The influence of systematic micro-environmental variation on individual plant yield within selection plots

Summary Moving average and polynomial response surfaces were used to estimate systematic micro-environmental variation within four different F₃ selection environments. At low density the response surfaces were efficient in estimating systematic variation. At high densities random variation due to intergenotypic competition predominates. It is concluded that the two major factors rendering single plant selection for yield inefficient are competition within selection plots and genotype-season interactions between the selection and test generations.     

The analysis and control of volatile hydrocarbon concentrations (e. g. benzene) during oil bioassays

It is well known that volatile hydrocarbons such as benzene, toluene, and xylene, which are abundant in many refined oils, affect phytoplankton growth. However, experiments to determine these effects in many cases have been improperly designed resulting in questionable conclusions. Experiments presented in this paper indicate that ambient benzene concentrations reported in the published literature may be lower than stated by an order of 10 to 100. By continuous monitoring the benzene concentration decrease was observed and it was possible to determine whether the loss was due to degassing because of loose closures or biological uptake. Unless tight closures are used benzene is quickly lost to the atmosphere (exponential decay rate ≌ 1.2d ^-1). Experiments demonstrated that benzene is quickly lost from cotton stoppered bioassay flasks that are typically used. Rubber stoppered flasks with little gaseous headspace showed minimum benzene loss. Biological uptake of benzene can be demonstrated when closures are secure and the effect of certain concentrations on growth can be correctly interpreted. Benzene concentrations above 10 to 20 ppm significantly reduce the growth rate of Skeletonema sp. The benzene concentration decreased quickly in 10 to 20 ppm benzene solutions implying metabolic uptake. These experiments indicate that proper closures and analysis of the volatile pollutant concentration during bioassay experiments increase the likelihood of correct interpretation and may yield additional insights into the causation factors.     

Arbuscular mycorrhizal fungi-induced alteration to tree-root architecture and longevity

Arbuscular mycorrhizal fungi (AMF) form mutualistic associations with most terrestrial plants, including trees. They can confer many benefits and are known to induce widespread changes in host plant physiology. For many years it was considered that colonisation by AMF did not alter root architecture but significant alteration has now been demonstrated unequivocally for several plants, including trees with AMF colonised plants usually possessing a more highly branched root system. More recently, alteration to root system longevity has also been measured with AMF colonised root systems being shorter lived. Mechanisms by which these changes occur are not understood but effects are not entirely due to altered phosphorus nutrition and are likely to involve AMF interaction with plant cell cycles. Future research should concentrate on defining the extent of AMF alteration to root system development and the importance of AMF interactions with plant cell cycles in determining these changes.     

An exploratory study to investigate animal health and reproductive wastage among Australian meat goat producers

The Australian goat meat industry has grown significantly in the last decade, with the value of exports nearly tripling. However, because carcase weight has remained constant over this time, the drivers of industry growth are price and supply. Animal health and reproduction are key factors contributing to supply and productivity, yet limitations to production management are poorly understood, hampering advice for effective intervention. This exploratory study aims to provide insights into the animal health and reproductive management practices and perceptions among meat goat producers in Australia. To achieve this aim, 20 producers, located in New South Wales, Queensland, Western Australia and Victoria, operating under different production systems were interviewed. The results of this study suggest that animal health management could be improved and that producers perceive a lack of relevant and species-specific information available to help them make informed decisions. Reproductive management and records varied greatly across producers interviewed. Kid loss was identified as an issue, with a 28% estimated average (6%–47% range) of losses from kidding until weaning. Producers identified predation, doe nutrition and mismothering as the biggest contributors to kid loss, with the majority of losses occurring within a week of birth. All producers believed management could minimise kid loss. This study highlights the importance of improving reproductive rates among goat enterprises and provides new information on the current practices within the Australian meat goat industry. This may assist the development of appropriate strategies for improving health and reproductive management and delivery of advice to producers.     

Brownfield regeneration to greenspace: Delivery of project objectives for social and environmental gain

In Europe and North America regeneration of brownfield land is an important objective of government policy. Regeneration to greenspace in particular, has been used to help reverse social and environmental decline, with typical benefits including increased flood retention capacity, temperature regulation, habitat for wildlife, building communities, encouraging local engagement and providing space for play and recreation.Regeneration project objectives are set to maximise the benefits of greenspace creation for a given location; setting the right objectives is critical to lever funding required to pump-prime activity. However, opportunities to heighten benefits delivered through the process of regeneration can be overlooked. This research identified that there was a disconnect between practices required to meet the defined objectives for a specific site and regeneration activity. This was often due to gaps in the project delivery plans: tasks which are important to realise improvement were missing. Emphasis was often found to be on site delivery, with a benign assumption that the benefits will arise as a result of project completion. Although there are some examples of practices to optimise benefits, a lack of consistency indicates scope for improvement.A logic model was co-produced with practitioners in a bid to address this issue and support project delivery planning. The model maps the social and environmental objectives for a site against specific project delivery stages. The model was refined through a workshop exercise involving discussion with practitioners who were planning new urban greenspaces on brownfield land.This paper presents the logic model to demonstrate what needs to be considered to improve the project delivery planning process, signposting the steps required to translate project objectives into outcomes, to optimise social and environmental benefits delivered during and after regeneration. The model could support those involved in project delivery planning and help raise the overall quality of new greenspace.     

Charge Transfer between Raindrops: Microwave temperatures of thunderstorms can be deduced from radiation emitted by colliding drops

Electric discharges between free-falling drops have been observed and studied quantitatively in the laboratory. These data and information from terrestrial thunderstorms suggest that augmentation of the UHF temperature of thunderstorms by discharges could amount to 117 degrees K. If similar discharges occurred in the atmosphere or on the surface (or in both regions) of Venus, 1.4 x 10(6) discharges per second per square meter would be required to produce the microwave temperature observed (approximately 650 degrees K). It is not probable that such radiation supplies the whole microwave temperature observed; some fraction must be true thermal radiation as described by Plummer and Strong (9), in which case the probable number of required discharges is reduced accordingly.     

Biofumigation for control of pale potato cyst nematodes: activity of brassica leaf extracts and green manures on Globodera pallida in vitro and in soil

The effects of brassica green manures on Globodera pallida were assessed in vitro and in soil microcosms. Twelve of 22 brassica accessions significantly inhibited the motility of G. pallida infective juveniles in vitro. Green manures of selected brassicas were then incorporated into soil containing encysted eggs of G. pallida. Their effect on egg viability was estimated by quantifying nematode actin 1 mRNA by RT-qPCR. The leaf glucosinolate profiles of the plants were determined by high-performance liquid chromatography. Three Brassica juncea lines (Nemfix, Fumus, and ISCI99) containing high concentrations of 2-propenyl glucosinolate were the most effective, causing over 95% mortality of encysted eggs of G. pallida in polyethylene-covered soil. The toxic effects of green manures were greater in polyethylene-covered than in open soil. Toxicity in soil correlated with the concentration of isothiocyanate-producing glucosinolate but not total glucosinolate in green manures.