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Context: Canopy architecture and associated light distribution, nitrogen distribution, and leaf physiological characteristics drive canopy photosynthesis, and ultimately determine grain yields. Breeding has increased those yields during the past decades of breeding history but it is not clear if this also improved efficiency in nitrogen allocation for optimal light use. Research questions: To what extent has selection for yields affected maize canopy architecture and the vertical distribution of light and nitrogen? Methods: A 2-year field experiment was conducted in Jilin province, Northeast China, involving six maize cultivars released between 1950 and 2004. The canopy architecture, the vertical distribution patterns of light and nitrogen, and grain yields of these cultivars were quantified and analysed. Results: The genetic gain in grain yield through breeding was 109 kg ha−1 year−1, and the concomitant increase in aboveground biomass was 16.1 g m−2 ground year −1 at maturity stage. Modern cultivars had more erect leaves compared to older cultivars, especially the leaves above the ear leaf, showing a decrease of 0.31° year−1. The changes in leaf area index (LAI) and leaf angle contributed to the improved light distribution within the canopy over generations of selection, as the light extinction coefficient KL decreased significantly by 0.67% year−1. The canopy nitrogen content increased by 0.09 g N m−2 ground year−1, but the average canopy specific leaf nitrogen (canopy N/LAI) tended to decrease. The relationship between light and nitrogen distribution within the canopy differed among cultivars but did not relate to year of release(YOR), indicating that breeding of maize cultivars from the 1950–2004 primarily led to changes in canopy N and canopy architecture and did not improve the coordination between light and nitrogen in maize canopy. Conclusion: Yield gain through breeding history from 1950 to 2004 was strongly associated with increases in canopy N and LAI li

This paper presents results of analyzing the second half of the 20th–early 21st century changes in lateral spatial structure of Larix sibirica Ledeb. population in the upper treeline ecotone located on the Rai-Iz massif (Polar Urals, Russia). The GIS layers characterizing distribution of Siberian larch trees and undergrowth together with their crowns was produced for a 7.32 square kilometer area based on aerial images recognition. Using statistical models, we assessed probabilities for assigning trees to age intervals of 1–10, 11–40, and 40+ years based on the average radius of tree crown projection. These maps and layer showing locations of trees that grew in the upper part of the ecotone, and died during the Little Ice Age, allow for assessing specifics of forest cover proliferation at different parts of upper treeline ecotone, and comparing current location of the trees with one from the past. The proposed method for probability-based recognition of Siberian larch tree generations in the upper treeline ecotone using average crown radius can be used to reconstruct time and spatial forest dynamics at the upper growth boundaries for time spans up to 100 years and more. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

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.

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.

Background and AimsShading by an overhead canopy (i.e., canopy shading) entails simultaneous changes in both photosynthetically active radiation (PAR) and red to far-red ratio (R:FR). As plant responses to PAR (e.g. changes in leaf photosynthesis) are different from responses to R:FR (e.g. changes in plant architecture), and these responses occur at both organ and plant levels, understanding plant photosynthesis responses to canopy shading needs separate analysis of responses to reductions in PAR and R:FR at different levels.MethodsIn a greenhouse experiment we subjected plants of woody perennial rose (Rosa hybrida) to different light treatments, and so separately quantified the effects of reductions in PAR and R:FR on leaf photosynthetic- and plant architectural traits. Using a functional-structural plant model, we separately quantified the effects of responses in these traits on plant photosynthesis, and evaluated the relative importance of changes of individual traits for plant photosynthesis under mild and heavy shading caused by virtual overhead canopies.Key ResultsModel simulations showed that the individual trait responses to canopy shading could have positive and negative effects on plant photosynthesis. Under mild canopy shading, trait responses to reduced R:FR on photosynthesis were generally negative and with a larger magnitude than effects of responses to reduced PAR. Conversely, under heavy canopy shading, the positive effects of trait responses to reduced PAR became dominant. The combined effects of low-R:FR responses and low-PAR responses on plant photosynthesis were not equal to the sum of the separate effects, indicating interactions between individual trait responses.ConclusionsOur simulation results indicate that under canopy shading, the relative importance of plant responses to PAR and R:FR for plant photosynthesis changes with shade levels. This suggests that the adaptive significance of plant plasticity responses to one shading factor depends

The global human population is rising rapidly every year, which in turn increases the demands for food production. For that reason, crop production must be intensified. Intensification of agriculture requires crop plants to grow in high densities, creating a very competitive environment especially for light. This competition becomes more intense in the presence of weeds. Light quality is changed inside the dense canopy due to the absorption of Red (R) and Blue (B) light for photosynthesis and the reflection of Far-red (FR) light from neighbour plants. A reduced R:FR ratio triggers the Shade Avoidance Syndrome (SAS); a suite of responses that enhance individual plant fitness in dense stands by allocating carbon to petiole or stem elongation and upward movement of the leaf, thus ensuring light capture. This goes at the expense of carbon allocation to leaf blades and to harvestable organs such as seeds or roots. These characteristics in combination with competition with weeds cause serious reductions of crop yield. To combat these yield reductions, sustainable ways to suppress weeds and to minimize the allocation of resources towards SAS in the unwanted organs should be developed. In this thesis, I tried to study the basic principles needed to achieve this by studying two different scenarios. The first one was to change the planting patterns in dense stands. While the second to modify the shade avoidance responses in dense stands from the very early stage up to a fully shade avoiding developed canopy. Finally, I also investigated molecular mechanisms of shade avoidance regulation to generate knowledge for future modifications of SAS components.

Remote sensing is revolutionizing the way we study forests, and recent technological advances mean we are now able – for the first time – to identify and measure the crown dimensions of individual trees from airborne imagery. Yet to make full use of these data for quantifying forest carbon stocks and dynamics, a new generation of allometric tools which have tree height and crown size at their centre are needed. Here, we compile a global database of 108753 trees for which stem diameter, height and crown diameter have all been measured, including 2395 trees harvested to measure aboveground biomass. Using this database, we develop general allometric models for estimating both the diameter and aboveground biomass of trees from attributes which can be remotely sensed – specifically height and crown diameter. We show that tree height and crown diameter jointly quantify the aboveground biomass of individual trees and find that a single equation predicts stem diameter from these two variables across the world's forests. These new allometric models provide an intuitive way of integrating remote sensing imagery into large-scale forest monitoring programmes and will be of key importance for parameterizing the next generation of dynamic vegetation models. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd., We thank the co-authors, field data collectors and funding agencies of the original data sources used in this study. We are also grateful to all curators of open-access databases from which we drew data for this study. In particular, we wish to thank Daniel Falster and Remko Duursma for compiling the biomass and allometry database (BAAD) for woody plants; Michael Keller and Maiza Nara for providing us access to data from the Sustainable Landscapes Brazil project; Kristina Anderson-Teixeira and her co-authors for archiving allometric data from the CTFS-ForestGEO forest dynamics plot at the Smithsonian Conservation Biology Institute (Virginia, USA); and KaDonna Randolph of the USDA forest service for her assistance in accessing the Forest Health Monitoring (FHM) database. We thank Bruno H?rault and an anonymous reviewer for their thoughtful and constructive comments on an earlier draft of our manuscript. T.J. was funded by NERC (grant number: NE/K016377/1). This work has benefited from ANR grants to J.C. (CEBA, ref. ANR-10-LABX-25-01 and TULIP, ref. ANR-10-LABX-0041). The Sustainable Landscapes Brazil project was supported by the Brazilian Agricultural Research Corporation (EMBRAPA), the US Forest Service, and USAID, and the US Department of State. Data collection for the UNECE ICP Forests PCC Collaborative Database was cofinanced by national or regional organizations and by the European Commission under regulations (EEC) No 2158/86, Forest Focus (EC) No 2152/200, FutMon (EC) LIFE07 ENV/D/218.

Remote sensing is revolutionizing the way we study forests, and recent technological advances mean we are now able – for the first time – to identify and measure the crown dimensions of individual trees from airborne imagery. Yet to make full use of these data for quantifying forest carbon stocks and dynamics, a new generation of allometric tools which have tree height and crown size at their centre are needed. Here, we compile a global database of 108753 trees for which stem diameter, height and crown diameter have all been measured, including 2395 trees harvested to measure aboveground biomass. Using this database, we develop general allometric models for estimating both the diameter and aboveground biomass of trees from attributes which can be remotely sensed – specifically height and crown diameter. We show that tree height and crown diameter jointly quantify the aboveground biomass of individual trees and find that a single equation predicts stem diameter from these two variables across the world's forests. These new allometric models provide an intuitive way of integrating remote sensing imagery into large-scale forest monitoring programmes and will be of key importance for parameterizing the next generation of dynamic vegetation models. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd., We thank the co-authors, field data collectors and funding agencies of the original data sources used in this study. We are also grateful to all curators of open-access databases from which we drew data for this study. In particular, we wish to thank Daniel Falster and Remko Duursma for compiling the biomass and allometry database (BAAD) for woody plants; Michael Keller and Maiza Nara for providing us access to data from the Sustainable Landscapes Brazil project; Kristina Anderson-Teixeira and her co-authors for archiving allometric data from the CTFS-ForestGEO forest dynamics plot at the Smithsonian Conservation Biology Institute (Virginia, USA); and KaDonna Randolph of the USDA forest service for her assistance in accessing the Forest Health Monitoring (FHM) database. We thank Bruno H?rault and an anonymous reviewer for their thoughtful and constructive comments on an earlier draft of our manuscript. T.J. was funded by NERC (grant number: NE/K016377/1). This work has benefited from ANR grants to J.C. (CEBA, ref. ANR-10-LABX-25-01 and TULIP, ref. ANR-10-LABX-0041). The Sustainable Landscapes Brazil project was supported by the Brazilian Agricultural Research Corporation (EMBRAPA), the US Forest Service, and USAID, and the US Department of State. Data collection for the UNECE ICP Forests PCC Collaborative Database was cofinanced by national or regional organizations and by the European Commission under regulations (EEC) No 2158/86, Forest Focus (EC) No 2152/200, FutMon (EC) LIFE07 ENV/D/218.

A recent meta-analysis suggested that differences in rainfall are a cause of variation in tree-grass interactions in savannas, with trees facilitating growth of understorey grasses in low-rainfall areas, but competing with them under higher rainfall. We hypothesized that this effect of rainfall upon understorey productivity is modified by differences in the growth form of the woody plants (i.e. the height of the lower canopy) or by their capacity to fix nitrogen. We performed a meta-analysis of the effects of woody plants on understorey productivity, incorporating canopy height and N-fixation, and their interaction with rainfall. N-fixing woody plants enhanced understorey productivity, whereas non-fixers had a neutral or negative effect, depending on high or low canopy, respectively. We found a strong negative correlation between rainfall and the degree to which trees enhanced understorey productivity, but only for trees with a high canopy.Synthesis. The effect of woody plants on understorey productivity depends not only on rainfall, but also on their growth form and their capacity to fix N. Facilitation occurs mostly when woody plants ameliorate both water and nitrogen conditions. However, a low canopy suppresses understorey vegetation by competing for light, regardless of water and nutrient relations.

The spatial heterogeneity of tropical forest epiphytes has rarely been quantified in terms of biomass. In particular, the effect of topographic variation on epiphyte biomass is poorly known, although forests on ridges and ravines can differ drastically in stature and exposure. In an Ecuadorian lower montane forest we quantified epiphytic biomass along two gradients: (1) the twig-branch-trunk trajectory, and (2) the ridge-ravine gradient. Twenty-one trees were sampled in each of three forest types (ridge, slope, ravine positions). Their epiphytic biomass was extrapolated to stand level based on basal area-epiphyte load relationships, with tree basal areas taken from six plots of 400 m 2 each per forest type. Our results document the successional addition and partial replacement of lichens by bryophytes, angiosperms and finally dead organic matter along the twig-branch-trunk trajectory. Despite having the highest tree basal area, total epiphytic biomass (mean ± SD) of ravine forest was significantly lower (2.6 ± 0.7 Mg ha -1) than in mid-slope forest (6.3 ± 1.1 Mg ha -1) and ridge forest (4.4 ± 1.6 Mg ha -1), whereas maximum bryophyte water storage capacity was significantly higher. We attribute this pattern to differences in forest dynamics, stand structure and microclimate. Although our study could not differentiate between direct effects of slope position (nutrient availability, mesoclimate) and indirect effects (stand structure and dynamics), it provides evidence that fine-scale topography needs to be taken into account when extrapolating epiphytic biomass and related matter fluxes from stand-level data to the regional scale. © Copyright Cambridge University Press 2011.

Canopy structure has long been thought to influence the productivity and ecological dynamics of tropical forests by altering the availability of light to leaves. Theories and methods that can connect detailed quantitative observations of canopy structure with forest dynamics, however, have been lacking. There is urgent need to resolve this uncertainty because human-caused climate change may alter canopy structure and function in the Amazon. This work addresses this problem by, first, developing methods based on LiDAR remote sensing of fine-scale structural variation to predict the spatial structure of leaf area and light in forest canopies of the central Amazon (Appendices B&C). I show that LiDAR-based leaf area and light estimates can be used to predict the productivity of tree size groups and one-hectare forest plots--as well as differences between 2 sites separated by 500km (App. B). Sites also differed in canopy structure and the distribution of tree frequencies over size (size or diameter distribution). A model based on tree architecture, however, was able to connect observed differences in canopy architecture with size distributions to predict plot and site differences (App. D). This model showed that tree architecture is plastic in different light environments. While plasticity may increase light absorption, the smallest size groups appeared light limited. Absorption over size groups in one site, but not the other, agreed with the hypothesis of energetic equivalence across size structure. Ultimately, the performance of individual trees of different sizes in different canopy environments links forest demography with canopy structure and ecosystem function--I present a study aimed at improving tests of individual level theories for the role of light dependence in tree growth (App. A). Together, this work quantitatively connects canopy structure with forest carbon dynamics and demographic structure and further develops LiDAR as premier tool for studying forest e

The composition and structure of tree stands near the timberline have been studied on different slopes and at different elevations in the Tylaisko-Konzhakovsko-Serebryanskii Massif, the North Urals. It has been found that the upper limits of tree stands with different degrees of canopy closure have risen considerably (by about 100 m of elevation) since the mid-19th century, although the formation of these stands started as early as the late 18th century. Woodless areas in the eastern part of the massif started to be colonized by Larix sibirica in the late 18th to early 19th centuries; those in the western part, by Picea obovata in the mid-19th century; and in the southern part, by Betula tortuosa in the late 19th century. Analysis of meteorological data provides evidence for warming and increasing humidity of the climate since the late 19th century. Favorable climatic changes that facilitated the expansion of the forest have taken place both in the summer (prolongation of the growing period) and in winter seasons (increase of air temperature and precipitation). The observed differences in the composition and dynamics of tree stands between the studied areas of the mountain range are most probably explained by different requirements of tree species for the depth of snow cover and the degree of soil freezing. © 2010 Pleiades Publishing, Ltd., This study was supported by the International Association for the Promotion of Cooperation with Scientists from the New Independent States of the Former Soviet Union (project no. INTAS 01 0052); the Russian Foundation for Basic Research (project nos. 05 04 48466, 08 04 00208, and 10 05 00778); and the Program for Development of Science and Education Centers (contract no. 02.740.11.0279).

The composition and structure of tree stands near the timberline have been studied on different slopes and at different elevations in the Tylaisko-Konzhakovsko-Serebryanskii Massif, the North Urals. It has been found that the upper limits of tree stands with different degrees of canopy closure have risen considerably (by about 100 m of elevation) since the mid-19th century, although the formation of these stands started as early as the late 18th century. Woodless areas in the eastern part of the massif started to be colonized by Larix sibirica in the late 18th to early 19th centuries; those in the western part, by Picea obovata in the mid-19th century; and in the southern part, by Betula tortuosa in the late 19th century. Analysis of meteorological data provides evidence for warming and increasing humidity of the climate since the late 19th century. Favorable climatic changes that facilitated the expansion of the forest have taken place both in the summer (prolongation of the growing period) and in winter seasons (increase of air temperature and precipitation). The observed differences in the composition and dynamics of tree stands between the studied areas of the mountain range are most probably explained by different requirements of tree species for the depth of snow cover and the degree of soil freezing. © 2010 Pleiades Publishing, Ltd., This study was supported by the International Association for the Promotion of Cooperation with Scientists from the New Independent States of the Former Soviet Union (project no. INTAS 01 0052); the Russian Foundation for Basic Research (project nos. 05 04 48466, 08 04 00208, and 10 05 00778); and the Program for Development of Science and Education Centers (contract no. 02.740.11.0279).

Maize (Zea mays L.) and alfalfa (Medicago sativa L.) were simultaneously irrigated in two adjoining plots with the same sprinkler solid-set system under the same operational and technical conditions. The Christiansen's uniformity coefficient (CUC) and the wind drift and evaporation losses (WDEL) were assessed from the irrigation depth (IDC) collected into pluviometers above each crop. A network of pluviometers was located above the maize canopy. Two networks of pluviometers were located above the alfalfa, one above the canopy and the other at the same level as that above the maize. The latter was used to analyze the effects of the water collecting plane. The wind velocity (WV) profile was measured above each crop using anemometers located at three levels. Both the CUC and the WDEL differed between maize and alfalfa. The crops modified both the wind velocity above the canopy and the water interception plane. Both effects were related to the height of the crops (h). When h increased, the water interception plane increased, and the overlap of the sprinklers decreased. The CUC of the IDC increased with the overlap. Because h was greater for maize than for alfalfa, the CUC was noticeably smaller for maize. The WV greatly decreased in proximity to the canopy. The WV at the level of the nozzles was smaller above the maize because the top of the canopy was closer to the nozzles than it was for alfalfa. However, the CUC of the IDC mainly depended on the WV at higher levels, where the WV was similar above both maize and alfalfa. The logarithmic wind profile overestimated the vertical variation of the WV in the space where the sprinklers distributed the water. The WDEL was greater above the maize than above the alfalfa. This finding was related to the underestimation of the IDC above maize, especially under windy conditions, because the pluviometers were located very close to the nozzles.

The retrieval of canopy architectural parameters using off-the-shelf digital cameras with fish-eye lens is investigated. The technique used takes advantage of the sensor’s linear response to light of these cameras to improve the estimation of gap fraction using: (1) the digital numbers of mixed sky-canopy pixels to estimate the within-pixel gap fraction; and (2) this process is done considering the variation in view zenith angle to take into account the sky radiance distribution and the canopy multiple scattering effects. The foliage element clumping index is retrieved over a wide range of view zenith angles using: (1) the accumulated gap size distribution theory developed for the TRAC by Chen and Cihlar (1995a); (2) the Lang and Xiang (1986) finite-length averaging method; and (3) a method combining the gap size distribution and the Lang and Xiang finite-length methods. Using data from Canadian and Russian boreal forests, comparisons of gap fraction, clumping index and plant area index measured with the tracing radiation and architecture of canopies (TRAC) and digital hemispherical photography are presented. Evaluation of the LAI estimated from digital hemispherical photography with allometric LAI of two boreal forest stands suggest that that the clumping index combined method may be more accurate.

Prohexadione-calcium (P-ca), as ApogeeTM, was evaluated in 2000 and 2001 for impact to grape vegetative and reproductive development. In 2000, P-ca (250 mg/L) was applied to Seyval, Cabernet Sauvignon, and Cabernet franc (125, 250, and 375 mg/L). P-ca reduced primary shoot growth for all cultivars and decreased cane pruning weight of Seyval. P-ca (375 mg/L) increased Cabernet franc canopy gaps but increased Cabernet Sauvignon lateral leaf area and leaf layer number. P-ca reduced components of yield for all cultivars. In 2001, P-ca (250 mg/L) was applied singularly at weekly intervals to Cabernet Sauvignon clusters and pre and post-bloom to Cabernet franc and Chardonnay canopies. Application at E-L stages 21 and 23 decreased Cabernet Sauvignon fruit set whereas application at E-L stages 26, 27, and 29 reduced berry weight without impacting fruit set. Berry weight reduction correlated to higher color intensity (420+520 nm), anthocyanins, total phenols and phenol-free glycosyl-glucose (PFGG). Cabernet franc vegetative and reproductive development was generally not affected yet treatment increased absorbance at 280, 420, and 520 nm, color intensity, anthocyanins and total phenols. Pre-bloom applications inhibited Chardonnay vegetative development, and reduced components of yield, and fruit chemistry values: hydroxycinnamates, total phenols, flavonoids, PPFG and absorbance at 280 and 320 nm. Post-bloom applications did not affect Chardonnay vegetative or reproductive development, yet increased PFGG. Treatment did not affect Chardonnay wine chemistry but two post-bloom applications increased Cabernet franc wine anthocyanins and total phenols. Wine aroma and flavor triangle difference tests did not indicate significant treatment differences.

van Etten, E. J., Belen, C. A., & Calviño-Cancela, M. (2020). Invasion patterns of Pinus pinaster in south-west Australia in relation to fire, vegetation type and plantation management. Forest Ecology and Management, 463, Article 118042. https://doi.org/10.1016/j.foreco.2020.118042

Current sugar beet varieties vary widely in their canopy architecture; some have a distinctively prostrate canopy angle whilst others are much more upright. Radiation use efficiency (RUE) is the amount of biomass accumulated per unit of light intercepted by the crop. In crops such as rice and wheat, where canopy architecture has been quantified, canopy angle has been shown to significantly influence light interception and RUE. This project quantifies canopy architecture and assesses its effect on RUE and yield of sugar beet. A combination of controlled environment and field experiments were conducted to classify varieties into canopy types according to petiole angle and assess the impact of canopy angle on light interception, photosynthesis and biomass accumulation in the crop. Prostrate canopy types were demonstrated as having the greatest canopy expansion rate and to intercept more light across the season than an upright or intermediate canopy type. However, despite intercepting the most light, this did not lead to the greatest sugar yield. This research shows evidence that prostrate canopy types have lower rates of photosynthesis, and that the canopy is acclimated to shaded conditions indicative of the overlapping nature of the leaves within and between rows. Upright canopy types had the greatest RUE of total biomass later in the season and could be suited to a later harvest due to potentially more efficient light interception at lower sun angles. Furthermore, the upright canopy angle was demonstrated as advantageous to the crop during hot and droughted weather conditions, when it retained more of its canopy. Intermediate canopy types had the greatest photosynthetic potential under optimal conditions. This trait can be associated with high carbon assimilation throughout the summer months in the absence of significant plant stress leading to high total biomass RUE. The Intermediate 2 variety also showed favourable biomass partitioning to the roots later in the sea

The arrangement of leaf material is critical in determining the light environment, and subsequently the photosynthetic productivity of complex crop canopies. However, links between specific canopy architectural traits and photosynthetic productivity across a wide genetic background are poorly understood for field grown crops. The architecture of five genetically diverse rice varieties - four parental founders of a multi-parent advanced generation intercross (MAGIC) population plus a high yielding Philippine variety (IR64) - was captured at two different growth stages using a method for digital plant reconstruction based on stereocameras. Ray tracing was employed to explore the effects of canopy architecture on the resulting light environment in high-resolution, whilst gas exchange measurements were combined with an empirical model of photosynthesis to calculate an estimated carbon gain and total light interception. To further test the impact of different dynamic light patterns on photosynthetic properties, an empirical model of photosynthetic acclimation was employed to predict the optimal light-saturated photosynthesis rate (Pmax) throughout canopy depth, hypothesising that light is the sole determinant of productivity in these conditions. First we show that a plant type with steeper leaf angles allows more efficient penetration of light into lower canopy layers and this, in turn, leads to a greater photosynthetic potential. Second the predicted optimal Pmax responds in a manner that is consistent with fractional interception and leaf area index across this germplasm. However measured Pmax, especially in lower layers, was consistently higher than the optimal Pmax indicating factors other than light determine photosynthesis profiles. Lastly, varieties with more upright architecture exhibit higher maximum quantum yield of photosynthesis indicating a canopy-level impact on photosynthetic efficiency.

Background and Aims: Intercropping systems contain two or more species simultaneously in close proximity. Due to contrasting features of the component crops, quantification of the light environment and photosynthetic productivity is extremely difficult. However it is an essential component of productivity. Here, a low-tech but high resolution method is presented that can be applied to single and multi-species cropping systems, to facilitate characterisation of the light environment. Different row layouts of an intercrop consisting of Bambara groundnut (Vigna subterranea (L.) Verdc.) and Proso millet (Panicum miliaceum) have been used as an example and the new opportunities presented by this approach have been analysed. Methods: Three-dimensional plant reconstruction, based on stereocameras, combined with ray-tracing was implemented to explore the light environment within the Bambara groundnut-Proso millet intercropping system and associated monocrops. Gas exchange data was used to predict the total carbon gain of each component crop. Key Results: The shading influence of the tall Proso millet on the shorter Bambara groundnut results in a reduction in total canopy light interception and carbon gain. However, the increased leaf area index (LAI) of Proso millet, higher photosynthetic potential due to the C4 pathway and sub-optimal photosynthetic acclimation of Bambara groundnut to shade means that increasing the number of rows of millet will lead to greater light interception and carbon gain per unit ground area, despite Bambara groundnut intercepting more light per unit leaf area. Conclusions: Three-dimensional reconstruction combined with ray tracing provides a novel, accurate method of exploring the light environment within an intercrop that does not require difficult measurements of light interception and data-intensive manual reconstruction, especially for such systems with inherently high spatial possibilities. It provides new opportunities for calculating potent

The arrangement of leaf material is critical in determining the light environment, and subsequently the photosynthetic productivity of complex crop canopies. However, links between specific canopy architectural traits and photosynthetic productivity across a wide genetic background are poorly understood for field grown crops. The architecture of five genetically diverse rice varieties - four parental founders of a multi-parent advanced generation intercross (MAGIC) population plus a high yielding Philippine variety (IR64) - was captured at two different growth stages using a method for digital plant reconstruction based on stereocameras. Ray tracing was employed to explore the effects of canopy architecture on the resulting light environment in high-resolution, whilst gas exchange measurements were combined with an empirical model of photosynthesis to calculate an estimated carbon gain and total light interception. To further test the impact of different dynamic light patterns on photosynthetic properties, an empirical model of photosynthetic acclimation was employed to predict the optimal light-saturated photosynthesis rate (Pmax) throughout canopy depth, hypothesising that light is the sole determinant of productivity in these conditions. First we show that a plant type with steeper leaf angles allows more efficient penetration of light into lower canopy layers and this, in turn, leads to a greater photosynthetic potential. Second the predicted optimal Pmax responds in a manner that is consistent with fractional interception and leaf area index across this germplasm. However measured Pmax, especially in lower layers, was consistently higher than the optimal Pmax indicating factors other than light determine photosynthesis profiles. Lastly, varieties with more upright architecture exhibit higher maximum quantum yield of photosynthesis indicating a canopy-level impact on photosynthetic efficiency.

Background and Aims: Intercropping systems contain two or more species simultaneously in close proximity. Due to contrasting features of the component crops, quantification of the light environment and photosynthetic productivity is extremely difficult. However it is an essential component of productivity. Here, a low-tech but high resolution method is presented that can be applied to single and multi-species cropping systems, to facilitate characterisation of the light environment. Different row layouts of an intercrop consisting of Bambara groundnut (Vigna subterranea (L.) Verdc.) and Proso millet (Panicum miliaceum) have been used as an example and the new opportunities presented by this approach have been analysed. Methods: Three-dimensional plant reconstruction, based on stereocameras, combined with ray-tracing was implemented to explore the light environment within the Bambara groundnut-Proso millet intercropping system and associated monocrops. Gas exchange data was used to predict the total carbon gain of each component crop. Key Results: The shading influence of the tall Proso millet on the shorter Bambara groundnut results in a reduction in total canopy light interception and carbon gain. However, the increased leaf area index (LAI) of Proso millet, higher photosynthetic potential due to the C4 pathway and sub-optimal photosynthetic acclimation of Bambara groundnut to shade means that increasing the number of rows of millet will lead to greater light interception and carbon gain per unit ground area, despite Bambara groundnut intercepting more light per unit leaf area. Conclusions: Three-dimensional reconstruction combined with ray tracing provides a novel, accurate method of exploring the light environment within an intercrop that does not require difficult measurements of light interception and data-intensive manual reconstruction, especially for such systems with inherently high spatial possibilities. It provides new opportunities for calculating potent

For plants grown in agriculture, productivity and yield are two consequential factors which must be maintained to ensure a continued supply of food for a burgeoning population. Rice is consumed in many regions in the world. The high-yielding rice genotypes cultivated today are the result of decades of breeding for shorter stems and leaves with more erect canopies that maximises grain number and weight. As we approach the theoretical upper limits of yield capacity set by the environment and crop genetics, increasing pressure has been placed on identifying the traits and mechanisms that would improve photosynthetic efficiency, both at the leaf and canopy levels. While rice is consumed in many locations of the world, it is mostly cultivated in tropical regions that are facing growing pressures both environmentally and economically. In Malaysia, rice is being cultivated in increasingly stressful environments, where the requirement for substantial amounts of nitrogen fertilisers is high. With the rising costs of fertiliser production and the increasing degradation of arable land, there is a need to select for more resilient rice varieties with improved photosynthetic efficiencies for cultivation in suboptimal conditions. Canopy architecture plays an important role in determining overall plant productivity. As an essential nutrient, nitrogen is critical in determining the structure of a plant canopy and thus changes in nitrogen concentrations may have a large impact on plant productivity. This has been demonstrated in the study below, on two popular Malaysian cultivars, MR219 and MR253, and an IRRI cultivar, IR64. These rice cultivars were grown in different nitrogen treatments and analysed for changes in canopy architecture using in-depth physiology measurements coupled with canopy reconstructions using a novel 3-dimensional image-based technique with ray tracing. This method allows for the capture of unique canopy traits and make predictions for whole plant canopy produ

The arrangement of leaf material is critical in determining the light environment, and subsequently the photosynthetic productivity of complex crop canopies. However, links between specific canopy architectural traits and photosynthetic productivity across a wide genetic background are poorly understood for field grown crops. The architecture of five genetically diverse rice varieties - four parental founders of a multi-parent advanced generation intercross (MAGIC) population plus a high yielding Philippine variety (IR64) - was captured at two different growth stages using a method for digital plant reconstruction based on stereocameras. Ray tracing was employed to explore the effects of canopy architecture on the resulting light environment in high-resolution, whilst gas exchange measurements were combined with an empirical model of photosynthesis to calculate an estimated carbon gain and total light interception. To further test the impact of different dynamic light patterns on photosynthetic properties, an empirical model of photosynthetic acclimation was employed to predict the optimal light-saturated photosynthesis rate (Pmax) throughout canopy depth, hypothesising that light is the sole determinant of productivity in these conditions. First we show that a plant type with steeper leaf angles allows more efficient penetration of light into lower canopy layers and this, in turn, leads to a greater photosynthetic potential. Second the predicted optimal Pmax responds in a manner that is consistent with fractional interception and leaf area index across this germplasm. However measured Pmax, especially in lower layers, was consistently higher than the optimal Pmax indicating factors other than light determine photosynthesis profiles. Lastly, varieties with more upright architecture exhibit higher maximum quantum yield of photosynthesis indicating a canopy-level impact on photosynthetic efficiency.

Background and Aims: Intercropping systems contain two or more species simultaneously in close proximity. Due to contrasting features of the component crops, quantification of the light environment and photosynthetic productivity is extremely difficult. However it is an essential component of productivity. Here, a low-tech but high resolution method is presented that can be applied to single and multi-species cropping systems, to facilitate characterisation of the light environment. Different row layouts of an intercrop consisting of Bambara groundnut (Vigna subterranea (L.) Verdc.) and Proso millet (Panicum miliaceum) have been used as an example and the new opportunities presented by this approach have been analysed. Methods: Three-dimensional plant reconstruction, based on stereocameras, combined with ray-tracing was implemented to explore the light environment within the Bambara groundnut-Proso millet intercropping system and associated monocrops. Gas exchange data was used to predict the total carbon gain of each component crop. Key Results: The shading influence of the tall Proso millet on the shorter Bambara groundnut results in a reduction in total canopy light interception and carbon gain. However, the increased leaf area index (LAI) of Proso millet, higher photosynthetic potential due to the C4 pathway and sub-optimal photosynthetic acclimation of Bambara groundnut to shade means that increasing the number of rows of millet will lead to greater light interception and carbon gain per unit ground area, despite Bambara groundnut intercepting more light per unit leaf area. Conclusions: Three-dimensional reconstruction combined with ray tracing provides a novel, accurate method of exploring the light environment within an intercrop that does not require difficult measurements of light interception and data-intensive manual reconstruction, especially for such systems with inherently high spatial possibilities. It provides new opportunities for calculating potent