bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing variability in manganese content of seeds, with emphasis on barley (Hordeum vulgare) and white lupins (Lupinus albus)
Authors: Longnecker NE , Uren C
Published: November 2004

Considerable variability can occur in the manganese (Mn) content and concentration of seeds. This variability can influence plant growth and development, crop yield and seed quality. In order to understand which factors affect seed Mn variability, the effects of site of growth, season and genotype on the Mn content of barley seed were examined. Plant-to-plant and within-plant variability of white lupin seed were also examined. Manganese concentrations of seeds of barley, wheat and faba bean grown at the same site were compared. For barley, site of growth was the most important determinant of Mn content of the seed. Cultivar differences were not statistically significant. There was a significant season by site interaction which indicated that season affected seed Mn content at a site with low Mn availability but not at a site with adequate Mn. Manganese concentrations in seeds of different species grown at the same site varied considerably. 'Tatiara' wheat had more than twice the Mn concentration of 'Schooner' barley (48 and 21 mg kg-1, respectively), while small-seeded faba bean had the lowest Mn concentration of the three (6 mg kg-1). In white lupin, there were significant differences in seed Mn content of plants growing side by side at the same site. Significant within-plant variation was also found for both white lupins and barley. The range of Mn concentration of seed from one plant was 1530 to 3750 mg kg-1for white lupins and 1 1 to 24 mg kg-1 for barley. In barley (and probably most plants), variability of seed Mn concentration can be minimized by selecting seed by weight from parents grown at the same site during the same season. Variability of Mn concentration and content of white lupin seeds is not as easily accounted for and thus is more difficult to minimize. For barley, there was a positive relationship between seed weight and Mn concentration (r2= 0.66), while in white lupins, no such relationship was apparent. For white lupins with high concentrations of Mn, seed Mn variability could not be accounted for by genotype or seed weight.
Expression of quantitative resistance to Colletotrichum gloeosporioides in Stylosanthes scabra at different inoculum concentrations and day-night temperatures
Authors: Chakraborty S
Published: November 2004

Expression of quantitative resistance to anthracnose was studied following inoculation of accessions of the tropical pasture legume Stylosanthes scabra with five different concentrations of Colletotrichum gloeosporioides conidia and at five day-night temperatures in separate experiments. According to Kendall's coefficient of concordance for rankings of accessions at the various inoculum concentrations, resistance in all six accessions was expressed consistently at 102,103, 104, 105 and 106 conidia/ml for race 3 but not for race 4a. Anthracnose severity did not increase with an increase in the inoculum concentration from l05 to 106 conidia/ml for either of the two races. Height and number of leaves/plant in the uninoculated control increased significantly at 30-25�C when glasshouse-grown seedlings were transferred to four controlled environment cabinets maintained at one of the four day-night temperatures of 30-25,32-22,30-15 or 34-14�C. Accessions were subjected to one of the four day-night temperatures for a 3 week pre- and 2 week post-inoculation exposures was not significant, predisposition of some accessions to anthracnose resulted in a significant accession X exposure interaction.
Distribution of magnesium in subterranean clover (Trifolium subterraneum L.) in relation to supply
Authors: Scott BJ , Robson AD
Published: November 2004

The objectives of this study were to examine Mg distribution in subterranean clover (Trifolium subterraneum L.), to identify an appropriate tissue for diagnosis of deficiency and to establish minimum tissue concentrations associated with maximum plant growth. Plants were grown in solution culture with both discontinued (40 8M and 160 8M reduced to nil) and constant supply (0, 5, 10, 20, 40, 80, 160 8M Mg). Magnesium was depleted from old leaves when Mg supply to the roots was interrupted. However, deficiency symptoms occurred first on the young tissue under these conditions. Under constant but inadequate supply, initial deficiency symptoms occurred in old tissue. Symptoms in leaves were associated with Mg concentrations in the leaf of < 1046 8g g-1 with constant root supply and 586 8g g-1 when supply was interrupted. At luxury constant supply, concentrations of Mg tended to be higher in the older leaves than in the young leaves; the reverse occurred with inadequate supply. Tissue choice for diagnosis was not critical, but the minimum Mg concentration in tissue commensurate with maximum shoot growth varied from 740 8g g-1 for the unifoliate leaf to 1310 8g g-1 in the youngest open leaf (YOL), when plants were grown under constant Mg supply. Current supply of Mg to roots was reflected more rapidly in the concentrations in young leaf than in old leaf tissue.
The incidence and spatial patterns of wheat plants infected by Fusarium graminearum group 1 and the effect of crown rot on yield
Authors: Klein TA , Burgess LW , Ellison FW
Published: November 2004

The incidence and spatial patterns of wheat plants infected by Fusarium graminearum Group 1 were assessed in six fields in northern New South Wales, Australia, over a four-year period. The incidence of infected plants declined from 1978 to 1981 in fields where wheat was sown each year, where there was a bare fallow of 18 months and where sunflowers were sown in one season. The pattern of infected plants tended to be regular (uniform) where the incidence of infected plants was particularly high (> 96%). In all fields where a clustered (aggregated) pattern was detected, 12% to 64.4% of plants were infected. A random pattern was observed at a number of sites. There was a positive association between loss in potential yield and the incidence of infection, basal browning of plants and whiteheads. Losses of up to 89% were recorded.
Maternal-foetal adaptation to mid pregnancy feed restriction in single-bearing ewes
Authors: Oddy VH , Holst PJ
Published: November 2004

In two experiments, restriction of feed to levels below maintenance for periods of up to 4 weeks was imposed on groups of ewes bearing single foetuses at 79, 87 or 95 days post coitus. In the first experiment, carried out at pasture, measurements were made of concentration of ovine placental lactogen (oPL) and progesterone in ewe plasma. Effects on lamb birth weight and gestation length were also examined. The second experiment investigated the effect of maternal feed restriction of (i) feed intake, (ii) maternal oPL, (iii) maternal plasma glucose concentration, (iv) lamb birth weight and (v) gestation length. In the first experiment, there were no significant effects of feed restriction on lamb birth weight or gestation length, although foetal growth rate had been reduced in some treatment groups. There were significant interactions between time of sampling and treatment for oPL and progesterone concentration. Control group ewes had lower oPL (P< 0.001) and progesterone (P < 0.05) concentrations than restricted ewes at the end of feed restriction, but higher oPL (P < 0.001) and progesterone (P <0.05) concentrations at 144 days post coitus. In the second experiment, lamb birth weight and gestation length were not significantly affected by maternal feed restriction (birth weight: restricted 4.94 kg, control 4.87 kg av. s.e.m. 0.17 kg; gestation length: restricted 148.3 days, control 147.0 days, av. s.e.m. 0.76 days). Feed restriction was associated with increased (P < 0.05) oPL and decreased glucose (P < 0.05) concentration in plasma. Maternal feed intake was significantly higher (P <0.05) in the restricted group in the week preceding lambing. These results strongly suggest that continuation of maternal feed intake over the last week of pregnancy is the major contributor to maintenance of 'normal' lamb birth weight in previously feed restricted ewes.
Tillage-induced differences in the growth and distribution of wheat-roots
Authors: Chan KY , Mead JA
Published: November 2004

Root growth and distribution of wheat under different tillage practices was studied in a 4-year-old tillage experimental site at Cowra, N.S.W. Tillage affected root density as well as distribution. Up to 98 days after sowing, root length density was lower (P < 0.05) in the 0.05-0.10 m layer of the direct-drilled soil than the conventionally cultivated soil. Poor root growth found in direct-drilled soils, which was significantly related to the poor shoot growth, was not caused by soil physical conditions, viz. higher bulk density and soil strength. Rather, biological factors were involved because fumigation completely eliminated the poor shoot growth and significantly increased root length density of the direct drilled soils. Compared to a compaction treatment, roots grown under direct drilling, in addition to having lower density, also had impaired function. Under conventional cultivation, significantly lower root length density was found in the surface soil layer (0-0.05 m) and maximum root length density was found in the 0-05-0.10 m layer. Fumigation did not change the root distribution pattern. This tillage-induced difference in root distribution reflected less favourable surface soil conditions as a result of cultivation, e.g. seedbed slumping, compared to the soil under direct drilling.
Irrigated plot trials in cotton: quantifying end effects and the influence of plot size upon intergenotypic competition
Authors: Luckett DJ , Williams ER , Reid PE , Thomson NJ
Published: November 2004

Individual rows of irrigated, multi-row plots in a cotton breeding trial were harvested, and seed cotton yields were measured. Intergenotypic competition had occurred between the neighbouring long sides of the oblong plots. A further trial was conducted to measure competition in three- and four-row plots and to establish which system gave the least biased genotype means for lint yield (kg/ ha). However, competition in this experiment was minimal and both systems gave comparable results. The effect of bare ground at the end of plots was investigated. When bare ground, as compared to a discarded border, was present during their growing season, then end plants, for seven out of eight genotypes, were larger and plot yields were inflated. These results provided no conclusive evidence that current practices for field trials with cotton should be changed.
Wheat stem rust in Australia dash 1969-1985
Authors: Zwer PK , Park RF , McIntosh RA
Published: November 2004

Pathogenic changes in Puccinia graminis f. sp. tritici (P. g. tritici) in Australia during the period 1969-1985 are reviewed. As found in a previous study covering the period 1954-1968, the frequencies of individual pathotypes were influenced by the combinations of resistance genes present in the most common wheat cultivars. From 1969 to 1978, pathotype composition and diversity varied between the four regions comprising the Australian wheat-growing area. However, from 1978 to 1985, pathotype 343-1,2,3,5,6 predominated in all regions. It is suggested that this pathotype was repeatedly derived from pathotype 326-1,2,3,5,6 at widely separated locations, and that these events facilitated its widespread increase. Another significant event was the specialization of P. g. tritici on triticale. Survey data suggest that pathotype 34-2,12, which rendered cultivar Coorong susceptible, developed from pathotype 34-2, possibly during 1979. A second pathotype which attacked cultivar Satu (designated 34-2,12,13) was detected in 1984. The deployment of different resistant genes in triticale and wheat has resulted in distinct populations within P. g. tritici adapted to each crop. Future Cultivar development for triticale should be aimed at maintaining this divergence.
Winter temperatures and reproductive development affect the productivity and growth components of white clover and phalaris growing in a mixed pasture
Authors: Kemp DR , Guobin L , Liu GB
Published: November 2004

The effects of low winter temperatures (means down to 5�C, daily air minimums to 3�C and 82 potential frost days), frost damage and reproductive development on productivity and growth components of white clover ( Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) growing together in a mixed pasture were studied during winter and spring. Initially there was a higher proportion of white clover in the pasture which was maintained throughout winter and early spring. Leaf appearance rates were similar for both species, but petiole extension rates of white clover were significantly less than leaf extension rates of phalaris. Growth rates were higher per tiller for phalaris than per stolon for white clover. Larger sward yields of white clover were only maintained because of the higher density of white clover growing points. The lower extension rates of white clover were due to a different temperature response curve to phalaris. Below 10�C there was little growth of white clover leaves whereas phalaris had some leaf growth down to below 5�C. There was evidence that leaf extension rates of both white clover and phalaris were stimulated by reproductive development. This had a larger effect on phalaris, but also resulted in greater susceptibility to frost damage, though the damage to phalaris was not enough to reduce leaf growth to the same level as white clover. Leaf damage from frost/low temperatures was generally marginal.
Calcium modifies pH effects on the growth of acid-tolerant and acid-sensitive Rhizobium meliloti
Authors: Howieson JG , Robson AD , Abbott LK
Published: November 2004

The growth of Rhizobium meliloti is sensitive to soil acidity, and its poor growth and survival limits the production from Medicago spp. on acid soils. In the selection of acid tolerant rhizobia for medics, growth in acidified laboratory media has been poorly related to persistence in acid soils. However, the Ca concentration in laboratory media may have been inadequate for growth of some rhizobial strains at low pH. Therefore, acid-tolerant and acid-sensitive strains of R. meliloti were grown in a buffered, defined medium at a range of Ca and P concentrations, and at several pH values. Growth rate was increased by increasing the Ca concentration from 200 to 2000 8M at low (5-70) and moderate (6.50) pH, but not at pH 7.30. Thus, the Ca requirement for the growth of R. meliloti under acid conditions is much higher than previously thought.
A multi element supplement for grazing sheep. I. Intake, mineral status and production responses
Authors: White CL , Masters DG , Peter DW , Purser DB , Roe SP , Barnes MJ
Published: November 2004

The safety and effectiveness of a loose mineral lick containing all known essential elements was investigated in an experiment in which 96 Merino weaner wethers grazed subterranean clover/grass pastures during summer and autumn. The treatments were no supplement or mineral mix ad libitum; there were four plots of 12 sheep per treatment. The mean intake was 29 � 1 g/head per day of the mix and those offered the minerals had blood concentrations of P, S, Se and vitamin BIZ in the normal range. Unsupplemented Control sheep had blood concentrations of P, S and Se in the deficient range for all or part of the experimental period. There was an estimated 1.6-fold range in mineral intake between sheep, and none refused the mix. Concentrations of Cu, Cd and F in tissues and bone of sheep offered the mineral mix were within accepted safety margins. The mineral lick increased live weights by 4.5 kg during summer (P < 0 - 05), increased clean fleece weight by 240 g (9%), (P < 0.01), and increased wool staple strength by 15 N/kt (40%), (P < 0.01). The pasture concentrations of most macro elements decreased between November and March, respective concentrations being (g/kg DM): K, 17- 7 and 1.9; Na, 4-0 and 0.31; S, 1.6 and 0.9; N, 12.9 and 10; P, 1-95 and 1-08; Ca, 7-86 and 9-75; Mg, 2.29 and 1-38. Changes in trace element concentrations were small, the respective values being (mg/kg): Cu, 9.7 and 10-3; Mn, 47 and 67; Fe, 56 and 323; Zn, 20 and 20; Mo, 0-2 and 0.35; and Se, 0.015 and 0.032. The loose mineral lick was a safe and effective means of supplying macro and trace elements to grazing sheep during summer.
Skin follicle development in the Australian cashmere goat
Authors: Parry AL , Norton BW , Restall BJ
Published: November 2004

Follicle densities, S/P ratios and follicle number indices (FNI) of fibre-bearing primary (Pf) and secondary (Sf) follicles, and body weights, were taken sequentially on 224 kids at birth and at mean ages of 57, 107 and 301 days. All primary follicles but few secondary follicles were mature (fibre-bearing) at birth and Sf number increased 10 fold in the first 57 days after birth. A decline in Pf number was recorded between 57 and 107 days of age. SFNI's, but not Sf density increased to weaning (107 days of age) then declined thereafter to 301 days of age. Single kids had higher (P < 0.01) SFNI than twin kids at all ages except birth, though Sf/Pf ratios of singles were significantly higher (P < 0.05) than those of twins at 57 days of age only. At 107 and,301 days of age, males had higher PFNI than females (24.8 v. 22.0 and 24-7 v. 22.0) and higher SFNI than females (179.0 v. 150.4 and 151.6 v. 131-1). Sex differences were not observed in Sf/Pf ratio. A description of follicle arrangement and accessory structures is given.
Heterosis in F1 hybrids derived from crosses of adapted Australian wheats
Authors: Uddin MN , Ellison FW , O'Brien L , Latter BDH
Published: November 2004

Data on the level of heterosis for grain yield under Australian dryland wheat growing conditions is essential before any decision can be made to commit resources to hybrid wheat breeding. Experiments were conducted at Narrabri, N.S.W., to determine the level and stability of heterosis for grain yield expressed by F1 hybrids derived from crosses of adapted Australian varieties. The hybrids and their parents were grown in hill plots in replicated experiments at three sowing times for two years (six environments). The hybrids outyielded their parents in each of the six environments with levels of mid- and high-parent heterosis up to 31.5 and 26.8%, respectively. The best hybrid outperformed the best check variety by an average yield margin of 18.2%. The hybrids were marginally but not significantly more stable in their yield performance across environments than their parents. While heterosis for grain protein content was generally negative, some hybrids were superior to the check varieties for both grain yield and protein content. Yield component analysis revealed no consistent pattern by which the best hybrids obtained their yield advantage over their parents. The levels of heterosis and the absolute yield advantage displayed by the hybrids over the best pure line check varieties were sufficient to sustain the commercial production of hybrid wheats in northern N.S.W.
The effect of variation in soil water availability, vapour pressure deficit and nitrogen nutrition on carbon isotope discrimination in wheat
Authors: Condon AG , Richards RA , Farquhar GD
Published: November 2004

Carbon isotope discrimination (-) is an integrative measure of leaf transpiration efficiency and has been proposed as a select criterion for greater water-use efficiency in breeding programs for water-limited environments. Here we assess the effects of variation in soil water status, vapour pressure deficit and nitrogen nutrition on the value of - measured in plant dry matter and the relative magnitudes of environmental and genotypic variation in - among conventional wheat cultivars. Experiments were done using container- and field-grown plants. Two genotypes, cv. Cleopatra and Yaqui 50E, were grown in large (23 L) containers to simulate field conditions. Plants were subjected to contrasting watering regimes, to different levels of atmospheric demand (by growing the plants outdoors and varying sowing time) and to two levels of nitrogen nutrition (equivalent to 150 and 30 kg N ha-1). A field experiment using eight genotypes was conducted at Moombooldool in south-west New South Wales, which has an annual rainfall total and distribution typical of much of the south-east wheat belt. Changes in - over the course of the season were followed by sampling recently expanded plant parts. In field-grown plants A measured in dry matter fell by 5x10-3 between early-formed leaves and the grain. A similar change (7x10-3) was observed in container-grown plants. For both field- and container-grown plants, environmental effects on - were attributed to stomatal closure in response to declining soil water and/or increasing vapour-pressure deficit. Low nitrogen nutrition of container-grown plants, which reduced above-ground dry matter at maturity and leaf area at flag leaf emergence by 30%, had a small but variable effect on thevalue of -. In the field experiment, variation among genotypes in - of different plant parts was always significant, and was typically c. l.8 x l 0-3 . Genotype ranking for - changed with different plant parts, but the magnitude of genotype x environment interaction was small in relation to genetic variation in -. Changes in ranking mainly occurred in the latter half of the season. These were attributed primarily to differences in the rate and extent of soil drying among genotypes. Variation in the extent of soil water depletion measured at anthesis was positively correlated with - of plant parts laid down early in the season.
Sodium chloride and soil texture interactions in irrigated field grown sultana grapevines. III. Soil and root system effects
Authors: Prior LD , Grieve AM , Slavich PG , Cullis BR
Published: November 2004

Five salinity treatments, ranging between 0.37 and 3.47 dS m-1, were applied through a trickle irrigation system to own-rooted sultana grapevines for six years. The changes in soil salinity levels and the relationship between soil salinity and yield were studied, and a simplified salt balance model was developed to calculate leaching fractions. Soil salinity was strongly influenced by soil texture as well as by salt treatment, because leaching fractions were lower in heavier soils; they averaged 23% in the lightest soils and 10% in the heaviest. Leaching fractions also increased with salt treatment, from 7% in the 0.37 dS m-1 treatment to 24% in the 3.47 dS m-1 treatment. This was probably because water use by salinized vines was lower. Yield was correlated with mean soil salinity, ECe, but the relationship was not as good as with plant salinity levels. The fitted model accounted for between 52 and 62% of the variance. It was concluded that soil salinity levels at the end of winter should be maintained below 1.0 dS m-1 in order to keep yield losses below 10%. For own-rooted sultana grapevines in Sunraysia, this requires a leaching fraction of about 8%. Rootzone depth and root density were lower in the heavier soils, and were decreased by salt treatment. The deleterious effects of salt treatment on clay dispersion and soil hydraulic conductivity were also greater in the heavier soils. Soil properties must therefore be considered when predicting the effects of saline water on crop productivity, especially in the long term.
The effect of long-term applications of phosphorus fertilizer on populations of vesicular-arbuscular mycorrhizal fungi in pastures
Authors: Thomson BD , Robson AD , Abbott LK
Published: November 2004

We assessed whether 6-year-old applications of phosphorus (P) fertilizer to a previously unfertilized field site resulted in the selection of populations of vesicular-arbuscular (VA) mycorrhizal fungi that were more 'tolerant' of added P than the original VA mycorrhizal population at the site. In 1977, four rates of P (0, 49, 97 and 200 kg P/ha) were applied to a field site at Mt Barker, Western Australia. In 1983, either no P or a rate of P sufficient for maximum plant growth (352 kg P/ha) was applied to each of these plots and the formation of spores and colonization of roots by VA mycorrhizal fungi were examined in the following 3 years. Residual P from fertilizers applied in 1977 increased both the percentage of root length colonized and the length of root colonized by VA mycorrhizal fungi in 1983, 1984 and 1985. Colonization by 'medium hyphae' Glomus spp., Acaulospora laevis Gerd. and Trappe and fine endophyte increased in response to the 1977 applications of P. By contrast, colonization by Scutellospora calospora (Nicol. and Gerd.) Walker and Sanders decreased with the 1977 applications of P. Application of an adequate rate of P to the field plots in 1983 generally decreased the development of VA mycorrhizal infection in plots, to a greater extent where larger rates of P had previously been applied in 1977. We attributed this effect to higher initial levels of mycorrhizal colonization in the plots which received larger rates of P in 1977. The 1977 applications of P are unlikely to have resulted in the selection of strains of VA mycorrhizal fungi that are less tolerant of added P than the strains present in the unfertilized plots. There was a common relationship between VA mycorrhizal colonization and the residual value of the P applications which provided indirect evidence that there was no change in the P-tolerance of the indigenous VA mycorrhizal population in response to P applied in 1977. Interpretation of the effects of the 1977 and 1983 applications of P on VA mycorrhizal colonization was compounded by the effects these applications of P had on the botanical composition of the pasture and also on the inoculum potential in each plot. Spores of A. laevis and S. calospora were recovered from each field plot. The number of spores of A. laevis increased in response to P applied in 1977 and generally decreased in response to P applied in 1983. These effects could be directly related to the effects the 1977 and 1983 applications of P had on the length of root colonized by A. laevis in the preceding growing season.
Sulfonylurea herbicides applied to acidic sandy soils: movement, persistence and activity within the growing season
Authors: Blacklow WM , Pheloung PC
Published: November 2004

Chlorsulfuron and triasulfuron were applied to the surface of acidic, sandy loam at a low rainfall site in 1989 (129 mm June-October) and a high rainfall site in 1990 (217 mm July-August). Four environments were obtained by early and late application times and lime addition in 1989 and by a wetter site in 1990. The pH of the surface 10 cm was 4.9 in 1989, 5.8 in 1990 and 6.5 after the addition of limestone in 1989. The plots were left fallow or sown, prior to herbicide applications, to wheat (cv. Kulin). Hourly averages of rainfall, soil and air temperature were recorded. The temperature range was 2.7�C to 23.2�C. The soil profiles were sampled on 5 to 7 occasions and herbicide residues were determined by a laboratory bioassay (sensitivity >0.4 8g kg-1 soil). Chlorsulfuron and triasulfuron were detected to 300 mm in the wetter environment but neither herbicide was as mobile in the profile as water. More herbicide moved to the lower layers of the profile in the higher pH environment. The half-lives for residues ranged from 12 to 28 days. Shoot biomass of wheat seedlings was suppressed by both herbicides but grain yields were unaffected. The residues failed to prevent reinvasion of the wheat plots by weeds, notably Arctotheca calendula.
Tolerance to iron deficiency of lupins grown on calcareous soils
Authors: Plessner O , Dovrat A , Chen Y
Published: November 2004

Lupins differ in their efficiency to utilize Fe3+ in soils containing CaCO3. Most lupin species are susceptible to Fe deficiency. The objective of this study was to screen different lupin species, including introduced cultivars and wild types collected in Israel, for susceptibility to Fe deficiency. In a greenhouse experiment, inoculated seedlings, 7 to 10 days old, were planted in 1 L pots filled with a mountain rendzina soil from Emek Haela (pH=7.3, CaCO3- 45%), or with a brown-red sandy-loam soil from Rehovot (pH=7.7) not containing CaCO3. On the calcareous soil, susceptible lupin plants from day 7 onward showed various degrees of chlorosis, suggesting Fe deficiency, which at a later stage caused reduction of growth, necrosis of the leaf tissue, leaf abscission and ultimately death of the plants. Soil application of FeEDDHA resulted in an immediate remedy of the deficiency symptoms. No deficiency symptoms were observed on plants growing on the sandy-loam soil lacking CaCO3. Ranking of lupins based on visual symptoms of Fe deficiency and on chlorophyll concentration of young leaves relative to their tolerance to soil lime was as follows (location of source plants in brackets). Very good: Lupinus pilosw (Emek Haela), L. cosentinii cv. Erregulla and L. angustifolfus cv. Yorrel. Moderate L. angustifolius cv. Illyarrie. Low L. palaestinus (Gesher Haziv), L. albus cv. L221, L. angustifolius (Gesher Haziv). Very low: L. angustifolius (Givat Brenner), L. palaestinus (Rehovot). The need for further exploration of wild lime-resistant genotypes is emphasized.
The productivity of dairy cows fed irrigated subterranean clover herbage
Authors: Stockdale CR
Published: November 2004

A number of experiments were undertaken to establish the productivity of lactating dairy cows when offered green, immature subterranean clover (Trifolium subterraneum) herbage and to study its utilization by these cows. The research included indoor feeding and grazing experiments and intensive metabolism studies. Levels of daily intake varied from 8 to 22 kg DM/cow and in early lactation, milk yields as high as 28 kg/day were sustained. Marginal returns to extra feeding, up to 15 kg DM/day in early lactation, averaged 1.4 kg milk for each additional kg of DM eaten above 8 kg DM/day. In late lactation, the return to additional feeding was 1.0 kg milk/kg of extra DM consumed over a similar range. Beyond 15 kg DM/day, the return increasingly diminished. Consideration of products of digestion suggested that fermentation of subterranean clover herbage in the rumen resulted in a balance of metabolites that is unlikely to be detrimental to animal production. Although the milk production data for the cows in the early lactation experiments fitted well together, one grazing experiment (in winter) did produce an unusual result. In this experiment, the cows offered most pasture did not perform as well as those offered an intermediate amount. It was considered that this was due to a characteristic of subterranean clover whereby the leaves are considerably less digestible than the rest of the plant; this resulted in selection of a lower quality diet by the supposedly best fed cows. The implications of this are discussed. It was concluded that, while few problems exist with the use of vegetative subterranean clover for lactating dairy cows, lenient grazing is not the most productive strategy when leaves constitute a large proportion of the sward.
Genotype × environment interactions in sugarcane. II. Use of performance in plant cane as an indirect selection criterion for performance in ratoon crops
Authors: Jackson PA
Published: November 2004

This study aimed to determine whether sugar yield of sugarcane genotypes in the plant crop could be used to predict relative yield in subsequent ratoon crops. Results from two series of trials, planted in 1985 and 1986, were examined. Within each series genotypes were planted at four locations and evaluated in plant, first ratoon and second ratoon crops. The genotypes used had not been selected previously in the test environments. Genetic correlations between sugar yield in plant and ratoon crop-years were moderate to high (greater than 0.65) for most locations. The relative efficiency of selection for yield in ratoon crop-years via indirect selection in the plant crop-year averaged 0.67. Realized gains from selection were compared for selection based on only plant crop results and selection based on average performance across all crop-years (the latter being the method routinely used in sugarcane breeding programs at present). In most cases the increases in realized gains in yield across independent environments brought about by considering results from more than the plant crop-year were small or non-existent. In the two series of trials, 11 and 12 of the top ranking 15 genotypes, respectively, based on mean performance across all crop-years, were also in the top 15 genotypes based on only the plant crop results. It is suggested that the testing of genotypes in only the plant crop may be appropriate in the early stages of selection in sugarcane breeding programs. Resources otherwise allocated to testing early stage material in ratoon crops may be more usefully employed elsewhere such as testing in more sites, with more replicates or more genotypes. It is emphasized, however, that this strategy may not be appropriate for highly selected populations, such as those in the final stages of selection, where genetic variance and genetic correlations between crop-years would be expected to be smaller than those obtained in this study.
The effect of plot type on the estimation of heterosis in bread wheat (T. aestivum)
Authors: Uddin MN , Ellison FW , O'Brien L , Latter BDH
Published: November 2004

The demonstration of an economically sustainable level of heterosis for grain yield is a key factor which determines the commercial viability of hybrid wheat production. Identification of sufficient hybrid advantage involves testing hundreds, possibly thousands of hybrid combinations each year. The design of an effective hybrid evaluation program depends on the characterization of genotypexplant density interaction effects. These were examined at Narrabri, N.S.W., using six hybrids and their parents and two commercial hybrids planted in four replicate, randomized complete block design experiments using three different plot types, viz. hill plots, space planted plots and multi-row plots. The level of heterosis for grain yield varied depending upon the plot type, with least heterosis being observed in multi-row plots. While the genotypexplot type interaction was significant for grain yield, it was non-significant for yield heterosis. The relative rankings of hybrids did not alter across plot type. Highly significant phenotypic and genotypic correlations between plot types for yield indicated that each plot type provided comparable information on relative genotype performance. The lesser seed requirement and ease of planting points to hill plots being the preferred plot type for preliminary evaluation of hybrid performance. The modulation of heterosis level by plot type suggests that while hill plots will provide an efficient first evaluation, performance would need to be substantiated in multi-row plots.
A simulation model of kenaf for assisting fibre industry planning in northern Australia. II. Leaf area development
Authors: Carberry PS , Muchow RC
Published: November 2004

Leaf area development is an important determinant of the proportion of the incident radiation intercepted and consequently of stem yield for paper pulp production in kenaf (Hibiscus cannabinus L.). Relationships were developed describing the component processes of node production, leaf area per node and leaf area senescence, to predict green leaf area of non-branching plants of kenaf during the period from sowing to flowering. Data were collected on cultivar Guatemala 4 grown under irrigation at a range of plant population densities at three sites in tropical Australia. The thermal time required for production of new nodes remained constant from sowing to flowering at 36.3�C days node-' at a population of 50 plants m-2. Leaf area per node was described quantitatively in terms of three phases where, as node number increased, leaf area per node at first increased linearly, reached a plateau and finally declined linearly. The rate at which the leaf area at old nodes was senesced was found to be equivalent to the rate of production of new nodes, such that the number of nodes bearing green leaves was relatively constant; at a population of 50 plants m-2 there was green leaf area at 7 nodes plant-1 over time. Empirical functions describing the effects of plant population on rates of node production and senescence and on maximum leaf area per node were developed. In limited testing, these functions predicted leaf area development of crops of kenaf grown under optimal conditions. The functions developed here, when combined with others in this series of papers, provide algorithms to be used in the development of a crop simulation model of kenaf for use in the semi-arid tropics of northern Australia.
Establishment of three species of lucerne aphids on 24 cultivars of lucerne
Authors: Holtkamp RH , Clift AD
Published: November 2004

A field trial involving 24 cultivars of lucerne was naturally infested by three species of aphids, Therioaphis trifolii (Monell) f. maculata, spotted alfalfa aphid, Acyrthosiphon kondoi Shinji, bluegreen aphid and A. pisurn (Harris), pea aphid. Aphid establishment was found to be related to the lucerne aphid resistance ratings of these cultivars. These observations suggest that both antixenosis and antibiosis resistance mechanisms are operating.
The domestication of the native grasses Danthonia richardsonii Cashmore and Danthonia linkii Kunth for agricultural use. II. Agronomic and morphologic variation
Authors: Lodge GM , Schipp AJ
Published: November 2004

Seven accessions of Danthonia richardsonii Cashmore and three plants of Danthonia linkii Kunth, selected for high inflorescence seed yield were further assessed in a comparative field experiment at Tamworth, N.S.W. The agronomic and morphological variation of these lines, three unselected native ecotypes and D. richardsonii cv. Hume also were examined as part of the process of identifying lines that met the criteria for registration in the schemes operated by the Registrar of Plant Variety Rights and the Registrar of Australian Herbage Plant Cultivars. Thirty plants of each line were planted in spaced nursery rows (1x1 m) on a black earth soil in July 1990 and agronomic and morphological characters were assessed in 1990-92. From these data the D. richardsonii accession T487 and D. linkii T28 were chosen to be registered as D. richardsonii cv. Taranna and D. linkii cv. Bunderra. cv. Taranna had higher (P < 0.05) seed production than all other D. richardsonii accessions, except T489. It was distinguishable from the latter accession by its significantly wider inflorescence. Compared with cv. Hume, the only other known cultivar of D. richardsonii, cv. Taranna had higher dry matter production in spring (P < 0.05), higher seed production, flowered earlier and had a shorter and wider inflorescence (P < 0.05) with a wider glume. It also differed from cv. Hume in having longer and wider (P < 0.05) flag and third tiller-leaves. There are no known cultivars of D. linkii. Compared with the accessions it was tested against, cv. Bunderra had significantly higher seed yields and dry matter production. It was also distinct from those accessions in having a higher number of reproductive tillers, a larger basal area and longer and wider flag and third tiller-leaves (P < 0.05).
The use of nitrogen, phosphorus and lime to limit the competitive ability of Aristida armata in the establishment phase
Authors: Armstrong RD , Brown RF , Helyar KR
Published: November 2004

The de Wit replacement series methodology was used to see if applying phosphorus, nitrogen and lime to the sandy red earth soils of mulga grazing lands can give a competitive advantage to the desirable species Cenchrus ciliaris C.V. U.S.A., Digitaria ammophila, and Thyridolepis mitchelliana over the less desirable Aristida armata. In monoculture, all species responded strongly to added nutrients, especially phosphorus. In mixtures, the preferred grasses responded even more strongly to nutrients, whereas A. armata responsed proportionally less. C. ciliaris, D. ammophila, and T. mitchelliana suppressed the growth of A. amnata in all but three situations: without added nutrients, A. armata was equally competitive with C. ciliaris; when P was added without lime, A. armata suppressed C. ciliaris; if P was added without N, A. armata suppressed T. mitchelliana. Adding either or both nitrogen or phosphorus usually increased the relative crowding coefficients, indicating that the degree of suppression of Aristida was increased by adding nutrients. Thus, C. ciliaris, D. ammophila, and T. mitchelliana appear to be equally competitive with or more competitive than A. armata if the soil is not fertilized and adding nutrients generally enhances this competitiveness. In all cases, except for A. armata/C ciliaris mixtures in soils low in phosphorus, the plants appeared to be competing for the same resource. The study demonstrated that A. armata is not a highly competitive species per se under controlled conditions and was generally suppressed by the preferred grasses, especially when nutrients were added.
Genetic parameters for tropical beef cattle in northern Australia: a review
Authors: Davis GP
Published: November 2004

This paper reviews published estimates of genetic parameters for traits of growth, reproduction and resistance to environmental stresses for Bos indicus and Zebu derived breeds in northern Australia. Most published estimates of heritabilities for growth and reproduction traits were higher for tropically adapted breeds in northern Australia than for Bos taurus breeds in temperate Australia. Weighted mean estimates of heritabilities for the direct component of weaning weight were 39% for the Brahman breed and 30% for Zebu-derived breeds in northern Australia compared with 13% for Bos taurus breeds in temperate areas of Australia. Mean estimates for the maternal component of weaning weight were 5, 24 and 13% respectively. Mean heritabilities for yearling and 550 day weights for Zebu derived breeds in northern Australia (24 and 25%) were similar to those for Bos taurus breeds in temperate areas, though estimates for Brahmans were higher (39 and 39%). Published estimates of heritabilities of later weights (700 and 900 days), which are most relevant to northern Australian production systems, were rare but averaged between 32 and 45% for Zebu-derived breeds and Brahmans. Weighted mean heritability for female calving success was 14% and for realised bull fertility was 5%. Published estimates of heritabilities of scrota1 circumference averaged 31%, and testosterone response to GNRH stimulation was 52%. Heritabilities of resistance to various environmental stresses were all moderate with weighted means between 20 and 34%. Genetic correlations between growth, reproduction and resistance to environmental stresses are also reviewed. There appears to be predictable variation in estimates of parameters between breeds in different environments which is related to level of resistance to environmental stresses, and this is likely to affect the prediction of breeding values for cattle in northern Australia.
Measurement of blood flow and metabolite uptake by the skin of fleeceweight-selected and control Romney rams
Authors: Harris PM , Lee J , Gurnsey MP , Dellow DW , Sinclair BR
Published: November 2004

Ten, 2 to 3 year old Romney rams (50-60 kg), five from the Massey University Fleeceweight Selection line (FW) and five from the Control line (C) had catheters implanted into the arterial supply and venous drainage of a patch of abdominal flank skin. A further catheter was implanted into the saphenous artery. Infusions of radio-labelled cysteine or glucose were given into the skin artery together with infusions of paraamino hippuric acid for measurement of blood flow by dye dilution. Five sheep (2FW and 3C) also had infusions of radio-labelled glutathione. During arterio/venous difference procedures, measurements were made of oxygen, cysteine, glucose and glutathione uptake, together with lactate production, by the skin. Wool production from the catheterised patch of skin was also measured. There were no significant differences found between the FW and C sheep in any parameter measured except glutathione concentration (FW = 911�39 8M; C = 789�28 8M) and, because of the low numbers of animals, only a trend for wool production (P = 0.06) to be greater in the FW sheep. When results from the two flocks were combined, cysteine flux per weight of skin (P = 0.04), the percentage uptake of 35SS-cysteine (P = 0.004) and the rate of cysteine utilization for protein synthesis per weight (P = 0.013) or area P 0.009) of skin were significantly related to wool production. The percentage uptake of 35S-glutathione was also significantly related to wool production (P = 0.013). However, blood flow, cysteine concentration in the blood and cysteine flux per area of skin were not significantly related to wool production. The results suggest that although nutrient supply, especially of cysteine to the skin is obviously important in wool production, it is not only the flux of nutrient itself which is critical but the rate of uptake (transport) of that nutrient by the cells of the skin which is enhanced in high wool producing sheep.
The impacts of shade on evaporation rates and temperatures in stock watering troughs
Authors: Webster IT , Day CRB
Published: November 2004

We have demonstrated experimentally that the use of a shade over a stock watering trough will significantly lower water temperatures and evaporation rates. During the 14day period of our trials undertaken during summer, peak temperatures in a shaded trough were on average 6.4�C lower than the average peak in an unshaded trough. Average evaporation rates in a shaded trough were 7.1 mm/day from a shaded trough compared with 11.1 mm/day from an identical unshaded trough. A mathematical model was used to obtain predictions of trough thermal behaviour in other conditions of humidity, air temperature, wind, and solar radiation than those occurring during the trials. These results show that the measured effects of shading on reducing trough evaporation rates and water temperatures can be expected to be appreciable over a wide range of other environmental conditions as well.
The colonization of a tropical grassland by Stylosanthes from seed transported in cattle faeces
Authors: Gardener CJ
Published: November 2004

The dynamics of the spread of four Stylosanthes species by grazing cattle from sown areas to nearby native grassland R& studied over ten years in the dry tropics of north Queensland. The first recruitment of Stylosanthes in the grassland occurred during the third growing season. Secondary colonization took place around the primary plants, and by the tenth year, 94% of the 0.25 m2 quadrats sampled in the grassland contained one or more species of Stylosanthes. Large seed numbers were produced by Stylosanthes on the sown areas during primary colonization. Mean yields of above-ground biomass were high (4000 kg ha-1year-1) despite heavy grazing pressures, and 6% of this biomass was channelled into seed production (25 000 seeds kg biomass-1). Seed content in the cattle faeces reached a peak at the end of the wet season and accounted for 8% of seed production. The numbers of seeds in the faeces were highly correlated with the numbers of seeds produced on the sown areas. Only 1.5% of the seed excreted in the grassland grew into established plants despite most seeds being viable. Varying the amount of grass had little effect on establishment. The two short-lived herbaceous species, S. guianensis and S. hamata, were more efficient colonizers (i.e. produced more seedlings per unit biomass) than the more perennial shrubby types, S. scabra and S. viscosa. The former two species produced more seeds per unit biomass and more plants per unit of seed in the faeces.