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Dwarf tomatoes are advantageous when cultivated in a plant factory with artificial light because they can grow well in a small volume. However, few studies have been reported on cultivation in a controlled environment for improving productivity. We performed two experiments to investigate the effects of photosynthetic photon flux density (PPFD; 300, 500, and 700 μmol m−2 s−1) with white light and light quality (white, R3B1 (red:blue = 3:1), and R9B1) with a PPFD of 300 μmol m−2 s−1 on plant growth and radiation-use efficiency (RUE) of a dwarf tomato cultivar (‘Micro-Tom’) at the vegetative growth stage. The results clearly demonstrated that higher PPFD leads to higher dry mass and lower specific leaf area, but it does not affect the stem length. Furthermore, high PPFD increased the photosynthetic rate (Pn) of individual leaves but decreased RUE. A higher blue light proportion inhibited dry mass production with the same intercepted light because the leaves under high blue light proportion had low Pn and photosynthetic light-use efficiency. In conclusion, 300 μmol m−2 s−1 PPFD and R9B1 are the recommended proper PPFD and light quality, respectively, for ‘Micro-Tom’ cultivation at the vegetative growth stage to increase the RUE.

In recent years, 3D imaging became an increasingly popular screening modality for high-throughput plant phenotyping. The 3D scans provide a rich source of information about architectural plant organization which cannot always be derived from multi-view projection 2D images. On the other hand, 3D scanning is associated with a principle inaccuracy by assessment of geometrically complex plant structures, for example, due the loss of geometrical information on reflective, shadowed, inclined and/or curved leaf surfaces. Here, we aim to quantitatively assess the impact of geometrical inaccuracies in 3D plant data on phenotypic descriptors of four different shoot architectures, including tomato, maize, cucumber, and arabidopsis. For this purpose, virtual laser scanning of synthetic models of these four plant species was used. This approach was applied to simulate different scenarios of 3D model perturbation, as well as the principle loss of geometrical information in shadowed plant regions. Our experimental results show that different plant traits exhibit different and, in general, plant type specific dependency on the level of geometrical perturbations. However, some phenotypic traits are tendentially more or less correlated with the degree of geometrical inaccuracies in assessing 3D plant architecture. In particular, integrative traits, such as plant area, volume, and physiologically important light absorption show stronger correlation with the effectively visible plant area than linear shoot traits, such as total plant height and width crossover different scenarios of geometrical perturbation. Our study addresses an important question of reliability and accuracy of 3D plant measurements and provides solution suggestions for consistent quantitative analysis and interpretation of imperfect data by combining measurement results with computational simulation of synthetic plant models.

Optimizing the N application amount and topdressing ratio can increase crop yield and decrease N loss, but its internal mechanisms have not been well studied, especially from the aspects of population dynamics and structure, ear fruiting traits. Here, field experiments, with three N rates 120 (N1), 180 (N2), and 240 (N3) kg N ha -1 and three N topdressing ratios T1 (7:3), T2 (6:4), and T3 (5:5) were conducted. At the same N level, results showed that the N accumulation amounts in the leaf, grain, and plant in T2 were higher than in T3 and T1, and increasing 60 kg N ha -1 (N3 compared to N2, N2 compared to N1) significantly enhanced N accumulation amounts. The effect of the N topdressing ratio on partial factor productivity of applied N was consistently T2 > T3 > T1, but T1 was more conducive to improving N utilization efficiency for grain and biomass production. After the jointing stage, compared to T1 and T3, T2 was more conducive to increasing the population growth rate of plant height, leaf area index, leaf area growth rate, dry matter weight, dry matter accumulation rate, light interception rate, and spikelets of population, and the above-mentioned indexes of population could be significantly enhanced by increasing 120 kg N ha -1 . T2 increased the fruiting spikelets per ear, grains per ear, grain weight per ear, fruiting rate per ear, grain filling rate per ear, and yield but decreased the sterile spikelets at the top and bottom and imperfect grains per ear. Increasing N from 120 kg ha -1 to 180 kg ha -1 or from 180 kg ha -1 to 240 kg ha -1 significantly enhanced yield. The N accumulation amount in the grain, leaf, plant, leaf area growth rate, dry matter accumulation rate, light interception rate, population spikelets, fruiting spikelets per ear, grain filling rate, and yield were significantly positively correlated with each other. This study demonstrates a suitable N application rate with a N topdressing ratio 6:4 would more effectively improve N efficiency, population dynamics, structure, ear fruiting traits, and yield, but the effect of the N topdressing ratio is not as significant as that of increasing 60 kg N ha -1 .

Seasonal drought limits the growth of plantations. Functional traits are effective indicators to clarify the controlling factors of plantation productivity. In this study, four treatments were carried out for the juvenile Eucalyptus urophylla × E.grandis plantations as (1) no dry-season irrigation or conventional fertilization (C); (2) only dry-season irrigation (W); (3) only conventional fertilization (F); (4) dry-season irrigation and conventional fertilization (WF). During the two years of treatment, growth traits, gas exchange characteristics, and structural properties were measured. The results showed that both dry-season irrigation and conventional fertilization could promote the growth of E. urophylla × E. grandis plantations. The effect of fertilization on increasing biomass of E. urophylla × E. grandis (3 times that of C) was greater than that of dry-season irrigation (only 1.5 times that of C). The biomass of WF was significantly higher than that of F. Dry-season irrigation could play the greatest role in promoting growth only when soil nutrients were sufficient. E. urophylla × E. grandis increased the total leaf area per tree but not the single leaf photosynthetic capacity, indicating the increased growth reflected greater canopy light interception. Fertilization increased the growth of E. urophylla × E. grandis plantations more than irrigation alone, but combining fertilization and dry-season irrigation further improved biomass yields of the juvenile plantations. Therefore, suitable dry-season irrigation management should be considered in seasonally arid areas to further improve the productivity of conventional plantations with only fertilization. This study elucidated the mechanism of dry-season irrigation to enhance the productivity of Eucalyptus plantations by functional traits, which provided strong data support for enhancing the productivity of plantation forests in seasonal arid areas.

Background: Understanding canopy light interception is essential for optimizing forage production and improving the efficiency of grazing systems. Accurate quantification of photosynthetically active radiation (PAR) intercepted by the canopy allows for better estimation of crop coefficients and growth dynamics. This study aimed to assess the forage mass and nutritional value of Guinea grass pastures managed under two grazing frequencies, defined by 90% and 95% light interception (LI) measured using AccuPar equipment, and two post-grazing stubble heights (30 and 50 cm). Evaluations were conducted during both the rainy season and a dry year to capture seasonal variability in pasture performance. Methods: The experimental design was of completely randomized blocks with four replications. Results: The treatment whit 90% LI resulted in higher values of crude protein and digestible. However, 95% LI resulted in higher values of neutral detergent insoluble nitrogen and acid detergent insoluble nitrogen values in grass pastures Guinea. The highest value of forage mass in Guinea grass was reported with 95% LI in association with a post-grazing height of 30 cm. Conclusions: Management of light interception at 90% provided a reduced amount of forage with better nutritional value. Pasture management considering the light interception technology with the AccuPar equipment was efficient as a pattern for interrupting pasture regrowth in the vegetative phase.

In plant factories, light is fully controllable for crop production but involves a cost. For efficient lighting, light use efficiency (LUE) should be considered as part of light environment design. The objectives of this study were to evaluate and interpret the light interception, photosynthetic rate, and LUE of lettuces under electrical lights using ray-tracing simulation. The crop architecture model was constructed by 3D scanning, and ray-tracing simulation was used to interpret light interception and photosynthesis. For evaluation of simulation reliability, measured light intensities and photosynthetic rates in a growth chamber were compared with those obtained by simulation at different planting densities. Under several scenarios modeling various factors affecting light environments, changes in light interception and LUE were interpreted. The light intensities and photosynthetic rates obtained by simulation showed good agreement with the measured values, with R2 > 0.86. With decreasing planting density, the light interception of the central plant increased by approximately 18.7%, but that of neighboring plants decreased by approximately 5.5%. Under the various scenarios, shorter lighting distances induced more heterogenetic light distribution on plants and caused lower light interception. Under a homogenous light distribution, the light intensity was optimal at approximately 360 μmol m−2 s−1 with an LUE of 6.5 g MJ−1. The results of this study can provide conceptual insights into the design of light environments in plant factories.

Coexistence of multiple species is a fundamental aspect of plant and forest ecology. Although spatial arrangement of leaves within crowns is an important determinant of light interception and productivity, shoot structure varies considerably among coexisting canopy species. We investigated the relative importance of structural traits in determining the light availability of leaves (I) and light interception efficiency at the current-year shoot level (LIECS; the total light interception of leaves divided by shoot biomass) at the top of crowns of 11 canopy species in a cool-temperate forest in Japan. In accordance with Corner’s rules, the total mass, stem mass, total mass of leaf laminae, individual leaf area, and stem cross-sectional area of current-year shoot were positively correlated with each other, and branching intensity (the number of current-year shoots per branch unit of 1-m length) was inversely correlated with these traits across species. In contrast, I was correlated not with these traits, but with leaf elevation angle (a L). Moreover, variation in LIECS across species was caused by variation in I (thus in a L). Thus, a L is a key parameter for the leaf light interception of canopy shoots in this cool-temperate forest. Differences in a L across species might be related to different physiological strategies that developed in the high light and water-limited environment of forest canopies. Small variation in the length of current-year shoots among species implies that variations in I and LIECS would be important for the coexistence of these canopy species.

Questions: Does functional diversity play a more important role than species richness in complementary resource use? Is the effect of functional diversity on complementarity greater when species evenness is higher? Does functional dominance play an important role in resource use when species evenness is low? Location: An arable field in Linhai City, Zhejiang Province, China. Methods: We assembled experimental plant communities with different species richness (one, two, four, eight and 12 species) and evenness (low and high). In each community, we quantified light interception efficiency (LIE) and light complementarity index (LC) to reflect light use. We measured four functional traits related to light capture to quantify functional diversity and functional dominance. We then tested effects of observed species richness, functional diversity and functional dominance on LIE, LC and above-ground biomass in the low and high evenness communities. Results: Functional diversity was positively related to LIE, LC and above-ground biomass in the high evenness communities, but not in the low evenness communities. In contrast, functional dominance was positively related to LIE and negatively related to LC in the low evenness communities, but not in the high evenness communities. Moreover, functional dominance had a larger promotion to above-ground biomass in the low evenness communities. Observed species richness and evenness had a significant interactive effect on LIE and LC. LIE of a species mixture of the low evenness communities was positively correlated with LIE of the monoculture consisting of the species with the highest initial abundance in the species mixture, while LC of a species mixture of the low evenness communities was negatively correlated with it. Conclusions: Functional diversity and functional dominance play a crucial role in light complementary use of plant communities, and their effects on light complementarity are mediated by species evenness. Thus, interactions of functional traits and evenness may greatly affect ecosystem functioning.

A new model for grapevines (Vitis vinifera) is the first perennial fruit crop model using the Agricultural Production System sIMulator (APSIM) Next Generation framework. Modules for phenology, light interception, carbohydrate allocation, yield formation and berry composition were adapted or added into APSIM Next Generation to represent the nature of fruit-bearing vines. The simulated grapevine phenological cycle starts with the dormancy phase triggered by a critical photoperiod in autumn, and then goes through the subsequent phenophases sequentially and finally returns to dormancy for a new cycle. The canopy microclimate module within APSIM Next Generation was extended to allow for row crop light interception. The carbohydrate arbitrator was enhanced to consider both sink strength and sink priority to reflect carbohydrate reserve as a concurrent competing sink. Weather conditions and source–sink ratio at critical developmental stages were used to determine potential grapevine yield components, e.g. bunch number, berry number and berry fresh weight. The model was calibrated and tested extensively using four detailed data sets. The model captured the variations in the timing of measured budburst, flowering and véraison over 15 seasons across New Zealand for five different varieties. The calculated seasonal dynamics of light interception by the row and alley were consistent with field observations. The model also reproduced the dynamics of dry matter and carbohydrate reserve of different organs, and the wide variation in yield components caused by seasonal weather conditions and pruning regimes. The modelling framework developed in this work can also be used for other perennial fruit crops.

Crown architecture usually is heterogeneous as a result of foraging in spatially and temporally heterogeneous light environments. Ecologists are only beginning to identify the importance of temporal heterogeneity for light acquisition in plants, especially at the diurnal scale. Crown architectural heterogeneity often leads to a diurnal variation in light interception. However, maximizing light interception during midday may not be an optimal strategy in environments with excess light. Instead, long-lived plants are expected to show crown architectures and leaf positions that meet the contrasting needs of light interception and avoidance of excess light on a diurnal basis. We expected a midday depression in the diurnal course of light interception both at the whole-crown and leaf scales, as a strategy to avoid the interception of excessive irradiance. We tested this hypothesis in a population of guava trees ( L.) growing in an open tropical grassland. We quantified three crown architectural traits: intra-individual heterogeneity in foliage clumping, crown openness, and leaf position angles. We estimated the diurnal course of light interception at the crown scale using hemispheric photographs, and at the leaf scale using the cosine of solar incidence. Crowns showed a midday depression in light interception, while leaves showed a midday peak. These contrasting patterns were related to architectural traits. At the crown scale, the midday depression of light interception was linked to a greater crown openness and foliage clumping in crown tops than in the lateral parts of the crown. At the leaf scale, an average inclination angle of 45° led to the midday peak in light interception, but with a huge among-leaf variation in position angles. The mismatch in diurnal course of light interception at crown and leaf scales can indicate that different processes are being optimized at each scale. These findings suggest that the diurnal course of light interception may be an important dimension of the resource acquisition strategies of long-lived woody plants. Using a temporal approach as the one applied here may improve our understanding of the diversity of crown architectures found across and within environments.