Assessment of benefits and risks of growing Jatropha (<Emphasis Type="Italic">Jatropha curcas</Emphasis>) as a biofuel crop in sub-Saharan Africa: a contribution to agronomic and socio-economic policies

In sub-Saharan Africa (SSA), the main goals behind the development of a biofuel industry are employment creation and income generation. Jatropha (Jatropha curcas L.) has emerged as a candidate for biodiesel production. It is a non-edible oil producing, drought-resistant plant that can be grown on marginal land with limited water and low soil fertility. However, these are also attributes that typify weedy and invasive plant species. Adding to these concerns are the general questioning of whether biofuel production will reduce Greenhouse gas (GHG) emissions globally. Currently, there is limited information on the potential invasiveness of many biofuel crops, and in particular, the potential risks of cultivating Jatropha. This paper aims to assess the benefits and risks, especially risks, of growing Jatropha for biodiesel production. Jatropha should be screened through a science-based risk-assessment procedure to predict the risk of becoming invasive before it is released for large-scale commercial cultivation. The net GHG savings can be achieved through the cultivation of Jatropha, considering two main factors: no land-use change and crop management without chemical fertilization.     

Assessment of benefits and risks of growing Jatropha(Jatropha curcas) as a biofuel crop in sub-Saharan Africa: a contribution to agronomic and socio-economic policies

In sub-Saharan Africa(SSA), the main goals behind the development of a biofuel industry are employment creation and income generation. Jatropha(Jatropha curcas L.) has emerged as a candidate for biodiesel production. It is a non-edible oil producing, drought-resistant plant that can be grown on marginal land with limited water and low soil fertility. However, these are also attributes that typify weedy and invasive plant species. Adding to these concerns are the general questioning of whether biofuel production will reduce Greenhouse gas(GHG)emissions globally. Currently, there is limited information on the potential invasiveness of many biofuel crops, and in particular, the potential risks of cultivating Jatropha. This paper aims to assess the benefits and risks, especially risks,of growing Jatropha for biodiesel production. Jatropha should be screened through a science-based risk-assessment procedure to predict the risk of becoming invasive before it is released for large-scale commercial cultivation.The net GHG savings can be achieved through the cultivation of Jatropha, considering two main factors: no landuse change and crop management without chemical fertilization.     

Effects of pH and ionic strength on elemental sulphur oxidation in soil

Elemental S oxidation in soil is a microbially mediated process and is hypothesised to be influenced by changes to soil chemical properties such as acidity and ionic strength, which may arise from co-granulation with macronutrients or elemental S oxidation itself. Soil incubation was conducted with a sandy soil from South Australia to assess the effect of acidification and increased ionic strength on bacterial abundance and community composition and on elemental S oxidation during a 14-week incubation at 25 °C and 70% field capacity. Prior to incubation, the soil was treated with HNO₃ to bring the pH to 6.7–4.4 or with KH₂PO₄ to increase the ionic strength by 0–0.7 M. Elemental S was applied at 200 mg kg^?1 air-dried soil. Acidification or increased ionic strength had no or little effect on elemental S oxidation but decreased the abundances of 16S ribosomal deoxyribonucleic acid (rRNA) and soxB genes and changed the bacterial community composition. A second experiment with two other soils also showed that acidification did not, or only slightly, decreased elemental S oxidation, even though acidification strongly reduced 16S rRNA and soxB gene abundances in one of the soils. This study suggests that shifts in bacterial population brought about by temporary changes in pH and ionic strength, as may occur around fertiliser granules, have no or little effect on elemental S oxidation, indicating that the S-oxidising bacterial community in these agricultural soils contains functionally redundant taxa, which responded to changing conditions.     

Modelling the dynamics of intramammary E. coli infections in dairy cows: understanding mechanisms that distinguish transient from persistent infections

The majority of intramammary infections with Escherichia coli in dairy cows result in transient infections with duration of about 10 days or less, although more persistent infections (2 months or longer) have been identified. We apply a mathematical model to explore the role of an intracellular mammary epithelial cell reservoir in the dynamics of infection. We included biological knowledge of the bovine immune response and known characteristics of the bacterial population in both transient and persistent infections. The results indicate that varying the survival duration of the intracellular reservoir reproduces the data for both transient and persistent infections. Survival in an intracellular reservoir is the most likely mechanism that ensures persistence of E. coli infections in mammary glands. Knowledge of the pathogenesis of persistent infections is essential to develop preventive and treatment programmes for these important infections in dairy cows.     

Species interactions in a parasite community drive infection risk in a wildlife population

Most hosts, including humans, are simultaneously or sequentially infected with several parasites. A key question is whether patterns of coinfection arise because infection by one parasite species affects susceptibility to others or because of inherent differences between hosts. We used time-series data from individual hosts in natural populations to analyze patterns of infection risk for a microparasite community, detecting large positive and negative effects of other infections. Patterns remain once variations in host susceptibility and exposure are accounted for. Indeed, effects are typically of greater magnitude, and explain more variation in infection risk, than the effects associated with host and environmental factors more commonly considered in disease studies. We highlight the danger of mistaken inference when considering parasite species in isolation rather than parasite communities.     

Quantitative trait loci of acid detergent fiber and grain chemical composition in hulled × hull-less barley population

Cultivated barley is the major livestock feed grain in the Northern Plains and Northwestern United States due to the fact that its short growing season and limited rainfall limit the planting and production of corn. Starch and fiber content play a significant role in feedlot performance of animals raised on barley feed. To study the underlying genetic locations and mechanisms for these traits, a recombinant inbred line population was derived from a cross between the hulled barley cultivar Valier and a hull-less Swiss landrace line, PI370970. Valier has a high acid detergent fiber content (ADF) and low starch and protein while PI370970 contains low ADF and high starch and protein content. To detect associated QTLs, data were collected and analyzed from irrigated and rain-fed environments. A total of 30 main effect QTLs and four epistatic QTLs were identified which conditioned ADF, starch and protein content under rain-fed, irrigated and combined analyses. These QTLs were located on chromosomes 2H, 3H, 5H, 6H and 7H. Major ADF and starch QTL were identified on chromosome 7H near the nud locus (the locus controlling hulled vs. hull-less caryopsis). High heritability estimates for both ADF and starch content suggest that early selection for these traits during breeding would be productive. Low ADF-QTL were independently verified in a second population in a different genetic background.     

掌握平衡日粮的成分

改善饲料的转换效率,提高养殖效益一直是牧场追求的目标。要实现这一目标,前提是尽可能地降低对环境的影响,同时要最大限度地利用所能利用的饲料资源。对每个牧场来说,饲料资源最重要的是当地可用的粗饲料和粗饲料的质量问题。奶牛场面临的另一个问题是,由于每次购买饲料批次不同和奶牛生活环境变异等原因,     

Factors contributing to the blackspot bruise potential of Idaho potato fields

Blackspot bruise is a major problem in the fresh market and frozen french fry industry. The blackspot bruise potential of Russet Burbank and Ranger Russet in Idaho potato fields was determined by surveying commercial fields during 1993 and 1994. Management factors were monitored to determine what practices were contributing to blackspot susceptibility in addition to mechanical damage. The survey included 17 Russet Burbank and 3 Ranger Russet fields in 1993, and 28 Russet Burbank and 8 Ranger Russet fields in 1994. The 1993 season was unusually cool and wet whereas 1994 was warmer than normal, resulting in a wide range of environmental conditions for the 2 year study. Blackspot bruise potential was determined at different stages of tuber physiological maturity by collecting samples several weeks prior to normal harvest, immediately before harvest, and after storing sub-samples for several months. The blackspot bruise potential was measured by both impact and abrasive peel tests. Field maturity was the factor most consistently related to blackspot potential both years. In 1994 a multiple regression of 3 independent variables — field maturity index, specific gravity, and percent available soil water at tuber sampling, compared with the blackspot potential as the dependent variable gave a correlation coefficient of r = 0.73 (p = 0.001). Due to the cool, wet growing season in 1993, there was not enough variability in specific gravity and available soil water among the fields sampled for these factors to correlate with the blackspot potential. The available fertility data, although not complete for all fields, indicated no direct relationship between N, P, or K fertilization and blackspot potential. Preharvest samples in late August had lower blackspot potential than harvest samples in mid September, and storage samples in February had the highest susceptibility. There was a consistent increase in blackspot severity when tubers were equilibrated at 4 C compared with 10 C prior to bruising.