bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrition during fetal life alters annual wool production and quality in young Merino sheep
Authors: Kelly RW , Macleod I , Hynd P , Greeff J
Published: March 2005

The effect of maintenance v, submaintenance diets of pregnant ewes in 1991 and 1992 on establishment of the wool follicle population in their progeny, and its effect on the progeny's wool production (quantity, quality and variation across the body of the animal) to 1.4 years of age was examined. The experimental protocol used cloned animals created by bisecting embryos at day 6 of pregnancy. Each clone was placed in a ewe, which was subsequently fed from about day 50 to 140 of pregnancy at maintenance or submaintenance. Ewes on maintenance nutrition maintained liveweight throughout pregnancy, while submaintenance ewes were 12.1 kg lighter (P<0.001) 10 days before lambing. In 1991, a total of 74 lambs were born, including 17 sets of surviving clones. In 1992, 102 lambs were born, including 18 sets of surviving clones. Only data for the 35 sets of genetically identical 'twin' progeny and their dams are reported. Birth weights of lambs born to ewes fed at the submaintenance rate were 0.5 kg lighter (P<0.01) than their 'twins' born to ewes fed at maintenance. Midside secondary:primary (Sf: Pf) ratios for mature wool follicles were less (P<0.01) at birth, lamb and hogget shearing (1.4, 1.5 and 2.1 units respectively) for the progeny born to ewes fed at submaintenance. Progeny from ewes on the submaintenance treatment produced less clean wool, 0.1 kg to 0.4 years of age (P<0.01) and 0.14 kg between 0.4 and 1.4 years of age (P = 0.10), than their maintenance counterparts. Hogget wool was 0.1 pm broader (P<0.05), with a 0.5% units lower coefficient of variation of fibre diameter (P<0.01), and a position of break closer to the staple tip (P<0.001) for progeny of submaintenance ewes than their maintenance counterparts. There were no significant differences in yield, staple length, staple strength and percentage of fibres greater than 30 pm in diameter. Differences in mean fibre diameter arose between 1 and 1.4 years of age, coinciding with the period that the animals were grazing high quality pasture. Effects of maternal undernutrition on mean fibre diameter and Sf: Pf follicle ratios of progeny were most pronounced on the hind leg (P<0.01), and not significant on the front leg. However, variations in other wool quality traits across the body of the hoggets, expressed as a percentage of the midside value, were not significantly affected by maternal undernutrition. Clearly when evaluating management strategies for the pregnant ewe, the effect on lifetime production and quality of wool of their progeny needs to be considered. Merino hoggets that produce an extra 0.14 kg clean wool that is 0.1 pm finer will compensate for some extra management and feeding of their dams during pregnancy to prevent weight loss. If these effects continue throughout the life of the animal, then it will increase the cost effectiveness of feeding to maintain maternal weight over pregnancy.
Effect of perches and solid sides on production, plumage and foot condition of laying hens housed in conventional cages in a naturally ventilated shed
Authors: Glatz PC , Barnett JL
Published: March 2005

The effect of modified cages on production, shell quality, feather cover and foot condition was measured in 2 Australian commercial laying strains housed in a naturally ventilated laying shed from 18 to82 weeks of age. Two cage modifications were investigated. Firstly , the inclusion of a perch within the cage, and secondly, the installation of solid sides. Compared with normal cages, installation of a perch in a cage reduced food intake (5.3%) and liveweight (4.5% at 82 weeks) and improved feather cover around the vent (feather score of 2.15 to 2.66). This was offset by a decrease in egg production (2.4%), shell weight (1.5%) and thickness (11%), an increase in cracked (53.8%) and dirty eggs (28.9%), and an increase in claw length (9.2%). Relative to control cages, the provision of solid sides in cages improved overall feather cover of hens (feather score of 2.46 to 2.67), but there was a 54.5% increase in hen mortality during a period of hot weather. Additional modifications to the cage are required to optimise the benefit of perches. Similarly, improvement in ventilation and cooling in naturally ventilated sheds are required to maximise the benefits of solid-sided cages for hens and avoid heat stress.
Comparison of winter-active phalaris with the Australian cultivar under rotational grazing. 1. Basal area and plant density
Authors: Culvenor RA , Oram RN
Published: March 2005

Basal area and plant density in fixed quadrats are presented from a grazing trial comparing the persistence of 2 'winter-active' cultivars (Sirosa, Holdfast) and a breeding population (Perla Retainer) of phalaris (Phalaris aquatica L.) possessing high seedling and winter growth rates with the original cultivar Australian. Four replicate pastures, 2 at each of 2 sites near Canberra, were grazed year-round at 15 wethers/ha for 3 years using a rotational system of management (2 weeks on, 4 weeks off,). The first site, The Elms, was located on a slope with shallow, coarse-textured soil; the second, Boundary Creek, was level with deep soil which was very acid in the upper 20 cm. Both sites were fertilised with superphosphate and, except for small areas, were limed before sowing. Significant mortality was observed only at The Elms during the summer-autumn drought after grazing commenced, when plant death was highest for Australian and lowest for Perla Retainer, an erect, summer-dormant population. Basal area of Australian and Sirosa, but not Holdfast and Perla Retainer, subsequently recovered. Australian established and maintained a 50-70% higher basal area due to a 30-40% higher area per plant and 15-25% more plants. The cultivars did not differ markedly in persistence measured as stability of basal area. However, Perla Retainer showed less vegetative expansion at the first site after grazing commenced and was considered less persistent than the cultivars there. Persistence was correlated with the productivity of individual plots, all cultivars being affected similarly. Regressions which varied with cultivar were derived in which basal area at establishment, but not subsequent changes in basal area under grazing, was positively related to soil fertility factors, mainly phosphorus, potassium and manganese. An association between the initial basal area of Sirosa and soil magnesium levels was also detected at 1 site. It was concluded from this study, which was conducted in the absence of major drought, that the winter-active cultivars of phalaris can be as persistent as Australian under rotational grazing and with adequate soil fertility, but that interactions with site will occur.
Comparison of winter-active phalaris with the Australian cultivar under rotational grazing. 2. Dry matter on offer, pasture composition and animal production
Authors: Culvenor RA , Wood JT , Oram RN
Published: March 2005

Composition and amount of pasture on offer and animal productivity are presented from an experiment in which 2 'winter-active' cultivars (Sirosa, Holdfast) and a breeding population (Perla Retainer) of phalaris (Phalaris aquatica L.) bred for rapid growth in autumn and winter were compared with the original cultivar, Australian, under rotational grazing at 15 wethersfha for 3 years at 2 sites near Canberra. A change of cultivar rank in phalaris herbage on offer occurred in winter of the second year, whereby Australian became the highest ranked cultivar, reflecting its 50-70% higher basal area and 70% higher tiller density. However, pastures of the winter-active lines had an average 30% more phalaris on offer per unit basal area and per tiller, and a larger component of other, mainly annual, grass. This resulted in total pasture on offer at least equivalent to that of Australian pastures, and possibly more herbage production in autumn and winter. Sheep on the winter-active phalaris pastures were slightly heavier on average due mainly to higher weight gains in the first half of the year. These sheep produced an average over both sites of 7% more wool than sheep on Australian pastures, the advantage being higher at a site with dense phalaris (10%, P<0.01) than at a site with shallow, coarse-textured soil and less phalaris (3.5%, P = 0.11). It was concluded that pastures of the winter-active phalaris lines can give higher wool production than pastures of Australian phalaris, but not necessarily because of higher amounts of phalaris in the pasture. Benefits in the long term would also depend on persistence. Breeders of phalaris should aim to increase yield per unit of basal area if animal production gains in the short term are to be made in this environment, but compromises may be necessary between productivity and long-term persistence.
Integration of satellite remote sensing, simple bioclimatic models and GIS for assessment of pastoral development for a commercial grazing enterprise
Authors: Hill MJ , Donald GE , Vickery PJ , Furnival EP
Published: March 2005

Satellite imagery, climatic, edaphic and topographic data, and a simple bioclimatic model were used to analyse the pastoral potential of a large cattle grazing enterprise, 'Cooplacurripa', on the central coast of New South Wales. Landsat Thematic Mapper and Spot XS satellite images were processed to create pasture growth status maps describing timbered and cleared areas, and priority areas for phosphorus fertiliser application. A digital elevation model was used to describe slope and aspect, and as a basis for interpolation of monthly surfaces of rainfall, temperature, radiation and evaporation from the Australian Climate Surfaces. These data were combined with a simple growth index model to create production surfaces for tropical, subtropical and temperature pasture types. The property was classified into zones defined by the seasonal growth patterns of the 3 pasture classes. The database was used to identify potential areas for further pasture improvement by a series of logical rules and map overlays to define pasture suitability for currently timbered areas with a slope of less than 20�. The northern section of the property with the highest rainfall, best suitability for temperate pasture and good road access was chosen for land capability and fauna impact studies on the basis of this analysis. The study provides an example of the application of spatial data to practical management issues in pastoral agriculture.
Compatibility of a petroleum spray oil and foliar zinc fertilisers
Authors: Hodgkinson MC , Joyce DC , Mackey AP , Sagatys DS , Schmiede TS , Smith G
Published: March 2005

The performance of 7 commercial zinc (Zn) foliar nutrients sprays, based on sulfate (Top ZM), hydrated sulfate (Pivot Zinsol; Pivot Mangasol-zinc), oxide (Phosyn Zintrac), and ligninsulfonate (Spray-gro Zn PC; Spray-gro Zn/Mn PC; SJB), were assessed with and without addition of a horticultural petroleum spray oil (PSO), Ampol D-C-Tron NR. Foliar Zn deposition and absorption was quantified by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) after solvent washing and acid extraction. Effects on photosystem II were measured by chlorophyll fluorescence. Although none of the Zn sprays were soluble in PSO, all but Zn oxide could be suspended adequately before spraying. A partial emulsion break occurred with Zn sulfate and hydrated sulfates. All treatments increased the Zn content of leaves by an amount likely to alleviate Zn deficiency. Addition of PSO decreased deposition and absorption of Zn when used with the inorganic formulations or with Spray-gro Zn PC. Zinc deposition and absorption were increased by PSO in Spray-gro Zn/Mn PC, and were unaffected by PSO in SJB. Plant chlorophyll fluorescence and phosphorus content did not differ among treatments. The ligninsulfonates Spray-gro Zn/Mn PC and SJB were most compatible with Ampol D-C-Tron NR, and had relatively low potential for Zn pollution of the environment.
Field evaluation of micropropagated and conventionally propagated ginger in subtropical Queensland
Authors: Smith MK , Hamill SD
Published: March 2005

The growth and performance of micropropagated ginger (Zingiber officinale Roscoe) was compared with 'seed'-derived plants in field trials conducted in south-eastern Queensland. In the first generation ex vitro, micropropagated plants had significantly (P<0.01) reduced rhizome yield with smaller knobs and more roots. Micropropagated plants had a greater (P<0.01) shoot: root (rhizome) ratio compared with seed-derived plants. Shoots from micropropagated plants were also significantly (P<0.01) smaller with a greater number of shoots per plant. The unusual shoot morphology of the micropropagated plants did not appear to be related to the presence of benzylaminopurine, a plant growth hormone added to the multiplication medium, as plants subcultured for 3 cycles on a hormone-free medium also exhibited similar characteristics. Seed collected from the micropropagated plants and seed-derived plants was harvested and, despite the micropropagated seed being significantly (P<0.01) smaller, by the second generation ex vitro there were no significant differences between the treatments. Factors that can improve rhizome size, while reducing production costs, need to be identified before micropropagated plants can be recommended for routine use in the ginger industry as a source of disease and pest-free planting material.
Creep feeding and prepartum supplementation effects on growth and fertility of Brahman-cross cattle in the dry tropics
Authors: Fordyce G , Cooper NJ , Kendall IE , O'Leary BM , Faveri Jde , De Faveri J
Published: March 2005

Post-partum anoestrus is a primary contributor to low branding rates in Bos indicus cattle herds in the dry tropics of northern Australia [Entwistle, K. W. (1983). Australian Meat Research Committee Review No. 431. To increase branding rates, it was hypothesised that creep feeding for a short period in mid-late lactation during the latter half of the growing season may trigger an earlier onset of post-partum oestrus cycling, just as short-term, high-level, prepartum supplementation can achieve. Two experiments were conducted using Fn Brahman-cross cows (1/2, 5/8 and 3/4 crosses with Beef Shorthorn) which calved from late October to late Januarv. Cows were mated from mid-late Januarv to mid-April. Calves in one treatment in both experiments had ad libitum access to creep feed (calf pellets: 16% crude protein, 10 MJ ME/kg) for 4042 days from late February to early April. In experiment 2, the effects on cow growth and fertility due to supplementation with either cottonseed meal (1.5 kg/day) or molasses with 7.4% (w/w) urea for 49 days late in the dry season before calving ('spike' feeding) were also evaluated. Control cattle were unsupplemented. Creep feed was only consumed at 0.1 and 0.4 kg/day in experiments 1 and 2, respectively. Short-term creep feeding had no consistent effects on cow liveweights, condition, or fertility, or on calf growth and temperaments under extensive grazing conditions during the tropical wet season. Spike feeding reduced weight loss by 0.2-0.4 kg/day (P<0.01). The effects on liveweights did not persist into the wet season. There were no effects on cow fertility in this year of extreme weather conditions, when 4 months of nutritional and climatic stress followed supplementation.
Effect of cultivation, sowing methods and herbicides on wild radish populations in wheat crops
Authors: Code GR , Donaldson TW
Published: March 2005

The effect of different cultivation and sowing methods on wild radish (Raphanus raphanistrum L.) density in 4 successive wheat crops was measured in an experiment in north-eastern Victoria. The number of seasons taken for populations to decline below an estimated threshold for economic spraying of wild radish (5-10 plants/m2) was examined. Two herbicide applications in each crop in all but one treatment prevented or significantly reduced wild radish seed production during the experiment. Wheat sown after mouldboard ploughing (MBP) in the first season contained wild radish at 42 plants/m2, before spraying. Densities were significantly higher (P<0.05) when wheat was direct drilled (96 plants/m2), or sown after cultivation to 80 mm (116 plants/m2) or to 50 mm (202 plants/m2). MBP in the first season followed by cultivation to 80 mm or direct drilling in subsequent seasons resulted in wild radish populations below the threshold for economic spraying in the second crop. Cultivation to 80 mm before sowing in the first 2 years, followed by direct drilling in subsequent years resulted in a wild radish population of 6.9 plants/m2 in the third crop. This density was within the range estimated as the threshold for economic spraying. Wild radish densities on treatments cultivated to 50 or 80 mm before sowing, or direct drilled each year, had declined to within or below the threshold for economic spraying by the fourth crop.
Effect of weeds and nitrogen fertiliser on yield and grain protein concentration of wheat
Authors: Mason MG , Madin RW
Published: March 2005

Field trials at Beverley (19911, Salmon Gums (1991; 2 sites) and Merredin (1992; 2 sites), each with 5 rates of nitrogen (N) and 3 levels of weed control, were used to investigate the effect of weeds and N on wheat grain yield and protein concentration during 1991 and 1992. Weeds in the study were grasses (G) and broadleaf (BL). Weeds reduced both vegetative dry matter yield and grain yield of wheat at all sites except for dry matter at Merredin (BL). Nitrogen fertiliser increased wheat dry matter yield at all sites. Nitrogen increased wheat grain yield at Beverley and Merredin (BL), but decreased yield at both Salmon Gums sites in 1991. Nitrogen fertiliser increased grain protein concentration at all 5 sites-at all rates for 3 sites [Salmon Gums (G) and (BL) and Merredin (G)] and at rates of 69 kg N/ha or more at the other 2 sites [Beverley and Merredin (BL)]. However, the effect of weeds on grain protein varied across sites. At Merredin (G) protein concentration was higher where there was no weed control, possibly due to competition for soil moisture by the greater weed burden. At Salmon Gums (G), grain protein concentration was greater when weeds were controlled than in the presence of weeds, probably due to competition for N between crop and weeds. In the other 3 trials, there was no effect of weeds on grain protein. The effect of weeds on grain protein appears complex and depends on competition between crop and weeds for N and for water at the end of the season, and the interaction between the two.
Seedling and adult plant evaluation of race variability in Leptosphaeria maculans on Brassica species in Australia
Authors: Ballinger DJ , Salisbury PA
Published: March 2005

Seedling and adult plant studies were used to identify the race structure of Leptosphaeria maculans (the cause of blackleg) on oilseed Brassica species in Australia. Host-pathogen interactions using a set of 12 differential host lines identified 14 seedling relationship, however, between seedling and adult plant reactions to individual isolates, indicating that seedling and adult plant resistance are under different genetic control. While non-specific adult plant resistance was observed in the B. napus line Jet Neuf, host-pathogen interactions confirmed the existence of race-specific adult plant resistances in other differential lines.
Effect of four different canopy shapes on apple yields
Authors: Campbell JE , Nicol HI , Cullis BR
Published: March 2005

The cultivars, Jonathan, Delicious and Granny Smith apple (Malus domestica Borkh.) trees on MM.106, Northern Spy, Seedling and MM.102 rootstocks were trained as-vase, central leader, palmette and Hawkes Bay multi-leade; systems for 18 years. Rootstock significantly affected tree size, and there were interactions of rootstock with training systems or cultivars. There was also an interaction between training ' systems and cultivars. In the early years, while the training systems were being established, fruit yield was inversely related to the severity of the pruning; central leader- and palmette-trained trees had higher yields and tree efficiency than Hawkes Bay trees whose yields and tree efficiency were higher than vase trees. When yields reached maximum and the training systems became well established (after about 8 years of cropping), the total annual yield and tree efficiency per tree of individual training systems within a cultivar and rootstock differed only slightly. Cumulative yields of central leader, palmette and Hawkes Bay were higher than vase in the early years of all training systems and cultivars, while tree size was often smaller. In the latter years, cumulative yields of the central leader, palmette and Hawkes Bay systems remained slightly higher than vase, except with the less vigorous Jonathan and Granny Smith/ MM.102 combinations where yields were similar.
Production and composition of milk by dairy cows fed lupin grain or blood meal as protein supplements to hay- or silage-based diets in early lactation
Authors: Valentine SC , Bartsch BD
Published: March 2005

In 2 concurrent experiments, milk production and composition were measured for 56 days in Holstein-Friesian cows fed concentrate rations based on a mixture of either lupin and barley grains or lupin grain, barley grain and blood meal. In experiment 1, 26 cows were fed 9 kg/day of isonitrogenous concentrate mixtures comprising either 50% barley grain and 50% lupin grain or 70% barley grain, 24% lupin grain and 6% blood meal, together with pasture silage ad libitum. In experiment 2, 32 cows were fed 9 kg/day of isonitrogenous concentrate mixtures comprising either 34% barley grain and 66% lupin grain or 54% barley grain, 40% lupin grain and 6% blood meal, together with pasture hay ad libitum. In both experiments, there were no significant differences between the treatments in the production and composition of milk, or in liveweight and liveweight change. In experiment 1, mean milk yield (L/day), protein content (g/kg), fat content (g/kg), liveweight (kg) and liveweight change (kg/day) were 28.2, 28.5, 40.8, 530 and 0.3, respectively. The corresponding means in experiment 2 were 30.8, 28.6, 39.5, 553 and -0.1. The rate and extent of degradation of nitrogen in the protein supplements incubated in dacron bags in the rumen of steers were lower for blood meal than for lupin grain. It was concluded that, under the conditions in these experiments, when cows were offered a high level of grain concentrate based on barley and lupin grains, as supplements to high quality conserved fodders, there were no benefits to production by replacement of part of the lupin grain by isonitrogenous amounts of blood meal, as a source of undegraded dietary protein.
Estimations of pasture and grain intake of prepartum single- and twin-bearing ewes
Authors: Holst PJ , Hall DG , Nolan JV
Published: March 2005

One hundred and thirty-one pregnant, parous Border Leicester x Merino ewes at pasture were supplemented with a mixture of lupin and oat grain for a minimum of 3 weeks prepartum, and an average of 1 week post-partum in a lamb production experiment. Supplement was group-fed daily at a rate of 400 g/ewe. Pasture and grain intake were determined on 1 day, at an average 7 days prepartum. On an individual ewe basis, there was considerable variation in supplement intake with 11% of ewes consuming <200 g/day and 10% consuming >700 g/day. Significantly (P<0.01) more supplement but less pasture (P<0.05) was eaten by twin-bearing ewes (440 � 23 g) than single-bearing ewes (340 � 36 g). Total feed intake was similar with less variation than in supplement or pasture intakes. Results suggest lower pasture intakes in twin-bearing ewes can be compensated by higher grain intakes which means that separation of single- and twin-bearing ewes may not always be warranted in a supplementation program.
Survey of weeds and diseases in cereal crops in the southern wheat belt of New South Wales
Authors: Lemerle D , Tang HongYuan , Murray GM , Morris S , Tang HY
Published: March 2005

A field survey of weeds in 86 cereal crops in southern New South Wales was conducted in spring 1993 to determine weed and disease distributions, and their levels of infestation. Fifty weed species from 19 families were identified. The most widespread species were Arctotheca calendula (capeweed) in 76% of fields, Avena spp. (wild oats) in 72%, Trifolium subterraneum (subterranean clover) in 69%, Lolium rigidum (annual ryegrass) in 69%, Vulpia spp. (silvergrass) in 63%, Juncus bufonius (toad rush) in 62%, Crassula spp. (stonecrop) in 37%, Polygonum aviculare (wireweed) in 37%, Fumaria spp. (fumitory) in 36%, Chondrilla juncea (skeleton weed) in 36%, Rumex acetosella (sorrel) in 28% and Hordeum spp. (barley grass) in 26%. Some species were associated with region and previous crop. Levels of weed infestation, based on a visual assessment of the relative weed-crop ground cover, plant density and height, were surprisingly high. A questionnaire completed by 181 farmers and 30 agronomists, to determine their perceptions of the most abundant weeds, showed close agreement with the field survey. Current weeds were generally considered difficult to control and expected to be a continuing problem. The exception was Raphanus raphanistrum (wild radish) which had a low incidence, but was expected to become more serious. The root disease, take-all (Gaeumannomyces graminis var. tritici), was recorded in 32% of the 56 wheat crops examined. It was associated with a previous pasture, lupin or cereal crop, but was absent when the previous crop was canola. Another root disease, rhizoctonia bare patch, was found in only one wheat crop. Common foliar diseases were ring spot (Pyrenophora semeniperda) in 57% of wheat crops, septoria tritici blotch (Mycosphaerella graminicola) in 23%, yellow spot (Pyrenophora tritici-repentis) in 2 1 %, stripe rust (Puccinia striiformis) in 3%, and septoria nodorum blotch (Phaeosphaeria nodorum) in 2%. These diseases were generally present on less than 5% of crop leaf area.
Colonisation of wheat in southern New South Wales by vesicular-arbuscular mycorrhizal fungi is significantly reduced by drought
Authors: Ryan MH , Ash JE
Published: March 2005

Colonisation of wheat crops by vesicular-arbuscular mycorrhizal (VAM) fungi was examined on a pair of adjacent organic and conventionally managed farms in southern New South Wales during 1993-94. Although intended to be part of a larger study on the roles of VAM fungi in organic and conventional farming systems, the severe drought of 1994 allowed an examination of the effects of drought on VAM fungi. In 1993, rainfall was above average, crop growth was good and VAM fungi colonised between 40 and 70% of crop root length. In 1994, low rainfall resulted in poor crop growth, and colonisation by VAM fungi was significantly lower than in 1993, ranging between 5 and 16% in the crops most affected by the drought. Wheat plants adjacent to tree lines exhibited particularly poor growth and low VAM colonisation, presumably due to the trees competing with the crop for water. The lower colonisation of crops by VAM fungi in 1994 resulted in reduced inoculum levels in the soil which could affect growth of a subsequent VAM-dependent crop. In contrast to the results of research carried out under conditions of milder drought stress, the low level of VAM colonisation found in this study suggests that the VAM fungi had no significant role in alleviating the drought stress experienced by the crop.
Fast resolution of identification problems in seed production and plant breeding using molecular markers
Authors: Poulsen DME , Ko HL , Meer JGvan der , Putte PMvan de , Henry RJ , Van der Meer JG , Van de Putte PM
Published: March 2005

Polymerase chain reaction (PCR) analysis with specific and arbitrary primers was used to identify germplasm from a barley breeding program. Through practical application of the technology, an F1 plant's identity was confirmed, the correct pedigrees 'of 2 incorrectly labelled F2 populations were determined, confusion in the identity of seed lots of an advanced breeding line was resolved and off-type barley plants were identified in a seed increase block. This illustrated the value of PCR-based genotype analysis in plant breeding programs.
Effects of timing and intensity of spider mite infestation on the oil yield of cotton crops
Authors: Sadras VO , Wilson LJ
Published: March 2005

We assessed the effects of timing and intensity of spider mite (Tetranychus urticae) infestation on the oil yield of cotton (Gossypium hirsutum L.) crops. Artificially infested crops of cv. Deltapine 90 (normal leaf) and Siokra 1-4 (okra leaf) were compared in 2 field experiments. Actual timing of infestation ranged from 59 to 127 days after sowing and intensity of infestations ranged from 64 mites per leaf in the most severe treatment to almost nil in controls. Mites significantly reduced oil yield in both experiments; yield reductions were greater in the normal-leaf than in the okra-leaf type. Oil yield losses declined with the delay in the onset of infestation. Under low and moderate levels of infestation, oil yield losses were associated with reductions in seed production. Under more severe infestations lower seed oil content also contributed to the reduction in oil yield.
Classification of Australian garlic cultivars by DNA fingerprinting
Authors: Bradley KF , Rieger MA , Collins GG
Published: March 2005

Garlic (Allium sativum L.) reproduces only by vegetative propagation yet displays considerable morphological variation within and between cultivars. The origins of Australian cultivars are uncertain and the descriptive names applied to them may not reflect their derivation. Twenty common Australian garlic cultivars were analysed by the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) technique using 20 random decamer primers. The amplification products of 5 of these primers resulted in 65 clear polymorphic bands. These bands were transformed into a binary format, and genetic similarities calculated using a simple matching coefficient. The similarities were used to perform a cluster analysis and produce a dendrogram grouping the cultivars. Bolting and intermediate/non-bolting types could be differentiated from each other. These could be further subdivided into 4 groups based on length of growing season.
Ewe colostrum and subsequent lamb suckling behaviour
Authors: Holst PJ , Hall DG , Allan CJ
Published: March 2005

Behavioural and colostral data were obtained from 70 parous Border Leicester x Merino ewes (and their lambs) that lambed in 0.25 ha paddocks. Data collected included a colostral sample immediately postpartum, lamb weight and temperature, site of parturition and lamb sucking attempts to 48 h post-partum. Colostrum dry matter percentage was 56.5 for ewes with single lambs and 61.5 for ewes with twins (P<0.05). Colostrum colour and consistency score (1-7) of twin-bearing ewes was 5.5 compared with single-bearing ewes of 6.5 (nearer normal milk). Lamb sucking behaviour suggested the more viscous the colostrum, the more often the lamb attempts to suck (P<0.001) and for a longer period at each attempt (P<0.05). This effect diminished over time so that by 24-48 h there was no difference in behaviour expressed as duration x number of sucking bouts, when normal milk would be expected. Twin lambs had significantly more sucking bouts than single lambs up to 4 h post partum. The consequences of these observations would be more serious for twin lamb survival and may explain why some individual twin lambs often die from starvation.
Use of glyphosate to prevent development of reproductive tillers and extend vegetative growth of bent grass (Agrostis castellana)
Authors: Hill RD , Missen DJ , Taylor RJ
Published: March 2005

The effect of glyphosate on seedhead development of bent grass (Agrostis castellana) was evaluated in an experiment at 2 sites in south-western Victoria.Application of glyphosate at 0.1350.225 kg a.i./ha on 7 November and 7 December 1993 prevented the formation of seedheads and stimulated the plant into renewed vegetative growth in response to following summer rain. The treatment with 0.135 kg a.i./ha of glyphosate, applied on 7 November, increased digestible dry matter of the regrowth by 20% and protein content by 70% compared with the unsprayed control which was dominated by seedheads. These results reflect the amount of new growth in treated plots and thus should not be confused with either the 'spraytopping' technique which aims to sterilise seeds after seedhead emergence or 'hay freezing' which and aims to preserve the feed value of existing vegetation by 'chemically curing' standing hay. We conclude that application of glyphosate at 0.135 kg a.i./ha in early November has the potential to reduce the dominance of bent grass, creating an opportunity for follow up fertiliser and management techniques to maintain productive pastures.
Sustaining productivity of a Vertisol at Warra, Queensland, with fertilisers, no-tillage or legumes. 2. Long-term fertiliser nitrogen needs to enhance wheat yields and grain protein
Authors: Strong WM , Dalal RC , Weston EJ , Cooper JE , Lehane KJ , King AJ , Chicken CJ
Published: March 2005

Cereal production in the summer-dominant rainfall region of Australia, especially the north-east, has relied heavily on natural soil fertility. Continued cereal production has so depleted the fertility of some soils that corrective strategies are required to restore the production of high protein wheat needed for domestic and export markets. Application of nitrogen (N) fertilisers, along with other strategies to improve soil N status, was evaluated between 1987 and 1994 on a Vertisol located in an area of unreliable winter rainfall. Responses of wheat grain yield and protein content to applied N (0-150 kg/ha) under zero tillage (ZT) and conventional tillage (CT) were determined each year, except 1991 when severe drought prevented wheat sowing. The ZT practices increased grain yields, particularly in 1988 and 1992-93 when antecedent soil water supplies were moderate (about 1 m wet soil in 1988 and 1992) or low (about 0.6 m wet soil in 1993), apparently due to increased antecedent soil water. Tillage practice had little effect on available nitrate-N (kg/ha) to 1.5 m, but the greater water supply in ZT soil usually benefited the wheat crop when N was applied. Applying N increased returns from 5 of the 7 crops because of grain yield and/or grain protein responses. Grain yield responses were inconsistent in the year of fertiliser application where no N fertiliser had been applied to preceding crops. Nevertheless, grain protein usually increased with increasing N application at sowing, except in 1994, when drought after sowing prevented secondary root development and fertiliser uptake. Where N was applied with each successive crop, the crops receiving small N applications (0, 12.5 or 25 kg/ha.crop) produced grain of a low protein concentration (<10%) and lower yields (<90% maximum yield) than crops which received larger N applications (75 kg/ha.crop). Profits were substantially reduced where the rate of N applied was insufficient to raise grain protein concentration to >11.5%, due to the low market value of low protein wheat, or because of lower grain yields. Routine N application to crops over the period 1987-94, which included the longest drought (1990-94) in the lifetime of most producers, caused similarly inconsistent grain yield increases but increased grain protein concentrations (>11.5%) in all except the first crop (1987). Increased frequency of high protein wheat and a high anticipated market value of the higher protein grain should encourage greater producer confidence with routine application of N throughout this region.
Sowing time and tillage practice affect chickpea yield and nitrogen fixation. 1. Dry matter accumulation and grain yield
Authors: Horn CP , Birch CJ , Dalal RC , Doughton JA
Published: March 2005

Mean protein concentrations in wheat (Triticum aestivum) on the Darling Downs of southern Queensland have fallen below 10% in recent years, preventing farmers from obtaining 'Prime Hard' status (13.0%) for their wheat crop. Two management options, for improving this situation are applications of nitrogenous fertiliser in a wheat monoculture or inclusion of a legume in rotation with wheat. Long-term trials at Warra, on the western Darling Downs, resulted in the selection of chickpea (Cicer arietinum) as a useful grain legume cash crop with potential for improvement of its nitrogen (N) fixing ability through management. This 2-year study examined the effect of sowing time and tillage practice on dry matter yield, grain yield, N accumulation and N2 fixation in chickpea and the subsequent soil N balance. There were 3 sowing times during autumn and winter of each year using conventional tillage (CT). Zero tillage (ZT) was introduced after the first crop for all sowing times. Greater total dry matter yield and grain yield (4.18-5.95 and 1.63-2.25 t/ha, respectively) resulted from sowing in autumn or early winter than from sowing in late winter (3.39-3.86 and 0.97-1.22 kg/ha, respectively). The effects of tillage practice were variable, depending on growth stage. At harvest, ZT plots produced greater total dry matter yield (4.20 t/ha) and grain yield (1.94 t/ha) than CT plots (3.01 and 1.29 t/ha, respectively), whereas at the time of maximum dry matter, yield was higher under CT for autumn sowings, and under ZT for winter sowings.
A micropropagation protocol for Melaleuca alternifolia (tea tree)
Authors: List SE , Brown PH , Low CS , Walsh KB
Published: March 2005

Micropropagation of Melaleuca alternifolia (tea tree) was achieved using stem segments from mature plants. A comparison of the source of explant material, and the form of cytolunin and mineral nitrogen on the induction of multiple shoots per node is reported. Further, the effect of shoot induction treatment, the age of plant used for explants and the value of the presence of charcoal, sucrose and light on subsequent root induction in plantlets is considered. A culture procedure involving nodes sourced from 1.5 to 3 cm from the shoot tip, cultured into a shoot induction medium of Murashige and Skoog (MS) basal salts supplemented with 4.5 �mol 6-benzylaminopurine/L and 60 mmol sucrose/L for 12 weeks, and then subcultured for root induction on medium containing MS basal salts, 60 mmol sucrose/L and 0.1 or 1 �mol indole-acetic acid/L for 8 weeks, is recommended.
Changes in the amount and nutritive characteristics of annual pastures from late spring to autumn on the south coast of Western Australia
Authors: Doyle PT , Carter DJ , Speijers EJ , Plaisted TW , Hetherington RE , Love RA
Published: March 2005

We examined declines in annual pasture dry matter on offer (DMO) from around peak accumulation in spring through summer-autumn in 14 supplementary feeding experiments across the south coast of Western Australia. Changes in dry matter digestibility (DMD) and concentrations of nitrogen, phosphorus, potassium (K), calcium, magnesium and sulfur were also measured. Plants which germinated in summer-autumn were manually separated, as far as possible, by removing green components from the dry material, and it was assumed all dry pasture had grown during the previous growing season. Measurements were made under grazing (stocking rates varying from 8 to 16.7 young wethers/ha) and in exclosures, and the experiments were carried out at 5 locations over 3 years. Within any experiment, there were no significant effects of supplementary feeding treatments on declines in DMO, DMD or digestible dry matter on offer (DDMO). Highest measured DMo and DMD varied from 2600 to 8600 kg DM/ha and from 63 to 8 I%, minimum measured values ranged from 100 to 1600 kg DM/ha and 45 to 54%, with amounts of DM0 lost varying from 2000 to 8500 kg DM/ha. The declines in DMO, DMD and DDMO under grazing through summer-autumn were described by exponential decay curves. Losses in DM0 and DDMO, as calculated from curve parameters, were positively correlated (P<0.001) with maximum DM0 or DDMO, respectively. Loss and average rate of loss in DMo were also correlated (P<0.01) with total rainfall through the period of measurement. The number of rainy days, stocking rate and botanical composition of pastures in spring were not significantly correlated with these losses under the conditions of these experiments. The percentage rate of decline in DM0 was not strongly correlated with any of these variables and its variation across experiments was small. Change and rate of change in DMD were positively correlated (P<0.001) with maximum measured DMD and negatively correlated (P<0.05) with the percentage of grass in the pasture. It was estimated that most of the lost material was not consumed by sheep. The concentrations of some essential minerals in grazed dry pasture approached, or fell below, their critical concentrations in most experiments. Of the minerals measured, only changes in K concentrations in dry pasture were well described by exponential regressions.
Continuous, alternate and double crop systems on a Vertisol in subtropical Australia
Authors: Russell JS , Jones PN
Published: March 2005

Three cropping systems using 5 crop species were compared over a 10-year period on a cracking clay soil (Vertisol) in the sub-humid subtropics of eastern Australia. The 3 cropping systems were continuous (the same crop every year), alternate (the same crop every second year) and double (a winter and summer crop in the one year). There were 2 cereal crops (sorghum and wheat) and 3 grain legumes (chickpea, green gram and black gram). The effect of cropping system was measured in terms of grain and protein yields and changes in soil organic carbon (surface 0-10 cm) and nitrogen concentrations. Summer and winter rainfall was below average in 8 and 5 years out of 10, respectively. Grain yield of cereal monocultures was about twice that of legume monocultures. The potential for double cropping, despite the generally below-average rainfall, was clearly shown with the highest grain and protein yields coming from the combination of green gram (summer) and wheat (winter). Averaged over 10 years, wheat yield (1460 kg/ha. year) was identical in the continuous and alternate cropping systems. Sorghum yields were marginally higher with alternate cropping (1340 kg/ha. year) than continuous cropping (1050 kg/ha. year). With double cropping, average wheat yields were 1081 and 698 kg/ha when combined with green and black gram, respectively. Black gram gave half the average yield of either green gram or chickpea (about 300 v. 600 kg/ha). This was attributed to the indeterminate nature of the crop in an environment with variable rainfall and to the detrimental effect of above-average rainfall during harvest time. Soil nitrogen and carbon levels, with initial values of 0.22 and 2.96%, were reduced at the end of 10 years by 16 and 27% respectively. Their rate of decline did not differ between cropping systems.
Early Pinus caribaea var. hondurensis root development. 1. Influence of matric suction
Authors: Costantini A , So HB , Doley D
Published: March 2005

This paper reports 2 experiments that examine the influence of matric suction on radicle elongation in Pinus caribaea var. hondurensis. Experiment 1 where mechanical impedance of root development was negligible and aeration was not limiting, and experiment 2 in low strength soils where both air-filled porosity and moisture were allowed to vary. In experiment 1, radicles were grown between sheets of Whatman No. 42 filter paper. The known wetting characteristic of this paper was used to prepare known pretrial suctions and define postharvest suctions. The midpoint of the pretrial-postharvest suction range was defined as nominal matric suction. Relationships between radicle elongation and nominal matric suction were developed for 6 P. caribaea var. hondurensis families. As matric suction increased from 0.0065 to 3.13 MPa, radicle elongation after 48 h of growth decreased monotonically to zero. Over the range of matric suctions, there was no critical level, below which radicle elongation was unaffected by increasing suction. It was concluded that radicles were able to sense, and respond to, increasing suction. Significant family x matric suction interactions were observed. In experiment 2, radicles were grown in 2 lowstrength repacked soils. An optimal level of matric suction for radicle elongation was observed in both soils. At suctions below and above the optima, inadequate air-filled porosity and moisture stress respectively adversely impacted upon elongation. The 2 experiments demonstrated that matric suction affects radicle elongation both directly and indirectly through interaction with other physical soil properties. Although increasing suction reduces radicle elongation, there may be a 'non-limiting' range of suctions in soil media over which radical elongation is relatively unaffected due to a concomitant improvement in aeration.
Early Pinus caribaea var. hondurensis root development. 2. Influence of soil strength
Authors: Costantini A , Doley D , So HB
Published: March 2005

The influence of penetration resistance (PR), an easily measured indicator of soil strength, on the growth of Pinus caribaea var. hondurensis radicles and seedlings was investigated. Negative exponential relationships between PR and both radicle and primary root elongation were observed. All root elongation ceased at PR levels of 3.25 MPa. Tip diameters of radicles and primary roots were positively correlated with PR values up to 2.4 MPa, whilst numbers of primary roots, total root lengths and lengths of longest roots were all negatively correlated with PR. Hypocotyl elongation was also reduced by increasing PR, although the reductions occurred at higher PRs than those which inhibited root development. In contrast, primary shoot development was unaffected by PR levels which were sufficient to stop root elongation, but was reduced in soil with a PR of 4.8 MPa. There were significant family x soil type and family x PR interactions for radicle, hypocotyl, primary root and primary shoot development. 1f these interactions are correlated with performance in the field, then they may serve as useful indicators of family suitability to both soil type and high strength soils.
Effect of irrigation on leaf gas exchange and yield of cashew in northern Australia
Authors: Schaper H , Chacko EK , Blaikie SJ
Published: March 2005

Gas exchange, leaf water status, soil water use and nut yield of cashew trees were monitored during the reproductive phase in 2 consecutive years (1988 and 1989). Treatment 1 comprised continuous irrigation from the end of the wet season in April until harvest in October; T2, irrigation between flowering (mid June) and harvest; and T3, no irrigation. Irrigation was applied by under-tree sprinkler at 43 mm/week in 1988 and 64 mm/week in 1989. Measurement of leaf gas exchange, chlorophyll content and nut production showed that trees in T2 were as productive as those in T1 (>1.3 kg kernel/tree). In T3, water deficit caused a 4-fold reduction in leaf photosynthesis and reduced leaf chlorophyll content from about 600 to 400 mg/m2 during fruit development. There was no effect on the number of hermaphrodite flowers produced (both ranging from 0 to 15 hermaphrodite flowers/panicle) but the water deficit was associated with a lower kernel yield (1.16 kg kernel/tree). Commercial yields (kg kernel/tree) in irrigated treatments were 20% greater than in the non-irrigated treatment and the kernels from irrigated trees were of a higher grade (kernel recovery >32% in T1 and T2 compared with 27.4% in T3). These results suggest that irrigation of established cashew plantations in the tropical regions of northern Australia can be restricted to the period between flowering and harvest without reducing yield.