Remote sensing of evapotranspiration (ET) can help detect, map and provide guidance for crop water needs in irrigated lands. Two remote sensing ET models based on thermal infrared (TIR), the ...Two-Source Energy Balance (TSEB) and the Satellite-Based Energy Balance for Mapping Evapotranspiration with Internalized Calibration (METRIC), were tested for accuracy, and bias at fine (1m) and moderate (30–120m) spatial scales. Airborne and Landsat data were collected over Maricopa, Arizona in 2009 and 2011 as part of a cotton irrigation scheduling study. Based on soil moisture observations at 112 locations across 4.9ha and image data spanning two growing seasons, TSEB and METRIC were found similarly accurate at both fine and moderate scales with average discrepancies no more than 1.9mm/day. Tests at 1-m scales showed that TSEB and METRIC model sensitivities were seasonally correlated, with greater sensitivity modeled by METRIC in early growth and slightly greater sensitivity by TSEB at maturity. Time integration of flux estimates was done by assuming constant evaporative fraction and was also tested for 2011 data using ground-based TIR radiometers; this latter approach improved daily ET estimates by 0.8mm/day or better in two cases. Time-series assessment of the utility of using evaporative fraction as a water-stress indicator was tested using Landsat data and both TSEB and METRIC. Two early season water depletion events were detected and none in mid-season. The impact of overpass frequency upon ET estimates was tested for the field as a whole and found that cumulative ET estimates were significantly affected, up to 200mm out of ~1000mm consumed. Results from this study showed that for ET accuracy, TSEB and METRIC perform similarly. METRIC is preferred when model ancillary data are sparse, while TSEB is preferred when support data are plentiful. Future ET modeling should consider implementing both to take advantage of their seasonally dependent sensitivities.
•Thermal infrared-based ET remote sensing models, TSEB and METRIC both accurate to 1.9mm/day.•TSEB and METRIC model sensitivities seasonally correlated.•8-day satellite overpass frequency significantly improves ET estimates compared to 16-days.
High-throughput phenotyping platforms (HTPPs) provide novel opportunities to more effectively dissect the genetic basis of drought-adaptive traits. This genome-wide association study (GWAS) compares ...the results obtained with two Unmanned Aerial Vehicles (UAVs) and a ground-based platform used to measure Normalized Difference Vegetation Index (NDVI) in a panel of 248 elite durum wheat (
L. ssp
Desf.) accessions at different growth stages and water regimes. Our results suggest increased ability of aerial over ground-based platforms to detect quantitative trait loci (QTL) for NDVI, particularly under terminal drought stress, with 22 and 16 single QTLs detected, respectively, and accounting for 89.6 vs. 64.7% phenotypic variance based on multiple QTL models. Additionally, the durum panel was investigated for leaf chlorophyll content (SPAD), leaf rolling and dry biomass under terminal drought stress. In total, 46 significant QTLs affected NDVI across platforms, 22 of which showed concomitant effects on leaf greenness, 2 on leaf rolling and 10 on biomass. Among 9 QTL hotspots on chromosomes 1A, 1B, 2B, 4B, 5B, 6B, and 7B that influenced NDVI and other drought-adaptive traits, 8 showed
effects unrelated to phenology.
► Identifying genetic markers for yield requires rapid quantification of crop traits. ► Proximal sensing offers promise for field-based phenotyping (FBP). ► Efficient data integration and ...modeling-assisted analysis are key for FBP. ► FBP scaled to thousands of field plots is a feasible, attainable goal. ► FBP systems require new, integrative collaborations that cross disciplines.
A major challenge for crop research in the 21st century is how to predict crop performance as a function of genetic architecture. Advances in “next generation” DNA sequencing have greatly improved genotyping efficiency and reduced genotyping costs. Methods for characterizing plant traits (phenotypes), however, have much progressed more slowly over the past 30 years, and constraints in phenotyping capability limit our ability to dissect the genetics of quantitative traits, especially those related to harvestable yield and stress tolerance. As a case in point, mapping populations for major crops may consist of 20 or more families, each represented by as many as 200 lines, necessitating field trials with over 20,000 plots at a single location. Investing in the resources and labor needed to quantify even a few agronomic traits for linkage with genetic markers in such massive populations is currently impractical for most breeding programs. Herein, we define key criteria, experimental approaches, equipment and data analysis tools required for robust, high-throughput field-based phenotyping (FBP). The focus is on simultaneous proximal sensing for spectral reflectance, canopy temperature, and plant architecture where a vehicle carrying replicated sets of sensors records data on multiple plots, with the potential to record data throughout the crop life cycle. The potential to assess traits, such as adaptations to water deficits or acute heat stress, several times during a single diurnal cycle is especially valuable for quantifying stress recovery. Simulation modeling and related tools can help estimate physiological traits such as canopy conductance and rooting capacity. Many of the underlying techniques and requisite instruments are available and in use for precision crop management. Further innovations are required to better integrate the functions of multiple instruments and to ensure efficient, robust analysis of the large volumes of data that are anticipated. A complement to the core proximal sensing is high-throughput phenotyping of specific traits such as nutrient status, seed composition, and other biochemical characteristics, as well as underground root architecture. The ability to “ground truth” results with conventional measurements is also necessary. The development of new sensors and imaging systems undoubtedly will continue to improve our ability to phenotype very large experiments or breeding nurseries, with the core FBP abilities achievable through strong interdisciplinary efforts that assemble and adapt existing technologies in novel ways.
Ionizing radiation causes acute radiation syndrome, which leads to hematopoietic, gastrointestinal, and cerebrovascular injuries. We investigated a population of mice that recovered from high-dose ...radiation to live normal life spans. These "elite-survivors" harbored distinct gut microbiota that developed after radiation and protected against radiation-induced damage and death in both germ-free and conventionally housed recipients. Elevated abundances of members of the bacterial taxa
and
were associated with postradiation restoration of hematopoiesis and gastrointestinal repair. These bacteria were also found to be more abundant in leukemia patients undergoing radiotherapy, who also displayed milder gastrointestinal dysfunction. In our study in mice, metabolomics revealed increased fecal concentrations of microbially derived propionate and tryptophan metabolites in elite-survivors. The administration of these metabolites caused long-term radioprotection, mitigation of hematopoietic and gastrointestinal syndromes, and a reduction in proinflammatory responses.
► Cotton plants were subjected to drought and heat stress under field conditions. ► Both drought and heat stresses were associated with water availability. ► Diffusive (drought-induced) and ...biochemical (heat-induced) limitations compromised photosynthetic performance. ► Rubisco inactivation was associated with the inhibition of photosynthesis caused by heat stress.
Heat and drought stresses are often coincident and constitute major factors limiting global crop yields. A better understanding of plant responses to the combination of these stresses under production environments will facilitate efforts to improve yield and water use efficiencies in a climatically changing world. To evaluate photosynthetic performance under dry-hot conditions, four cotton (Gossypium barbadense L.) cultivars, Monseratt Sea Island (MS), Pima 32 (P32), Pima S-6 (S6) and Pima S-7 (S7), were studied under well-watered (WW) and water-limited (WL) conditions at a field site in central Arizona. Differences in canopy temperature and leaf relative water content under WL conditions indicated that, of the four cultivars, MS was the most drought-sensitive and S6 the most drought-tolerant. Net CO2 assimilation rates (A) and stomatal conductances (gs) decreased and leaf temperatures increased in WL compared to WW plants of all cultivars, but MS exhibited the greatest changes. The response of A to the intercellular CO2 concentration (A–Ci) showed that, along with stomatal closure, non-stomatal factors associated with heat stress also limited A under WL conditions, especially in MS. The activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) decreased in WL compared to WW plants, consistent with thermal inhibition of Rubisco activase activity. The extent of Rubisco deactivation could account for the metabolic limitation to photosynthesis in MS. Taken together, these data reveal the complex relationship between water availability and heat stress for field-grown cotton plants in a semi-arid environment. Both diffusive (drought-stress-induced) and biochemical (heat-stress-induced) limitations contributed to decreased photosynthetic performance under dry-hot conditions.
Improvement of crop water use efficiency (CWUE), defined as crop yield per volume of water used, is an important goal for both crop management and breeding. While many technologies have been ...developed for measuring crop water use in crop management studies, rarely have these techniques been applied at the scale of breeding plots. The objective was to develop a high-throughput methodology for quantifying water use in a cotton breeding trial at Maricopa, AZ, USA in 2016 and 2017, using evapotranspiration (ET) measurements from a co-located irrigation management trial to evaluate the approach. Approximately weekly overflights with an unmanned aerial system provided multispectral imagery from which plot-level fractional vegetation cover ( f c ) was computed. The f c data were used to drive a daily ET-based soil water balance model for seasonal crop water use quantification. A mixed model statistical analysis demonstrated that differences in ET and CWUE could be discriminated among eight cotton varieties ( p < 0 . 05 ), which were sown at two planting dates and managed with four irrigation levels. The results permitted breeders to identify cotton varieties with more favorable water use characteristics and higher CWUE, indicating that the methodology could become a useful tool for breeding selection.
The regio- and stereocontrolled functionalisation of carbon-carbon double bonds bears enormous potential in organic synthesis. This area has been extensively studied and reviewed as alkenes are ...amongst the most important starting materials for synthetic chemists, accessible in many varieties and in large quantities. We focus in this tutorial review only on recent developments using iodine electrophiles for the functionalisation of alkenes although transition-mediated reactions and functionalisations with chalcogen electrophiles also play an important role. New synthetic applications using this methodology showing scope and limitations of iodine-mediated processes also within the context of other electrophilic reactions are highlighted.
Background. Elevated interleukin 6 (IL-6) levels have been linked to cardiovascular disease, cancer and death. Persons with human immunodeficiency virus (HIV) infection receiving treatment have ...higher IL-6 levels, but few data are available on factors associated with circulating IL-6. Methods. Participants in 3 trials with IL-6 measured at baseline were included (N = 9864). Factors associated with IL-6 were identified by linear regression. Demographic and HIV variables (nadir/entry CD4⁺ cell count, HIV RNA level, antiretroviral therapy regimen) were investigated in all 3 trials. In the SMART (Strategies for Management of Anti-Retroviral Therapy) trial, CD4/CD8 ratio, smoking, comorbid conditions, serum lipids, renal function (estimated glomerular filtration rate eGFR), and educational level were assessed. Results. Demographics associated with higher IL-6 levels were older age and lower education, whereas black race was associated with lower IL-6. Higher HIV RNA levels were associated with higher IL-6 levels, and higher nadir CD4⁺ cell counts with lower IL-6 levels. Compared with efavirenz, protease inhibitors were associated with higher and nevirapine with lower IL-6 levels. Smoking and all comorbid conditions were related to higher IL-6. IL-6 levels increased with decreasing eGFR and decreasing serum lipids. Conclusions. Higher levels of IL-6 were associated with older age, nonblack race, higher body mass index, lower serum lipid levels, HIV replication, low nadir CD4⁺ cell count, protease inhibitor use, comorbid conditions, and decreased eGFR. Multiple factors affect inflammation in HIV and should be considered in studies of IL-6 as a biomarker of clinical outcomes.
PDF
