Relay intercropping improves growth and fiber quality of Bt Cotton

The optimal time of wheat harvest is the second fortnight of April, while Bt cotton is sown in March in cotton-based cropping systems of Pakistan. There is a time conflict of four to six weeks between harvesting of wheat and sowing of Bt cotton. Relay-intercropping of cotton in wheat crop near to maturity could help to resolve the conflict. The information regarding the effect of relay-intercropping on growth and quality of cotton is scanty. This two-year study compared the growth and fiber quality of relay-intercropped Bt cotton (sown in early/late March) in standing wheat crop with conventionally-tilled (CT) cotton planted after wheat harvest in late April. The relay-intercropped cotton was sown on ridges/beds in wheat, whereas CT cotton was sown after wheat harvest in late April or sown on fallow land in early or late March at Multan and Vehari sites. The CT Bt cotton grown on fallow land in early March had the best performance as indicated by plant growth and fiber quality. However, the relay-intercropped Bt cotton in bed-sown wheat had better growth and fiber quality than the CT cotton planted after wheat harvest in late April. At both sites, the taller plants and higher biomass production were recorded in relay-intercropped Bt cotton in bed-sown wheat in early March as compared with the CT cotton sown after harvest of flat-sown wheat in late April. Fiber firmness, its uniformity, length and strength were also improved in the relay-intercropped Bt cotton in bed-sown wheat in early March as compared to CT cotton sown after wheat harvest in late April. In conclusion, relay intercropping of Bt cotton in the standing wheat during early March improved plant growth and fiber quality in cotton-wheat cropping system

The influence of different row spacing and weed control intervals on weed infestation and yield-related traits of American (Gossypium hirsutum L.) and Desi (Gossypium arboreum) cotton

Narrow row spacing has attracted significant attention due to its beneficial impacts on weed management in cotton. This study compared the effects of normal and ultra-narrow row spacing on critical periods of weed control in American (Gossypium hirsutum L.) and ‘Desi’ (Gossypium arboreum) cotton. Two different row spacings (i.e., recommended (75 cm) and ultra-narrow (30 cm)) and three weed control intervals (i.e., weed control at 30, 60 and 90 days after sowing (DAS)) were included in the study. Weedy-check and weed-free treatments were included in the experiment as controls for comparison. ‘Desi’ cotton grown under ultra-narrow spacing recorded the lowest weed density and individual density of Trianthema portulacastarum L., Cyperus rotundus L., Cynodon dactylon L., Echinochloa colona (L.) Link and Digera muricata (L.) Mart. Moreover, ‘Desi’ cotton sown under ultra-narrow spacing with weed-free and weed control at 30 DAS resulted in the highest leaf area index (LAI), leaf area duration (LAD), net assimilation late (NAR), root elongation rate (RER) and root growth rate (RGR) at all sampling dates. Likewise, ‘desi’ cotton sown under recommended row spacing and weed-free conditions produced the highest number of sympodial and monopodial branches, number of flowers and bolls per plant, whereas the highest seed cotton yield of ‘Desi’ cotton was noted under ultra-narrow spacing and weed-free conditions. It is concluded that sowing both cotton types in ultra-narrow row spacing and controlling weeds at 30 DAS will result in lower weed infestation and higher seed cotton yield

Impact of different mulching treatments on weed flora and productivity of maize (Zea mays L.) and sunflower (Helianthus annuus L.)

The concerns on weed control through herbicides are increasing due to their negative impacts on environment and human health. Therefore, alternative weed management methods are inevitable for sustainable crop production and lowering the negative consequences of herbicides. Mulching is an environment-friendly weed management approach capable of substituting herbicides to significant extent. Therefore, this study evaluated the role of different mulching treatments on suppressing weed flora in maize (Zea mays L.) and sunflower (Helianthus annuus L.) crops. Furthermore, the impact of different mulching treatments on the productivity of both crops was also investigated. Three mulch treatments, i.e., plastic mulch (PLM), sorghum mulch (SM) and paper mulch (PM) along with two controls, i.e., weed-free (WF) and weedy-check (WC) were included in the study. Different mulch treatments significantly altered weed flora in both crops. The PLM and PM resulted in the highest suppression (43–47%) of weed flora compared to WC treatment in both crops. The highest and the lowest weed diversity was recorded for WC and WF treatments, respectively. Different allometric traits, i.e., leaf area index, crop growth rate and root length of both crops were significantly improved by PLM as compared to the WC. Overall, maize crop recorded higher density of individual and total weeds compared to sunflower with WC treatment. The density of individual and total weeds was significantly lowered by PLM compared to WC treatment in both crops. Similarly, higher growth and yield-related traits of both crops were noted with PLM compared to the rest of the mulching treatments. Results of the current study warrant that PLM could suppress weed flora and improve the productivity of both crops. However, PLM alone could not provide 100% control over weed flora; therefore, it should be combined with other weed management approaches for successful weed control in both crops

The Fine Line Between Normal and Starburst Galaxies

Recent literature suggests that there are two modes through which galaxies grow their stellar mass - a normal mode characterized by quasi-steady star formation, and a highly efficient starburst mode possibly triggered by stochastic events such as galaxy mergers. While these differences are established for extreme cases, the population of galaxies in-between these two regimes is poorly studied and it is not clear where the transition between these two modes of star formation occurs. We utilize ALMA observations of the CO J=3-2 line luminosity in a sample of 20 infrared luminous galaxies that lie in the intermediate range between normal and starburst galaxies at z ~ 0.25-0.6 in the COSMOS field to examine the gas content and star formation efficiency of these galaxies. We compare these quantities to the galaxies' deviation from the well-studied "main sequence" correlation between star formation rate and stellar mass (MS) and find that at log($SFR/SFR_{MS}$) < 0.6, a galaxy's distance to the main sequence is mostly driven by increased gas content, and not a more efficient star formation process.Comment: 21 pages, 10 figure

Biomechanical comparison of screw-based zoning of PHILOS and Fx proximal humerus plates

Background Treatment of proximal humerus fractures with locking plates is associated with complications. We aimed to compare the biomechanical effects of removing screws and blade of a fixed angle locking plate and hybrid blade plate, on a two-part fracture model. Methods Forty-five synthetic humeri were divided into nine groups where four were implanted with a hybrid blade plate and the remaining with locking plate, to treat a two-part surgical neck fracture. Plates’ head screws and blades were divided into zones based on their distance from fracture site. Two groups acted as a control for each plate and the remaining seven had either a vacant zone or blade swapped with screws. For elastic cantilever bending, humeral head was fixed and the shaft was displaced 5 mm in extension, flexion, valgus and varus direction. Specimens were further loaded in varus direction to investigate their plastic behaviour. Results In both plates, removal of inferomedial screws or blade led to a significantly larger drop in varus construct stiffness than other zones. In blade plate, insertion of screws in place of blade significantly increased the mean extension, flexion valgus and varus bending stiffness (24.458%/16.623%/19.493%/14.137%). In locking plate, removal of screw zones proximal to the inferomedial screws reduced extension and flexion bending stiffness by 26–33%. Conclusions Although medial support improved varus stability, two inferomedial screws were more effective than blade. Proximal screws are important for extension and flexion. Mechanical consequences of screw removal should be considered when deciding the number and choice of screws and blade in clinic

Morpho-physiological diversity and its implications for improving drought tolerance in grain sorghum at different growth stages

Abstract Sorghum grown under rain-fed conditions is usually affected by drought stress at different stages resulting in negative effect on yield. The assessment and quantification of morpho-physiological diversity for the traits contributing towards drought tolerance at these stages is of vital importance. For this purpose, drought stress was imposed on 44 sorghum accessions at seedling stage and natural incidence of water stress at post anthesis stage. The data of 21 different morpho-physiological traits were subjected to different multivariate techniques, including correlation, principal component (PC) and cluster analysis to assess the diversity for drought tolerance in sorghum. The correlation analysis revealed that selection for long roots; higher root/shoot ratio, leaf area and leaf dry matter could be performed simultaneously. There was positive association between relative water contents and cell membrane stability but both of these traits were negatively correlated with residual transpiration and excised leaf weight loss. Principal component (PC) analysis showed first 7 PCs having Eigen value &gt;1 explaining 77.653% of the total variation with head width, head weight, grain yield per plant, fresh and dry shoot weight being the most important characters in PC1. Cluster analysis classified 44 accessions into four divergent groups. The members of first two clusters exhibited adequate degree of drought tolerance on the basis of majority of morpho-physiological traits, whereas, cluster 3 and 4 included genotypes with lower level of drought tolerance. The D 2 statistics revealed the highest distances between 2 nd and 3 rd clusters, while 3 rd and 4 th clusters displayed maximum similarity. Scatter plot and tree diagrams demonstrated sufficient diversity among the sorghum accession for various traits and some extent of association between different clusters. The results concluded that morpho-physiological diversity in the studied material is structured by genotypes and this diversity could be utilized for cultivar breeding and germplasm conservation programs aimed at improving drought tolerance in sorghum

Parametric design optimisation of proximal humerus plates based on finite element method

Optimal treatment of proximal humerus fractures remains controversial. Locking plates offer theoretical advantages but are associated with complications in the clinic. This study aimed to perform parametric design optimisation of proximal humerus plates to enhance their mechanical performance. A finite element (FE) model was developed that simulated a two-part proximal humerus fracture that had been treated with a Spatial Subchondral Support (S3) plate and subjected to varus bending. The FE model was validated against in vitro biomechanical test results. The predicted load required to apply 5 mm cantilever varus bending was only 0.728% lower. The FE model was then used to conduct a parametric optimisation study to determine the orientations of inferomedial plate screws that would yield minimum fracture gap change (i.e. optimal stability). The feasible design space was automatically identified by imposing clinically relevant constraints, and the creation process of each FE model for the design optimisation was automated. Consequently, 538 FE models were generated, from which the obtained optimal model had 4.686% lower fracture gap change (0.156 mm) than that of the manufacturer’s standard plate. Whereas its screws were oriented towards the inferomedial region and within the range of neck-shaft angle of a healthy subject. The methodology presented in this study promises future applications in patient-specific design optimisation of implants for other regions of the human body

Mechanical weed control

Evolution of herbicide resistance in weeds has increased the importance and scope of mechanical weed control. In many parts of the world, the efficacy of mechanical weed control has been reevaluated. Tillage (used for soil preparation for planting), although among the oldest methods of weed control, is still the preferred method of weed control for many farmers. Similarly, subsequent weeding (weed removal through manual or mechanical means) after the crop emergence is also a successful tool for effective weed management. Wise use of mechanical weeding can provide effective weed control in vegetables, fruits, and field crops. The use/choice of mechanical weeding method depends upon technical and economic factors. Weeds evolving herbicide resistance ultimately required either tillage, weeding, or other non-chemical methods; nevertheless, tillage has been considered the most effective among all non-chemical weed control methods. Development of intelligent weeders or automatic weeding tools may revolutionize mechanical weed control through the selective use of weeders in crops. However, a great deal of research work and investment is needed to develop robotic weeders, which are capable of functioning without human intervention for automated weed control in the future. © 2018 Elsevier Inc. All rights reserved