bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of four grain legumes to water stress in south-eastern Queensland. II.Plant growth and soil water extraction patterns
Authors: Lawn RJ
Published: November 2004

Growth and water use of soybean (Glycine max), black gram (Vigna mungo), green gram (V. radiata) and cowpea (V. unguiculata) in response to water stress were evaluated in the field at Dalby in southeast Queensland. Differing strategies of growth and water use which reflected the differential expression of dehydration avoidance and developmental plasticity in response to stress were identified among species. The primary difference between strategies related to differences in dehydration avoidance. Soil water extraction during the initial phases of drought was faster, and leaf area development and plant growth were relatively less affected, in soybean than in the Vigna spp. Where adequate soil water existed, these differences were sustained during the drought period but were reversed where soil water was limited. Soil water extraction by soybean occurred to greater depths, and to lower potentials, than in the Vigna spp. Developmental plasticity influenced growth pattern in the Vigna spp. to varying degrees. Drought periods invariably curtailed growth and hastened maturity in green gram and black gram, but rain prior to maturity induced renewed growth in black gram. Moderate stress curtailed growth and hastened maturity in cowpea, which also responded to late rains with renewed growth. Severe stress inhibited growth and delayed development in cowpea indefinitely.
Earliness of an indeterminate crop, Vigna unguiculata (L.) Walp., as affected by drought, temperature, and plant density
Authors: Grantz DA , Hall AE
Published: November 2004

Earliness of an indeterminate crop, Vigna unguiculata (L.) Walp., was studied to aid development of selection techniques for improving adaptation to semiarid environments. Earliness was based upon the time of first appearance of floral buds and flowers, proportion of shoot dry matter in reproductive parts at midseason, and time of maturity. A cowpea land race, Chino 3, was earlier than cultivars California Blackeye No. 3 and No. 5, with respect to all of these criteria. Time to flowering from different sowing dates was related to heat units, which were calculated from daily mean air temperature above a base temperature of c. 10�C. The proportions of shoot dry matter in reproductive parts during early stages of pod-filling were greater with moderate drought but were unaffected by severe drought, compared with the response of adequately irrigated plants. Widely spaced plants exhibited greater proportions of shoot dry matter in reproductive parts at midseason than did closely spaced plants. Adaptation of cowpeas to semiarid environments may be improved by selecting for early partitioning of carbohydrates to reproductive parts. Selection for early partitioning may be more effective in adequately watered conditions, owing to extreme variability under drought, and at wide and precise spacing.
Energy and nitrogen utilization for body growth in young sheep from two breeds with differing capacities for wool growth
Authors: Graham NM , Searle TW
Published: November 2004

Utilization of energy and nitrogen was assessed by serial slaughter and intake/loss balances, and wool growth was measured, as young sheep grew from c. 25 to 30 kg on either 700 or 1000 g/day of a high-protein diet. Comparisons were made between animals with low (Dorset Horn) and high (Corriedale) propensities to produce wool. Depending on feed intake, fleece-free liveweight gain was 102-215 g/day in the Dorsets and 88-172 g/day in the Corriedales; corresponding growth rates of clean dry wool were c. 5 and 10 g/day, there being little effect of feed intake. Digestibilities of protein and energy were 84 and 74% respectively in both breeds at the lower level of feeding; at the higher level the values were 80 and 71 % in the Dorsets and significantly lower, 77 and 69 %, in the Corriedales. Metabolizable energy was 83 � 0.3 % of digestible energy at the low intake and 86 � 0.5 % at the high intake in both breeds. It averaged 11.7 �. 0.07 MJ/kg feed dry matter, being 0.2 MJ/kg more at the low than at the high intake and, in the latter case only, 0.3 MJ/kg more in the Dorsets than in the Corriedales. At the low and high levels of feeding respectively, the fleece gained 0.18-0.16 MJ and 0.93-0.89 g nitrogen daily in the Dorsets compared with 0.31-0.34 MJ and 1.65-1.81 g nitrogen daily in the Corriedales. The corresponding average daily retentions in the body were 1.74-2.46 MJ and 1.80-3.49 g nitrogen in the Dorsets and 1.34-2.08 MJ and 1.25-3.07 g nitrogen in the Corriedales. Thus body growth accounted for 91-94% of the energy retention and 6640% of the nitrogen retention in the Dorsets, but only 81-86 % and 43-63 % respectively in the Corriedales. The composition of weight gain was the same in both breeds and 15-20% of the energy stored in the body was in protein. It is estimated that the marginal efficiency of use of metabolizable energy was 31-34% for body growth and 16-19% for wool growth. It is concluded that, given a high protein diet, animals with a strong propensity to grow wool diverted an appreciable amount of metabolizable energy from body growth to wool production, thereby restricting deposition of both fat and protein.
Intake, digestibility and rumen characteristics of sheep given grass fertilized with phosphorus
Authors: Rees MC , Minson DJ
Published: November 2004

Pangola grass (Digitauia decumbens) was grown on an infertile sand and fertilized with low and high levels of phosphorus (P) and adequate levels of other nutrients. Regrowths were cut at 8, 11, 13 and 14 weeks, dried and fed to sheep to measure their voluntary intake and digestibility with and without a P supplement. Retention time of feed in the reticulo-rumen was determined by a total emptying procedure using rumen-fistulated sheep. Fertilizer P increased mean P levels in the grass from 0.16 to 0.26%, but had no significant effect on other elements and carbohydrate fractions. P fertilizer had no significant effect on the intake and digestibility of the dry and organic matter of the unsupplemented grass. However, when the P-fertilized grass was supplemented with P, intake was depressed. This adverse effect on voluntary intake may be attributed to a narrowing of the Ca : P ratio, which was associated with an increase in the time grass was retained in the reticulorumen.
Intake of selenium and other nutrients in relation to selenium status and productivity of grazing sheep
Authors: Hunter RA , Peter DW , Quinn MP , Siebert BD
Published: November 2004

The selenium status of the sheep and seasonal fluctuations in the intake of dry matter, digestible dry matter and selenium over a 12-month period were measured in an experiment with 80 ewes and their offspring on annual pasture in the south-west of Western Australia. Forty of the ewes received an intraruminal selenium pellet 1 month prior to lambing in June. At weaning half of the lambs born to ewes in each treatment also received an intraruminal selenium pellet. There was a distinct seasonal pattern in the quality and quantity of pasture ingested. Dry matter digestibility was highest in winter (68.9%), declined during spring and was lowest during summer (32.3 %) when intake of digestible dry matter was not sufficient to maintain the liveweight of weaner sheep. Selenium intake by ewes was highest in winter (64 �g/day), when dry matter (DM) intake was maximum (1348 g/day). The intake of selenium (31 �g/day) and the plasma selenium concentration (7.8 �g/l) of unsupplemented ewes was least in spring when pasture was actively growing and its selenium concentration was declining. Plasma and liver selenium concentrations were least at weaning, both in lambs from unsupplemented ewes (3 �g/l and 0.093 mg/kg DM respectively) and from supplemented ewes (7 �g/l and 0.120 mg/kg DM respectively). Selenium supplementation of ewes resulted in elevated selenium concentrations in the plasma of their lambs up to 8 weeks of age. Plasma concentrations declined thereafter and by weaning, at c. 18 weeks, there was little difference between plasma selenium concentrations of lambs from supplemented and unsupplemented ewes. Despite a low selenium status of unsupplemented weaners, supplementation did not improve growth rate during the summer and autumn, the period when problems of selenium inadequacy have been recorded previously.
Relationships between the duration of phases in the pre-anthesis life cycle of spring barley
Authors: Appleyard M , Kirby EJM , Fellowes G
Published: November 2004

Ear development and ear growth were studied in the progeny of two crosses between a six-row and two two-row spring barley varieties. There were no differences in the rates of primordium initiation amongst the progenies and parents. Duration of ear initiation and ear growth varied amongst the genotypes, and there was a strong negative correlation between the duration of these phases. Duration of ear initiation was correlated with number of leaves, as was the length of life cycle from sowing to anthesis. Survival of spikelets was related to the number of spikelet primordia initiated. However, the proportion of spikelet primordia that survived to form grains was less in ears with most spikelet primordia. This may be due to competition for resources in the ear. It is suggested that optimal ear size and life-cycle duration may be achieved by breeding for appropriate durations of the component phases of the life cycle.
Flowering responses of 48 lines of oilseed rape (Brassica spp.) to vernalization and daylength
Authors: Myers LF , Christian KR , Kirchner RJ
Published: November 2004

Forty-eight lines of Brassica spp, of diverse origins were grown in the glasshouse either under natural daylengths or daylengths extended to 16 h by artificial illumination. Plants were either unvernalized or had been subjected to 6 weeks at 8�C day and 6�C night temperatures as seedlings. Lines could be classified into two major groups, according to whether or not vernalization or long photoperiods were essential for 50% flowering within 21 weeks. In six lines, both vernalization and long days were essential for prompt flowering, while only five lines did not respond to either treatment. Strong interactions between lines and treatments were found in the number of leaves and subtended buds at flowering. The results show that a wide range of responses is obtainable from material currently available, offering considerabk, scope for adaptation to different environments.
The productivity of breeding ewes grazing on lucerne or grass and clover pastures on the tablelands of Southern Australia. 1. Reproduction
Authors: Donnelly JR , Morley FHW , McKinney GT
Published: November 2004

The reproductive performance of Merino and Border Leicester x Merino ewes was measured over 3 years near Canberra. Ewes were stocked at six rates, from 9 to 18 ha-1, and lambed at two times (starting in mid-August or in early September) on pastures sown to subterranean clover and in which the main perennial species was either lucerne or phalaris. The effect of stocking rate on the proportion of ewes having multiple births was significant (P < O.05), and closely correlated to its effect on weight. The effect of stocking rate on the proportion of fertile ewes (i.e. ewes which were pregnant) was slight. Ewes grazing on lucerne were heavier at joining and gained more weight in the weeks before joining than did ewes on phalaris pastures. Although the proportion of fertile ewes was similar on both pastures, ewes grazing lucerne had fewer multiple births; this resulted in 8% fewer lambs per ewe joined in crossbreds and 9 % fewer in Merinos. The time of joining did not affect reproductive performance. Reproductive performance of both genotypes increased with the age of the ewes. There appeared to be year effects which were not related to weight or to weight gain at joining, although increases in reproductive performance with higher weight at joining were consistent from year to year.
Osmoregulation as a selection criterion for drought tolerance in wheat
Authors: Morgan JM
Published: November 2004

A method is described in which measurements of osmoregulation made on glasshouse-grown wheat plants may be used to select lines which yield higher under conditions of water deficit in the field. The procedure involved growing F4 breeding lines in pots in a semi-controlled glasshouse. When the plants reached booting stage, they were transferred to a controlled environment chamber and droughted by withholding water. During the water deficit cycle approximately 10 flag leaf samples from each line were taken, and measurements were made of relative water content, osmotic potential and water potential. The lines were evaluated using estimates of the relative water content at either osmotic or water potential values of -2.5 MPa, after relationships between these measurements and relative water content had been established. The distribution of data into two main groups with a smaller intermediate group indicated possible single gene control. Under drought conditions in the field, lines selected from the high osmoregulating group maintained turgor to lower water potentials and gave grain yields which were 1.6 and 1.5 times greater than those selected from the low group at the F4 and F6 stages respectively.
Response of four grain legumes to water stress in south-eastern Queensland. IV. Interaction with sowing arrangement
Authors: Lawn RJ
Published: November 2004

The effect of spatial arrangement and population density on growth, dry matter production, yield and water use of black gram (Vigna mungo cv. Regur), green gram (V. radiata cv. Berken), cowpea (V. unguiculata CPI 28215) and soybean (Glycine rnax CP126671), under irrigated, rain-fed fallowed and rain-fed double-cropped culture was evaluated at Dalby in south-eastern Queensland. Equidistant spacings increased initial rates of leaf area index (LAI) development and crop water use compared with 1-m rows at the same population densities. In the irrigated and rain-fed fallowed treatments, where more water was available for crop growth, both seed yields and total crop water use were higher in the equidistant spacings. However, in the double-cropped treatment, where water availability was limited, there was no yield difference between rows and equidistant spacings, primarily because initially faster growth in the latter was offset by more severe water stress later in the season. Higher population density also increased initial crop growth rate and water use, particularly in the equidistant spacings. However, there was no significant yield response to density, presumably because subsequent competition for light/ water offset initial effects on growth. Although absolute yield differences existed between legume cultivars within cultural treatments, there were no significant differential responses to either spatial arrangement or population density among these four cultivars.
Calorimetric studies on selected lines of Japanese quail
Authors: Atmamihardja SI , Pym RAE , Farrell DJ
Published: November 2004

Calorimetric measurements were made on groups of Japanese quail selected for increased body weight at either 20 or 35 days on either a high- or low-nutrient density diet. For the majority of biological parameters measured, the selected lines outperformed the unselected controls. Weight gain, metabolizable energy (ME) intake, food conversion efficiency, and energy retention were greater for the selected than for the control line. The major difference between the two groups was the higher mean food consumption of the selected lines. Quail selected at 35 days on the high nutrient density diet ate more food, gained more weight and retained more energy and body fat than those selected at the same age on the low nutrient density diet. Net availability of ME for growth was the same (0.69) for the selected and unselected lines; it was 0.66 for protein deposition and 0.83 for fat deposition. Maintenance energy requirement for eight quail was 1.2 MJ ME (kg wt)-1 day-1. Retention of dietary nitrogen was 0.61 of nitrogen intake. There was no difference between the lines in starvation heat production. However, birds fed ad libitum prior to starvation had a 12% higher heat production than those restricted to 70% of ad libitum feed.
The digestion of barley-based diets by cattle: the effect of feeding of three diets containing different amounts of formaldehyde-treated soybean meal
Authors: Lindsay JA , Davies HL , Leibholz J
Published: November 2004

Six growing cattle, with intestinal fistulae, were fed on barley-based diets to which were added increments of formaldehyde-treated soybean meal; the latter was substituted for whole-grain barley. The digestion of organic matter (OM), �-linked glucose polymer (starch), nitrogen (N) and rumen volatile fatty acids (VFA) were measured at a restricted level of intake. The cattle were offered air-dried feed at 3.4 kg per head daily, or approximately ad libitum (i.e. 4.2 kg air-dried feed per head per day). The three diets contained 19.7, 27.8 or 42.9 g nitrogen (N) per kg and were fed in a Latin-square design. When the feed was offered ad libitum there was a significant increase in OM digestibility, from 78% on the lowest N diet to 84% on the highest N diet. Relatively large quantities of starch (140-477 g/day) entered and were apparently digested in the small intestine, especially on the 19.7 g N/kg dry matter (the highest starch diet) on ad libitum feeding. The molar proportions of VFA in rumen liquor largely reflected the amount of starch which was fermented in the rumen. The digestion of nitrogen was characterized by a net gain in flow to the duodenum compared with intake. There was a significant increase in the amount of N apparently digested in the small intestines on the 42.9 g N/kg dry matter diet. The proportion of microbial N at the duodenum declined as more formaldehyde-treated soybean meal was added to the diet. Compared with that of the lowest N diet, the amount of amino acids entering and being apparently digested in the small intestines doubled in the highest N diet, and the concentrations of plasma-free amino acids reflected this. The feed intake comparison indicated that differences in interpretations of digestion studies were likely if animals were fed solely at restricted intakes. The main discrepancies were in OM digestibility, starch digestion in the small intestine, the proportion of microbial N flow at the duodenum and in the estimation of amino acid absorption and requirement.
Effect of burial on the softening of hard seeds of subterranean clover
Authors: Taylor GB
Published: November 2004

Burrs of eight varieties of subterranean clover (Trifolium subterraneum L.), which had experienced one summer at the soil surface, were placed on the soil surface and at depths of 2, 6 and 10 cm in the soil. The numbers of residual hard seeds were determined after 1, 2 and 3 years. The effects of laboratory treatment at a diurnally fluctuating temperature of 60/15�C on the softening of buried seeds and of seeds stored in the laboratory for 1 and 3 years were determined. Rate of seed softening in all varieties decreased with increasing depth of burial, apparently because the soil insulated the seeds from high soil surface temperatures. Few seeds of the varieties Northam and Geraldton softened during 3 years of burial at 6 or 10 cm; while, at the other extreme, few seeds of Yarloop survived 3 years at any depth. Some evidence was found for microbial decomposition of hard seeds in the field. Seeds softened more readily at 60/15�C (in the laboratory) as the preceding periods of either laboratory storage or field burial increased. Such storage or burial experiences have a preconditioning effect on hard seeds, making them more amenable to softening once they are subjected to wide diurnal temperature fluctuations. The results indicate that soil tillage associated with cropping should build up a useful soil seed reserve of the harder seeded varieties.
Fungal and enzymic degradation of alkaloids from the capsule of the poppy (Papaver somniferum L.)
Authors: Hofman PJ , Menary RC
Published: November 2004

The ability of fungi parasitic on Papaver somniferum L. capsules, and capsule enzymes to degrade morphine, codeine, and thebaine was studied, with the aim of determining the causal factors involved in alkaloid losses from the mature capsule during rainy periods. When whole, mature capsules were inoculated with fungal spore suspensions and incubated for 21 days, Alternuria alternutu decreased dry matter and morphine yields by 12 and 48% respectively. Ernbellisia sp. caused a 30% decrease in morphine yield, but Dendryphion penicillatum and Cladosporiurn cladosporioides had no effect. Codeine and thebaine yields were not affected. Acetone powder extracts showed that mature capsule enzymes caused morphine and thebaine losses in the order of 10 and 50%, but only in the presence of p-cresol, a substrate for polyphenoloxidase. These findings, indicating the ability of fungi and enzymes to cause alkaloid losses from mature capsules during moist periods, are discussed with regard to commercial alkaloid production.
A comparison of particulate markers for the estimation of digesta flow from the abomasum of sheep offered chopped oaten hay
Authors: Egan JK , Doyle PT
Published: November 2004

Five sheep with simple cannulae in the rumen and abomasum were given a diet of chopped oaten hay at 95-98% of ad libitum intake from continuously moving belts. Flows of digesta from the abomasum were estimated by a double marker method by reference to 51Cr-EDTA as the fluid marker, and either 103Ru-P, lignin, or acid insoluble ash (AIA) as the particulate marker. Estimates were also made by reference to lignin as a single marker. Estimates of the weight of digesta leaving the abomasum daily were unaffected by the choice of particulate marker when used with 51Cr-EDTA, but were 25% lower when lignin was used alone. The estimated flows of dry matter and acid detergent fibre (ADF) were dependent upon the choice of markers. Compared with estimates of ADF flow given by 51Cr-EDTA and lignin, estimates given by AIA were lower (-24.6%) and those given by 103Ru-P were higher (+26.2%). Lignin alone gave estimates 1.6% higher. Observations on the distribution of 103Ru-P in digesta dry matter indicated a markedly higher concentration on fine than on large particles. It is concluded that lignin may be preferable to 103Ru-P as a particulate marker when certain coarsely chopped roughages are given to sheep, and when samples of digesta from the abomasum are obtained through a simple cannula.
Toxicity of Echium plantagineum (Paterson's Curse). 1. Marginal toxic effects in Merino wethers from long-term feeding
Authors: Culvenor CCJ , Jago MV , Peterson JE , Smith LW , Payne AL , Campbell DG , Edgar JA , Frahn JL
Published: November 2004

Groups of 10 Merino wethers were pen-fed pelleted diets containing 80 or 20% Echium plantagineum, for four periods of 12 weeks alternating with four similar periods on control diet. Mild liver damage, characteristic of pyrrolizidine alkaloid poisoning, aas induced in one wether consuming 80% E. plantagineum. The other animals on the 80% diet showed only a small increase in the size of the hepatocytes, which was not unequivocally due to alkaloids. There were no effects on liver function, serum enzymes, weight gain or wool growth attributable to alkaloids. The 80 and 20% Echium diets contained 0.11-0.15 and 0.032-0.047% alkaloid respectively, indicating that approximately onequarter to one-third of the alkaloid of the fresh plant was lost during diet preparation and storage. Echlum feeding induced a high rate of destruction of pyrrolizidine alkaloids in the sheep rumen. The conversion of the Echium alkaloids into pyrrolic metabolites by microsomal preparations from livers of the experimental sheep taken at necropsy was unaffected by the feeding schedule.
Root morphology, water uptake, growth and survival of seedlings of ryegrass and Phalaris
Authors: Cornish PS , McWilliam JR , So HB
Published: November 2004

The development of secondary roots was prevented or delayed in ryegrass and phalaris, and the effects on plant water relations, growth and survival were studied in a controlled environment. Delayed development of secondary roots reduced transpiration within 15 days of emergence and reduced tillering and leaf area by the 22nd day in ryegrass and the 28th (leaf area) or 42nd day (tiller number) in phalaris. These effects were apparently due to high axial resistances to water flow through the plant, rather than to an inadequate capacity of the seminal roots for water uptake. Measurements of water flow through xylem vessels agreed well with predictions from the Poiseuille equation. Secondary roots were able to support seedlings from about 20 days after sowing in the absence of seminal roots, but most seedlings survived less than 4 months in the absence of secondary roots, even when subsoil water was available to the seminal roots. Delays in the establishment of secondary roots (up to 63 days) and phosphorus deficiency both reduced the number of secondary root axes forming, but this did not affect survival because the conductance of each secondary root axis was about two orders of magnitude higher than that of the seminal axis.
Primary growth and regrowth responses of temperate grasses to different temperatures and cutting frequencies
Authors: Hill MJ , Pearson CJ
Published: November 2004

Primary growth and regrowths of Italian ryegrass (Lolium multiforum), prairie grass (Bromus catharticus) and tall fescue (Festuca arundinacea), grown in glasshouses at temperatures ranging from 15/10 to 30/25�C, were measured when defoliated every 4 or 8 weeks. Prairie grass, tall fescue, Ucivex Italian ryegrass, and Tama Italian ryegrass each had different patterns of regrowth. Growth was fastest at 21/16 and 24/19�C in primary growth and at 15/10�C in regrowth, except for fescue which had fastest regrowth at 24/19�C. Frequent defoliation (every 4 weeks) halved the total dry matter yield harvested throughout the experiment. The mean number of tillers and leaves produced was halved by frequent defoliation and leaf area was reduced to one-quarter of that for plants defoliated every 8 weeks. Reproductive development was earlier in plants grown at lower temperatures and did not occur in those grown at 24/19 and 30/25�C. Primary growth of Italian ryegrass and prairie grass was faster than that of tall fescue. Yield and the number of tillers increased at successive regrowths under 8-week defoliation, but only Tama Italian ryegrass maintained its productivity under frequent defoliation owing to its ability to maintain a high tiller population and high individual leaf areas. Productivity of prairie grass was limited by low tiller number despite its high yield per tiller, and productivity of tall fescue was restricted by both low tiller number and low yield per tiller. The extent to which current growth was influenced by prior growth and, by implication, previous defoliation management differed between the grasses. For example, productivity in any regrowth of Tama was essentially independent of growth during the primary growth or previous regrowth periods, whereas regrowths of prairie grass were highly dependent on growth during previous regrowth periods.
Effect of irrigation on soil oxygen status and root and shoot growth of wheat in a clay soil
Authors: Meyer WS , Barrs HD , Smith RCG , White NS , Heritage AD , Short DL
Published: November 2004

Two watering treatments (flood and control) were applied to undisturbed (bulk density �? 1.6 mg mm-3 ) and repacked �? 1.2 mg mm-3 ) cylinders of Marah clay loam. The cylinders (0.75 m o.d. by 1.4 m deep) were housed in a lysimeter facility. Wheat (cv. Egret) was grown in the cylinders and the soil was either kept well watered with frequent small amounts of water (control treatment) or subjected to three separate periods, ranging from 4 to 72 h, of surface inundation (flood treatment). The greater pore space and better drainage of the repacked soil ensured that its average level of soil oxygen (O2) was about three times that of the undisturbed soil. Nevertheless, inundation of the soil surface for either 48 or 72 h rapidly decreased soil O2 levels in both soils. Root growth in these soils appeared to be slowed when soil O2 levels became less than 15% of the maximum that would occur in dry, aerated soil. Root growth ceased in both repacked and undisturbed soil cores after a 48-h flooding, when the soil O2 status was probably < 10% of the maximum. Root growth was greatest in the repacked soil with controlled water additions. The ranking of treatments, by either root intercept counts or O2 status, were the same. Leaf and stem growth were not very sensitive to the root zone conditions, but this may have been due to the advanced stage of plant growth when the treatments were applied and to the generally low nitrogen status of all treatment plants. There was a 44% reduction in yield from the best to the worst aerated soil treatment. The data show that if soil O2 levels become low as the result of flooding, root growth of wheat will stop and grain yield will be substantially decreased. Greatly improved aeration of these fine-textured soils is only possible if both the internal drainage properties of the soil are improved and prolonged periods of surface inundation are avoided.
Variations in seed dormancy and rates of development of great brome, Bromus diandrus Roth., as adaptations to the climates of southern Australia and implications for weed control
Authors: Gill GS , Blacklow WM
Published: November 2004

Seeds of great brome, B. diandrus, were collected from 14 sites across southern Australia and sown at Perth, W.A. The duration of seed dormancy varied among the seed accessions when produced at the common field site of Perth, which suggested that variations in dormancy were genetically controlled. The environment of Perth shortened the duration of dormancy in all the accessions but did not affect their ranking, indicating a lack of genotype x environment interaction. The duration of dormancy was positively correlated (r = 0.78) with the duration of the rain-free summers of the site of collection. Dormancy was not due to hard-seededness and non-dormant seeds germinated within 40 h of wetting at 20�C. The seed dormancy was limited to about 5 months under the storage conditions examined. Dormant seed was stimulated to germinate by gibberellic acid (2.89 mM) and dormant seed of the accession from Geraldton also responded to removal of the lemma and palea or to leaching with water. The time taken for accessions to 'panicle peep' was positively correlated (r = 0.83) with the length of the rainy winters of the sites of collection. The results show great brome has adapted genetically to the climate of southern Australia. Cropping systems that exploit the lack of residual dormancy and the potential for rapid and complete germination s
Nutritional value of chickpea (Cicer arietinum) and pigeonpea (Cajanus cajan) meals for growing pigs and rats. 1. Energy content and protein quality
Authors: Visitpanich T , Batterham ES , Norton BW
Published: November 2004

Two lines of chickpea meal (CPI 56296-b of low fibre content, and CPI 61277 of high fibre content) and one pigeonpea meal (UQ 50) were evaluated, relative to soybean meal, as energy and protein sources for growing pigs and rats. The digestible and metabolizable energy contents of the three protein sources were (MJ kg-1, air-dry basis): chickpea CPI 56296-b, 16.2 and 15.3; chickpea CPI 61277, 14.9 and 14.3; and pigeonpea meal, 15.1 and 14.2, respectively. Both lines of chickpea produced a similar growth performance to soybean meal for growing pigs. Feeding pigeonpea meal resulted in a lower dressing percentage (P < 0.05), and growth rate and feed conversion ratio were inferior on a carcass basis (P < 0.01) relative to the other three diets. There were no differences in backfat thickness or lean content in the ham between the groups of pigs fed on the four diets. With rats, both lines of chickpea produced lower dressing percentages and carcass gains relative to soybean meal (P < 0.05). Pigeonpea was inferior, on a carcass basis, to both soybean and chickpea meals. We conclude that both chickpea meals were suitable as energy and protein sources for pigs, and that short-term rat assays predicted the pig response for pigeonpea but not for chickpea meal.
The influence of wheat density and spatial arrangement on annual ryegrass, Lolium rigidum Gaudin, competition
Authors: Medd RW , Auld BA , Kemp DR , Murison RD
Published: November 2004

The influence of wheat (Triticum aestivum L.) planting arrangement and density on the competitive effect of the weed, annual ryegrass (Lolium rigidum Gaudin), was examined in field experiments over three climatically contrasting years on the central western slopes of New South Wales. Results for three experiments conformed to a common trend. Geometrical arrangement of the crop (rectangularities of 1 to 6.4) at any one of a range of crop densities had no significant effect (P > 0.05) on ryegrass competition, expressed as relative wheat grain yield reduction. However, the effect of ryegrass was substantially reduced by increasing wheat sowing density from 40 or 75 to 200 plants m-2. In analysing models of weed competition a reciprocal yield model (I/ Y = 0.0092 + 0.0037X, r2= 0.89) predicted yield reduction (Y, as per cent of weed-free controls), especially when used with the ratio of weed density to crop density (X), with residual sums of squares lower than for other models.
Growth and mineral composition of the sultana grapevine as influenced by salinity and rootstock
Authors: Downton WJS
Published: November 2004

Sultana grapevine growing on its own root system, or else grafted to Dogridge, 1613, Harmony and Ramsey rootstocks, was irrigated with 0, 12.5, 25, 50 or 75 mM solutions of chloride salts under glasshouse conditions for three consecutive growing seasons. Cations accompanying chloride were sodium, magnesium and calcium in the ratio of 0.6:0.2:0.2 m.e./l. Growth was progressively suppressed by salinity in all vines, but scions on stocks of Vitis champini (Dogridge and Ramsey) showed linear decreases in growth, whereas self-rooted vines and scions on Harmony and 1613 stocks gave curvilinear responses in which the rate of decline in growth was greater at lower salinities than at higher salinities. Scions on 1613 rootstocks performed poorest, particularly when salt treatments were applied before budburst. With the exception of Dogridge, rootstocks growing under glasshouse conditions generally lowered the chloride concentration in leaves of scions below that of self-rooted vines. Canes on 1613 stock accumulated much higher concentrations of chloride than did the other vines. Rootstocks lowered sodium, particularly in petioles and raised potassium concentrations in all plant parts. Dogridge and Harmony stocks led to very high concentrations of potassium in petioles even in the absence of salt treatment. Salt treatment resulted in greatly elevated phosphorus concentrations within scions. Magnesium showed increases in leaves and canes with increasing external salinity, whereas calcium did not. Nitrogen concentrations did not change with rootstock or salt treatment. The results have relevance for irrigated horticultural areas along the River Murray, for which the ionic composition of the watering medium was formulated, and for situations where saline wastewater is to be reutilized.
Models of growth and development of wheat in relation to plant nitrogen
Authors: Angus JF , Moncur MW
Published: November 2004

Wheat plants were grown in culture solutions differing in nitrogen concentration and transferred between the solutions at the time of floral initiation. Rates of growth and development were expressed in relation to the nitrogen concentrations of the whole plants. Growth rate increased and developmental rate decreased with increased plant nitrogen concentration, the extent depending on the developmental stage when the nitrogen was supplied, the duration of supply, and the concentration of nitrogen in the solution. Simple dynamic models fitted to the data accounted for 97% of the variation in observed biomass and 93% of the variation in rate of development. The models are based on a concept of relative nitrogen concentration, an expression of the actual nitrogen concentration of the plant in relation to the maximum and minimum possible nitrogen concentrations at a particular developmental stage. The models suggest possibilities for calculating the growth response to nitrogen fertilizer applied at any time during the development of a crop.
Relationship between climate and relative performance of cotton in New South Wales
Authors: Thomson NJ
Published: November 2004

Cumulative day-degrees, total rainfall and the mean daily values for evaporation rate, maximum temperature, minimum temperature and radiation for a period of 200 days from 1 October to 18 April were used to characterize the climates of cotton-growing seasons at Narrabri (30�S.), N.S.W. Yields (expressed as percentages of standards) of some cultivars included in field trials in cotton-growing districts of New South Wales, were then regressed on these climatic indices. In a number of cases strong, significant linear associations of performance with one or more of the indices were found. Such cultivars were either more or less advantaged by warm, dry conditions than the standards, and vice versa for cool, wet conditions. The implications of these results in studies of genotype x environmental interaction are discussed.
Selenium excretion in sheep
Authors: Langlands JP , Bowles JE , Donald GE , Smith AJ
Published: November 2004

Factors affecting the fate of selenium (Se) in the gastro-intestinal tract and its excretion in faeces were examined in four experiments. Large quantities of Se were secreted into the anterior region of the small intestine and were absorbed from the posterior region. These processes were not affected by the infusion of arsenite or by tying off the pancreatic duct. Faecal and urinary Se excretion were increased in sheep of higher Se status; the increase in faecal excretion was evident for several weeks after a change in Se intake but was not significant because of high variability between animals; it was attributed to the release of Se when tissues were turned over as tissue Se concentration equilibrated with contemporary Se intake. The bile was a possible route for the entry of such Se into the gastro-intestinal tract, and relationships between biliary Se and whole blood and plasma Se concentrations are presented. Faecal Se excretion was more sensitive to an increase in the organic matter intake than to an increase in forage Se concentration in one experiment. It is postulated that Se excretion was increased because rumen microbial activity was stimulated by the increased nutrient intake, and this increased the quantity of dietary Se which was reduced to an unavailable form by rumen microbial action.
Patterns of change in seed dormancy and persistence of Bromus diandrus Roth. (great brome) in the field
Authors: Cheam AH
Published: November 2004

Mature seeds of great brome (Bromus diandrus Roth;.) from Western Australia were dormant when freshly harvested. This dormancy was lost progressively over summer. The rate of loss of dormancy was more rapid in the northern than in the southern accessions. Compared with bare soil, a wheat stubble microenvironment favoured the relief of dormancy during the initial period of dormancy breakdown. Shallow burial of newly shed dormant seeds also accelerated the after-ripening process. Germination of non-dormant seeds during summer was minimised by high temperatures and low soil moisture content. By autumn/winter, almost all the seeds became germinable. At 20/10�C, the temperature regime corresponding to late autumn, 95-99% germination occurred under constant darkness, but in the light germination varied from 55 to 95%. In the field, complete mass germination did not occur but germination was a well-defined event. There was little germination following this pulse until the succeeding autumn/winter. The seed bank of great brome appears to be essentially a transient one, but this is the subject of further work. The concentration of germination at a single time of year, and the very small carryover of seeds to successive years, suggest that good control should be achieved by a single, timely cultivation or spraying.
Selection by grazing sheep of pasture plants at low herbage availability and responses of the plants to grazing
Authors: Broom DM , Arnold GW
Published: November 2004

Merino sheep grazing annual pasture at the beginning of the growing season when the amount of herbage on offer was small, preferred to graze Wimmera ryegrass Lolium rigidum or subterranean clover Trifolium subterraneum rather than capeweed Arctotheca calendula, and Erodium botrys was avoided completely. Behaviour observations showed that capeweed plants were usually avoided. When the plants were grasped they were sometimes pulled up by the roots and then dropped so that the number of capeweed plants in the pasture declined. Supplementation with oats reduced grass intake. Harvesting behaviour changed with pasture conditions: as grass height declined in the pasture, the rates of biting, stepping and head swinging increased. Pasture measurements showed that, whilst capeweed plants continued to increase in height during grazing, as did ungrazed controls, ryegrass and clover plants decreased or remained short. Herbage dry matter increased in all species, owing especially to basal growth. The proportion of shoots and petioles which were erect increased in ungrazed plants, but the proportion which were prostrate was much greater in grazed plants. Individual plants adapted their growth form in a way which counteracted the depredations of grazers. The ecological implications of these findings are important. Firstly, the sheep were not foraging optimally in terms of maximising rate of intake, since two abundant species were largely ignored even though food availability was low. Secondly, because of their selectivity the sheep were giving the capeweed and Erodium a competitive advantage which, in these pastures, will persist through the growing season.
Low survival of Rhizobium japonicum inoculant leads to reduced nodulation, nitrogen fixation and yield of soybean in the current crop but not in the subsequent crop
Authors: Herridge DF , Roughley RJ , Brockwell J
Published: November 2004

Reports of nodulation failures in first-year crops of soybean, resulting in nitrogen deficiency and low yield, have been common in Australia. In experiments simulating commercial practice, successive crops (1982-83, 1983-84) of soybean were sown into soil containing either a very small population of Rhizobium japonicum (rhizobia-low; 2 g-1 soil, 3-9 cm), or a large population (rhizobia-high; 270 000 g-1). The soil was a vertisol at Breeza, N.S.W. Each crop was inoculated with R. japonicum at a normal rate (n = 25 x 1010 organisms per 100 kg of seed) or at 100 x normal (100n) or was not inoculated (o). The 1982-83 crop was sown in hot (maximum air temperature 3g�C), dry weather, and < 1% of the inoculant survived the first day. This did not affect nodulation in rhizobia-high plots and production of foliage and seed nitrogen was satisfactory, irrespective of rate of inoculation. In contrast, nodulation was inadequate in all rhizobia-low soil (although 100n > n > o) and the N content of foliage and seed was correspondingly reduced. In spite of poor nodulation in these rhizobia-low treatments, a substantial population of R. japonicum (18 000 g-1soil) developed between seasons. When the plots were re-sown in 1983-84, nodulation, growth and yield of the crops, irrespective of the initial rhizobial status of the soil, were equally good, and there was no response to further inoculation. Poor nodulation of first-year crops of soybean is a likely consequence of failure to establish adequate numbers of R. japonicum in the soil at sowing.
Responses to nitrogen and maize supplements by young cattle offered a low-quality pasture hay
Authors: Lee GJ , Hennessy DW , Nolan JV , Leng RA
Published: November 2004

Twenty-seven Hereford steers (227�3 kg) were offered ad libitum low-quality grass pasture hay containing 4.3 g N/kg DM. These steers were offered one of three maize supplements (nil, 570 g/day crushed maize or 680 g/day whole maize) alone or with one of two nitrogen (N) supplements (1 12 g/day urea: 250 g/day molasses, or 800 g/day pelleted protein meals). The crushed maize, whole maize and protein meal supplements were calculated to be isoenergetic on a metabolisable energy basis, and the urea and protein meal supplements were isonitrogenous.Both urea and protein meal supplements increased the intakes of hay and total digestible organic matter (DOMI), but there was a significant interaction between maize and N supplements such that maize increased hay and DOM intakes when offered alone. Unsupplemented steers ate only 1.98 kg OM of hay/day, whereas N supplemented steers ate 3.96-4.40 kg OM/day, and those supplemented with crushed and whole maize alone ate 2.45 and 2.85 kg OM/day respectively. The intakes of hay by the urea and protein meal supplemented groups were not significantly different.Both N and maize supplements had positive effects on liveweight change (P < 0.01), with N having the largest effect. Steers supplemented with protein meal gained 210 g/day more than those offered urea (P < 0.05), although DOMI was only 110 g/day more, indicating an effect of protein on the efficiency of utilisation of absorbed nutrients.N supplements increased rumen ammonia concentrations from 10�3.0 mg NH3-N/l in unsupplemented steers to 169� 19.3 and 105� 19.0 mg NH3-N/l in steers offered urea and protein meal respectively; there was a significant interaction between the form of N supplement and form of maize supplement (P < 0.05). Total volatile fatty acid concentrations in the rumen (65� 1.9 mM) did not differ significantly between supplements.Glucose entry rate was positively related to liveweight change and was increased by both the N supplements and whole maize. Glucose entry rate, adjusted for DOMI, was higher in protein meal supplemented steers than those receiving urea or no N supplement (P < 0.01), and these steers had the highest growth rate.Urea pool size, and synthesis rate in the body, were greater in steers given the urea and protein meal supplements (P < 0.05), but there were no significant differences in these measurements between urea and protein meal supplements.
Sensitivities of spring wheat cultivars to chlorsulfuron measured as inhibitions of leaf elongation rates and there were genotype multiply environment interactions
Authors: Bowran DG , Blacklow WM
Published: November 2004

Inhibitions of the rates of elongation of the third leaf of seedlings of spring wheat (ARLE3) were used to identify differences in cultivar sensitivities to chlorsulfuron. The standard test was 408g chlorsulfuron/kg sandy soil, pH 6.2, high nitrogen and phosphorus nutrition and 2O�C/15�C (day/ night). Timstein and Gabo were found to be the most tolerant cultivars with -RLE3s of 4 and 5 mm day-1 (9 and 11 % of untreated RLE3) and Sonora and Miling the most sensitive with -RLE3s of 19 and 21 mm day-1 (45 and 48% of untreated RLE3s); 16 cultivars were intermediate with -RLE3s of 9-15 mm day-1 The cultivars most sensitive to chlorsulfuron were semi-dwarf types carrying the Rht/ Gai genes for stature/insensitivity to gibberellic acid. There were significant genotype x environment interactions; Sonora treated with chlorsulfuron failed to respond to increases in soil nitrogen and phosphorus, and sensitivity was increased at temperatures below 20�C. The -RLE3 test was simple, rapid and non-destructive, and may be suitable for use by plant breeders. Identification of genotypes sensitive to chlorsulfuron based on inhibitions of grain yield would be more protracted and less efficient than those based on -RLE. The herbicide was degraded and leached in the field plots with 0.4 8g chlorsulfuron/kg soil found at 40 cm in the profile 8 weeks after application.