Leaf Movement Research Articles

Pharmacognostical studies on whole plant of Mimosa pudica L

Background: Mimosa pudica is a creeping, diffuse, prickly undershrub of genus mimosa, native to tropical America which is also scattered along tropical and subtropical parts of India. It is well known as a sensitive plant, shame plant, touch-me-not, humble plant, shyness princess, and sleeping plant by virtue of rapid leaf movements in response to touch. Aim: The intention of this research was to investigate the morphological, micro anatomical, powder microscopy, proximate, and phytochemical analysis in whole plant of M. pudica. Materials and Methods: The investigation on macroscopy, microscopy, and physiochemical and phytochemical analyses were implemented using standard methods. Results: This study divulged unique macroscopical and anatomical characters present in the whole plant of M. pudica. The powder microscopy revealed the presence of trichomes, paracytic stomata, starch grains, prismatic crystals, mucilage, and brownish content. The quantitative microscopy performed in epidermal peelings of leaf quantified the epidermal number, stomatal number, stomatal index, and palisade ratio which determine its quality and purity. The proximate analysis performed was within the specific limits. The phytochemical analysis identifies different phytoconstituents in n-hexane and ethyl acetate extract. Further quantitative estimation disclosed that the total quercetin equivalent in 1 g of ethyl acetate extract of M. pudica was to be 13.39 mg and 27.5 mg of total β-sitosterol equivalent in n-hexane extract of M. pudica. Conclusion: This research concludes the assessment in whole plant of M. pudica by pharmacognostical, physiochemical, and phytochemical estimation for its identification and confirmation of species epithet from adulterated, substituted, or similar distant group species such as Albizia julibrissin, Acacia dealbata, Neptunia gracilis, and Mimosa tenuiflora.

Memory and habituation to harmful and non-harmful stimuli in a field population of the sensitive plant,Mimosa pudica

AbstractMimosa pudicais a Neotropical legume that closes its leaves rapidly in response to touch stimulation, hypothetically as herbivory defence. Habituation to non-harmful stimuli and long-term memory of past events have been demonstrated in this species, the former with relatively heavy objects and the latter under laboratory conditions. This species should not habituate to harmful stimuli if leaf movement is a response to herbivore damage. We tested in Monteverde, Costa Rica, whether (1) memory occurs in wild plants, (2) whether habituation occurs under harmful stimuli: simulated herbivory, and (3) whether wild plants can habituate to light non-harmful stimuli. The degree of closing of the leaflets and time until reopening was measured in response to repeated harmful and non-harmful stimuli. The results showed habituation to repeated non-harmful very light stimuli and showed lack of habituation to simulated leaf damage. Wild plants also showed faster rehabituation to repeated non-harmful stimuli when they had been exposed 15 days previously, suggesting possible long-term memory. These results indicate that wild plants are capable of (1) distinguishing between harmful and non-harmful stimuli (only habituating to the latter), (2) memorizing previous events, and 3) habituating very light tactile stimuli commonly experienced in the field.

The relationship of cold acclimation and extracellular ice formation to winter thermonasty in two Rhododendron species and their F1 hybrid.

Thermonastic leaf movements in evergreen Rhododendron species have been used to study plant strategies for winter photoprotection. To add to the current fundamental understanding of this behavior, we addressed the following questions: (1) Is the cold-acclimated (CA) state necessary for thermonasty, and do cold-induced leaf movements also occur in non-acclimated (NA) plants? (2) Which of the two movements, leaf rolling versus curling, is more responsive to freezing, if any, in a non-thermonastic species? (3) What is the temporal relationship between extracellular freezing and thermonasty? (4) What genetic inferences can be drawn from leaf movement in an F1 hybrid relative to its parents? A temperature-controlled, gradual cooling regime was used to quantify freeze-induced leaf movements. Infrared thermography was used to confirm extracellular ice-formation in leaves. Both NA and CA plants of thermonastic species exhibited thermonasty, but leaf rolling/curling increased significantly in CA plants. In the cold-acclimated condition, a non-thermonastic species showed almost no rolling during freezing, while the thermonastic species and F1 hybrid did, the latter exhibiting a response intermediate to the parents. Freezing-induced leaf curling in the non-thermonastic species and the F1 hybrid was equivalent and significantly less than the degree of curling in the thermonastic species. Milder thermonasty in NA than CA leaves could be associated with differential anisotropy in the rolling forces and/or response of aquaporins to freezing. Leaf movements in the hybrid suggest that leaf rolling and curling are additive and dominant genetic traits, respectively. Infrared thermography confirms that ice formation in tissues precedes cold-induced thermonasty in R. catawbiense.

Avoiding rather than resisting herbivore attacks is often the first line of plant defence

Abstract A common idea is that resisting or blocking herbivore attacks by structural, chemical and molecular means after they have commenced is the first line of plant defence. However, these are all secondary defences, operating only when all the various methods of avoiding attack have failed. The real first line of plant defence from herbivory and herbivore-transmitted pathogens is avoiding such attacks altogether. Several visual, chemical and ‘statistical’ methods (and commonly their combined effects) have been proposed to allow avoidance of herbivore attacks. The visual types are camouflage, masquerade, aposematic coloration of toxic or physically defended plants (including Müllerian/Batesian mimicry), undermining herbivorous insect camouflage, delayed greening, dazzle and trickery coloration, heterophylly that undermines host identification, leaf movements, and signalling that colourful autumn leaves are soon to be shed. The mimicry types include: herbivore damage, insects and other animals, fungal infestation, dead/dry leaves or branches, animal droppings, and stones and soil. Olfactory-based tactics include odour aposematism by poisonous plants, various repelling volatiles, mimicry of faeces and carrion odours, and mimicry of aphid alarm pheromones. The ‘statistical’ methods are mast fruiting, flowering only once in many years and being rare. In addition to the theoretical aspects, understanding these mechanisms may have considerable potential for agricultural or forestry applications.

Spontaneous rapid leaf movements and action potentials in Mimosa pudica L.

Movements and action potentials of Mimosa pudica L. plants, commonly known for their sensitivity to touch, were measured using time-lapse photography and extracellular electrical potential recording methods in 4-day experiments. In intact plants, spontaneous rapid leaf movements (RLMs) were revealed. The rapid downward movement of the leaf lasted approx. 1 s and the return to the previous position took approx. 17 min. Additionally, spontaneous action potentials (SAPs) with amplitudes of 3-100 mV and half-time of approx. 15 s were observed for the first time in M. pudica. Spontaneous APs propagated basipetally or acropetally with a velocity of 3-75 cm min-1 . 36% of SAPs passing along the shoots were accompanied by RLMs. There was a delay between the appearance of SAP and RLM, indicating that SAPs may trigger the RLMs.

A digital sensor to measure real-time leaf movements and detect abiotic stress in plants.

Plant and plant organ movements are the result of a complex integration of endogenous growth and developmental responses, partially controlled by the circadian clock, and external environmental cues. Monitoring of plant motion is typically done by image-based phenotyping techniques with the aid of computer vision algorithms. Here we present a method to measure leaf movements using a digital inertial measurement unit (IMU) sensor. The lightweight sensor is easily attachable to a leaf or plant organ and records angular traits in real-time for two dimensions (pitch and roll) with high resolution (measured sensor oscillations of 0.36 ± 0.53° for pitch and 0.50 ± 0.65° for roll). We were able to record simple movements such as petiole bending, as well as complex lamina motions, in several crops, ranging from tomato to banana. We also assessed growth responses in terms of lettuce rosette expansion and maize seedling stem movements. The IMU sensors are capable of detecting small changes of nutations (i.e. bending movements) in leaves of different ages and in different plant species. In addition, the sensor system can also monitor stress-induced leaf movements. We observed that unfavorable environmental conditions evoke certain leaf movements, such as drastic epinastic responses, as well as subtle fading of the amplitude of nutations. In summary, the presented digital sensor system enables continuous detection of a variety of leaf motions with high precision, and is a low-cost tool in the field of plant phenotyping, with potential applications in early stress detection.

The Adaptive Power of Ammophila arenaria: Biomimetic Study, Systematic Observation, Parametric Design and Experimental Tests with Bimetal.

The aim of our study was to apply a biomimetic approach, inspired by the Ammophila arenaria. This organism possesses a reversible leaf opening and closing mechanism that responds to water and salt stress (hydronastic movement). We adopted a problem-based biomimetic methodology in three stages: (i) two observation studies; (ii) how to abstract and develop a parametric model to simulate the leaf movement; and (iii) experiments with bimetal, a smart material that curls up when heated. We added creases to the bimetal active layer in analogy to the position of bulliform cells. These cells determine the leaf-closing pattern. The experiments demonstrated that creases influence and can change the direction of the bimetal natural movement. Thus, it is possible to replicate the Ammophila arenaria leaf-rolling mechanism in response to temperature variation and solar radiation in the bimetal. In future works, we will be able to propose responsive facade solutions based on these results.

Mechanisms of far-red light-mediated dampening of defense against Botrytis cinerea in tomato leaves.

Plants detect neighboring competitors through a decrease in the ratio between red and far-red light (R:FR). This decreased R:FR is perceived by phytochrome photoreceptors and triggers shade avoidance responses such as shoot elongation and upward leaf movement (hyponasty). In addition to promoting elongation growth, low R:FR perception enhances plant susceptibility to pathogens: the growth–defense tradeoff. Although increased susceptibility in low R:FR has been studied for over a decade, the associated timing of molecular events is still unknown. Here, we studied the chronology of FR-induced susceptibility events in tomato (Solanum lycopersicum) plants pre-exposed to either white light (WL) or WL supplemented with FR light (WL+FR) prior to inoculation with the necrotrophic fungus Botrytis cinerea (B.c.). We monitored the leaf transcriptional changes over a 30-h time course upon infection and followed up with functional studies to identify mechanisms. We found that FR-induced susceptibility in tomato is linked to a general dampening of B.c.-responsive gene expression, and a delay in both pathogen recognition and jasmonic acid-mediated defense gene expression. In addition, we found that the supplemental FR-induced ethylene emissions affected plant immune responses under the WL+FR condition. This study improves our understanding of the growth–immunity tradeoff, while simultaneously providing leads to improve tomato resistance against pathogens in dense cropping systems.

Petiole hormones act as regulators in the early phototropic leaf movements of grape (Vitis vinifera L.) revealed by comparative transcriptome profiling

Phototropism is of great importance in orienting their photosynthetic organs towards the light so as to optimize the light capture capacity of the aerial parts in seedlings of higher plants. Approximately 20-day-old grape (Vitis vinifera L.) leaves were the fastest in response to phototropism. However, the molecular network and genetic regulatory mechanisms that govern phototropism in grape leaves remained elusive. Leave blades and petioles were sampled from shoots of V. vinifera cv. ‘Italian Riesling’ trees that were artificially fixed on the wire with strings under the condition of the blade abaxial side face-upward in the field (fixation of shoots did not interfere with leaves rotation), respectively. Leaves growing in the natural state (not artificially fixed on the wire) as control. The treated blades rotate from the abaxial side to the adaxial side after fixation for 2 h, and the phototropic response was completed after 6–10 hours. The endogenous hormone concentrations were measured from the time series in blades and petioles. After irradiating the abaxial side of treated blades for 3 h, leaves were sampled for RNA sequencing analysis. Here, the results of endogenous hormone concentrations showed that phototropic response was beneficial to increase IAA content in blades and petioles, but had opposite effect on GA content. The contents of ZT and ABA in treated petioles were considerably higher than those of control during the phototropic response. A total number of 181 and 1,810 differentially expressed genes (DEGs) were identified in blades and petioles, respectively. KEGG enrichment analysis showed that DEGs involved in the hormone signal transduction pathway were significantly enriched in petioles. A total of 44 genes involved in the hormone signalling pathways of auxin, CTK, GA, ABA, ethylene (ETH), BR, jasmonic acid (JA) and salicylic acid (SA), including 32 up-regulated and 12 down-regulated genes. In addition, the expression of key transcription factors (TFs) and candidate genes, including HY5, AUX1, AUX/IAA, SAUR, HP3, ARR9, BKI1, PP2C8, ABI5 and PIF3, were responsible for grape leaf phototropism. In conclusion, our study provides an initial understanding of the response of petiole hormones to phototropic leaf movements in grape, and also provides possible candidate genes involved in grape leaf phototropism that could be used to guide future efforts in this field.

The geometry of the compound leaf plays a significant role in the leaf movement of Medicago truncatula modulated by mtdwarf4a.

In most legumes, two typical features found in leaves are diverse compound forms and the pulvinus-driven nyctinastic movement. Many genes have been identified for leaf-shape determination, but the underlying nature of leaf movement as well as its association with the compound form remains largely unknown. Using forward-genetic screening and whole-genome resequencing, we found that two allelic mutants of Medicago truncatula with unclosed leaflets at night were impaired in MtDWARF4A (MtDWF4A), a gene encoding a cytochrome P450 protein orthologous to Arabidopsis DWARF4. The mtdwf4a mutant also had a mild brassinosteroid (BR)-deficient phenotype bearing pulvini without significant deficiency in organ identity. Both mtdwf4a and dwf4 could be fully rescued by MtDWF4A, and mtdwf4a could close their leaflets at night after the application of exogenous 24-epi-BL. Surgical experiments and genetic analysis of double mutants revealed that the failure to exhibit leaf movement in mtdwf4a is a consequence of the physical obstruction of the overlapping leaflet laminae, suggesting a proper geometry of leaflets is important for their movement in M. truncatula. These observations provide a novel insight into the nyctinastic movement of compound leaves, shedding light on the importance of open space for organ movements in plants.

Effects of leaf response velocity on spray deposition with an air-assisted orchard sprayer

The interaction between leaves and airflow has a direct effect on the droplet deposition characteristics of the leaf canopy. In order to make clear the mechanism of droplet deposition in terms of the interaction between the droplets and leaves from the point of the leaf aerodynamic response velocity, the leaf movement under different airflow velocities and the influence of the leaf aerodynamic response on droplet coverage ratio were investigated. The effect of the aerodynamic response velocity of a leaf on the droplet deposition of the leaf surface was investigated. The aerodynamic characteristics of the leaf were analyzed theoretically. Boundary layer theory from fluid mechanics was used to develop a model of the leaf aerodynamic response velocity to nonperiodic excitations based on a convolution integral method. Target leaf aerodynamic velocities were detected using a high-speed camera, and the results indicated that the modeled leaf aerodynamic response velocity matched the measured values. At given conditions of spray liquid and leaf surface texture, the spray test showed that the droplet coverage ratio was influenced by the leaf aerodynamic response velocity, the droplet coverage ratio increased and then decreased with the leaf response velocity. Through analyze four droplets deposition state, the highest droplet deposition ratio and best deposition state on the leaf surface occur when the leaf aerodynamic response velocity was less than 0.14 m/s. According to the analysis of droplet deposition states, the uniformity of the droplet size and quantity distribution of droplets on the leaf surface related to the leaf aerodynamic response velocity. The results can provide a basis for the design and optimization of orchard air sprayers. Keywords: air-assisted spray, leaf wind vibration, leaf aerodynamic response velocity, droplet deposition states, droplet retention, orchard DOI: 10.25165/j.ijabe.20211401.5435 Citation: Li J, Li Z Q, Ma Y K, Cui H J, Yang Z, Lu H Z. Effects of leaf response velocity on spray deposition with an air-assisted orchard sprayer. Int J Agric & Biol Eng, 2021; 14(1): 123–132.

The F-box protein MIO1/SLB1 regulates organ size and leaf movement in Medicago truncatula.

The size of leaf and seed organs, determined by the interplay of cell proliferation and expansion, is closely related to the final yield and quality of forage and crops. Yet the cellular and molecular mechanisms underlying organ size modulation remain poorly understood, especially in legumes. Here, MINI ORGAN1 (MIO1), which encodes an F-box protein SMALL LEAF AND BUSHY1 (SLB1) recently reported to control lateral branching in Medicago truncatula, was identified as a key regulator of organ size. We show that loss-of-function of MIO1/SLB1 severely reduced organ size. Conversely, plants overexpressing MIO1/SLB1 had enlarged organs. Cellular analysis revealed that MIO1/SLB1 controlled organ size mainly by modulating primary cell proliferation during the early stages of leaf development. Biochemical analysis revealed that MIO1/SLB1 could form part of SKP1/Cullin/F-box (SCF) E3 ubiquitin ligase complex, to target BIG SEEDS1 (BS1), a repressor of primary cell division, for degradation. Interestingly, we found that MIO1/SLB1 also played a key role in pulvinus development and leaf movement by modulating cell proliferation of the pulvinus as leaves developed. Our study not only demonstrates a conserved role of MIO1/SLB1 in the control of organ size in legumes, but also sheds light on the novel function of MIO1/SLB1 in leaf movement.

Experimental plant research and the discovery of carbon dioxide-mediated global greening: a tribute to Wilhelm Pfeffer (1845–1920)

One century ago, the German chemist and botanist Wilhelm Pfeffer (1845–1920) died, shortly after finishing his last lecture at the University of Leipzig. Pfeffer was, together with Julius Sachs (1832–1897), the founder of modern plant physiology. In contrast to Sachs, Pfeffer’s work was exclusively based on the principles of physics and chemistry, so that with his publications, notably the ca. 1.600 pages-long Handbuch der Pflanzenphysiologie (2. ed., Vol. I/II; 1897/1904), experimental plant research was founded. Here we summarize Pfeffer’s life and work with special emphasis on his experiments on osmosis, plant growth in light vs. darkness, gravitropism, cell physiology, photosynthesis and leaf movements. We document that Pfeffer was the first to construct/establish constant temperature rooms (growth chambers) for seed plants. Moreover, he pioneered in outlining the carbon-cycle in the biosphere, and described the effect of carbon dioxide (CO2)-enhancement on assimilation and plant productivity. Wilhelm Pfeffer pointed out that, at ca. 0.03 vol% CO2 (in 1900), photosynthesis is sub-optimal. Accordingly, due to human activities, anthropogenic CO2 released into the atmosphere promotes plant growth and crop yield. We have reproduced Pfeffer’s classical experiments on the role of CO2 with respect to plant development, and document that exhaled air of a human (ca. 4 vol% CO2) strongly promotes growth. We conclude that Pfeffer not only acted as a key figure in the establishment of experimental plant physiology. He was also the discoverer of the phenomenon of CO2-mediated global greening and promotion of crop productivity, today known as the “CO2-fertilization-effect”. These topics are discussed with reference to climate change and the most recent findings in this area of applied plant research.

Rapid movements in plants

Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in animals relies on the contraction machinery of muscles, many plant movements use turgor pressure as the primary driving force together with secondarily generated elastic forces. The movement of stomata is the best-characterized model system for studying turgor-driven movement, and many gene products responsible for this movement, especially those related to ion transport, have been identified. Similar gene products were recently shown to function in the daily sleep movements of pulvini, the motor organs for macroscopic leaf movements. However, it is difficult to explain the mechanisms behind rapid multicellular movements as a simple extension of the mechanisms used for unicellular or slow movements. For example, water transport through plant tissues imposes a limit on the speed of plant movements, which becomes more severe as the size of the moving part increases. Rapidly moving traps in carnivorous plants overcome this limitation with the aid of the mechanical behaviors of their three-dimensional structures. In addition to a mechanism for rapid deformation, rapid multicellular movements also require a molecular system for rapid cell-cell communication, along with a mechanosensing system that initiates the response. Electrical activities similar to animal action potentials are found in many plant species, representing promising candidates for the rapid cell–cell signaling behind rapid movements, but the molecular entities of these electrical signals remain obscure. Here we review the current understanding of rapid plant movements with the aim of encouraging further biological studies into this fascinating, challenging topic.

Palmer Amaranth Control by Glufosinate Depends on Application Time of Day

Glufosinate is used widely to control glyphosate-resistant Palmer amaranth (Amaranthus palmeri S. Wats.) in cotton (Gossypium hirsutum L.). Previous research has shown weed control with several herbicides, including glufosinate, can be affected by application time of day. The response sometimes has been attributed to diurnal leaf movement (leaf orientation) in the weeds. The objectives of our research were to determine the influence of time of day of glufosinate application on Palmer amaranth control and to determine if the response was related to diurnal leaf orientation. Field experiments in five states evaluated Palmer amaranth control with glufosinate applied at nine intervals ranging from 1 h before sunrise to 6 h after sunrise and nine intervals ranging from 6 h before sunset to 1 h after sunset. Greatest Palmer amaranth control was achieved with glufosinate applied 2 h after sunrise to 1 h before sunset. Ammonium sulfate, added only to glufosinate 1 h before sunrise or 1 h after sunset treatments, did not improve control. Leaf angles of Palmer amaranth and velvetleaf (Abutilon theophrasti L.) were determined in a greenhouse at 1 h before light, 2 h after light, mid-day, 2 h before dark, and 1 h after dark. Leaves of velvetleaf oriented downward during the dark periods but time of day had no effect on leaf orientation of Palmer amaranth. These results demonstrate the need for sunlight for optimum glufosinate efficacy on Palmer amaranth.

Cover Image: Nyctinastic leaf movement in legume

Diurnal leaf movement, named nyctinasty, has been of great interest to researchers since Darwin's time. In this issue, Kong et al. (pp. 1880–1894) report that leaf movement is orchestrated by clock gene MtLHY in a legume species Medicago truncatula, which is also influenced by the availability of nitrogen produced by the nodules in an MtLHY dependent manner.

Reducing shade avoidance can improve Arabidopsis canopy performance against competitors.

Plants that grow in high density communities activate shade avoidance responses to consolidate light capture by individuals. Although this is an evolutionary successful strategy, it may not enhance performance of the community as a whole. Resources are invested in shade responses at the expense of other organs and light penetration through the canopy is increased, allowing invading competitors to grow better. Here we investigate if suppression of shade avoidance responses would enhance group performance of a monoculture community that is invaded by a competitor. Using different Arabidopsis genotypes, we show that suppression of shade‐induced upward leaf movement in the pif7 mutant increases the pif7 communal performance against invaders as compared to a wild‐type canopy. The invaders were more severely suppressed and the community grew larger as compared to wild type. Using computational modelling, we show that leaf angle variations indeed strongly affect light penetration and growth of competitors that invade the canopy. Our data thus show that modifying specific shade avoidance aspects can improve plant community performance. These insights may help to suppress weeds in crop stands.

The nodulation and nyctinastic leaf movement is orchestrated by clock gene LHY in Medicago truncatula

As sessile organisms, plants perceive, respond, and adapt to the environmental changes for optimal growth and survival. The plant growth and fitness are enhanced by circadian clocks through coordination of numerous biological events. In legume species, nitrogen-fixing root nodules were developed as the plant organs specialized for symbiotic transfer of nitrogen between microsymbiont and host. Here, we report that the endogenous circadian rhythm in nodules is regulated by MtLHY in legume species Medicago truncatula. Loss of function of MtLHY leads to a reduction in the number of nodules formed, resulting in a diminished ability to assimilate nitrogen. The operation of the 24-h rhythm in shoot is further influenced by the availability of nitrogen produced by the nodules, leading to the irregulated nyctinastic leaf movement and reduced biomass in mtlhy mutants. These data shed new light on the roles of MtLHY in the orchestration of circadian oscillator in nodules and shoots, which provides a mechanistic link between nodulation, nitrogen assimilation, and clock function.

Daily rhythmic leaf movements and expression of circadian clock genes are differentially synchronized by light in Phaseolus vulgaris

Efforts of recent years have achieved significant progress towards the elucidation of the molecular mechanisms underlying the plant circadian clock function. Daily rhythmic leaf movements of leguminous plants belong to the physiological processes controlled by the clock. However, their function and the way they are synchronized by light constitute a controversial subject of plant physiology. Thus, the aim of our study is to explore the role of circadian clock genes in the synchronization of the daily rhythmic leaf movements of the leguminous plant Phaseolus vulgaris. By applying a prototype experimental approach that differentiates the effect of light according to the circadian time, we were able to show that the synchronization of rhythmic leaf movements and of expression of the clock genes PvLHY and PvTOC1 proceeds according to different patterns. By our detailed gene expression analysis we demonstrate that these genes are strongly coupled regarding their adaption to the new phase which suggests that they are interlocked elements of the bean oscillator. Under the same conditions, the leaves' synchronization evolved independently from that of the genes mimicking a rhythm not related to the imposed photoperiod. This novel finding reveals for the first time that the crosstalk between rhythmic transcription and leaf movements is not direct. Our observations establish that the control of the endogenous clock underlying bean leaf movements is exerted on at a level beyond transcription, suggesting many new directions for study.

Automated leaf movement tracking in time-lapse imaging for plant phenotyping

The analysis of the rhythm of leaf movement is a simple yet effective method to quantify the impacts of external (e.g. abiotic stress) and/or internal (e.g. gene mutations) perturbations on plant growth. We developed an automated monitoring system to quantify leaf movement using time-lapse imaging and a subsequent leaf-tracking algorithm. The leaf-tracking algorithm was based on dense optical flow algorithm to directly record temporal motion events. The algorithm measures motion directly, rather than detecting leaf or cotyledon tip in every image, so multiple leaves, including occluded leaves, can be measured simultaneously. To test the monitoring system, wild-type and drought-tolerant mutant genotypes of Arabidopsis (Arabidopsis thaliana) were subjected to a combinatorial two water and two nitrogen levels. High-frequency time-lapse images were acquired from top view for little over 6 consecutive days at a frequency of 4 min. Results showed that nitrogen and water treatments elicited differences in mean plant displacement in both genotypes. It also showed significant differences among the two different genotypes in the mean displacement when plants were under water or nitrogen stress. These results confirmed the new monitoring system’s ability to discern environmental and genotypic differences in plant response.