Maple Seeds Research Articles

Effects of wing loading on the aerodynamic characteristics of autorotating maple seeds

Natural maple seeds can fall into stable autorotation when descending. Their excellent aerodynamic performance can be applied to biomimetic aircraft design. Wing loading plays an important role in flight performance. To make clear the effects of wing loading on the aerodynamic characteristics of autorotating maple seeds, experiments integrated with numerical simulation were performed. In the experiment, the free fall test and the wind tunnel test were conducted on maple seeds with variable wing loadings. During the free fall process, four typical stages can be divided for the maple seed according to different kinematic characteristics. In the numerical simulation, the Moving Reference Frame method was used to simulate the fluid of autorotating maple seeds. Both experiment and simulation results show that descending velocities and spinning rates rise almost linearly with the increase in wing loadings, and descending velocity is closely related to spinning rate. Obvious leading-edge vortexes were observed on seed wing, which are the flow mechanism of high lift. The pressure differences between the top and lower surfaces of seeds grow with increasing wing loadings. Larger wing loadings lead to more serious separation of leading-edge vortex. The parameter influence analysis demonstrates that smaller conning angles or larger spinning rates are beneficial for high-lift flight. The spinning rate has a more significant effect on the autorotating maple seeds. However, when the spinning rate is larger than 200 rad/s, the lift does not increase anymore. The spinning rate should be controlled smaller than 200 rad/s when applied to biomimetic aircraft.

Functional bio-inspired hybrid fliers with separated ring and leading edge vortices.

Recent advances in passive flying systems inspired by wind-dispersed seeds contribute to increasing interest in their use for remote sensing applications across large spatial domains in the Lagrangian frame of reference. These concepts create possibilities for developing and studying structures with performance characteristics and operating mechanisms that lie beyond those found in nature. Here, we demonstrate a hybrid flier system, fabricated through a process of controlled buckling, to yield unusual geometries optimized for flight. Specifically, these constructs simultaneously exploit distinct fluid phenomena, including separated vortex rings from features that resemble those of dandelion seeds and the leading-edge vortices derived from behaviors of maple seeds. Advanced experimental measurements and computational simulations of the aerodynamics and induced flow physics of these hybrid fliers establish a concise, scalable analytical framework for understanding their flight mechanisms. Demonstrations with functional payloads in various forms, including bioresorbable, colorimetric, gas-sensing, and light-emitting platforms, illustrate examples with diverse capabilities in sensing and tracking.

Bioinspired rotary flight of light-driven composite films

Light-driven actuators have great potential in different types of applications. However, it is still challenging to apply them in flying devices owing to their slow response, small deflection and force output and low frequency response. Herein, inspired by the structure of vine maple seeds, we report a helicopter-like rotary flying photoactuator (in response to 0.6 W/cm2 near-infrared (NIR) light) with ultrafast rotation (~7200 revolutions per minute) and rapid response (~650 ms). This photoactuator is operated based on a fundamentally different mechanism that depends on the synergistic interactions between the photothermal graphene and the hygroscopic agar/silk fibroin components, the subsequent aerodynamically favorable airscrew formation, the jet propulsion, and the aerodynamics-based flying. The soft helicopter-like photoactuator exhibits controlled flight and steering behaviors, making it promising for applications in soft robotics and other miniature devices.

Modeling, Control and Implementation of Adaptive Reconfigurable ROtary Wings (ARROWs)

Inspired by the self-rotating motion of the descending maple seeds, we introduce a novel modular aerial robotic platform—ARROWs. With customized wing and control modules, ARROWs can be easily reassembled into different configurations. Unlike conventional multirotor aerial vehicles which rely on the direct thrust from propellers, ARROWs can generate more lift by their revolving wings. However, the complex dynamics causes difficulties in flight controller development. In this work, we first analyze the flight dynamics by considering a combination of effects from the propeller, aerodynamic force on the wing, as well as self-rotating motion. As a result, a cascaded flight controller with a unified framework is designed based on reduced flight dynamics and relaxed hovering conditions to achieve stable flights in all proposed configurations. In addition, a set of inertial measurement units is employed for each flight module to estimate the flight configuration to overcome the dynamic uncertainties caused by manual re-construction. Finally, our proposed platform and flight control strategy are validated using several flight experiments in 12 different configurations (include both centrosymmetric and centrally asymmetric cases). The results show an average position error of 8.9 cm with a deviation of 2.4 cm among all configurations in hovering tests.

A Self-Rotary Aerial Robot With Passive Compliant Variable-Pitch Wings

Inspired by maple seeds, the self-rotary winged aerial robots reflect the advantages of both multi-rotor aircraft and fixed-wing robots. However, their self-rotating speed is related to the takeoff weight, which may affect their application and flight stabilization. To provide a practical and feasible solution, this work proposes a passive compliant variable-pitch mechanism on the self-rotary winged aircraft without requiring extra actuators. Depending on the weight of the payload, the pitching angle of the wings can be passively varied to minimize the increase in the rotating speed and enhance attitude stabilization ability. Besides, an adaptive attitude controller is also designed to address the challenges in attitude stabilization, which are caused by parameter uncertainties and the variable pitching angle. To elaborate on the design and fabrication of the prototype, necessary identification experiments are arranged to find the relationship of pitching angle, thrust generation, power draw, and rotating speed. The experimental findings indicate the proposed robot with optimal pitch angles achieves around 56.8% more power loading than using propellers directly, from 4.4 to 6.9 g/w. The combination of the passive compliant mechanism and adaptive controller improves flight performance from 0.16 to 0.08 meters (mean of absolute translational error).

An experimental study of the aerodynamic performance of a maple wing model at low Reynolds numbers

Maple seeds are widely known for their autorotation and may achieve remarkably long-distance flights owing to their unique wing morphology. These features suggest the adaptability of the blades to wind turbines and air vehicles. However, the effects of these morphological features on aerodynamic force generation are still poorly understood. An enlarged replica of a sample 3D maple wing was produced using additive manufacturing. Direct force experiments were conducted in a low-speed wind tunnel using a two-component force balance to obtain the lift and drag coefficients of the model wing. The polar curves of the wing were obtained for three different Re numbers by repeating the experiments over a wide angle of attack range of -50 to 50°. The best aerodynamic performance is obtained at 18° and -12° attack angles for positive and negative angles, respectively, regardless of the Re number. This preliminary study shows that maple seed can be mimicked in the design of propellers and wind-turbine blades.

The chances in the redox priming of nondormant recalcitrant seeds by spermidine.

The problems posed by seed sensitivity to desiccation and aging have motivated the development of various techniques for mitigating their detrimental effects. The redox priming of seeds in antioxidant solution to improve their postharvest performance is one of the approaches. Spermidine (Spd) was tested as an invigorating solution on nondormant recalcitrant (desiccation sensitive) seeds of the silver maple (Acer saccharinum L.). The treatment resulted in an 8-10% increase in germination capacity in seeds subjected to mild and severe desiccation, while in aged seeds stored for six months, no significant change was observed. The cellular redox milieu, genetic stability, mitochondrial structure and function were investigated to provide information about the cellular targets of Spd activity. Spd improved the antioxidative capacity, especially the activity of catalase, and cellular membrane stability, protected genome integrity from oxidative damage and increased the efficiency of mitochondria. However, it also elicited a hydrogen peroxide burst. Therefore, it seems that redox priming in nondormant seeds that are highly sensitive to desiccation, although positively affected desiccated seed performance, may not be a simple solution to reinvigorate stored seeds with a low-efficiency antioxidant system.

Tracking maple seeds falling through wind

Single-winged maple seeds in a crosswind reveal surprising bimodal dynamics.

Particle image velocimetry measurements of the flow structures induced by the free-falling spin flight of maple seeds

Most measurements of flow field caused by a rotating maple seed were performed in a vertical wind tunnel limited to fixing the vertical axis to simulate the stable falling spin period. In the nature, however, the free-falling motion of maple seeds induces airflow, which makes the seeds spin and generates lift to reduce falling speed. In this study, the flow structures around free-falling Japanese maple seeds in spin are measured using particle image velocimetry. In general, the free-falling spin flight of a seed is divided into three stages: transition period I, transition period II, and the stable period. In transition period II, it can be observed that the sizes of wingtip and root vortices increase with decreasing coning angle of the seed wing and result in an increase in seed rotation speed and decrease in free-falling speed. We also find that the flow structures induced by the free-falling motion of the maple seed in the stable period are different from those that suspend the rotation seed in a vertical wind tunnel. The leading-edge vortex (LEV) and trailing-edge vortex (TEV) are observed above the front of the leading edge and at the top back of the trailing edge, respectively. The position of the LEV core is located above the front of the leading edge, and it gradually approaches the leading edge of the seed along the spanwise direction, toward the wing tip. As the seed enters the stable period, the root vortex shrinks, and the tip vortex grows.

Regional variation drives differences in microbial communities associated with sugar maple across a latitudinal range.

Climate change is prompting plants to migrate and establish novel interactions in new habitats. Because of the pivotal roles that microbes have on plant health and function, it is important to understand the ecological consequences of these shifts in host-microbe interactions with range expansion. Here we examine how the diversity of plant-associated microbes varies along the host's current range and extended range according with climate change predictions, and assess the relative influence of host genotype (seed provenance) and environment in structuring the host microbiome. We collected sugar maple seeds from across the species current range, then planted them in temperate and mixedwood/transitional forests (current range) and in the boreal region (beyond range but predicted future range in response to climate change). We used amplicon sequencing to quantify bacterial, fungal, and mycorrhizal communities from seedling leaves and roots. Variation among sites and regions were the main drivers of the differences in host microbial communities, whereas seed provenance did not play a large role. No unifying pattern was observed for microbial community richness, diversity, or specialization, demonstrating the complexity of responses of different taxa on above- and belowground plant compartments. Along the latitudinal gradient, we (1) observed reductions in mycorrhizal diversity that can negatively impact maple establishment; (2) and revealed reductions in fungal leaf pathogens that can have opposite effects. Our results highlight the need for an integrated approach including the examination of various microbial taxa on different plant compartments to improve our understanding of plant range shifts and plant-microbe interactions.

Nutritional and environmental factors influence small mammal seed selection in a northern temperate forest

AbstractRodents can influence the succession and assembly of plant communities by preying on and dispersing seeds. Using a seed tray experiment with three common seeds, American beech (Fagus grandifolia), red maple (Acer rubrum), and eastern hemlock (Tsuga canadensis), we assessed factors that influence seed selection and foraging time of three rodents: deer mice (Peromyscus maniculatus), white‐footed mice (Peromyscus leucopus), and southern red‐backed voles (Myodes gapperi). All three rodents preferred beech seeds, likely due to its large size and high lipid content. However, when beech availability was low, secondary seed selection differed by rodent species with P. maniculatus equally selecting hemlock and red maple, P. leucopus preferring hemlock, and M. gapperi preferring red maple. Red maple seeds contained high levels of phenolic compounds, which hinder digestion, and the elongated cecum of M. gapperi may allow for better processing of these compounds relative to Peromyscus. Beech seeds were nearly always removed from trays intact, suggesting rodents could be important dispersers compared to the small‐seeded species, which were generally processed on trays. The influence of environmental factors on seed selection was only notable when beech seed availability was low. Beech seed availability was also the primary factor influencing foraging time on trays, with individuals increasing foraging time as beech availability decreased. Consistent with predator avoidance behaviors, denser shrub cover increased foraging time for P. maniculatus, whereas moon luminosity decreased foraging for all three species. Our findings underscore that seed quality drives seed selection but that preferences are context dependent, varying with seed availability and digestive capacity.

Effects of the CG Positions on the Autorotative Flight of Maple Seeds

Effects of the CG Positions on the Autorotative Flight of Maple Seeds

Flight characteristics and flow structure of the autorotating maple seeds

Flight characteristics and flow structure of the autorotating maple seeds

Nicotinamide adenine dinucleotides are associated with distinct redox control of germination in Acer seeds with contrasting physiology.

Seed germination is a complex process enabling plant reproduction. Germination was found to be regulated at the proteome, metabolome and hormonal levels as well as via discrete post-translational modification of proteins including phosphorylation and carbonylation. Redox balance is also involved but less studied. Acer seeds displaying orthodox and recalcitrant characteristics were investigated to determine the levels of redox couples of nicotinamide adenine dinucleotide (NAD) phosphate (NADP) and integrated with the levels of ascorbate and glutathione. NAD and NADP concentrations were higher in Norway maple seeds and exceptionally high at the germinated stage, being the most contrasting parameter between germinating Acer seeds. In contrast, NAD(P)H/NAD(P)+ ratios were higher in sycamore seeds, thus exhibiting higher reducing power. Despite distinct concentrations of ascorbate and glutathione, both seed types attained in embryonic axes and cotyledons had similar ratios of reduced/oxidized forms of ascorbate and half-cell reduction potential of glutathione at the germinated stage. Both species accomplished germination displaying different strategies to modulate redox status. Sycamore produced higher amounts of ascorbate and maintained pyridine nucleotides in reduced forms. Interestingly, lower NAD(P) concentrations limited the regeneration of ascorbate and glutathione but dynamically drove metabolic reactions, particularly in this species, and contributed to faster germination. We suggest that NAD(P) is an important player in regulating redox status during germination in a distinct manner in Norway maple and sycamore seeds.

Integration of MsrB1 and MsrB2 in the Redox Network during the Development of Orthodox and Recalcitrant Acer Seeds.

Two related tree species, Norway maple (Acer platanoides L.) and sycamore (Acer pseudoplatanus L.), produce desiccation-tolerant (orthodox) and desiccation-sensitive (recalcitrant) seeds, respectively. We compared the seeds of these two species to characterize the developmentally driven changes in the levels of peptide-bound methionine sulfoxide (MetO) and the abundance of methionine sulfoxide reductases (Msrs) B1 and B2, with respect to the cellular redox environment. Protein oxidation at the Met level was dynamic only in Norway maple seeds, and the reduced MsrB2 form was detected only in this species. Cell redox status, characterized by the levels of reduced and oxidized ascorbate, glutathione, and nicotinamide adenine dinucleotide (NAD)/phosphate (NADP), was clearly more reduced in the Norway maple seeds than in the sycamore seeds. Clear correlations between MetO levels, changes in water content and redox status were reported in orthodox Acer seeds. The abundance of Msrs was correlated in both species with redox determinants, mainly ascorbate and glutathione. Our data suggest that MsrB2 is associated with the acquisition of desiccation tolerance and that ascorbate might be involved in the redox pathway enabling the regeneration of Msr via intermediates that are not known yet.

Peptide-Bound Methionine Sulfoxide (MetO) Levels and MsrB2 Abundance Are Differentially Regulated during the Desiccation Phase in Contrasted Acer Seeds.

Norway maple and sycamore produce desiccation-tolerant (orthodox) and desiccation-sensitive (recalcitrant) seeds, respectively. Drying affects reduction and oxidation (redox) status in seeds. Oxidation of methionine to methionine sulfoxide (MetO) and reduction via methionine sulfoxide reductases (Msrs) have never been investigated in relation to seed desiccation tolerance. MetO levels and the abundance of Msrs were investigated in relation to levels of reactive oxygen species (ROS) such as hydrogen peroxide, superoxide anion radical and hydroxyl radical (•OH), and the levels of ascorbate and glutathione redox couples in gradually dried seeds. Peptide-bound MetO levels were positively correlated with ROS concentrations in the orthodox seeds. In particular, •OH affected MetO levels as well as the abundance of MsrB2 solely in the embryonic axes of Norway maple seeds. In this species, MsrB2 was present in oxidized and reduced forms, and the latter was favored by reduced glutathione and ascorbic acid. In contrast, sycamore seeds accumulated higher ROS levels. Additionally, MsrB2 was oxidized in sycamore throughout dehydration. In this context, the three elements •OH level, MetO content and MsrB2 abundance, linked together uniquely to Norway maple seeds, might be considered important players of the redox network associated with desiccation tolerance.

NAD(P)-Driven Redox Status Contributes to Desiccation Tolerance in Acer seeds.

Desiccation tolerance is a developmental program enabling seed survival in a dry state and is common in seeds categorized as orthodox. We focused on NAD and its phosphorylated form (NADP) because their continual switching between reduced (NAD(P)H) and oxidized (NAD(P)+) forms is involved in the modulation of redox signaling and the determination of the reducing power and further antioxidant responses. Norway maple and sycamore seeds representing the orthodox and recalcitrant categories, respectively, were used as models in a comparison of responses to water loss. The process of desiccation up to 10% water content (WC) was monitored in Norway maple seeds, while dehydration up to 30% WC was monitored in desiccation-sensitive sycamore seeds. Norway maple and sycamore seeds, particularly their embryonic axes, exhibited a distinct redox status during dehydration and desiccation. High NADPH levels, NAD+ accumulation, low and stable NAD(P)H/NAD(P)+ ratios expressed as reducing power and high NADPH-dependent enzyme activity were reported in Norway maple seeds and were considered attributes of orthodox-type seeds. The contrasting results of sycamore seeds contributed to their low antioxidant capacity and high sensitivity to desiccation. NADPH deficiency, low NADPH-dependent enzyme activity and lack of NAD+ accumulation were primary features of sycamore seeds, with implications for their NAD(P)H/NAD(P)+ ratios and reducing power and with effects on many seed traits. Thus, we propose that the distinct levels of pyridine nucleotides and their redox status contribute to orthodox and recalcitrant phenotype differentiation in seeds by affecting cellular redox signaling, metabolism and the antioxidant system.

Consumption of red maple in anticipation of beech mast-seeding drives reproduction in eastern chipmunks.

Understanding the determinants of reproduction is a central question in evolutionary ecology. In pulsed-resource environments, the reproduction and population dynamics of seed consumers are driven by pulsed production of seeds by trees or mast-seeding. In Southern Québec, eastern chipmunks Tamias striatus exclusively reproduce during the summer before and the spring after a mast-seeding event of American beech. They thus seem to anticipate beech mast by reproducing during early summer, so that juveniles can emerge at the time of maximum beechnut abundance during late summer. However, the cues allowing chipmunks to anticipate beech mast remain unknown, and the existence of the anticipation process itself has been questioned. To tackle those issues, we investigated the links between the nutritional ecology and reproduction of adult chipmunks and compared their spring diet in mast- versus post-mast years. We monitored female reproductive status (N=446), analysed cheek pouch contents at capture (n=3,761 captures) and recorded seed production by deciduous trees on three different sites in Mont-Sutton from 2006 to 2018. Results revealed a systematic shift in chipmunk diet towards red maple seeds in springs preceding a beech mast, with red maple seeds composing more than 77% of chipmunk diet. However, red maple consumption was unrelated to red maple production, but was related to beech seed production in the upcoming fall. We also found that red maple consumption best predicted the proportion of females in summer oestrus. Our results confirm that chipmunks anticipate beech mast-seeding and highlight a key role of red maple consumption in that anticipation. Results also suggest that red maple seeds may contain nutrients or secondary plant components essential to sustain or trigger the summer reproduction in chipmunks, which allow them to remain synchronized with pulsed productions of both red maple and beech and improve their fitness.

Massively Deployable, Low-Cost Airborne Sensor Motes for Atmospheric Characterization

A low-cost airborne sensor mote has been designed for deployment en masse to characterize atmospheric conditions. The designed environmental sensing mote, or eMote, was inspired by the natural shape of auto-rotating maple seeds to fall slowly and gather data along its descent. The eMotes measure and transmit temperature, air pressure, relative humidity, and wind speed estimates alongside GPS coordinates and timestamps. Up to 2080 eMotes can be deployed simultaneously with a 1 Hz sampling rate, but the system capacity increases by 2600 eMotes for every second added between samples. All measured and reported data falls within accuracy requirements for reporting with both the World Meteorological Organization (WMO) and the National Oceanic and Atmospheric Administration (NOAA). This paper presents the design and validation of the eMote system alongside discussions on the implementation of a large-scale, low-cost sensor network. The eMote represents unprecedented in-situ atmospheric measurement capabilities with the ability to deploy more than 260 times the number of sensing units as the most comparable commercially available dropsonde.

Impact of Cover Crop Usage on Soilborne Diseases in Field Nursery Production

Soilborne pathogens are a significant economic problem for nursery production in the Southeastern United States. The goal of this study was to determine the impact of cover crops on soilborne disease suppressiveness in such systems. Soils from red maple (Acer rubrum L.) plantation fields grown with and without cover crops were sampled, either while the cover crops were growing (pre-disked) or post-season, following cover crop incorporation into the soil (post-disked). Greenhouse bioassays were conducted using red maple seeds on inoculated (with Rhizoctonia solani (J.G. Kühn) or Phytophthora nicotianae (Breda de Haan)) and non-inoculated field soils. The damping-off, root rot disease severity, percent recovery of Rhizoctonia and Phytophthora, and pseudomonad population were examined during the two years of the experiment. Results showed that cover crop incorporation was beneficial for inducing disease supressiveness characteristics of soil. Cover crop incorporation into the soil significantly or numerically reduced disease severity and pathogen recovery in infested soil compared to the bare soil treatment. Cover crop incorporation was found to be partially associated with the reduction of seedling damping-off. The pseudomonad microbial population was greater when cover crop was present, and is thought to be antagonist to soilborne pathogens. Therefore, cover crops can be integrated in field nursery production systems to suppress soilborne pathogens.