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Adelaide, Australia

Humphries A.W.,SARDI Aquatic Sciences Center
Crop and Pasture Science | Year: 2012

Lucerne is a deep-rooted herbaceous perennial legume with high levels of summer production and adaptation to a broad range of agro-ecological environments in southern Australia. The ability of lucerne to extend the growing season of winter-based pasture and respond quickly to rainfall after periods of drought makes it one of the most valuable plants in our feed base. However, for all the advantages of lucerne, it remains underutilised. Lucerne is often considered to be a speciality fodder crop, requiring careful management to achieve high levels of production and persistence. This paper investigates the opportunity of whole-farm integration of lucerne; from speciality fodder crop to traditional pasture. The future trends of lucerne production in temperate grazing and intensive dairy systems are discussed in relation to breeding objectives identified to meet these demands. If lucerne is to be used more commonly as a pasture, the plant and systems must adapt. This paper investigates the plant traits and management principles that are important for growing lucerne in mixtures with other plants and improving the integration of lucerne into the whole-farm plan. Journal compilation © CSIRO 2012. Source

The epifaunal and infaunal assemblages associated with Caulerpa taxifolia in the Port River/Barker Inlet estuary of Adelaide, South Australia were compared to those associated with the co-occurring seagrass Zostera muelleri. Both taxa contained an abundant and diverse fauna, but with substantial differences between them. In particular, ophiuroids (brittle stars) were abundant in Caulerpa, but almost absent from Zostera. Crustaceans, mostly amphipods, and annelids, mostly polychaetes, were abundant in both Caulerpa and Zostera, but the families present differed substantially. Taxa that dominated in Caulerpa include the amphipods: Amphithoidae, Corophiidae, and Talitridae; and the polychaetes: Cirratulidae, Nephtyidae, and Nereididae. Zostera was dominated by the polychaetes: Capitellidae; amphipods: Caprellidae; isopods: Sphaeromatidae; and Neballidae. Some taxa (arthropods, nemerteans, and echinoderms) had their peak abundance during summer, when Caulerpa biomass was highest, while others did not seem to respond to changes in Caulerpa biomass. Overall, epifauna were 4-9 times more abundant in Caulerpa than Zostera, while infauna were slightly more abundant in Zostera, indicating that at least in South Australia, Caulerpa provides a functional habitat for a diverse array of taxa. © 2011 Coastal and Estuarine Research Federation. Source

Soede N.M.,Wageningen University | Langendijk P.,SARDI Aquatic Sciences Center | Kemp B.,Wageningen University
Animal Reproduction Science | Year: 2011

The oestrous cycle in pigs spans a period of 18-24 days. It consists of a follicular phase of 5-7 days and a luteal phase of 13-15 days. During the follicular phase, small antral follicles develop into large, pre-ovulatory follicles. Being a polytocous species, the pig may ovulate from 15 to 30 follicles, depending on age, nutritional status and other factors. During the luteal phase, follicle development is less pronounced, although there is probably a considerable turnover of primordial to early antral follicles that fail to further develop due to progesterone inhibition of gonadotrophic hormones. Nevertheless, formation of the early antral follicle pool during this stage probably has a major impact on follicle dynamics in the follicular phase in terms of number and quality of follicles. Generally, gilts are mated at their second or third estrous cycle after puberty. After farrowing, pigs experience a lactational anoestrus period, until they are weaned and the follicular phase is initiated, resulting in oestrus and ovulation 4-7 days after weaning. This paper describes the major endocrine processes during the follicular and luteal phases that precede and follow ovulation. The role of nutrition and metabolic status on these processes are briefly discussed. © 2011 Elsevier B.V. Source

Zhang S.,Northwest University, China | Sadras V.,SARDI Aquatic Sciences Center | Chen X.,China Agricultural University | Zhang F.,China Agricultural University
Field Crops Research | Year: 2013

Improvement of wheat water use efficiency (WUE = grain yield per unit seasonal evapotranspiration) in the dryland area of Loess Plateau of China is an imperative imposed by the critical situation of water resources, as well as by the demographic pressure. The aims of this study were (i) assessing WUE of dryland wheat in the Loess Plateau, and (ii) identifying management practices returning higher efficiencies. We compiled a data base of 39 sets of experiments spanning 20 years, where conventional practice was compared with alternatives including NT, no tillage without straw mulching; RT, reduced tillage without straw mulching; NTS, no tillage with straw mulching; SS, subsoiling with straw mulching; CTS, conventional tillage with straw mulching; PM, plastic film mulching 100%; RM, ridge mulched with plastic film + bare furrow; RMS, ridge mulched with plastic film + furrow mulched with crop straw.Yield ranged from 818 to 7900kgha-1 and WUE from 3.4 to 23.4kgha-1mm-1; the maximum yield and WUE were achieved under RM and RMS and the minimum under NT/RT. Practices had small and inconsistent effect on seasonal evapotranspiration, hence variation in both yield and WUE were attributable to changes in the contribution of soil evaporation to total evapotranspiration, and the partitioning of seasonal water use before and after anthesis. The yield-evapotranspiration relationship indicated that present yields are limited by environmental (e.g. seasonal distribution of rainfall) and management factors. The range of WUE is very large for the same or various practices, and thus offers tremendous opportunities for maintaining or increasing WUE. Implications for crop management and further improvement in yield and WUE are discussed. © 2013 Elsevier B.V. Source

Wedderburn S.D.,University of Adelaide | Hammer M.P.,South Australian Museum | Bice C.M.,SARDI Aquatic Sciences Center
Hydrobiologia | Year: 2012

Over-abstraction of water places unsustainable pressures on river ecosystems, with the impacts amplified under drought conditions. Freshwater fishes are particularly vulnerable due to associated changes in water quality, and habitat availability, condition and connectivity. Accordingly, fish assemblages are ideal indicators of the impacts of drought and over-abstraction. The Murray-Darling Basin (MDB), south-eastern Australia, terminates at the Ramsar listed Coorong and Lower Lakes, which comprise Lake Alexandrina and Lake Albert. Over-abstraction and extreme drought during the last decade has placed these lakes under severe environmental stress. The purpose of this study was to investigate shifts in fish assemblages caused by substantial water level recession and salinization in the Lower Lakes. Small-bodied fish assemblages were sampled at the beginning and several years into the drought. Off-lake habitats held diverse fish assemblages in 2003, but most sites were dry by 2009. Remaining habitats were disconnected, salinities increased substantially, and aquatic vegetation shifted from freshwater to salt-tolerant species. There was a substantial decline in the proportion of specialist species, especially diadromous and threatened species, and an emerging dominance of generalist freshwater and estuarine species. The findings warn of the inevitable ecological impact of over-allocating water for human use in drought-prone regions, and highlight the need for adequate environmental water allocations. This study also emphasises that understanding the ecological attributes of a fish species, and the subsequent assignment to a functional group, will help predict vulnerability to decline and extirpation. © 2012 Springer Science+Business Media B.V. Source

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