Above-Ground Biomass Estimation in Oats Using UAV Remote Sensing and Machine Learning

Current strategies for phenotyping above-ground biomass in field breeding nurseries demand significant investment in both time and labor. Unmanned aerial vehicles (UAV) can be used to derive vegetation indices (VIs) with high throughput and could provide an efficient way to predict forage yield with high accuracy. The main objective of the study is to investigate the potential of UAV-based multispectral data and machine learning approaches in the estimation of oat biomass. UAV equipped with a multispectral sensor was flown over three experimental oat fields in Volga, South Shore, and Beresford, South Dakota, USA, throughout the pre- and post-heading growth phases of oats in 2019. A variety of vegetation indices (VIs) derived from UAV-based multispectral imagery were employed to build oat biomass estimation models using four machine-learning algorithms: partial least squares (PLS), support vector machine (SVM), Artificial neural network (ANN), and random forest (RF). The results showed that several VIs derived from the UAV collected images were significantly positively correlated with dry biomass for Volga and Beresford (r = 0.2–0.65), however, in South Shore, VIs were either not significantly or weakly correlated with biomass. For Beresford, approximately 70% of the variance was explained by PLS, RF, and SVM validation models using data collected during the post-heading phase. Likewise for Volga, validation models had lower coefficient of determination (R2 = 0.20–0.25) and higher error (RMSE = 700–800 kg/ha) than training models (R2 = 0.50–0.60; RMSE = 500–690 kg/ha). In South Shore, validation models were only able to explain approx. 15–20% of the variation in biomass, which is possibly due to the insignificant correlation values between VIs and biomass. Overall, this study indicates that airborne remote sensing with machine learning has potential for above-ground biomass estimation in oat breeding nurseries. The main limitation was inconsistent accuracy in model prediction across locations. Multiple-year spectral data, along with the inclusion of textural features like crop surface model (CSM) derived height and volumetric indicators, should be considered in future studies while estimating biophysical parameters like biomass.

Multifunctional Eco-Friendly Synthesis of ZnO Nanoparticles in Biomedical Applications

This study describes an eco-friendly synthesis of ZnO nanoparticles using aqueous oat extract. The advanced electrochemical and optical features of green synthesized ZnONPs displayed excellent antibacterial activity, and exhibited an important role in pharmaceutical determinations. The formation of nanoscale ZnO was confirmed using various spectroscopic and microscopic investigations. The formed nanoparticles were found to be around 100 nm. The as-prepared ZnONPs were monitored for their antibacterial potential against different bacterial strains. The inhibition zones for ZnONPs were found as E. coli (16 mm), P. aeruginosa (17 mm), S. aureus (12 mm) and B. subtilis (11 mm) using 30 µg mL-1 sample concentration. Also, ZnONPs exhibited significant antioxidant effects 58 to 67 % with an average IC50 value of 0.88 ± 0.03 scavenging activity and 53 to 71 % (IC50 value 0.73 ± 0.05) against the DPPH and ABTS scavenging free radicals, respectively. The photocatalytic potential of ZnONPs for Rhodamine B dye degradation dye under UV irradiation was performed. The photodegradation process was carried out as a function of time-dependent and the complete degradation (nearly 98 %) with color removal after 120 min. Conclusively, the synthesized ZnONPs using oat biomass might provide a great promise in the future for biomedical applications.

CHARACTERIZATION OF OAT BIOMASS FOR ENERGY PRODUCTION1

ABSTRACT Biomass produced in agricultural areas stores energy that can be used, contributing to regional development. Among the widely cultivated agricultural species is oats, destined for the production of not only grains and forage, but also biomass. The objective of this study was to characterize oat biomass in terms of the potential for energy generation considering the genetic and cultivation environment variability. Four field experiments were conducted in the state of Paraná and one in the state of São Paulo, Brazil, with black oat (Avena strigosa) and white oat (Avena sativa) cultivars. At the milky grain stage, plants were collected to quantify the production of shoot biomass and its qualitative variables for energy production and energy potential. Biomass yield varied between cultivars and cultivation sites. The mean higher calorific value was 17.9 MJ Kg-1, varying more between cultivation sites than between cultivars, being inversely proportional to the ash content. The contents of carbon, fixed carbon, volatile materials and nitrogen in the biomass did not vary between oat cultivars. The power generation potential varied widely between cultivars and cultivation sites, from 1557 to 3091 KWh ha-1, influenced mainly by the biomass yield, which overlaps the effects of the variations found in biomass quality. We concluded that oats are a species with high potential for use as an energy product, and the selection of the most productive cultivars regionally is crucial.

Kochia (Kochia scoparia) and Wild Oat (Avena fatua) Intraspecific and Interspecific Interference

Kochia (Kochia scoparia) and wild oat (Avena fatua) are highly problematic western Canadian weeds. Wild oat is widely distributed and has been a long-standing agricultural pest across Manitoba, Saskatchewan, and Alberta. Kochia populations are patchy and occur more frequently within the southern regions of the Prairie provinces. Kochia is exhibiting an ever-evolving, aggressive, herbicide resistance survival strategy which may facilitate range expansion. The experimental objective was to study the interspecific and intraspecific interference between wild oat and kochia. The study was developed with the context of kochia tumbleweeds travelling and depositing seed within wild oat infestations. Greenhouse experiments were conducted in Saskatoon, SK. The experimental design was a two factor factorial arranged as a randomized complete block. The main factors were kochia and wild oat pot density at either 0, 1, or 2 plants per pot. Treatment combinations resulted in species ratios of 1:1, 2:1, 1:2, and 2:2, with single species controls. Kochia biomass was reduced by >70% after 3 months of competition with a single wild oat plant. Wild oat biomass was consistently impacted by intraspecific competition, demonstrating a 25 to 50% reduction at the trial end. Kochia interspecific interference with wild oat at a 2:1 ratio did reduce wild oat biomass by 50% but this trend was not consistent across experimental runs. Kochia dispersal through wild oat infestations should induce competitive stress when crop competition is considered. Three-species interference patterns to include western Canadian crops require additional study.

Growth and development of spring crops in competition with oat in the dryland Mediterranean climate of eastern Washington

Weed management during spring crop production in eastern Washington presents many challenges. Many spring crops are weak competitors with weeds. In May of 2010 and 2011, two spring crop trials were initiated near Pullman, WA, to compare the relative competitiveness of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), lentil (Lens culinaris Medik.), and pea (Pisum sativum L.) using cultivated oat (Avena sativa L.) as a surrogate for wild oat (Avena fatua L.) competition. The experiment was arranged as a split-block split-plot design with four replications. One set of main plots included three oat density treatments (0, 63, and 127 plants m−2), while a second set included each crop species. Crop species main plots were then split into subplots of two different seeding rates (recommended and doubled). Crop populations decreased as oat density increased and increased as crop seeding rate increased. As oat density increased, preharvest crop biomass decreased for all crops, while oat biomass and yield increased. Oat biomass and yield were greater in legume plots compared with cereal plots. Increasing oat density decreased yields for all crops, whereas doubling crop seeding rate increased yields for barley and wheat in 2010 and barley in 2011. Compared with legumes, cereals were taller, produced more biomass, and were more competitive with oat.

Influence of tillage, vertical seed distribution, and pyroxasulfone application timing and rate on control of wild oat (Avena fatua L.)

Tillage and new herbicide options may be necessary for the control of herbicide-resistant wild oat. The efficacy of soil-applied herbicides such as pyroxasulfone can be influenced by edaphic factors and weed seed recruitment depth, which varies with tillage system. We investigated the effect of tillage and pyroxasulfone rate when applied in the fall and spring on wild oat biomass at three locations in Alberta in 2014–2015. The vertical position of wild oat seeds, with and without tillage, was examined at each site. Wild oat biomass was greater in untilled plots compared with plots with fall tillage at all locations. In two out of three locations, pyroxasulfone efficacy was superior when applied in the fall compared with spring, possibly influenced by low spring rainfall. A single tillage pass at the Edmonton and Kinsella locations did not affect wild oat seed distribution, but there was an increase in seeds present in the surface layer in the untilled treatment at Lacombe. Tillage, used in combination with soil-applied herbicides, may be an option to achieve acceptable control of herbicide-resistant wild oat.

Altering the competitiveness of tame oat (Avena sativa L.) versus wild oat (Avena fatua L.) with phosphorus and seeding rate

Currently, no in-crop herbicide is registered to control wild oat (Avena fatua L.) in tame oat (Avena sativa L.). Wild oat must be controlled in tame oat using other agronomic practices. The objective of this research was to determine if side-banded phosphorus (P) in combination with seeding rate would increase the competitiveness of tame oat with wild oat, increasing yield and quality. An experiment was conducted from 2003–2005 at Indian Head, SK. The experimental design was a strip-plot design with four replications. The strips were low and high wild oat density. A two-way factorial, seeding rate (150, 250, 350, and 450 plants m−2), and P rate (0, 15, and 30 kg P2O5 ha−1) were seeded across the strips. Phosphorus affected seed density, grain yield, oat biomass, and wild oat fecundity. Seeding rate affected most of the measured variables and interacted with wild oat and year. The application of P increased the competiveness of oat by increasing crop biomass by 7.6% and grain yield by 3.4% and decreasing wild oat seed from 1.26% to 0.76% in the harvested grain. Wild oat decreased grain yield by 23% in 2003, 4.4% in 2004, and 11% in 2005. Increasing the seeding rate increased grain yield by 5% when wild oat was present. Wild oat did not interfere with the uptake of side-banded P. Producers need to use both P fertilization and higher seeding rates to improve the competitiveness of tame oat and the management of wild oat in tame oat.

Removal of chromium (VI) in aqueous solution by oat biomass (Avena sativa)

Chromium (VI) removal capacity in aqueous solution by oat biomass was analyzed by the diphenylcarbazide method. Bioadsorption was evaluated at different pH values (1, 2, 3 and 4) and at different times. The effect of temperature in the range of 28 °C to 60 °C and the removal at different initial Cr (VI) concentrations of 200 to 1000 mg/L were also studied. The highest bioadsorption (100% with 100 mg/L of the metal and 1 g of biomass) was at 8 h, at pH of 1.0 and 28 °C. With regard to temperature, the highest removal was to 60 oC, with a 100% removal at 90 min. Removal was more efficient when higher concentrations of biomass were used (100%, 3 h and 5 g of biomass). Untreated biomass (washed and ground biomass) showed excellent metal removal capacity in situ, 82.6% and 85.3% removal in contaminated soil and water, respectively, after 10 days of incubation, using 25 g of the biomass (100 mL of water). These results show that Cr (VI) can be removed from industrial wastewater using oat biomass.

Diverse Rotations and Optimal Cultural Practices Control Wild Oat (Avena fatua)

In western Canada, more money is spent on wild oat herbicides than on any other weed species, and wild oat resistance to herbicides is the most widespread resistance issue. A direct-seeded field experiment was conducted from 2010 to 2014 at eight Canadian sites to determine crop life cycle, crop species, crop seeding rate, crop usage, and herbicide rate combination effects on wild oat management and canola yield. Combining 2× seeding rates of early-cut barley silage with 2× seeding rates of winter cereals and excluding wild oat herbicides for 3 of 5 yr (2011 to 2013) often led to similar wild oat density, aboveground wild oat biomass, wild oat seed density in the soil, and canola yield as a repeated canola–wheat rotation under a full wild oat herbicide rate regime. Wild oat was similarly well managed after 3 yr of perennial alfalfa without wild oat herbicides. Forgoing wild oat herbicides in only 2 of 5 yr from exclusively summer annual crop rotations resulted in higher wild oat density, biomass, and seed banks. Management systems that effectively combine diverse and optimal cultural practices against weeds, and limit herbicide use, reduce selection pressure for weed resistance to herbicides and prolong the utility of threatened herbicide tools.