Absorbance-modulated lithography is a relatively new optical patterning method where a thin layer of photochromic molecules is placed between the far-field optics and photoresist. These molecules can ...be made transparent or opaque by illuminating with wavelengths λ1 or λ2, respectively. By simultaneously illuminating this layer with patterns of both wavelengths it is possible to create an absorption mask capable of subwavelength resolution. This resolution comes at the price of limited contrast and depth-of-focus resulting in poor process latitude. Here it is shown that by using TM polarization for λ1 and integrating a plasmonic reflector process latitude is increased by up to 66%.
Radiation use efficiency can be predicted with ~70% accuracy. Canopy water content, greenness, and gas exchange spectral indices are the best predictors for RUE, biomass accumulation, and light ...interception.
Abstract
Wheat yields are stagnating or declining in many regions, requiring efforts to improve the light conversion efficiency, known as radiation use efficiency (RUE). RUE is a key trait in plant physiology because it links light capture and primary metabolism with biomass accumulation and yield, but its measurement is time consuming and this has limited its use in fundamental research and large-scale physiological breeding. In this study, high-throughput plant phenotyping (HTPP) approaches were used among a population of field-grown wheat with variation in RUE and photosynthetic traits to build predictive models of RUE, biomass, and intercepted photosynthetically active radiation (IPAR). Three approaches were used: best combination of sensors; canopy vegetation indices; and partial least squares regression. The use of remote sensing models predicted RUE with up to 70% accuracy compared with ground truth data. Water indices and canopy greenness indices normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) are the better option to predict RUE, biomass, and IPAR, and indices related to gas exchange, non-photochemical quenching photochemical reflectance index (PRI) and senescence structural-insensitive pigment index (SIPI) are better predictors for these traits at the vegetative and grain-filling stages, respectively. These models will be instrumental to explain canopy processes, improve crop growth and yield modelling, and potentially be used to predict RUE in different crops or ecosystems.
Objective Objective structured clinical examinations (OSCE) are widely used for summative assessment in surgery. Despite standardizing these as much as possible, variation, including examiner ...scoring, can occur which may affect reliability. In study of a high-stakes UK postgraduate surgical OSCE, we investigated whether examiners changing stations once during a long examining day affected marking, reliability, and overall candidates’ scores compared with examiners who examined the same scenario all day. Design, Setting, and Participants An observational study of 18,262 examiner-candidate interactions from the UK Membership of the Royal College of Surgeons examination was carried at 3 Surgical Colleges across the United Kingdom. Scores between examiners were compared using analysis of variance. Examination reliability was assessed with Cronbach’s alpha, and the comparative distribution of total candidates’ scores for each day was evaluated using t -tests of unit-weighted z scores. Results A significant difference was found in absolute scores differences awarded in the morning and afternoon sessions between examiners who changed stations at lunchtime and those who did not (p < 0.001). No significant differences were found for the main effects of either broad content area (p = 0.290) or station content area (p = 0.450). The reliability of each day was not affected by examiner switching (p = 0.280). Overall, no difference was found in z -score distribution of total candidate scores and categories of examiner switching. Conclusions This large study has found that although the range of marks awarded varied when examiners change OSCE stations, examination reliability and the likely candidate outcome were not affected. These results may have implications for examination design and examiner experience in surgical OSCEs and beyond.
Root architecture impacts water and nutrient uptake efficiency. Identifying exactly which root architectural properties influence these agronomic traits can prove challenging. In this paper, ...approximately 300 wheat (Triticum aestivum) plants were divided into four groups using two binary classifications, high versus low nitrogen uptake efficiency (NUpE), and high versus low nitrate in the growth medium. The root system architecture for each wheat plant was captured using 16 quantitative variables. The multivariate analysis tool, linear discriminant analysis, was used to construct composite variables, each a linear combination of the original variables, such that the score of the plants on the new variables showed the maximum between-group variability. The results show that the distribution of root-system architecture traits differs between low- and high-NUpE plants and, less strongly, between low-NUpE plants grown on low versus high nitrate media.
Embryo and caryopsis dormancy, abscisic acid (ABA) responsiveness, after-ripening (AR), and the disorder pre-harvest sprouting (PHS) were investigated in six genetically related wheat varieties ...previously characterized as resistant, intermediate, or susceptible to PHS. Timing of caryopsis AR differed between varieties; AR occurred before harvest ripeness in the most PHS-susceptible, whereas AR was slowest in the most PHS-resistant. Whole caryopses of all varieties showed little ABA-responsiveness during AR; PHS-susceptible varieties were responsive at the beginning of the AR period whereas PHS-resistant showed some responsiveness throughout. Isolated embryos showed relatively little dormancy during grain-filling and most varieties exhibited a window of decreased ABA-responsiveness around the period of maximum dry matter accumulation (physiological maturity). Susceptibility to PHS was assessed by overhead misting of either isolated ears or whole plants during AR; varieties were clearly distinguished using both methods. These analyses allowed an investigation of the interactions between the different components of seed development, compartments, and environment for the six varieties. There was no direct relationship between speed of caryopsis AR and embryo dormancy or ABA-responsiveness during seed maturation. However, the velocity of AR of a variety was closely associated with the degree of susceptibility to PHS during AR suggesting that these characters are developmentally linked. Investigation of genetic components of AR may therefore aid breeding approaches to reduce susceptibility to PHS.
The appearance of blotch/ tiger stripe on chickpea seeds is a genotype-specific seed marking which, although not considered a defect during seed inspection, is often rejected based on consumer trait ...preferences.
This study aimed to investigate the expression of blotch/tiger stripe, thousand grain weight (TGW) and days to podding in Australian desi-type chickpea.
A single seed-descent mapping population of 242 F7 derived progeny lines was selected from a controlled cross of two homozygous parent genotypes, PBA Slasher x Sonali. An independent set of nineteen cultivars/advanced genotypes was used to validate the results of the mapping population. Field trials were carried out over two years in Narrabri, north-western NSW, Australia. We phenotypically analysed the mapping population and validation set of cultivars/genotypes for the proportion of blotch/tiger stripe and then carried out composite interval mapping QTL analysis to identify genetic loci linked with the traits of interest. Significant markers that were identified in the mapping population were validated on the additional nineteen cultivars/genotypes.
Significant phenotypic variation in the expression of blotch/tiger stripe was observed (P<0.001) and blotch/tiger stripe was found to be highly heritable (H2 = 0.98). TGW of seeds marked with blotch/tiger stripe (200.9 g) was significantly lower than that of unmarked seeds (208.2 g) (P<0.001). Five Quantitative Trait Loci (QTL) relating to blotch/tiger stripe were identified consistently across the two seasons. A major QTL linked with the reduced expression of blotch/tiger stripe was identified at QTL 1 which reduced the expression of the trait by up to 9.92%. KASP (Kompetitive Allele-specific PCR) markers were developed for this locus and validated in the set of nineteen cultivars/genotypes in which 13–19% of phenotypic variation was accounted for.
Significant phenotypic variation in the expression of blotch/tiger stripe was observed and the trait was found to be highly heritable. Five QTL relating to blotch/tiger stripe were identified and the region at QTL 1 was identified as a candidate for fine mapping to determine the genetic variant which is responsible for the trait. KASP markers developed in this study will be of value to breeders, allowing marker assisted selection (MAS) to screen for this trait in the absence of phenotypic symptoms.
This study will benefit the chickpea industry by increasing industry awareness of the marking and reducing the prevalence of blotch/tiger stripe in breeding germplasm, therefore reducing seed rejection and protecting grower profits.
•Blotch/tiger stripe is an often rejected based on consumer trait preferences.•Blotch/tiger stripe is highly heritable.•Five QTLs for blotch/tiger stripe were identified.•KASP markers were developed which will be of use for Marker Assisted Selection.
Nitrogen fertilizer is the most used nutrient source in modern agriculture and represents significant environmental and production costs. In the meantime, the demand for grain increases and ...production per area has to increase as new cultivated areas are scarce. In this context, breeding for an efficient use of nitrogen became a major objective. In wheat, nitrogen is required to maintain a photosynthetically active canopy ensuring grain yield and to produce grain storage proteins that are generally needed to maintain a high end‐use quality. This review presents current knowledge of physiological, metabolic and genetic factors influencing nitrogen uptake and utilization in the context of different nitrogen management systems. This includes the role of root system and its interactions with microorganisms, nitrate assimilation and its relationship with photosynthesis as postanthesis remobilization and nitrogen partitioning. Regarding nitrogen‐use efficiency complexity, several physiological avenues for increasing it were discussed and their phenotyping methods were reviewed. Phenotypic and molecular breeding strategies were also reviewed and discussed regarding nitrogen regimes and genetic diversity.
Human observers can perceive their direction of heading with a precision of about a degree. Several computational models of the processes underpinning the perception of heading have been proposed. In ...the present study we set out to assess which of four candidate models best captured human performance; the four models we selected reflected key differences in terms of approach and methods to modelling optic flow processing to recover movement parameters. We first generated a performance profile for human observers by measuring how performance changed as we systematically manipulated both the quantity (number of dots in the stimulus per frame) and quality (amount of 2D directional noise) of the flow field information. We then generated comparable performance profiles for the four candidate models. Models varied markedly in terms of both their performance and similarity to human data. To formally assess the match between the models and human performance we regressed the output of each of the four models against human performance data. We were able to rule out two models that produced very different performance profiles to human observers. The remaining two shared some similarities with human performance profiles in terms of the magnitude and pattern of thresholds. However none of the models tested could capture all aspect of the human data.
Rising demands for protein worldwide are likely to drive increases in livestock production, as meat provides ∼40% of dietary protein. This will come at a significant environmental cost, and a shift ...toward plant-based protein sources would therefore provide major benefits. Although legumes provide substantial amounts of plant-based protein, cereals are the major constituents of global foods, with wheat alone accounting for 15%–20% of required dietary protein intake. Improvement of protein content in wheat is limited by phenotyping challenges, lack of genetic potential of modern germplasms, negative yield trade-offs, and environmental costs of nitrogen fertilizers. Using wheat as a case study, we discuss how increasing the protein content of cereals through a revised breeding strategy combined with robust phenotyping could ensure a sustainable protein supply while minimizing the environmental impact of nitrogen fertilizer.
The nutritional quality of food is a growing challenge, as global demand for protein production is predicted to double by 2050. Cereals supply a large proportion of global caloric and protein needs, and they provide a more environmentally friendly option for sustainable protein production than livestock. With new information on the effects of altered plant vasculature and senescence on grain protein levels, there are new opportunities for cereals to make a significant contribution to overall protein supply.
Photosynthetic acclimation (photoacclimation) is the process whereby leaves alter their morphology and/or biochemistry to optimize photosynthetic efficiency and productivity according to long-term ...changes in the light environment. The three-dimensional architecture of plant canopies imposes complex light dynamics, but the drivers for photoacclimation in such fluctuating environments are poorly understood. A technique for high-resolution three-dimensional reconstruction was combined with ray tracing to simulate a daily time course of radiation profiles for architecturally contrasting field-grown wheat (Triticum aestivum) canopies. An empirical model of photoacclimation was adapted to predict the optimal distribution of photosynthesis according to the fluctuating light patterns throughout the canopies. While the photoacclimation model output showed good correlation with field-measured gas-exchange data at the top of the canopy, it predicted a lower optimal light-saturated rate of photosynthesis at the base. Leaf Rubisco and protein contents were consistent with the measured optimal light-saturated rate of photosynthesis. We conclude that, although the photosynthetic capacity of leaves is high enough to exploit brief periods of high light within the canopy (particularly toward the base), the frequency and duration of such sunflecks are too small to make acclimation a viable strategy in terms of carbon gain. This suboptimal acclimation renders a large portion of residual photosynthetic capacity unused and reduces photosynthetic nitrogen use efficiency at the canopy level, with further implications for photosynthetic productivity. It is argued that (1) this represents an untapped source of photosynthetic potential and (2) canopy nitrogen could be lowered with no detriment to carbon gain or grain protein content.
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