Control of Imperata cylindrica (L.) Raeuschel (speargrass) with nicosulfuron and its effects on the growth, grain yield and food components of maize

Imperata cylindrica (speargrass) is one of the most invasive weeds in the moist savannah zone of sub-saharan Africa. This study was conducted in 2001 and 2002 at Ijaye and Ilorin, Nigeria, to investigate the influence of four nicosulfuron doses (35, 70, 105, and 210 g a.i./ha) on the performance of maize, and its efficacy in the control of Imperata. The experiment was designed as a split-plot with three replications. Nicosulfuron was applied 2 weeks after planting maize. Hoe weeded and unweeded treatments were controls. In both years, 7 weeks after treatment, the unweeded control had lower maize leaf area index (LAI) (19% at Ijaye and 25% at Ilorin) than the weeded control. Maize LAI was highest in plots that received 35 g a.i./ha of nicosulfuron at Ijaye and the weeded control at Ilorin in both years. All plots that received nicosulfuron had significantly higher maize grain yield than the unweeded control at both locations in both years. Maize grain yield in the weeded control was similar to plots that received nicosulfuron at 35–210 g a.i./ha at Ijaye in 2002, 70–210 g a.i./ha at Ilorin in 2001, and 35 g a.i./ha at Ilorin in 2002. The protein content of maize in the weeded control and at 70 g a.i./ha was similar and higher than that at doses of 105 and 210 g a.i./ha while the carbohydrate content was not significantly different. The unweeded control had significantly higher weed LAI, shoot and rhizome biomass than all other treatments at both locations in both years . An increase in the nicosulfuron dose led to a decrease in weed LAI. Imperata rhizome biomass in the weeded control was similar to that in all nicosulfuron-treated plots. The findings of this study show that nicosulfuron is a suitable postemergence herbicide for speargrass control in maize in the moist savannah of Nigeria

Phylogenomics and the rise of the angiosperms

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods1,2. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome3,4. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins5,6,7. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes8. This 15-fold increase in genus-level sampling relative to comparable nuclear studies9 provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical science. © The Author(s) 2019. Published by Oxford University Press