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Wild lettuce (Lactuca serriola L.) is a significant emerging agricultural and environmental weed in many countries. This invasive species is now naturalised in Australia and is claimed to cause significant losses within the agricultural industry. Sustainable management of wild lettuce has been hampered by a lack of detailed knowledge of its seed ecology. Laboratory-based studies were performed to examine the potential influence of environmental factors including temperature and light conditions, salinity, pH, moisture availability and burial depth on the germination and emergence of two spatially distant populations of wild lettuce. Results suggested that the germination of wild lettuce seeds occurred across a broad range of temperature conditions (12-h cycle: 30°C/20°C, 25°C/15°C and 17°C/7°C) for both populations. We also found that these seeds are non-photoblastic; germination was not affected by darkness, with >80% germination in darkness for both populations at all tested temperature ranges. Germination significantly declined as salinity and osmotic stress increased for both populations, with seeds from the Tempy population were more affected by NaCl >100 mM than seeds from Werribee, but in neither population was there any observed effect of pH on germination (>80% germination in both populations at all tested pH ranges). For both populations, germination significantly decreased as burial depth increased; however, the two populations differed with regard to response to burial depth treatment, whereby seeds from the Tempy population had higher emergence than those from Werribee at 0.5 cm burial depth. These results suggest that light-reducing management techniques such as mulching or use of crop residues will be unsuccessful for preventing germination of wild lettuce. By contrast, burial of seeds at a depth of at least 4 cm will significantly reduce their emergence. The seed ecology of two spatially varied populations of Lactuca serriola was examined to understand the effect of various environmental factors. Results show >80% germination across a range of temperatures; however, emergence decreased with increase in burial depth. To manage this species, we recommend burying the seeds at least 4 cm deep to reduce emergence and subsequent establishment. [ABSTRACT FROM AUTHOR]

The rapid increase of herbicide resistance in some of the most problematic annual weeds, and potential negative impacts of herbicides on human health and the environment have led growers to look for alternative non-chemical weed control. Harvest weed seed control (HWSC) is a non-chemical weed control tactic based on reduction of seed return of primarily annual weed species to the soil seed bank that has been successfully adopted by farmers in Australia. The strategy is to collect and/or destroy the weed seeds in the chaff material during harvest using chaff carts, bale direct system, integrated impact mills, windrow burning, chaff tramlining and chaff lining or other methods of targeting the chaff material containing the weed seeds. Two biological characteristics are exploited with successful HWSC: the level of weed seed retention at crop harvest above crop canopy height and coincidence of weed and crop maturity. Initial research efforts in Europe have found that there are several candidates for HWSC among weed species with a high importance in European cropping systems. The highest potential has been found for weeds such as Galium aparine, Lolium rigidum and Silene noctiflora. However, there are several challenges for the adoption of these systems under European conditions compared to e.g., Australia. The challenges include that crop and weed maturity are not concomitant which results in lower seed retention values at crop harvest. In addition, there has not been a concerted research effort to evaluate HWSC systems in European cropping systems. Until now, research on HWSC in Europe mainly focused on the rate of weed seed retention in specific weed species. For HWSC to contribute to the mitigation of herbicide resistance and add to the toolbox of integrated weed management measures, there is an urgent need to take HWSC research to the next level. Although HWSC is not functionally equivalent to herbicide application, it may help to reduce herbicide inputs in the long-term when used in combination with other tactics. Future research and development should focus on the evaluation of HWSC strategies for the practical adoption of these tactics in European cropping systems. • Harvest weed seed control (HWSC) may help to reduce herbicide use in the long-term. • HWSC is a mitigation tool for resistance management. • Despite its potential, the adoption of HWSC is minor in Europe. • Opportunities and challenges for the implementation of HWSC in European is discussed. • Areas for further HWSC research and development in the region are identified. [ABSTRACT FROM AUTHOR]

Background: Various charts based on body mass index (BMI) and per cent body fat (%BF) are used to classify childhood body composition but outcomes may vary. Aim: The study investigated variation in incidences of childhood obesity as depicted by four classification charts. Subjects and methods: BMI and DXA-derived %BF were assessed in 741 children. Incidences of overweight and obesity were compared between two BMI charts and two bioelectrical impedance (BIA)-based %BF charts. Results: The International Obesity Task Force (IOTF)-adopted BMI chart designated 21%, 6% (boys), and 26%, 9% (girls) as overweight and obese, respectively. Corresponding figures using the USA CDC BMI chart were 27%, 11% (boys) and 27%, 12% (girls). Using a USA-derived %BF chart incidences were 17%, 2% (boys) and 21%, 8% (girls) and using a UK-derived %BF chart 51%, 24% (boys) and 53%, 36% (girls). Sensitivity of BMI varied according to the %BF reference chart. Conclusions: In contrast to the BMI-based charts, there were considerable variations in depicted incidences of obesity between the %BF-based charts. These discordances were considered to result from previously reported variation within and between BIA and DXA %BF assessments underlying the charts. The present study highlights the need for valid, reliable, unchanging BIA and DXA procedures. [ABSTRACT FROM AUTHOR]

This methods paper outlines the overall design of a community-based multidisciplinary longitudinal study with the intent to stimulate interest and communication from scientists and practitioners studying the role of physical activity in preventive medicine. In adults, lack of regular exercise is a major risk factor in the development of chronic degenerative diseases and is a major contributor to obesity, and now we have evidence that many of our children are not sufficiently active to prevent early symptoms of chronic disease. The lifestyle of our kids (LOOK) study investigates how early physical activity contributes to health and development, utilizing a longitudinal design and a cohort of eight hundred and thirty 7-8-year-old (grade 2) school children followed to age 11-12 years (grade 6), their average family income being very close to that of Australia. We will test two hypotheses, that (a) the quantity and quality of physical activity undertaken by primary school children will influence their psychological and physical health and development; (b) compared with existing practices in primary schools, a physical education program administered by visiting specialists will enhance health and development, and lead to a more positive perception of physical activity. To test the first hypothesis we will monitor all children longitudinally over the 4 years. To test the second we will involve an intervention group of 430 children who receive two 50min physical education classes every week from visiting specialists and a control group of 400 who continue with their usual primary school physical education with their class-room teachers. At the end of grades 2, 4, and 6 we will measure several areas of health and development including blood risk factors for chronic disease, cardiovascular structure and function, physical fitness, psychological characteristics and perceptions of physical activity, bone structure and strength, motor control, body composition, nutritional intake, influence of teachers and family, and academic performance.