Plant responses to shade are often studied under constant light reduction, but rarely under intermittent shading which is frequent in natural environments and multilayered systems such as agrivoltaics and agroforestry. We investigated in controlled environments how a 38% reduction in daily radiation, applied either continuously or as several intermittent periods per day, affected morphology, phenology, aboveground biomass, yield components, and photosynthetic traits of 14 rice cultivars. Plants were grown under full light with 24 MJ m⁻² day⁻¹, and both shading treatments received the same daily light integral. On average, continuous shading reduced grain yield by 28% and aboveground biomass by 27%, whereas intermittent shading resulted in greater decreases, by 32% and 31%, respectively. Yield losses were mainly attributed to reduced tillering and to a lesser extent to 1000-kernel weight. Growth reduction was sub-proportional to light resources, indicating increased incident radiation use efficiency under shading. However, this increase was less pronounced under intermittent shading, chiefly attributable to the curvi-linear response of photosynthesis to light. Furthermore, a decrease in the maximum electron transport rate under intermittent shading conditions suggested reduced photosynthetic capacity as well. Despite substantial variation among cultivars in morphology and photosynthetic parameters under full light, none of these traits predicted differential responses to shading regimes. These findings highlight that diurnal light distribution strongly influences crop performance, beyond the effects of mean light reduction. Consideration of intermittent shading is thus crucial for understanding and modeling plant responses in multilayered systems such as agrivoltaics, intercropping, and agroforestry.

Abstract We present Sketch2Growth , an interactive system for generating a family of 3D branching shapes and animating their growth from a single user‐drawn style sketch. The sketch, seen as a 2D idealized representation of the desired shape, is converted into a concise format called the Seed . This representation consists of a Directed Acyclic Graph (DAG) that encodes the recursive branching topology, and a series of Gaussian Mixture Models (GMMs) that capture statistical visual‐style at branching points and in terms of branch curvature. During synthesis, the Seed serves as support for a lightweight, stochastic generator: Branches are recursively expanded by unfolding the DAG and sampling from learned distributions, which maintains the expected correlation between parent and child branches. Further growth and variability of the generated shapes are achieved through similarity‐based looping in the Seed structure (re‐starting from a similar node), stochastic mutations and clamping. Only requiring a light learning process through the GMMs, Sketch2Growth ensures perceptual similarity between the generated shapes and the input style sketch, as validated through a user study. In addition, interactive handles enable users to fake the effect of external forces during growth. As results show, our system allows to easily model and animate the continuous growth of complex branching shapes inspired by trees, plants, corals or anatomical structures.

Tree growth and reproduction results from the balance between internal and environmental factors. Knowledge is lacking on this balance in evergreen fruit trees characterised by a permanent contrasted light environment within the crown. This study hypothesised that architectural traits and light environment of terminal growth units (GUs) affected their vegetative and reproductive bud burst in the mango tree. Bud burst was monitored on terminal GUs of four adult mango trees, cv. ‘Cogshall’, during vegetative growth and flowering. Some GUs architectural traits (diameter, apical vs lateral position, outer vs inner location within the crown) and their light environment (quantity: relative transmitted PPFD, TrPPFD, and quality: red to far-red ratio, ζ) were measured at sampling. Factors affecting the occurrence, intensity and dynamics of bud burst were evidenced using generalised linear mixed models. The occurrence of vegetative and reproductive bud burst increased with ζ. For vegetative buds, it also increased with GU diameter at medium to high ζ values. The occurrence of reproductive bud burst was higher in the outer than the inner part of the crown, and on the apical than the lateral GUs. Two vegetative and reproductive flushes occurred. The dates of vegetative and reproductive bud burst were globally delayed by low ζ and high TrPPFD. For GUs that burst during the main reproductive flush, bud burst occurred earlier in the outer than the inner part of the crown. The interplay between the signals leading to the observed spatial and temporal patterns of bud burst is discussed.

Bud outgrowth is a major component of plant architectural plasticity and is influenced by light conditions. While the inhibitory effect of low light intensity on branching is well documented, the underlying regulators remain debated and, especially, the role of sugar availability has never been thoroughly evaluated. Here, we combined experiments with a computational approach quantifying carbon source-sink balance in single-axis rose plants to investigate how continuous and transient light limitation regulate bud outgrowth. Continuous low light reduced photosynthesis, leading to decreased sugar availability and inhibited bud outgrowth. In contrast, a transient period of low light followed by high light unexpectedly stimulated bud outgrowth, shortened the delay between outgrowth of successive buds, and produced an over-branched phenotype. This response resulted from a non-reversible reduction in the growth of apical organs appearing under low light, which lowered carbon demand and caused sugar over-accumulation after the return to high light. Manipulating carbon supply and demand through leaf masking, photosynthetic inhibition, and targeted sucrose feeding supported a causal contribution of sugar availability in these contrasting responses. Beyond these findings, key requirements for models simulating branching plasticity were identified and this work provides a basis for predicting branching responses under fluctuating and complex light environments.

In the past 50 years, the formalism of L-systems has been successfully used and developed to model the growth of filamentous and branching biological forms. These simulations take place in classical 2-D or 3-D Euclidean spaces. However, various biological forms actually grow in curved, non-Euclidean, spaces. This is, for example, the case of vein networks growing within curved leaf blades, of unicellular filaments, such as pollen tubes, growing on curved surfaces to fertilise distant ovules, of teeth patterns growing on folded epithelia of animals, of diffusion of chemical or mechanical signals at the surface of plant or animal tissues, etc. To model these forms growing in curved spaces, we thus extended the formalism of L-systems to non-Euclidean spaces. In a first step, we show that this extension can be carried out by integrating concepts of differential geometry in the notion of turtle geometry. We then illustrate how this extension can be applied to model and program the development of both mathematical and biological forms on curved surfaces embedded in our Euclidean space. We provide various examples applied to plant development. We finally show that this approach can be extended to more abstract spaces, called abstract Riemannian spaces, that are not embedded into any higher-dimensional space, while being intrinsically curved. We suggest that this abstract extension can be used to provide a new approach for effective modelling of growth of branching systems within non-uniform substrates and illustrate this idea on a few conceptual examples.

Hazelnut (Corylus avellana) cultivation is increasing worldwide. A 3D model of its structure could improve managerial techniques such as pruning. This study aims to analyse, over two successive years, hazelnut architectural development to implement a functional structural plant model. One hundred and four one-year-old shoots of own-rooted hazelnut trees were selected and analysed in winter 2020 and 2021. Exploratory analyses, generalized linear models and multinomial regression models were used to describe the architectural processes. The existence of sylleptic shoots on hazelnut one-year-old shoots, characterized by the presence of the male inflorescence on apical position, was detected. Along proleptic shoots, the branching pattern was described by (i) blind nodes located in the proximal part (ii) sylleptic shoots and mixed buds in the median part (iii) vegetative buds in the distal part. Apical bud died during the growing season, suggesting that Tonda di Giffoni has a sympodial branching. The models revealed dependencies among buds located at the same node, in the case of proleptic shoots. Especially, the probability of a bud bursting depended on both its type (i.e. mixed or vegetative) and the presence of other buds, either mixed or vegetative. Based on these local models and on a flow diagram, which defines the steps that led to the construction of hazelnut tree architecture, the first functional-structural plant model of hazelnut tree architecture was built. Further experiments will be needed and should be repeated over the following years to extend this study towards the juvenile phase and tree architecture over time.

Mango tree is a tropical evergreen tree whose leaves live for several years and gradually fall over time. It is important to understand the pattern of leaf fall because foliage distribution affects tree functioning. The objective of this work was to identify the growth unit (GU) characteristics and the environmental factors affecting leaf fall at the GU scale during one year. In January 2021, 240 GUs were sampled on five adult mango trees of the cultivar 'Cogshall' at three depths, expressed as the number of GUs from the terminal GU (1, 2 and 4 GUs) along the branches. GU depth was used as a proxy for GU age. The numbers of nodes and remaining leaves were counted for each GU. Their light environment was estimated from hemispherical photographs. The number of leaves per GU was then counted monthly during one year. The number of nodes per GU increased with GU length and was higher for GUs in apical position than for GUs in lateral position. The number of leaves remaining on the GUs in January 2021 was negatively related to GU depth. From February 2021 to January 2022, the occurrence of leaf fall was 10 times higher during the rainy season than during the dry season, and it increased with GU depth. Light environment did not affect leaf fall, except when analysis was restricted to December 2021. During that month, light environment had a negative effect on leaf fall for GUs in depths 1 and 2, but no effect for GUs at depth 4. This work highlighted the seasonal pattern of leaf fall and the major effect of GU depth, i.e., GU age, on leaf fall in the evergreen mango tree.

Yield reduction over the years is a phenomenon that affects many fruit tree species, including hazel (Corylus avellana).Studying plant architecture could provide useful information for improving crop management, such as pruning, to reduce the impact of yield reductions.This study aimed to compare the relationship between budcomposition and shoot length in hazel shoots.The experiment was carried out in January 2020 and 2021 in Deruta, Perugia (Italy).In 2020, 120 1-year-old shoots of C. avellana 'Tonda di Giffoni' were sampled.In 2021, the same observations were performed on lateral and apical 1-year-old shoots that had burst from parental buds in spring 2020.Depending on its length, each shoot was sorted into four categories: short (Sh) when shorter than 5 cm, medium (Me) when between 5 and 20 cm, long (Lo) when between 20 and 40 cm, and very long (VLo) when longer than 40 cm.For each shoot, shoot length, axillary and apical bud fate was recorded at each node: vegetative bud, latent bud, catkin, and mixed bud (V, B, C, and M, respectively).Percentage of lateral mixed buds was higher in longer shoots than in shorter ones while that of vegetative buds remained constant whatever the length.Fruit set, computed as the ratio between the number of nuts and the number of mixed buds, was significantly higher in Lo and VLo shoots.It was observed that the length of lateral proleptic shoots, developed in 2021, was related to the length of the bearer shoot from which it was developed.Proleptic lateral Sh shoots were the most frequent among all length categories while longer proleptic shoots (Lo and VLo) were originated only from Lo and VLo shoots.Managing tree architecture, considering a good balance between long and short shoots, and mixed and vegetative buds, could help control and prevent yield decrease in hazelnut trees.

In a context of climate change, the selection of fruit tree cultivars that perform well under sub-optimal growing conditions becomes essential. Architectural traits must be considered to assess the intrinsic production potential of cultivars, their interactions with the environment and the easiness of management. To phenotype such traits at high throughput on a core-collection of apple trees, we tested an approach based on UAV-LiDARs that allow rapid 3D scanning of an orchard and compared it to our previous approach, based on TLS. With the UAV-LiDAR different acquisition protocols were tested, with varying height or speed for the drone, that resulted in different densities and qualities of points. To process the point clouds, we built a pipeline composed of steps including the identification and removal of undesired elements (soil, pole, etc.), the segmentation of individual trees, and the characterization of architectural traits. For the first step, two methods were tested: CANUPO and RandLA-NET. For the tree segmentation, we used a semi-supervised method of label spreading. The initial seeds for the labels were determined from the GPS location of the trees. Architectural traits such as height, projected leaf area, convex and alpha volume, eccentricity were then determined and their broad sense heritabilities were estimated to assess genotypic variability and measure repeatability. The use of UAV-LiDAR scans was compared and validated with terrestrial LiDAR scans. The influence of the acquisition protocol on the resulting architectural traits was characterized. Correlations greater than or equal to 0.5 were found between the estimated indices from the different protocols, except for eccentricity. Indices from UAV scans (F2, F3) presented values similar to those obtained with the TLS. As a result, indices obtained with TLS can be approximated using UAV-LiDAR.

Light is a key factor in plant ecophysiological modeling because of its crucial effects on plant growth and development. However, solar light quantity and quality change with environmental factors such as sky condition and solar elevation. When passing through a tree crown, light is modified by its interaction with the phytoelements, leaves and axes. This leads to a variability of light quantity and quality within the crown, with consequences on light-related processes such as photosynthesis and photomorphogenesis. We evaluated the effects of positional (depth within the crown) and environmental (sky condition, solar elevation) factors on light quantity and quality within the crown of the tropical evergreen mango tree. Functional relationships were modeled between morphogenetically active radiation variables that describe light quality [narrowband red (Rn), narrowband far-red (FRn), the ratio ζ=Rn : FRn, and UVA-blue (UVA-BL)] and light quantity [photosynthetic photon flux density (PPFD) and relative transmitted PPFD (TrPPFD)]. Light quantity and quality varied within the mango tree crown in a wide range similar to that of a forest. This variability was structured by the depth within the crown as well as by sky condition and solar elevation. Linear relationships linked Rn, FRn and UVA-BL to PPFD, and non-linear relationships linked ζ to TrPPFD. These relationships were strong, accurate and unbiased. They were affected by positional and environmental factors. The results suggested that these relationships were shaped by the characteristics of incident solar light and/or by the interactions between light and phytoelements. Two consequences of interest emerged from this research: i) the modeled relationships allow to infer light quality, that is difficult and time-consuming to simulate, from light quantity modeling within a tree crown, and ii) sky condition and solar elevation should be considered to improve light modeling within a tree crown.

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Functional-structural plant modelling approaches (FSPM) explore the relationships between the 3D structure and the physiological functioning of plants in relation to environmental conditions. In this study, we present a methodological approach that integrated architectural responses to planting design in an oil palm FSPM, and test the impact of planting design and architectural plasticity on physiological responses such as light interception and carbon assimilation. LiDAR-derived and direct measurements were performed on five planting designs to assess the phenotypic plasticity of architectural traits, and allowed evaluating the variations of the main parameters of an existing 3D plant model. Accordingly, we proposed a neighbourhood index (NI) as a simple explanatory variable of architectural plasticity, and used NI-based allometries to simulate architectural variations in 3D virtual plants. Light interception and carbon assimilation were then simulated on virtual plots reproducing the five studied designs. We found that the main traits affected by plant proximity were leaf dimensions, leaf weight and leaf erectness, whereas other structural traits like the frequency of leaflets along the rachis or biomechanical properties of leaves remained unchanged. Our simulation study highlighted model compliance to reproduce architectural plasticity and illustrated how architectural plasticity improved light interception via leaf area expansion, but how the competition for light imposed by the design can counterbalance this benefit in terms of carbon assimilation at stand scale. We conclude on the importance of planting patterns for plants with low architectural plasticity such as oil palm, and how in silico experiments can help in designing innovative planting patterns.

Pruning is one of the most important management practices for the mango tree. Pruning affects vegetative growth and may also affect mango tree flowering, at least indirectly, as close relationships exist between vegetative growth and reproduction. The objective of this study was to quantify the effects of pruning on flowering in the mango tree. An experiment was conducted in 2016 on Reunion Island on adult mango trees of the cultivar 'Cogshall'. Pruning was carried out after harvest and characterized by pruning intensity (defined as the amount of fresh biomass removed per unit volume of canopy) and pruning severity (defined as the distance between the distal end of the axis and the pruning point). Vegetative growth was recorded on 30 pruned and 30 unpruned terminal growth units (GUs) per tree. After vegetative growth and the resting period, flowering was described, in terms of probability, intensity, and dynamic, on four populations of terminal GUs partly formed as a result of pruning: daughter GUs produced by initial pruned and unpruned GUs, and initial pruned and unpruned GUs themselves when they did not produce daughters GUs. The results showed the complex effects of pruning on mango flowering at the GU scale. The effects of pruning intensity and severity on flowering probability, intensity, and dynamics varied among GU populations. This suggested that mango tree flowering would depend on the proportion of each of these GU populations at the canopy scale, these proportions depending themselves on the pruning conditions. As a next step, vegetative and flowering responses to pruning at the GU scale may be integrated into a functional-structural mango tree model to analyze further the global effect of pruning at the tree scale.

Axillary bud outgrowth is a major process allowing the plant to adapt its architecture to environmental constraints. Indeed, the dormant buds formed at each leaf axil contain meristems, which depending on the environment, remain quiescent or resume activity leading to bud outgrowth and the development of a new axis [1]. Studies on apical dominance, i.e. the inhibition of buds by the growing apical zone, have highlighted the opposite roles of auxin and sugar, which is involved in a signaling and trophic regulation of bud activity [2-4]. However, understanding the interaction between the environment and the mechanisms of apical dominance is a major issue [3]. Our study tests the long-standing hypothesis that sugar availability is involved in the mediation of light effect on bud outgrowth at plant-level. We combined experimental studies and computer simulations, using rose as a plant model. First, using buds grown in vitro , high sugar availability was demonstrated to reduce auxin repressing effect on bud outgrowth, indicating that it could reduce the auxin-related apical dominance in planta . Sugar effect was highlighted to be due to a repression of a pathway downstream of auxin by testing different possible scenarios in a model [5]. Then, we demonstrated the ability of sugar availability to modulate bud outgrowth rate and to explain, at least partly, light effect in planta . Plants were grown under comfort