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• C. sativa plants were shorter when exposed to LED light with a lower blue:red ratio. • The smallest leaf area was observed under the LED light with a lower blue:red ratio. • Inflorescence biomass increased under the LED light with a lower blue:red ratio. • The efficiency of PSII was altered under the LED light with a lower blue:red ratio. • The LED light with a lower blue:red ratio affected the cannabinoid profile. Changes in the light spectrum elicit responses in development and secondary metabolite biosynthesis and storage. The aim of this study was to determine the effect of two light sources on the physiological and yield parameters of three varieties of C. sativa cultivated under greenhouse conditions. The non-psychoactive varieties Calotoweed, Higthcol, and Souce Cauca were treated with two light sources [LED1(100% white) and LED2 (90% red, 8% blue, <1% far red)] during the vegetative phase. Under LED2, reductions in plant height (4%-26.7%), leaf area (21%-55%), and shoot dry mass (1.9%-30.3%) were observed; however, there was a higher distribution of biomass towards the inflorescences (40.1%-51.6%). No effect of the light type on the relative chlorophyll content was observed. In all three varieties grown under LED2, reductions in stomatal conductance (4.7%-27.4%), quantum efficiency of PSII (1%-11.7%), and electron transport rate (9.2%-15.8%) were observed compared to plants under LED1. There were no significant differences in dry flower yield between light types used or varieties. Under LED1, higher CBD contents (11.9%-13.4%) and CBD per gram of inflorescence (12.9 CBD g/inflorescence – 13.8 CBD g/inflorescence) were observed compared to LED2. Under LED2, the Calotoweed (0.5%) and Soucecauca (0.6%) varieties showed higher THC concentrations compared to plants under LED1. These results demonstrate that LED2 modified canopy architecture, resulting in more compact plants with greater biomass accumulation in the inflorescence; however, these plants exhibited limitations in photosynthetic performance, which decreased CBD production and increased THC production. In conclusion, the type of light not only modified plant architecture but also affected photosynthetic performance and the production of CBD and THC. [ABSTRACT FROM AUTHOR]

Optimized maize (Zea mays L.) canopy architecture enhances density-tolerance. DHEAP (N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt) has been shown to increase maize upper canopy strata compactness, but its overall effect on the whole canopy structure and how it shapes the canopy structure remain unclear. This study examined how DHEAP affected the canopy structure of maize hybrids Zhengdan 958 (ZD958) and Xianyu 335 (XY335), with distinct canopy structures, under different planting densities. The results showed that DHEAP increased the leaf orientation value (LOV) of upper canopy strata by 8.0% while reducing middle and lower strata LOV by 11.7% and 18.4%, respectively. This indicates that DHEAP shaped a canopy structure that was compact in the upper strata and loose in the middle and lower strata. Multiple linear regression analysis showed that leaf angle had a greater impact on the upper canopy strata, while leaf auricle size had a greater impact on the middle and lower canopy strata. After DHEAP treatment, light transmission above different canopy strata increased at the reproductive stage. Concurrently, the middle canopy captured more light energy, enhanced yield formation, and boosted radiation use efficiency by 21.9% under high density. In terms of grain yield, DHEAP treatment resulted in a 9.1% and 23.9% increase in ZD958 and XY335, respectively, under high-density conditions. These results suggest that DHEAP shaped the maize canopy structure with high density tolerance, improved the distribution of light within the canopy, and increased grain yield.

This study focused on developing a novel semi-empirical model for maize's light extinction coefficient (kp) by integrating multiple remotely sensed vegetation features from several different remote sensing platforms. The proposed kp model's performance was independently evaluated using Campbell's (1986) original and simplified kp approaches. The Limited Irrigation Research Farm (LIRF) in Greeley, Colorado, and the Irrigation Innovation Consortium (IIC) in Fort Collins, Colorado, USA, served as experimental sites for developing and evaluating the novel maize kp model. Data collection involved multiple remote sensing platforms, including Landsat-8, Sentinel-2, Planet CubeSat, a Multispectral Handheld Radiometer, and an unmanned aerial system (UAS). Ground measurements of leaf area index (LAI) and fractional vegetation canopy cover (fc) were included. The study evaluated the novel kp model through a comprehensive analysis using statistical error metrics and Sobol global sensitivity indices to assess the performance and sensitivity of the models developed for predicting maize kp. Results indicated that the novel kp model showed strong statistical regression fitting results with a coefficient of determination or R2 of 0.95. Individual remote sensor analysis confirmed consistent regression calibration results among Landsat-8, Sentinel-2, Planet CubeSat, the MSR, and UAS. A comparison with Campbell's (1986) kp models reveals a 44% improvement in accuracy. A global sensitivity analysis identified the role of the normalized difference vegetation index (NDVI) as a critical input variable to predict kp across sensors, emphasizing the model's robustness and potential practical environmental applications. Further research should address sensor-specific variations and expand the kp model's applicability to a diverse set of environmental and microclimate conditions. [ABSTRACT FROM AUTHOR]

A high-quality canopy architecture is central to obtaining high crop yields. A field experiment was carried out at the Wuqiao Experimental Station from 2015 to 2019 under four irrigation schemes (W0, no irrigation after sowing; W1, 75 mm irrigation at jointing stage; W2, 75 mm irrigation at jointing and anthesis stages, respectively; W3, 75 mm irrigation at tillering, jointing and anthesis stages, respectively) to investigate the canopy structure, canopy apparent photosynthesis (CAP), canopy temperature (CT), yield and water use efficiency (WUE). The results showed that increasing irrigation times improved the leaf area index (LAI), non-leaf area index (NLAI) and light interception (LI) of the spike and total canopy but decreased the canopy temperature (CT) after anthesis. The CAP in the W3 treatment was consistently lower than that in the W1 treatment, suggesting lower effective utilization of light energy under the W3 treatment. Increasing irrigation times improved wheat yield, but the W2 treatment had no significant difference in yield compared to the W3 treatment. In addition, the W1 and W2 treatments had higher WUEs. The CT, organ temperature and LI were closely positively associated with each other, but they were all strongly negatively related to the yield. Overall, the W2 treatment was the best irrigation scheme for constructing a reasonable canopy architecture for winter wheat, obtaining more efficient water use and yield in the North China Plain (NCP). CT and organ temperature can be used as proxy parameters to estimate the canopy structure. [ABSTRACT FROM AUTHOR]

Under the pro-environmental principles of agricultural production, soil cultivation and organic fertilization are of particular importance as strategical elements in reducing weed infestation in the context of sustainable agriculture. The aim of this study was to determine the effect of long-term practices that are used in regenerative agriculture (reducing soil tillage, cover crop management, and mineral nitrogen fertilization) on canopy weed infestation and the elements of spring barley architecture. Understanding the impact of the studied factors influences decision-making regarding weed infestation control, and thus may contribute to a reduction in herbicide use. A two-factor field experiment was conducted using the split-plot method. The main factors were four cultivation methods: 1. conventional tillage without a cover crop, 2. conventional tillage + cover crop, 3. reduced tillage + cover crop, and 4. no tillage + cover crop. The subplot factor was differentiated via nitrogen fertilization, at 40, 80, or 120 kg N∙ha−1. The research covered canopy weed infestation and the parameters of spring barley canopy architecture. The species composition; the number and weight of weeds; and, for barley, the leaf area index (LAI), density, length, and tillers were determined. The test results were statistically analyzed (ANOVA) in a series of experiments while using Tukey's test for a significance level of p = 0.05. Additionally, simple linear regression analysis, principal component analysis (PCA), and data clustering (CA) were utilized. The study showed that simplified tillage contributed to reducing the number of weeds in the barley tillering stage, while also contributing to an increase in weed infestation during grain harvest. Plowing in the cover crop did not reduce the presence of undesirable plants in the canopy, while increasing doses of nitrogen fertilization contributed to a reduction in the number of weeds without affecting their mass. Weed infestation was also affected by meteorological conditions. Increased rainfall in the early stages of barley development benefits the number of weeds, especially in terms of traditional cultivation. Simplified tillage resulted in a reduction in barley density, height, and LAI, as well as an increase in the branching of the tested cereal. A significant negative correlation was also found between the weed infestation of the barley canopy and the characteristics of the canopy architecture. The PCA showed that the highest tillering of barley was provided at the lowest intensity of weed infestation. In turn, the CA indicated that the significantly higher LAI that resulted from a higher density and length of barley was attributed to the simplified cultivation treatments and the practice of direct sowing. It is a comprehensive method that can favor barley growth and development conditions while weakening weed infestation potential. [ABSTRACT FROM AUTHOR]

The spatial distribution of water is mainly controlled by the vegetation canopy, which determines the partitioning of rainfall into interception, throughfall (TF) and stemflow. TF is known to be a critical component of hydrological and biogeochemical cycles. Spatiotemporal patterns of TF have been studied in different ecosystems, although the majority of studies focused on forests. Few reports on small‐scale TF variability and drivers in semi‐arid desert steppes have been published. Herein, we investigated the variability of TF of two morphologically distinct artificial revegetation shrubs (Caragana liouana and Salix psammophila) within a semi‐arid desert steppe, synthesized the data and analysed the characteristics of TF distribution and drivers at the rainfall event scales. We found that (1) morphological differences were sufficient to generate significant (p < 0.05) differences in TF between the two shrub species under the same rainfall and meteorological conditions, with a TF percentage of 70.22% for C. liouana and 79.87% for S. psammophila; (2) a linear outward radical increase in TF was identified with increasing distance from the base of the isolated shrubs. Wind speed had a greater effect on the distribution of TF beneath the shrub structure for C. liouana, whereas the distribution of TF beneath the shrub structure for S. psammophila was more affected by wind direction; and (3) canopy architecture, in particular the stem angle and canopy base area, which affected the openness of the canopy and played an important role in the distribution of TF in the two shrubs. The results reveal the key factors driving water use under rainfall during revegetation and the TF utilization mechanism in semi‐arid areas and highlight the complementary effect of different species on ecosystem hydrological functions. [ABSTRACT FROM AUTHOR]

Summary: Wind‐induced movement in the canopy produces rapid fluctuations in irradiance, called 'windflecks'. They create a dynamic environment for photosynthesis that bears little resemblance to the stable controlled conditions under which plants are typically measured.We recorded time series of irradiance to assess the diversity of windfleck properties (intensity, duration, frequency, clustering, and spectral composition) in canopies of four crops and five tree species. We also measured traits associated with leaf morphology and canopy architecture, which could be associated with canopy‐specific differences in windflecks.Distinct features of windfleck properties were identified both between and among crop and tree canopy. Windflecks in crops were generally more intense and longer, and baseline irradiance was much higher than even the peak irradiance during a windfleck in a forest. The change in spectral composition during a windfleck was species‐specific. Overall, irradiance fluctuations were less frequent and less intense in tall canopies and with increased depth from the canopy.Our systematic exploration of how canopy structure dictates light dynamics provides new insight into windfleck creation. Coupled with progress in elucidation of the mechanisms of photosynthetic induction, this knowledge should improve our capacity to model canopy ecophysiology and understand light use efficiency in shade. [ABSTRACT FROM AUTHOR]

Cannabis sativa is cultivated for multiple uses including the production of cannabinoids. In developing improved production systems for high‐cannabinoid cultivars, scientists and cultivators must consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Determining factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids. Thirty‐two high‐cannabinoid hemp cultivars were characterized for traits including flowering date and shoot‐tip cannabinoid concentration. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post‐harvest to quantify intra‐plant variation in inflorescence biomass production and cannabinoid concentration. Some cultivars showed intra‐plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra‐ and inter‐cultivar variation in architecture that correlated with intra‐plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from various positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders. [ABSTRACT FROM AUTHOR]

Abstract Cannabis sativa is cultivated for multiple uses including the production of cannabinoids. In developing improved production systems for high‐cannabinoid cultivars, scientists and cultivators must consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Determining factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids. Thirty‐two high‐cannabinoid hemp cultivars were characterized for traits including flowering date and shoot‐tip cannabinoid concentration. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post‐harvest to quantify intra‐plant variation in inflorescence biomass production and cannabinoid concentration. Some cultivars showed intra‐plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra‐ and inter‐cultivar variation in architecture that correlated with intra‐plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from various positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders.

Maize germplasm has greater latent potential to address the global food and feed crisis because of its high radiation, water and nutrient efficiencies. Photosynthetic and canopy architectural traits in maize are important in determining yield. The present study aimed to screen a subset of local maize accessions in Sri Lanka to evaluate their photosynthetic, biomass and yield related traits and to identify resource efficient germplasm. Experiments were carried out in the Ampara district of Sri Lanka. Eight maize accessions viz; SEU2, SEU6, SEU9, SEU10, SEU14, SEU15, SEU17 and SEU17 and two elite F1 cultivars (cv. Pacific-999 and cv. Bhadra) were analyzed under field conditions. Our results showed that maize genotypes produced a lower leaf area index (LAI) at the third and tenth week after field planting (WAP). However, the LAI was significantly increased in six WAP by Pacific-999, SEU2, SEU9, and SEU15. A similar trend was observed for percentage of light interception at three WAP (47%), six WAP (>64%), and decreased at 10 WAP. In addition, LAI maximum values were between 3.0 and 3.5, allowing 80% of the incident light to be intercepted by maize canopies. The estimated light extinction coefficient (k) remained lower (<0.5), suggesting that maize leaves are eractophilic canopies. Although fractional interception (f) varies, SEU2 and SEU9 had the highest values (0.57), and quantum yields of PSII (>0.73) in dark-adapted leaves. In addition, Pacific-999, SEU2, SEU9, and SEU17 had significantly higher rates of photosynthesis with minimal stomatal conductance and transpiration rates. As a result, they outperformed the control plants in terms of biomass, cob weight and grain yield. This suggests that native maize germplasm could be introduced as novel, less resource-intensive cultivars to sustain global food security. [ABSTRACT FROM AUTHOR]

Hair lichens are distinctive for their capillary growth and typically arboreal occurrence, especially in temperate and boreal forests. They consist of two morphogroups based on cortical pigments: a brown-black group with fungal melanin and a pale yellow-green group with usnic acid. Here we test the hypothesis that these morphogroups are ecologically distinct and thus appropriately regarded as functional groups. We examine their respective horizontal occurrence in the lower canopy of 60-year-old conifer forests on a 250 m tall volcanic cone in south-central British Columbia. Trees on open south-facing slopes and near the summit were found to support mainly melanic hair lichens (Bryoria and Nodobryoria) , whereas more densely spaced trees on north-facing slopes and at the base had higher cover values of usnic lichens (especially Alectoria sarmentosa and Ramalina thrausta). The cover of melanic hair lichens was strongly correlated with canopy openness but not for their usnic counterparts. We suggest that investment in light-absorbing melanic pigments is an extreme form of specialization for high light, favouring persistence in dry, sun-exposed canopies of otherwise cool forests. By contrast, the cortex of pendent usnic hair lichens appears to facilitate optimum light transmission to underlying photobionts in shaded sites, though at the cost of sensitivity to light in open habitats, especially in rather dry regions. [ABSTRACT FROM AUTHOR]

The application of far-red (FR; 700–800 nm) light can improve plant growth, especially in leafy green vegetables, through enhancing leaf expansion and photon capture. However, higher levels of FR light may induce excessive stem elongation at the expense of leaf expansion. The morphological responses to FR light are mediated by phytochrome photoreceptors, with their activity further dependent on temperature. We aimed to quantify if different plant species respond differently to FR light and temperature conditions. Six economically-important plant species, including three cool-season species (lettuce, kale, and petunia) and three warm-season species (tomato, African marigold, and zinnia) were grown under three FR fractions [FR/(Red+FR); 0, 0.13, and 0.25] and two temperature set points (22 and 28 ℃) to characterize their growth and morphological responses. Increasing the FR fraction from 0 to 0.25 led to a 26–47 % increase in leaf expansion in lettuce, kale, petunia, and zinnia at 22 ℃. However, the total leaf area of tomato and African marigold decreased by 14–26 % as the FR fraction increased to 0.25 at 22 ℃. At a warmer temperature of 28 ℃, unlike the response observed under cooler temperature, increasing the FR fraction resulted in excessive stem elongation (a 36–101 % increase) and a 16–49 % reduction in leaf expansion in lettuce, kale, and petunia. For tomato, African marigold, and zinnia, the total leaf area increased by 15–26 % as the FR fraction increased from 0 to 0.13 at 28 ℃; however, further increasing the FR fraction from 0.13 to 0.25 resulted in a reduction in total leaf area. Across all six species, a high FR fraction combined with warm temperature synergistically stimulated stem elongation at the expense of leaf expansion. Shoot biomass responded to FR light and warm temperature similarly to leaf expansion in all six species. We further characterized the physiological responses to FR light and temperature in lettuce and tomato. In both crops, FR light generally increased the quantum yield of photosystem II, while decreasing the net CO 2 assimilation rate per unit leaf area, chlorophyll and carotenoid contents, and chlorophyll a:b ratio. Additionally, FR light increased soluble sugar:starch ratio in leaves at 28 ℃, but not at 22 ℃, suggesting that the synergistic effect of FR light and warm temperature on stem elongation may be mediated by increased soluble sugar translocation from leaves to stem. We concluded that the enhanced stem growth under FR light and warm temperature can lead to reduced plant biomass. Our results further indicate that the interactive effects between FR light and temperature on plant growth and morphology were species-dependent, with distinct responses observed among species with different temperature preferences. • Far-red light and warm temperature synergistically promote stem elongation at the expense of leaf expansion. • Increased biomass allocation from leaves to stem under far-red light and warm temperature can reduce biomass production. • Warm-season plants are less responsive to far-red light as a shade signal under cooler temperature. • Changes in leaf carbohydrate composition (increased soluble sugar:starch ratio) may contribute to enhanced stem growth. [ABSTRACT FROM AUTHOR]

Crop canopy architecture is a central component of yield. The arrangement of leaves in three-dimensional space defines the efficiency of absorption of radiation and its conversion into dry matter at the canopy level. The description of architecture is normally associated with light since the optimal distribution of light is associated with that of other essential components such as nitrogen and pigments. However, architecture has been influenced by a number of other unrelated processes through breeding and selection that may have acted independently or even against light use efficiency. This review attempts to provide a broad view and interpretation of canopy architectural properties and the factors affecting crop architecture starting with evolution, domestication, climatic conditions and cultivation patterns, predominantly focusing on field grown agricultural crops. Using examples of modelling with a virtual canopy, we will discuss how architectural traits affect light interception and photosynthesis. Finally, we will discuss the future of architectural research: the concept of the ideal plant type (the ideotype) and which features we can expect to see, as well as the social constraints that may govern future crop architecture.

Gamboge disorder has a detrimental effect on mangosteen. The leakage of the gamboge may result from water availability. Thus, modifying the transpiration of the fruit by bagging might minimize the inappropriate leak of the gamboge produced by the fruit. The study’s objective was to understand the relationship between different fruit positions and bagging treatment on the gamboge disorder in mangosteen. The experiment was conducted on 10-years old trees by tagging young fruits, five replicates with two fruit positions (inside and outside), and bagging treatment (no bagging, transparent and black plastic bagging). The result showed that bagging the fruits inside the canopy does not affect fruit mass. However, bagging with transparent and black plastic of the fruits inside the canopy decreases fruit size. The fruit quality improves by black bagging on the inside canopy fruits. These findings demonstrate that bagging fruits outside the canopy lowers their quality. Black bags used to package fruits inside the canopy improve fruit quality. However, the treatment also causes more fruit to fall from the tree and decreases the nutrient content.

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Introduction: Pearlmillet is themain subsistence crop for smallholder farmers systemswhere it is grown at low plant density. Intensifying pearl millet cultivation could boost productivity although it may have trade-offs. Increasing planting density would indeed increase the leaf area and the related water budget, whereas a denser canopy could create a more favorable canopymicroclimate to the benefit of the water use efficiency (WUE) of the crops. The first aim of this work was to test the yield response of popular pearlmillet varieties to an increased density and to assess possible genotypic variation in this response. The second aim was to measure the water use and the WUE of the crop in different densities. Method: To this end we designed several field and lysimetric experiments To increase the robustness of the results, these trials were carried out in India and Senegal, using two independent sets of genotypes adapted to both sites. Results: In the field, the higher sowing density significantly increased yield in all genotypes when trials were carried out in high evaporative demand conditions. There was no genotype x density interaction in these trials, suggesting no genotypic variation in the response to density increase. The high-density treatment also decreased the vapor pressure deficit (VPD) in the canopies, both in the field and in the lysimeter experiments. In the lysimeter trials, although the higher density treatment increased water use, the resulting increase in biomass was proportionally higher, hence increasingWUE of the crops in all genotypes under high density. The increase in yield under high density was closely related to the increase in WUE, although this link was more tight in the high- than in the low evaporative demand seasons. This confirmed a strong environmental effect on the response to density of all genotypes tested. Discussion: Although they did not open a scope for breeding density tolerant cultivars, these results highlight the possibility to improve pearl millet yield by increasing the density, targeting specifically areas facing high evaporative demand. [ABSTRACT FROM AUTHOR]

Efforts to reduce the production costs of fruit trees are very important to increase competitiveness. One of the production costs in cultivation is pruning. Self-pruning or cladoptosis has the potential to reduce the cost of pruning fruit trees. However, research on the self-pruning phenomenon is still very limited to horticultural crops. The research aimed to identify the occurrence of self-pruning incident in fruit trees to explore their potential to reduce pruning activities. Observations used a randomized block design with a single factor, namely six species of fruit tree (avocado, citrus, guava, kapulasan, longan, and tamarind. Fruit plants aged 2.5 years were maintained in drum pots. Observations included canopy size, branch size, and self-pruning events on branches. The results showed that there was self-pruning on secondary branches, tertiary branches, and quarter branches on all tree species. However, each species has a tendency to self-pruning on different branches. In avocado, self-pruning occurred in secondary and tertiary branches. Self-pruning of tertiary branches occurred in litchi plants. In other plants, self-pruning occurred on all types of branches. This study is the first to observe self-pruning in fruit trees. Further research is needed on the factors of self-pruning variables in fruit plants. [ABSTRACT FROM AUTHOR]

Abstract Background Improvement in photosynthesis is one of the most promising approaches to increase grain yields. Transgenic rice plants overproducing Rubisco by 30% (RBCS-sense rice plants) showed up to 28% increase in grain yields under sufficient nitrogen (N) fertilization using an isolated experimental paddy field (Yoon et al. in Nat Food 1:134–139, 2020). The plant N contents above-ground sections and Rubisco contents of the flag leaves were higher in the RBCS-sense plants than in the wild-type rice plants during the ripening period, which may be reasons for the increased yields. However, some imprecise points were left in the previous research, such as contributions of photosynthesis of leaves below the flag leaves to the yield, and maintenance duration of high photosynthesis of RBCS-sense rice plants during ripening periods. Result In this research, the photosynthetic capacity and canopy architecture were analyzed to explore factors for the increased yields of RBCS-sense rice plants. It was found that N had already been preferentially distributed into the flag leaves at the early ripening stage, contributing to maintaining higher Rubisco content levels in the enlarged flag leaves and extending the lifespan of the flag leaves of RBCS-sense rice plants throughout ripening periods under sufficient N fertilization. The higher amounts of Rubisco also improved the photosynthetic activity in the flag leaves throughout the ripening period. Although the enlarged flag leaves of the RBCS-sense rice plants occupied large spatial areas of the uppermost layer in the canopy, no significant prevention of light penetration to leaves below the flag leaves was observed. Additionally, since the CO2 assimilation rates of lower leaves between wild-type and RBCS-sense rice plants were the same at the early ripening stage, the lower leaves did not contribute to an increase in yields of the RBCS-sense rice plants. Conclusion We concluded that improvements in the photosynthetic capacity by higher leaf N and Rubisco contents, enlarged leaf area and extended lifespan of flag leaves led to an increase in grain yields of RBCS-sense rice plants grown under sufficient N fertilization.

IntroductionPearlmillet is themain subsistence crop for smallholder farmers systemswhere it is grown at low plant density. Intensifying pearl millet cultivation could boost productivity although it may have trade-offs. Increasing planting density would indeed increase the leaf area and the related water budget, whereas a denser canopy could create a more favorable canopymicroclimate to the benefit of the water use efficiency (WUE) of the crops. The first aim of this work was to test the yield response of popular pearlmillet varieties to an increased density and to assess possible genotypic variation in this response. The second aim was to measure the water use and the WUE of the crop in different densities.MethodTo this end we designed several field and lysimetric experiments To increase the robustness of the results, these trials were carried out in India and Senegal, using two independent sets of genotypes adapted to both sites.ResultsIn the field, the higher sowing density significantly increased yield in all genotypes when trials were carried out in high evaporative demand conditions. There was no genotype x density interaction in these trials, suggesting no genotypic variation in the response to density increase. The high-density treatment also decreased the vapor pressure deficit (VPD) in the canopies, both in the field and in the lysimeter experiments. In the lysimeter trials, although the higher density treatment increased water use, the resulting increase in biomass was proportionally higher, hence increasingWUE of the crops in all genotypes under high density. The increase in yield under high density was closely related to the increase in WUE, although this link was more tight in the high- than in the low evaporative demand seasons. This confirmed a strong environmental effect on the response to density of all genotypes tested.DiscussionAlthough they did not open a scope for breeding density tolerant cultivars, these results highlight the possibility to improve pearl millet yield by increasing the density, targeting specifically areas facing high evaporative demand.

A high-quality canopy architecture is central to obtaining high crop yields. A field experiment was carried out at the Wuqiao Experimental Station from 2015 to 2019 under four irrigation schemes (W0, no irrigation after sowing; W1, 75 mm irrigation at jointing stage; W2, 75 mm irrigation at jointing and anthesis stages, respectively; W3, 75 mm irrigation at tillering, jointing and anthesis stages, respectively) to investigate the canopy structure, canopy apparent photosynthesis (CAP), canopy temperature (CT), yield and water use efficiency (WUE). The results showed that increasing irrigation times improved the leaf area index (LAI), non-leaf area index (NLAI) and light interception (LI) of the spike and total canopy but decreased the canopy temperature (CT) after anthesis. The CAP in the W3 treatment was consistently lower than that in the W1 treatment, suggesting lower effective utilization of light energy under the W3 treatment. Increasing irrigation times improved wheat yield, but the W2 treatment had no significant difference in yield compared to the W3 treatment. In addition, the W1 and W2 treatments had higher WUEs. The CT, organ temperature and LI were closely positively associated with each other, but they were all strongly negatively related to the yield. Overall, the W2 treatment was the best irrigation scheme for constructing a reasonable canopy architecture for winter wheat, obtaining more efficient water use and yield in the North China Plain (NCP). CT and organ temperature can be used as proxy parameters to estimate the canopy structure.

Under the pro-environmental principles of agricultural production, soil cultivation and organic fertilization are of particular importance as strategical elements in reducing weed infestation in the context of sustainable agriculture. The aim of this study was to determine the effect of long-term practices that are used in regenerative agriculture (reducing soil tillage, cover crop management, and mineral nitrogen fertilization) on canopy weed infestation and the elements of spring barley architecture. Understanding the impact of the studied factors influences decision-making regarding weed infestation control, and thus may contribute to a reduction in herbicide use. A two-factor field experiment was conducted using the split-plot method. The main factors were four cultivation methods: 1. conventional tillage without a cover crop, 2. conventional tillage + cover crop, 3. reduced tillage + cover crop, and 4. no tillage + cover crop. The subplot factor was differentiated via nitrogen fertilization, at 40, 80, or 120 kg N∙ha−1. The research covered canopy weed infestation and the parameters of spring barley canopy architecture. The species composition; the number and weight of weeds; and, for barley, the leaf area index (LAI), density, length, and tillers were determined. The test results were statistically analyzed (ANOVA) in a series of experiments while using Tukey’s test for a significance level of p = 0.05. Additionally, simple linear regression analysis, principal component analysis (PCA), and data clustering (CA) were utilized. The study showed that simplified tillage contributed to reducing the number of weeds in the barley tillering stage, while also contributing to an increase in weed infestation during grain harvest. Plowing in the cover crop did not reduce the presence of undesirable plants in the canopy, while increasing doses of nitrogen fertilization contributed to a reduction in the number of weeds without affecting their mass. Weed infestation was also affected by meteorological conditions. Increased rainfall in the early stages of barley development benefits the number of weeds, especially in terms of traditional cultivation. Simplified tillage resulted in a reduction in barley density, height, and LAI, as well as an increase in the branching of the tested cereal. A significant negative correlation was also found between the weed infestation of the barley canopy and the characteristics of the canopy architecture. The PCA showed that the highest tillering of barley was provided at the lowest intensity of weed infestation. In turn, the CA indicated that the significantly higher LAI that resulted from a higher density and length of barley was attributed to the simplified cultivation treatments and the practice of direct sowing. It is a comprehensive method that can favor barley growth and development conditions while weakening weed infestation potential.

Studies of traits related to nitrogen (N)-use efficiency (NUE) in wheat cultivars are important for breeding N-efficient cultivars. Canopy structure has a major effect on NUE, as it determines the distribution of light and N. However, the mechanism by which canopy structure affects the distribution of light and N within the canopy remains unclear. The N-efficient winter wheat varieties YM49 and ZM27 and N-inefficient winter wheat varieties XN509 and AK58 were grown in the field under two N levels. Light transmittance was enhanced, and the leaf area index and photosynthetically active radiation were lower in the N-efficient cultivar population, which was characterized by moderately sized flag leaves, a low frequency of canopy leaf curling, a low light attenuation coefficient (KL), and high plant compactness. Reductions in the amount of shade increased the distribution of light and N resources to the middle and lower layers. The photosynthetic rate, transpiration rate, instant water-use efficiency, and canopy photosynthetic NUE were higher, N remobilization of the upper and middle canopy leaves was reduced, and the leaf N content was high in the N-efficient cultivars. A higher ratio of the N extinction coefficient (KN) to KL reflects the assimilation ability of the N-efficient winter wheat cultivars, resulting in improved canopy structure and distribution of light and N, higher 1000-grain weight and grain yield, and significantly increased light and NUE. An improved match between gradients of light and N in the leaf canopy promotes balanced C and N metabolism and reduces energy and nutrient losses. This should be a goal when breeding N-efficient wheat cultivars and implementing tillage regimes. [ABSTRACT FROM AUTHOR]

Leaf area index (LAI) and leaf area distribution within the maize plant are important traits used to explain and predict light interception and thus crop productivity. Here we investigate breeding and plant density effects of leaf area traits. Our objectives are to 1) quantify maize breeding impacts on leaf area distribution and determine bell-shape coefficients used in crop modeling, 2) dissect the contribution of breeding from plant density, and 3) explore the relationship between LAI and crop yields. We studied 18 hybrids released between 1983 and 2017 at two density treatments: current (8.5 pl m−2) and historical increasing density (from 4.6 to 8.5 pl m−2) in Iowa, USA. Results indicated that concurrent changes in hybrids and increases in plant density have increased LAI from 3.4 (in 1983) to 5.9 m2 m−2 (in 2017), with the highest LAI increases (>50 %) to be realized in the middle canopy. At historical increasing in plant density treatment, the LAI increased by 1.6 % year−1, but the individual plant leaf area decreased by 0.33 % year−1 from 1983 to 2017. This trade-off indicates that new hybrids are more tolerant to higher plant populations than old hybrids. At current plant density treatment, the year of hybrid release did not affect LAI or individual plant leaf area. New hybrids had 5 % narrower leaf area distributions, 23 % higher optimum LAI values (5.2 vs 4.2 m2 m−2) and 19 % higher grain yields compared to old hybrids. The main reason for the increase in maize LAI in the US Corn Belt is plant density. However, an increase in LAI does not necessarily translate to higher grain yields as new hybrids had significantly higher grain yields than older hybrids at similar LAI values. Present results contribute to our understanding of maize canopy architecture and allow us to better calibrate crop models to accurately estimate LAI and grain yield. • Changes in hybrids and increases in plant density nearly doubled maize LAI over the last 40 years. • Middle canopy leaves realized the largest increases in area. • Breeding did not significantly affect maize leaf area distribution. • Plant density had 3-fold larger impacts on leaf area distribution than breeding. • New hybrids maximize yields at higher LAI values than the old hybrids. [ABSTRACT FROM AUTHOR]

Abstract Light attenuation within a row of crops such as cotton is influenced by canopy architecture, which is defined by size, shape and orientation of shoot components. Level of light interception causes an array of morpho-anatomical, physiological and biochemical changes. Physiological determinants of growth include light interception, light use efficiency, dry matter accumulation, duration of growth and dry matter partitioning. Maximum light utilization in cotton production can be attained by adopting cultural practices that yields optimum plant populations as they affect canopy arrangement by modifying the plant canopy components. This paper highlights the extent to which spatial arrangement and density affect light interception in cotton crops. The cotton crop branches tend to grow into the inter-row space to avoid shade. The modification of canopy components suggests a shade avoidance and competition for light. Maximum leaf area index is obtained especially at flowering stage with higher populations which depicts better yields in cotton production.

Late-season bunch rot can cause substantial yield loss in grapevines grown in humid regions. Fruit-zone leaf removal has been widely used to reduce bunch rot and pesticide applications through improvements in canopy microclimate and grape cluster morphology. In this study, we evaluated whether mechanical leaf removal can be a valid alternative to a labor-intensive manual application by comparing prebloom manual (PB-MA) and mechanical (PB-ME) leaf removal. We also evaluated the effects of the timing of mechanical application, prebloom (PB-ME) versus fruit set (FS-ME), on fruit traits and bunch rot, caused by Botrytis cinerea . Our trials were conducted on two Vitis vinifera 'Pinot noir' and 'Pinot gris' vineyards in the Northeastern United States over two seasons (2017 to 2018). Major findings were overall consistent between cultivars and years. Leaf removal provided reductions in fruit-zone canopy density regardless of method or timing. In general, PB-ME provided similar shifts in cluster morphological traits to PB-MA, including lower number of berries per cluster, cluster compactness, and cluster weight compared with control (no leaf removal) vines. At harvest, both prebloom leaf removal methods equally reduced Botrytis bunch rot severity, whereas Botrytis bunch rot incidence in Pinot noir was lowest for PB-ME in 1 year and PB-MA in the next year. When comparing timing of mechanical leaf removal, FS-ME provided Botrytis bunch rot reductions similar to PB-ME, without effects on cluster weight. Thus, under our growing conditions, FS-ME was considered the best mechanical leaf removal option to help manage Botrytis bunch rot without causing undesirable yield reductions., Competing Interests: The author(s) declare no conflict of interest.

Background: Improvement in photosynthesis is one of the most promising approaches to increase grain yields. Transgenic rice plants overproducing Rubisco by 30% (RBCS-sense rice plants) showed up to 28% increase in grain yields under sufficient nitrogen (N) fertilization using an isolated experimental paddy field (Yoon et al. in Nat Food 1:134–139, 2020). The plant N contents above-ground sections and Rubisco contents of the flag leaves were higher in the RBCS-sense plants than in the wild-type rice plants during the ripening period, which may be reasons for the increased yields. However, some imprecise points were left in the previous research, such as contributions of photosynthesis of leaves below the flag leaves to the yield, and maintenance duration of high photosynthesis of RBCS-sense rice plants during ripening periods. Result: In this research, the photosynthetic capacity and canopy architecture were analyzed to explore factors for the increased yields of RBCS-sense rice plants. It was found that N had already been preferentially distributed into the flag leaves at the early ripening stage, contributing to maintaining higher Rubisco content levels in the enlarged flag leaves and extending the lifespan of the flag leaves of RBCS-sense rice plants throughout ripening periods under sufficient N fertilization. The higher amounts of Rubisco also improved the photosynthetic activity in the flag leaves throughout the ripening period. Although the enlarged flag leaves of the RBCS-sense rice plants occupied large spatial areas of the uppermost layer in the canopy, no significant prevention of light penetration to leaves below the flag leaves was observed. Additionally, since the CO2 assimilation rates of lower leaves between wild-type and RBCS-sense rice plants were the same at the early ripening stage, the lower leaves did not contribute to an increase in yields of the RBCS-sense rice plants. Conclusion: We concluded that improvements in the photosynthetic capacity by higher leaf N and Rubisco contents, enlarged leaf area and extended lifespan of flag leaves led to an increase in grain yields of RBCS-sense rice plants grown under sufficient N fertilization. [ABSTRACT FROM AUTHOR]

Purpose: Canopy light interception and extinction play a crucial role in determining crop yield. Developing new rice varieties with improved canopy architecture along with modified intrinsic photosynthetic mechanisms will ensure the global food security. However, a comprehensive understanding of local rice varieties addressing on such avenues have not been reported. Hence, our pioneering experiments were carried out to elucidate such underlying properties among locally developed two elite rice varieties viz; At-362 and Bg 94-1 grown in the Ampara district of Sri Lanka. Research Method: The field experiment was carried out at the Agro Tech Park, Malwatta (7°20'N and 81°44'E altitude 16.0 m above sea level) between October 2019 to January 2020 implemented with Randomized Complete Block Design with four replicates. The Photosynthetically Active Radiation (PAR) distribution on the above and below canopy level was measured during the pre and post-anthesis stages. Then leaf stomatal conductance, chlorophyll fluorescence parameters and the chlorophyll content were also measured. At harvest, the final biomass produced were compared. Findings: The result revealed that variety At-362 had a higher Leaf Area Index (LAI) of 2.64 at pre anthesis and tend to decline at the latter part of their growth cycle. The striking feature was the extinction coefficient (k) seems to be much lower (0.47) in the At-362 variety than the Bg 94-1 (0.60) depicting that the former has produced vertical leaves (erect-leaf type) while the latter tends to produce horizontal leaf plans in the canopy. Hence, light attenuation was high and eventually, the bottom canopy layer received much lower PAR. Furthermore, LAI had a strong negative correlation with understory PAR indicating that the canopy architecture with an improved light interception will lead to permit more light penetration and utilization through the improved quantum yield efficiencies than the horizontal canopies. Hence significantly (p<0.05) improved above-ground biomass and panicle weight were observed in At-362. Originality/value: This experiment depicts that rice yield could be further improved through introgression of canopy architectural features along with improved photosynthetic traits. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sunburn in grapevine berries is known as a recurring disorder causing severe yield losses and a decline in berry quality. The transition from healthy to sunburnt along a temporal trajectory is not fully understood. It is driven by light-boosted local heat impact and modulated by, e.g., past environments of the berry and its developmental state. Events of berry sunburn are often associated with heatwaves, indicating a link to climate change. In addition, the sensitivity of grapevine architecture to changing environmental condition indicates an urgent need to investigate and adapt mitigation strategies of berry sunburn in future vineyards. In this perspective, we want to identify missing links in predicting berry sunburn in vineyards and propose a modeling framework that may help us to investigate berry sunburn in future vineyards. For this, we propose to address open issues in both developing a model of berry sunburn and considering dynamic canopy growth, and canopy interaction with the environment and plant management such as shoot positioning or leaf removal. Because local environmental conditions drive sunburn, we aim at showing that identifying sunburn-reducing strategies in a vineyard under future environmental conditions can be supported by a modeling approach that integrates effects of management practices over time and takes grapevine architecture explicitly into account. We argue that functional-structural plant models may address such complex tasks. Once open issues are solved, they might be a promising tool to advance our knowledge on reducing risks of berry sunburn in silico.

Summary: Leaf angle and leaf area index together influence canopy light interception and canopy photosynthesis. However, so far, there is no effective method to identify the optimal combination of these two parameters for canopy photosynthesis.In this study, first a robust high‐throughput method for accurate segmentation of maize organs based on 3D point clouds data was developed, then the segmented plant organs were used to generate new 3D point clouds for the canopy of altered architectures. With this, we simulated the synergistic effect of leaf area and leaf angle on canopy photosynthesis.The results show that, compared to the traditional parameters describing the canopy photosynthesis including leaf area index, facet angle and canopy coverage, a new parameter – the canopy occupation volume (COV) – can better explain the variations of canopy photosynthetic capacity. Specifically, COV can explain > 79% variations of canopy photosynthesis generated by changing leaf angle and > 84% variations of canopy photosynthesis generated by changing leaf area.As COV can be calculated in a high‐throughput manner based on the canopy point clouds, it can be used to evaluate canopy architecture in breeding and agronomic research. [ABSTRACT FROM AUTHOR]

Sunburn in grapevine berries is known as a recurring disorder causing severe yield losses and a decline in berry quality. The transition from healthy to sunburnt along a temporal trajectory is not fully understood. It is driven by light-boosted local heat impact and modulated by, e.g., past environments of the berry and its developmental state. Events of berry sunburn are often associated with heatwaves, indicating a link to climate change. In addition, the sensitivity of grapevine architecture to changing environmental condition indicates an urgent need to investigate and adapt mitigation strategies of berry sunburn in future vineyards. In this perspective, we want to identify missing links in predicting berry sunburn in vineyards and propose a modeling framework that may help us to investigate berry sunburn in future vineyards. For this, we propose to address open issues in both developing a model of berry sunburn and considering dynamic canopy growth, and canopy interaction with the environment and plant management such as shoot positioning or leaf removal. Because local environmental conditions drive sunburn, we aim at showing that identifying sunburn-reducing strategies in a vineyard under future environmental conditions can be supported by a modeling approach that integrates effects of management practices over time and takes grapevine architecture explicitly into account. We argue that functional-structural plant models may address such complex tasks. Once open issues are solved, they might be a promising tool to advance our knowledge on reducing risks of berry sunburn in silico. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Leaf angle (LA) is one of the most important canopy architecture related traits in maize (Zea mays L.). However, the genetic basis of LA at canopy-wide levels is still not completely understood. In this study, one RIL population derived from two parent lines with distinct plant architecture was used for QTL mapping of LA at eight leaves below the tassel across three environments. Fifty-six QTL for LA of eight leaves were identified in single environment analysis and 44 QTL for LA of eight leaves were detected in joint analysis. Among them, nine common QTL were identified because they were detected for LA more than 1 leaves or in 2 or 3 environments. The single QTL could explain 1.29–20.14% of the phenotypic variation with affecting LA of 1–8 leaves, included qLA5.1 affected LA of all eight leaves, qLA3.1 affected LA of the upper leaves (1stLA–4thLA), and qLA9.1 affected LA of the lower leaves (5thLA–8thLA). Furthermore, the 8thLA was mainly affected by major and minor QTL; the 1stLA, 4thLA and 5thLA were affected by major QTL, minor QTL and epistatic interactions; the other four LAs were simultaneously affected by major QTL, minor QTL, epistatic interactions and environments, inferred that the genetic architecture of LA of eight leaves was different. These results provide a comprehensive understanding of genetic basis of LA at canopy-wide levels, which will be helpful to design the ideal plant architecture in maize. [ABSTRACT FROM AUTHOR]

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. Hyponastic response in canopies facilitates light interception, but also light penetration. Inhibition of this response to neighbours increased canopy biomass, canopy closure and suppression of competitors. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to evaluate the use of plant height as a calibration variable for improving indirect measurements of the leaf area index (LAI). Three experiments were conducted with different crops - corn (Zea mays), soybean (Glycine max), and sugarcane (Saccharum officinarum) -, to compare the performance of the LAI measured indirectly (LAIind) and corrected by the calibration variable with the LAI measured directly (LAIref). Without the proposed correction, the LAIind tended to be overestimated by 20%, on average, compared with the LAIref, for the three crops. After crop height was used to adjust the LAIind, a strong positive relationship was observed between the LAIref and the corrected LAIind (R2 = 0.96); overestimation was reduced to 4% and the root-mean-square error decreased to 0.35 m2 m-2. The variable canopy height is promising for the correction of the LAI of the soybean, corn, and sugarcane crops.

Abstract Optimizing crops to improve light absorption and CO2 assimilation throughout the canopy is a proposed strategy to increase yield and meet the needs of a growing population by 2050. Globally, the greatest population increase is expected to occur in Sub‐Saharan Africa where large yield gaps currently persist; therefore, it is crucial to develop high‐yielding crops adapted to this region. In this study, we screened 50 cowpea (Vigna unguiculata (L.) Walp) genotypes from the multi‐parent advanced generation inter‐cross (MAGIC) population for canopy architectural traits, canopy photosynthesis, and water‐use efficiency using a canopy gas exchange chamber in order to improve our understanding of the relationships among those traits. Canopy architecture contributed to 38.6% of the variance observed in canopy photosynthesis. The results suggest that the light environment within the canopy was a limiting factor for canopy CO2 assimilation. Traits favoring greater exposure of leaf area to light such as the width of the canopy relative to the total leaf area were associated with greater canopy photosynthesis, especially in canopies with high biomass. Canopy water‐use efficiency was highly determined by canopy photosynthetic activity and therefore canopy architecture, which indicates that optimizing the canopy will also contribute to improving canopy water‐use efficiency. We discuss different breeding strategies for future programs aimed at the improvement of cowpea yield for the Sub‐Saharan African region. We show that breeding for high biomass will not optimize canopy CO2 assimilation and suggest that selection should include multiple canopy traits to improve light penetration.

Standardizing gross volume increment on periodic height increment of the dominant trees is a means of minimizing the effects of site quality and age in growth–growing-stock relations; however, volume increment per height increment contains more information than just a normalization method for fitting growth models. This study builds on previous work suggesting that the cumulative sum of the ratios between individual-tree volume increment and height increment may be a direct measure of stand density. We used data from several levels of growing-stock studies for Douglas-fir, ponderosa pine, and red pine to explore this hypothesis. Regression analysis indicated that the sum of the ratios is proportional to (D q x ⋅ N) ⁠ , the underlying equation form of Reineke's stand density index. Stem growth is a function of canopy dynamics, and additional analyses showed that volume added per unit of height growth was also related to canopy architecture, increasing with decreasing live-crown ratio and increasing foliage density. The linkages between growth, canopy architecture, intermediary canopy dynamics, and (D q x ⋅ N) support the hypothesis that the sum of the tree ratios between volume increment and height increment is a direct measure of site occupancy due to its association between growth and corresponding resource use. [ABSTRACT FROM AUTHOR]

The potential of oilseed rape to suppress weed growth while maintaining optimal yield and quality is not well understood under field conditions in Australia. This study, conducted in Condobolin and Wagga Wagga, New South Wales (NSW), during 2015 and 2016, examined a diverse range of commercial oilseed rape cultivars for their inherent ability to suppress weeds and maintain yields when in competition with natural weed infestations, with and without pre‐emergent herbicide treatment. Cultivar differences were observed in oilseed rape canopy architecture and yield; however, early‐season biomass, light interception, leaf area index and visual vigour ratings exhibited both year and location interactions. Cultivars with the highest biomass, light interception, leaf area indices and visual vigour were typically also the most weed‐suppressive, in particular GT‐50 and Hyola 600RR. Although crop and weed biomass accumulation differed significantly among cultivars for both location and year, weed biomass was inversely related to cultivar biomass in both years and locations. Hybrid Hyola and GT‐50 cultivars exhibited up to 50% less weed biomass while maintaining consistently high levels of dry crop biomass. In addition, pre‐emergent herbicide applications reduced weed infestation and contributed to higher crop yield in both locations and years. Given the consistent aboveground competitive ability of certain oilseed rape cultivars, our study demonstrated that diverse cultivar‐dependent competitive traits such as early growth vigour, biomass production, absorption of photosynthetically active radiation and production and retention of crop residue significantly impacted weed establishment and total weed biomass. Our findings suggest that cultivar selection offers potential as a tool for maintaining suitable grain yield in the presence of weeds while potentially delaying the development of herbicide resistance through efficacious weed suppression. [ABSTRACT FROM AUTHOR]

Optimizing crops to improve light absorption and CO2 assimilation throughout the canopy is a proposed strategy to increase yield and meet the needs of a growing population by 2050. Globally, the greatest population increase is expected to occur in Sub‐Saharan Africa where large yield gaps currently persist; therefore, it is crucial to develop high‐yielding crops adapted to this region. In this study, we screened 50 cowpea (Vigna unguiculata (L.) Walp) genotypes from the multi‐parent advanced generation inter‐cross (MAGIC) population for canopy architectural traits, canopy photosynthesis, and water‐use efficiency using a canopy gas exchange chamber in order to improve our understanding of the relationships among those traits. Canopy architecture contributed to 38.6% of the variance observed in canopy photosynthesis. The results suggest that the light environment within the canopy was a limiting factor for canopy CO2 assimilation. Traits favoring greater exposure of leaf area to light such as the width of the canopy relative to the total leaf area were associated with greater canopy photosynthesis, especially in canopies with high biomass. Canopy water‐use efficiency was highly determined by canopy photosynthetic activity and therefore canopy architecture, which indicates that optimizing the canopy will also contribute to improving canopy water‐use efficiency. We discuss different breeding strategies for future programs aimed at the improvement of cowpea yield for the Sub‐Saharan African region. We show that breeding for high biomass will not optimize canopy CO2 assimilation and suggest that selection should include multiple canopy traits to improve light penetration. [ABSTRACT FROM AUTHOR]

Background and Aims Shading 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. Methods In a glasshouse 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 traits 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 Results Model 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. Conclusions Our 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 on plant responses to the other. [ABSTRACT FROM AUTHOR]

Background and Aims Understanding how climate change influences crop productivity helps in identifying new options to increase crop productivity. Soybean is the most important dicotyledonous seed crop in terms of planting area. Although the impacts of elevated atmospheric [CO2] on soybean physiology, growth and biomass accumulation have been studied extensively, the contribution of different factors to changes in season-long whole crop photosynthetic CO2 uptake [gross primary productivity (GPP)] under elevated [CO2] have not been fully quantified. Methods A 3-D canopy model combining canopy 3-D architecture, ray tracing and leaf photosynthesis was built to: (1) study the impacts of elevated [CO2] on soybean GPP across a whole growing season; (2) dissect the contribution of different factors to changes in GPP; and (3) determine the extent, if any, of synergism between [CO2] and light on changes in GPP. The model was parameterized from measurements of leaf physiology and canopy architectural parameters at the soybean Free Air CO2 Enrichment (SoyFACE) facility in Champaign, Illinois. Key Results Using this model, we showed that both a CO2 fertilization effect and changes in canopy architecture contributed to the large increase in GPP while acclimation in photosynthetic physiological parameters to elevated [CO2] and altered leaf temperature played only a minor role in the changes in GPP. Furthermore, at early developmental stages, elevated [CO2] increased leaf area index which led to increased canopy light absorption and canopy photosynthesis. At later developmental stages, on days with high ambient light levels, the proportion of leaves in a canopy limited by Rubisco carboxylation increased from 12.2 % to 35.6 %, which led to a greater enhancement of elevated [CO2] to GPP. Conclusions This study develops a new method to dissect the contribution of different factors to responses of crops under climate change. We showed that there is a synergestic effect of CO2 and light on crop growth under elevated CO2 conditions. [ABSTRACT FROM AUTHOR]

Background and Aims Light interception is closely related to canopy architecture. Few studies based on multi-view photography have been conducted in a field environment, particularly studies that link 3-D plant architecture with a radiation model to quantify the dynamic canopy light interception. In this study, we combined realistic 3-D plant architecture with a radiation model to quantify and evaluate the effect of differences in planting patterns and row orientations on canopy light interception. Methods The 3-D architectures of maize and soybean plants were reconstructed for sole crops and intercrops based on multi-view images obtained at five growth dates in the field. We evaluated the accuracy of the calculated leaf length, maximum leaf width, plant height and leaf area according to the measured data. The light distribution within the 3-D plant canopy was calculated with a 3-D radiation model. Finally, we evaluated canopy light interception in different row orientations. Key Results There was good agreement between the measured and calculated phenotypic traits, with an R 2 >0.97. The light distribution was more uniform for intercropped maize and more concentrated for sole maize. At the maize silking stage, 85 % of radiation was intercepted by approx. 55 % of the upper canopy region for maize and by approx. 33 % of the upper canopy region for soybean. There was no significant difference in daily light interception between the different row orientations for the entire intercropping and sole systems. However, for intercropped maize, near east–west orientations showed approx. 19 % higher daily light interception than near south–north orientations. For intercropped soybean, daily light interception showed the opposite trend. It was approx. 49 % higher for near south–north orientations than for near east–west orientations. Conclusions The accurate reconstruction of 3-D plants grown in the field based on multi-view images provides the possibility for high-throughput 3-D phenotyping in the field and allows a better understanding of the relationship between canopy architecture and the light environment. [ABSTRACT FROM AUTHOR]

Little information is available about the effects of different species of shrubs on the composition of the soil seed bank (SSB) and how the SSB could contribute to restoration of degraded grasslands. We determined the role of three dominant shrubs on SSB characteristics and evaluated their potential for their possible use in rangeland restoration projects. Ten sites, each containing three shrub species (Onobrychis cornuta, Berberis integerrima and Juniperus sabina) and a herbaceous patch (control) in close proximity, were sampled and their SSB density, richness and diversity were determined. Density of the SSB at 0–5 cm depth was lowest under J. sabina and highest under herbaceous vegetation, but did not differ between B. integerrima and O. cornuta. SSB density at 5–10 cm depth was significantly greater under B. integerrima than under the other shrubs or herbaceous patch. Species richness of the SSB was significantly greater under B. integerrima at 5–10 cm depth than under the other shrubs. This study revealed that the extent to which vegetation affected SSB characteristics did not only depend on the presence of shrubs, but also on the species of shrub. We recommend B. integerrima as a priority species in restoration projects due to its significant positive influences on SSB. [ABSTRACT FROM AUTHOR]