var. brevispina cultivars
Authors: Barbetti MJ , Fang CS
Published: November 2004

A field trial was conducted to determine the relationship between Phoma black stem disease (Phoma medicaginis) severity, herbage and seed yields and coumestrol content in Medicago polymorpha var. brevispina medic cultivars Circle Valley, Santiago and Serena. There was a significant negative correlation between Phoma black stem disease severity with herbage yields in early spring (mid to late September) (r =-0.65, P < 0.01) and mid spring (mid October) (r = -0.81, P < 0. 0 l ) , seed yields at the end of the growing season in late spring (r =-0.83, P< 0.01) and 100 seed weight (r =-0.83, P< 0.001). In addition, there was significant positive correlation at the end of the growing season between Phoma black stem disease severity and coumestrol content of dry stems ( r = 0.72, P<0.001) and pods (r = 0.77, P < 0.001). Meaned over all cultivars, severe Phoma black stem disease resulted in overall reductions in mid spring herbage yields of up to 17% and in end of season seed yields of up to 36% and increases in coumestrol content of up to 75 and 321% for stems and pods respectively. The highest level of coumestrol measured in stems was 550 ppm for cv. Serena and in pods was 525 ppm in cv. Circle Valley. Of the three culitvars, cv. Santiago was the least susceptible to Phoma black stem disease.
Increasing grain yield and water use of wheat in a rainfed Mediterranean type environment
Authors: Anderson WK
Published: November 2004

Factorial experiments were conducted at eight sites in the central wheatbelt of Western Australia over two seasons. Time of sowing (mid-May, early June), cultivar (old tall, new semi-dwarf), nitrogen (N) fertilizer (- or +) and amount of seed sown (low and high) were combined as treatments, and grain yield, yield components, biomass, grain quality, water use, soil chemical and weather variables were measured. The aim was to increase grain yield by combining relevant agronomic inputs and increasing the seasonal water use or water use efficiency. Grain yields were increased by from 30 to over 100% by the combination of mid-May sowing, semi-dwarf cultivar, N fertilizer and increased seed level (high-inputs) compared to early June sowing, old tall cultivar, without N and lower seed level (low-inputs). The yield improvements mostly came from increased dry matter production at anthesis, largely due to increased applications of N and seed. Ear and kernel numbers were also increased by earlier sowing and N fertilizer and to a lesser extent by cultivar and increased weight of seed sown. Water use was increased at most sites, especially in the post-anthesis period and water use efficiency of grain production was increased at all sites. Soil evaporation was reduced by the high-input treatments and the low-input treatments did not use water supplies of > 250 mm efficiently in grain production. It was concluded that appropriate combinations of cultivar and agronomic practices can increase grain yields linearly up to about 5 t ha-1 at seasonal water use of about 400 mm, even in situations where considerable water stress occurs during grain filling. Grain protein concentration was generally increased and hectolitre weight and small grain sievings were not adversely affected by increasing agronomic inputs.
Response of annual medics (Medicago spp.) and field peas (Pisum sativum) to high concentration of boron: genetic variation and the mechanism of tolerance
Authors: Paull JG , Nable RO , Lake AWH , Materne MA , Rathjen AJ
Published: November 2004

The genetic range and mechanism of tolerance to high concentrations of B were examined for field peas and annual medic species. Both genera showed a wide range in response to B. The most tolerant Australian varieties of pea included Early Dun, Partridge, Dun, Derrimut, Dundale, Alma and Maitland, while Parraggio, Ghor and Cyprus were the most tolerant of the Australian medics. Accessions more tolerant than the Australian varieties were identified for both species. The highest percentage of tolerant accessions of medics originated from the central and western Mediterranean regions, while the two tolerant peas identified originated from India. The mechanism of tolerance consisted of exclusion of B from the roots and shoots of tolerant lines, and was therefore consistent with previous results for wheat and barley.
Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum
Authors: Mott JJ , Ludlow MM , Richards JH , Parsons AD
Published: November 2004

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.
The effect of nutritional supplements in late pregnancy on ewe colostrum production plasma progesterone and IGF-1 concentrations
Authors: Hall DG , Holst PJ , Shutt DA
Published: November 2004

Mechanisms by which nutritional supplementation might improve colostrum production and enhance lamb survival were examined in adult Border LeicesterxMerino ewes. Ewes were either unsupplemented or supplemented with 500 g/day of oat grain, lupin grain or a formaldehyde-protected sunflowerseed meal (SFM) from day 130 of gestation until parturition while grazing spring pastures containing about 1000 kg green DM/ha. Blood samples were obtained on day 140, day 145 and immediately after parturition. Colostrum production at parturition and for the next 6 h was determined. A new method to determine concentrations of insulin-like growth factor-1 (IGF-1) is presented. Colostrum production at parturition (P.< 0.01) and IGF-1 concentration on day 140 (P.< 0.01) and at parturition (P.< 0.001) were higher, and progesterone concentrations on days 140, 145 and at parturition were lower (P.< 0.001) for single than twin bearing ewes. The unsupplemented ewes and ewes fed oat grain, lupin grain or SFM had an average weight of colostrum at parturition of 292, 328, 452 and 392 g (P.< 0.01), milk secretion rate to 6 h after parturition of 58, 64, 85 and l00g DM/h (P.< 0.05), IGF-1 concentrations after parturition of 199, 223, 262 and 265 ng/mL (P.< 0.001) and progesterone concentrations on day 140 of 49, 43, 39 and 41 nmol/L (P.< 0.01) respectively. Twin compared to single bearing ewes had about half the amount of colostrum at parturition per kg of lamb birthweight. Progesterone concentrations on day 140 and at parturition (P.< 0.01) were negatively related to estimated pasture intake during pregnancy, which was 17% higher for single than twin bearing ewes (P.< 0.05). Supplementation with lupins and SFM may be expected in similar circumstances to enhance the survival of multiple born lambs, while oat grain would not.
Cellular characteristics of wool follicles and fibres in finewool and strongwool Merinos
Authors: Edwards JEH , Hynd PI
Published: November 2004

The genetic differences in the structure and function of wool follicles and their association with wool and fibre production were examined in 6 finewool Merinos (Camden Park) and 6 strongwool Merinos (East Bungaree). The strongwool Merinos produced 2.4 times more wool per unit area of skin and 3.5 times the volume of fibre per follicle than the finewool Merinos, when both groups were maintained under similar environmental conditions. The finewool Merinos had a higher follicle density, but a lower average volume of germinative tissue in the follicle bulb and the skin, than the strongwool Merinos. The number and volume of cells in the bulb, bulb cell production rate, cortical cell size and the proportion of bulb cells entering the fibre tended to be greater in the strongwool Merinos than the finewool Merinos, but were not statistically different between strains due to a high between-sheep, within-strain variation. In a stepwise linear regression, wool production per unit area was best predicted by the volume of germinative tissue in the bulb, together with follicle density. It is concluded that genotype determines the volume of potential mitotically-active tissue in the skin, however the dynamic mechanism of fibre production is not controlled by a single character, but rather a combination of a number of characteristics.
Conditions under which flavomycin increases wool growth and liveweight gain in sheep
Authors: Murray PJ , Winslow SG , Rowe JB
Published: November 2004

Flavomycin, a glycolipid feed additive, was evaluated for its potential to improve wool growth and liveweight gain in sheep of two ages and from two different sources. Sheep came from two locations in the Mediterranean climatic region of Western Australia's agricultural area-Mount Barker, with a relatively high rainfall and Wongan Hills with a relatively low rainfall and shorter pasture growing period. Forty weaner sheep, from each source, initially eight months of age and with a mean liveweight of 29 kg (s.e. � 0.3) were studied. There were also 40 adult sheep, from each source, initially 20 months of age with mean liveweights (Wongan Hills) 42 kg (s.e. �0.5) and (Mount Barker) 51 kg (s.e. � 0.7). All animals were housed individually in the one shed and fed a pelleted ration at a level equivalent to 3.1% (weaner) and 3.5% (adult) of each animal's liveweight. The pelleted ration was based on wheat and lucerne chaff, lupin grain and fishmeal. Flavomycin was included at 20 mg/kg pellets and there were 16 sheep of each age and source fed this medicated diet. Twenty-four sheep were fed the unmedicated diet. Wool growth was increased by flavomycin by 14.5% (P < 0.05) but only in adult sheep from Mount Barker. Inclusion of flavomycin in the diet increased liveweight gain in sheep of both ages and from both sources. There was no significant effect of flavomycin on fibre diameter of wool in sheep from the different age groups and sources.
Development, growth, water-use and yield of a spring and a winter wheat in response to time of sowing
Authors: Connor DJ , Theiveyanathan S , Rimmington GM
Published: November 2004

The development, growth, water-use and yield of spring (Banks) and winter (Quarrion) cultivars of wheat were measured in response to time of sowing under rainfed conditions. Crop duration shortened in both cultivars (210 to 120 days) as sowing was delayed from May to August with Quarrion maintaining the longer cycle. The difference between cultivars was small (3 days) at the May sowing increasing to 21 days in August, but there were large differences in the relative durations of the component phenophases. Consistent with the shorter cycle, growth of both cultivars decreased as sowing was delayed from May to July (11.3 to 9.9 t ha-1). With August sowing, the pattern continued in Banks (6.7 t ha-1) but not in Quarrion. Seasonal evapotranspiration (ETa) of both cultivars was similar, declining from 306 to 262 mm as sowing was delayed from May to July. On average, Quarrion used more water (34%) of ETa than Banks (19%) during emergence to floral initiation (E-FI), and a corresponding smaller proportion during subsequent phenophases, floral initiation to anthesis (FI-A ) (31 v. 41%) and anthesis to maturity (A-M) (35 v. 41%). The differences between cultivars increased as sowing was delayed from May to August. Maximum evapotranspiration (ETm), estimated by the Penman equation, was evaluated against measurements made with weighed lysimeters. The ratio ETa/ETm fell progressively during the crop cycles and was always smaller for the later-developing Quarrion than for Banks. Crops of both cultivars had adequate water supply during E-FI, mean value of the ratio 0.93, but experienced water stress during FI-A and A-M. Stress was greater in Quarrion (ratios 0.71 and 0.56) than in Banks (0.88 and 0.62). In Quarrion, yield decreased progressively from 4.3 t ha-1 when sown in May to 1.6 t ha-1 in August. In contrast, yield of Banks increased from 3.7 t ha-1 in May to 4.5 t ha-1 in June and then decreased to 3.5 t ha-l in July and 2.6 t ha-1 in August. Crop water-use efficiencies are analysed for ETa (WUE) and for transpiration (TE). Excluding the August-sown crops, they ranged respectively over 11.9 to 14.8 and 25.0 to 32.5 for Quarrion and over 11.0 to 15.7 and 23.3 to 31.6 kg ha-1 mm-1 for Banks. Maximum efficiencies were not achieved by the crops of greatest yield.
A multi-element supplement for grazing sheep. II. Accumulation of trace elements in sheep fed different levels of supplement
Authors: Masters DG , White CL , Peter DW , Purser DB , Roe SP , Barnes MJ
Published: November 2004

Sheep were fed an oaten hayllupin mixture (88: 12 W/W) containing either 0, 1.7, 3.3, 6.3, 12 or 21% of a multi-element mineral mix for 6 months. Each sheep was fed sufficient ration to provide 800 g DM of the oaten hay/lupin mixture per day. The accumulation of essential and of potentially toxic elements in the tissues of the sheep was measured together with feed intake and growth. Some sheep which were offered 12% and all of the sheep which were offered 21% minerals in the diet refused to eat part or all of the ration and were removed from the experiment. All sheep in the other groups and two sheep which were fed 12% minerals ate all or most of the ration for 6 months. All sheep in the groups which were fed 0, 1.7, 3.3 and 6.3% (equivalent to 0, 15, 30 and 60 g/day of minerals) grew at 27-35 g/day and had similar dry matter intakes after intake of minerals was excluded from the calculation. The two sheep which were fed 12% mineral throughout (equivalent to 120 g/day) lost 6 g/day during the experiment. Intake of minerals increased selenium concentrations in whole blood and liver, and vitamin B12 in plasma. Selenium did not accumulate to levels that resulted in toxicity to the sheep nor exceed maximum permitted levels for human consumption. Fluorine in rib bone increased as mineral intake increased, and sheep which were fed 12% minerals in the diet were at risk of chronic fluorosis. The intake of mineral mix had no significant effect on the concentrations of copper and iron in the liver or the concentration of cadmium in the kidney.
Effects of growth path and post-slaughter chilling regime on carcass composition and meat quality of ewe lambs
Authors: Thatcher LP , Gaunt GM
Published: November 2004

Sixty-five Poll Dorset x (Border Leicester/Merino) ewe lambs. were grown at pasture on one of four growth paths commencing at mean age of 24 weeks and a mean liveweight of 37-5 kg. These were, continuous growth between 24 and 34 weeks (HH), maximum possible growth for 6 weeks followed by weight loss for 4 weeks (HL), no gain for 6 weeks followed by rapid gain for 4 weeks (LH) and weight maintenance (LL). Lambs were slaughtered as soon as possible after LH and HL lambs were the same full weight. There were significant differences between treatments in average growth rate, liveweight, hot carcass weight (HCW) and dressing percentage. After adjustment for HCW, LH had significantly (P < 0.05) less omental and kidney fat than HH, and there was a strong tendency for less subcutaneous fat, intermuscular fat and a lower tissue depth over the twelfth rib (at the GR site). Eye muscle area was significantly larger in LH than HH, but this did not translate to a significant difference in dissectible 'soft tissue' measurement. The Warner Bratzler shear value for LL in the M. longissimus dorsi was significantly higher than LH and HH. There were no differences between treatments for pH, Warner Bratzler shear values of the M. semimembranosus, cooking loss, or the colour measurements using a Minolta chromameter of L* (lightness) or b* (yellowness). The difference in a* (redness) between HL and LH was significant. Warner Bratzler shear values for M. longissimus dorsi and M.semimembranosus were significantly higher at 4�C than 10�C. The a* was significantly higher at 10�C, but there were no differences between L* and b*. There were no interactions between the post-slaughter chilling regime and the pre-slaughter nutritional management. It was concluded that the growth path had little effect on meat quality unless the lamb had been continuously on a restricted diet. Therefore there was some potential for the use of growth paths to manipulate carcass composition, and further research into management systems at pasture is recommended.
Increase in dermal papilla cells by proliferation during development of the primary wool follicle
Authors: Adelson DL , Kelley BA , Nagorcka BN
Published: November 2004

The growth of the demand condensate and dermal papilla of developing primary wool follicles was investigated by counting cells in paraffin of foetal sheep skin. The number of cells in the dermal condensate of prepapilla was found to increase approximately two-fold between follicle initiation and maturation (stages F1 and F8). This increase was not continuous but was interrupted by a no growth period from stages F2a to F6. The proportion of dividing dermal condensate cells, determined by the BrdU/Anti-BrdU technique, was shown to peak during periods of cell number increase. In addition, we were able to demonstrate that the increase in cell number described above could be accounted for entirely by cell proliferation, with no contribution from migration. The developmental modulation of dermal condensate cell proliferation is discussed in relation to both the Reaction-Diffusion theory of hair follicle initiation and morphogenesis and our current knowledge of the transforming growth factor-G superfamily of proteins.
Irrigation management of soybean (Glycine max (L.) Merrill) in a semi-arid tropical environment. II. Effect of irrigation frequency on soil and plant water status and crop water use
Authors: Garside AL , Lawn RJ , Muchow RC , Byth DE
Published: November 2004

Plant and soil water status, crop water use and water use efficiency, as affected by irrigation treatment, were monitored over two seasons for soybean cv. Ross, sown in the late wet season in the Ord Irrigation Area in north Western Australia. Irrigation treatments were, in both seasons, furrow irrigation after cumulative open pan evaporative losses of 30, 60 120 and 240 mm, and in the second year, an additional treatment, saturated soil culture (continuous furrow irrigation, analogous to irrigation after 0 mm pan evaporation). As expected, during periods of strong evaporative demand plant water status, as indicated by leaf water potential and leaf conductance of water vapour, was consistently greater in the more frequently irrigated treatments, while soil water depletion occurred to greater extent and depth in the less frequently irrigated treatments. However, total soil water use was directly proportional to crop growth, so that there was little evidence that water use efficiency was enhanced by restricting water supply in this environment. Indeed, efficiency of water use even under the continuous furrow irrigation system was comparable with that from other irrigation treatments. The responses are interpreted to imply that there is unlikely to be any economic advantage to the use of limited supplemental irrigation in this environment.
The flowering of sesame (Sesamum indicum L.) in response to temperature and photoperiod
Authors: Suddihiyam P , Steer BT , Turner DW
Published: November 2004

Sesame (Sesamum indicum L.) is reported to be a quantitative short day plant in its flowering response. The cultivars Aceitera and Hnan Dun were able to respond to short days as early as the cotyledonary stage, and only one 8 h photoperiod was necessary at this stage for flowering to be accelerated above the 15 h photoperiod control. To see whether geographic origins of cultivars would influence their response to photoperiod, the flowering responses to 8, 13 and 15 h photoperiods among 20 varieties were analysed using cluster analyses. The groupings were consistent enough to suggest a broad relationship between geographic origins of the cultivars and response to photoperiod, but there were several exceptions. There were significant interactions of temperature and photoperiod on the rate of flowering of sesame. However, when the rate of vegetative development (plastochron index of the plant at the time the first floral bud appeared) was used as a covariate in analyses of covariance, significant effects of photoperiod on flowering disappeared. Temperature, however, remained a significant factor. The flowering of some varieties was independent of temperature over the range 20/15 to 30/25�C; other varieties flowered more rapidly at the higher temperatures. The quantitative short day nature of the flowering of sesame appears to act through the rate of vegetative development but not directly on floral bud induction. Temperature, on the other hand, affects both vegetative development and the rate of floral induction in some varieties.
Particle size determines the efficiency of calcitic limestone in amending acidic soil
Authors: Scott BJ , Conyers MK , Fisher R , Lill W
Published: November 2004

There is a commonly held view that limestone particles <0.25 mm are fully effective in amending acidic soils. However, this is not consistent with some available data. We assessed the importance of particle size in a field experiment using six particle size segregations covering a range of mean diameters from 3 mm to 0.005 mm. These products were applied at rates of 2.5, 5 and 10 t ha-1. Lime was incorporated in April 1986 and soil samples were collected 6, 12, 24 and 36 months later. The experiment was cropped to wheat in 1986, 1987 and 1989. Effectiveness was evaluated as the capacity of the particle size segregation to increase soil pH, exchangeable calcium (Caex,) or grain yield of wheat. No minimum particle size for maximum effectiveness was identified. Throughout the range of particle sizes evaluated, progressively finer particles produced larger increases in pH and Caex. Wheat yield was related to soil pH. Changes in soil pH and Caex between 6 months and 3 years after lime application were small compared to the changes in the first 6 months. Fine lime products should be preferred in practice, subject to cost considerations and handling difficulties.
Responses of different strains of Australian broiler chickens to feed restriction at an early age
Authors: Plavnik I , Balnave D
Published: November 2004

Male chickens from the three most common commercial broiler strains in Australia were fed conventionally or on a regimen which restricted growth by approximately 58% between 6 and 12 days of age followed by ad libitum feeding. Early age feed restriction had no significant effect on bodyweight at 47 days of age, and feed was utilized significantly more efficiently with all three strains. Restriction significantly reduced abdominal fat and had no significant effect on the yield of breast meat. The large improvements in feed efficiency and reductions in abdominal fat have major implications with regard to the economics of broiler meat production.
Responses in egg shell quality from dietary ascorbic acid supplementation of hens receiving saline drinking water
Authors: Balnave D , Zhang D
Published: November 2004

Three experiments were conducted to determine whether the poor shell quality of eggs from hens receiving saline drinking water could be improved by the simultaneous addition of ascorbic acid to the diet. In one experiment, the responses were compared with those of hens receiving ascorbic acid in the drinking water. In this experiment, providing the ascorbic acid in the drinking water on a daily basis was compared with dosing the water on alternate days. The results showed that saline water increased the incidence of egg shell defects without affecting food and water intakes, egg production or egg weight. Changes in a range of shell quality measures mirrored the changes in the incidence of egg shell defects. Supplementation of the diet or drinking water with ascorbic acid prevented the increase in shell defects and the decrease in shell quality. The degree of response to dietary ascorbic acid was dependent on the concentration used, a response similar to that observed previously when the ascorbic acid was added to the drinking water.
Genetic parameters for liveweights of beef cattle in the tropics
Authors: Robinson DL , O'Rourke PK
Published: November 2004

This paper describes a genetic analysis of 20000 weighings from 1980-1988 on the progeny of more than 210 sires from three straightbred Brahman and one crossbred herd (Brahman or SahiwalxBritish breeds) in the Australian tropics. 200 day weight averaged 192 kg, very slightly less than 200 day weight in temperate Australia with similar phenotypic variance of 520 kg2. Mean 550, 700, and 900 day weights of 310, 350 and 450 kg and phenotypic variances of 800, 800 and 1485 kg2 were lower than in temperate regions at the same ages. Direct heritabilities for weight averaged 41% in the Brahmans and 31% in the crossbred herd. Genetic correlations amongst 200 day and later weights were 81-92%, except for an estimate of 63% between 200 and 900 day weights. Estimates of heritabilities for maternal effects were quite high in the crossbred herd for 200 and 365 day weights (19 and 14%), but only 4-5% for Brahmans. Models and statistical analyses are discussed and results compared with other published estimates from subtropical and temperate regions.
Factors differentiating between high and low wool producing sheep in western Queensland
Authors: Pritchard DA , O'Rourke PK
Published: November 2004

Four experiments were carried out to examine factors which may influence the phenotypic expression of wool growth. High wool producing sheep (HPS) and low wool producing sheep (LPS) were selected from a commercial flock and studied under grazing and controlled feeding conditions. Results are discussed in relation to management of HPS for increased wool production. In the paddock experiment, advantages to HPS in wool growth per unit surface area were least (7%) when pasture quality was low (11 g N/kg DM) and greatest (20%) when pasture quality was best (21 g N/kg DM). Despite the greater live weight of HPS compared with LPS (16%), the HPS produced 25% more clean wool per unit of live weight. Daily clean wool production was always greater in HPS than in LPS. Values ranged from 9.1 v. 7.5 g/day to 15.1 v. 11.6 g/day. During the period following the peak in nitrogen content of the pasture, HPS produced a greater volume of fibre than LPS (194 v. 167 8m3/dayx103), this difference being primarily associated with the greater fibre diameter of wool from HPS (25.4 v. 24.6 8m). In pen experiment 1, the efficiency of conversion of feed to wool was determined under controlled feeding conditions. Differences in wool growth between HPS and LPS at maintenance (M) and above maintenance (M+) were 21% and 49% respectively. Relative efficiency of conversion of feed to wool was 5% higher for HPS during the period immediately following the change in ration and greatest (38-48%) after sheep had made liveweight gains. Wool growth differences between HPS and LPS in pen experiment 2 could not be attributed to either differences in follicle density (66 v. 64 follicles/mm2) or the ratio of secondary to primary follicles (24 : 1 v. 22 : 1). The efficiency of retention of apparently absorbed nitrogen was similar (21.4 v. 20.8%) for HPS and LPS at below maintenance (M-) but differed at M-t (26.8 v. 11.7%). Rumen dry matter turnover time at M- was faster in HPS than in LPS (29.8 v. 38.4 h) but similar at M+ (30.4 v. 34.4 h). At M-, volumetric fibre production of HPS increased from 79 to 106 ,8m3/dayx 103 and from 59 to 75 ,8m3/day x103 for LPS following the subcutaneous administration of the sulfur containing amino acid methionine. These increases were associated with increases in both fibre diameter (1.5 8m) and fibre linear growth (42 8m/day) in HPS, but only linear growth (52 ,8m/day) in LPS. At M+, when basal wool growth was high, there was little increase in wool growth by either group following supplementary methionine. Wool growth responses to methionine were 25 and 19% for HPS and LPS respectively at M+ in pen experiment 3.
Plant attributes leading to persistence in grazed annual medics (Medicago spp.) growing in rotation with wheat
Authors: Cocks PS
Published: November 2004

Attributes of 84 accessions of 12 medics (Medicago spp.) were measured in nursery rows in two successive years. Multiple regression, principal component, and cluster analyses were used to relate 14 attributes of the medics to persistence in the seed bank of grazed pasture growing in rotation with wheat. Principal component analysis distinguished between the attributes of the species. For example, M. rigidula had short petioles, high frost tolerance, many seeds per pod, and large leaves and seeds; while M. polymorpha had long petioles, low frost tolerance, few seeds per pod, and small seeds and leaves. M. noeana produced many flowers per raceme, small pods and seeds, long peduncles, and was hard-seeded and late flowering; while M. aculeata produced few flowers per raceme, large pods and seeds, short peduncles, and was soft-seeded and early flowering. M. trulncatula and M. rotata were intermediate. Long peduncles and high levels of hardseededness were the attributes most closely associated with persistence of the medics in grazed pasture. It was concluded that (1) long peduncles place the flowers above the canopy in spring where they are in full sun light, and (2) hardseededness levels of up to 90% protect seeds against germination in the cereal year. The results also suggest that small leaves and short internodes and petioles protect young plants against over-grazing in winter, and small pods and seeds are less likely than large pods and seeds to be selected and digested by grazing sheep in summer.
Changes in the size and composition of the seed bank of medic pastures grown in rotation with wheat in north Syria
Authors: Cocks PS
Published: November 2004

A mixture of 84 accessions of 12 medic (Medicago) species were sown in two successive years into a two-course pasture/wheat rotation in north Syria. Changes in the size and botanical composition of the seed bank were monitored for two cycles of the rotation. At the end of the first year the seed bank consisted of 550 kg ha-1 (sowing 1) and 330 kg ha-1 (sowing 2) of medic seed. Subsequent grazing reduced these seed banks to 225 kg ha-1 and 255 kg ha-1 respectively, and germination in the following wheat crop further reduced it to 205 kg ha-1 and 150 kg ha-1. The seed banks reached 700 kg ha-1 and 790 kg ha-1 respectively, during the second pasture phase of the rotation. The seedling density of medics in the regenerating pasture was 750 m-2 (sowing 1) and 1120 m-2 (sowing 2). Medics comprised about 95% of the pasture by mid-spring in both phases, the remaining 5% being wheat and broad-leaved weeds. The productivity of regenerating pasture was 5 t ha-1 (sowing 1) and 8 t ha-1 (sowing 2). Only three medic species, M. rotata, M. noeana, and M. rigidula, increased as a proportion of the seedbank. The increase was greatest in the first year, though M. noeana and M. rigidula increased further in the next two years. M. littoralis and M. turbinata, initially unsuccessful, became more successful later, while M. scutellata and M. constricta continued to decline throughout the experiment. There were also appreciable differences in the seed bank of individual accessions of several species. The results are discussed in terms of (a) the grazing strategies required in pasture/wheat rotations, and (b) the use of mixtures to select medics suitable for such rotations.
Subterranean clover mottle virus infection of subterranean clover: widespread occurrence in pastures and effects on productivity
Authors: Wroth JM , Jones RAC
Published: November 2004

In 1989 and 1990, infection with subterranean clover mottle sobemovirus (SCMV) was widespread in subterranean clover ( Trifolium subterraneum L.) pastures in the south-west of Western Australia. The virus was detected in 61% of the pastures sampled and incidences of infection ranged from 1 to 50%. The virus was more common in old pastures than in pastures resown with newer cultivars during the preceeding 5 year period. When 12 isolates of SCMV were inoculated to subterranean clover plants grown in the glasshouse, symptoms varied from mild to severe. SCMV isolates P23 and F4 decreased the herbage dry weight of cw. Daliak and Woogenellup grown in plots as spaced plants by 81-88% while the Type isolate caused losses of 92%. By contrast, losses were 37-49% with cv. Karridale, a cultivar in which systemic infection was either delayed or prevented during winter. Infection decreased seed yield by c. 90% in cvv. Karridale and Woogenellup with all three isolates; seed weight was decreased 21-55%. A small proportion of cv. Woogenellup transplants outgrew the infection in new shoots during late spring to produce abundant healthy foliage. SCMV seed transmission rates in seed collected from infected transplants of cv. Woogenellup were 0.06, 0.07 and 0.43% for the Type, P23 and F4 isolates respectively. It was concluded that SCMV was present in most pastures, but at low incidences, and that it persists in them from year to year. Extended growing seasons and hard grazing are likely to increase its incidence.