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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]

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]

Summary: There is evidence that mosses with miniature foliage elements have extremely large leaf area index (LAI) values, but it is unclear what canopy traits are responsible for these high LAI values in architecturally divergent mosses, and how the inherent trade‐offs limiting maximum LAI in vascular plants can be overcome in mosses.To determine the quantitative significance of different traits in determining LAI, we developed a method to dissect LAI into underlying functionally dependent constituent traits at leaf, shoot and canopy scales. The suites of structural traits were studied altogether for 43 moss canopies from 11 species with contrasting light and water requirements along gap‐understory gradients to obtain as large a range of variation in moss architecture as possible and evaluate the differentiation in moss LAI in relation to species ecology.Extensive variation in moss structural traits, 11‐ (shoot length) to 77‐fold (shoot number per area, NS¯), was observed at all structural scales from leaf to canopy. However, LAI only varied nine‐fold, as the result of two key trade‐offs: leaf size vs number trade‐off and shoot leaf area vs shoot density trade‐off. Owing to these negative relationships, and greater variability in NS¯, LAI primarily scaled with NS¯. NS¯ and LAI increased with site light availability, and LAI was greater in open and dry habitat species.This study highlights a huge structural diversity among moss canopies, but indicates that canopies converge to a much narrower range of LAI due to trait trade‐offs such that, counterintuitively, minute leaf size and densely leafed stems are not necessarily responsible for high LAI in mosses. [ABSTRACT FROM AUTHOR]

CAM species, which taxonomically are at least five times more numerous than C4 species, often grow slowly, as is the case for various short-statured cacti and many epiphytes in several families. However, slow growth is not a necessary corollary of the CAM photosynthetic pathway, as can be appreciated by considering the energetics of CO2 fixation. For every CO2 fixed photosynthetically, C3 plants require 3 ATP and 2 NADPH, whereas the extra enzymatic reactions and compartmentation complexity for C4 plants require 4 or 5 ATP and 2 NADPH, and CAM plants require 5.5-6.5 ATP and 2 NADPH. Photorespiration in C3, plants can release some of the CO2 fixed and also has an energetic cost, whereas photorespiration is much less in C and CAM plants. Therefore, CAM plants can perform net CO2 fixation 15% more efficiently than C3 plants, although 10% less efficiently than C4 plants. Using a simple model that assumes 8 photons per CO2 fixed and a processing time per excitation of 5 ms, a maximum instantaneous rate for net CO2 uptake of 55 μmol m 2 s1 is predicted. Measured maximal rates average 48 μmol m -2 s-1 for leaves of six C3species with the highest rates and 64 μmol m -2 s-1 for six such C4 species; CAM plants take up CO2 mainly at night, which is not directly related to the instantaneous rate of photon absorption. Net CO2 uptake integrated over 24 h, which is more pertinent to productivity than are instantaneous CO2 uptake rates, is similar for the three pathways, although the higher water-use efficiency of CAM plants can be an advantage during drought. [ABSTRACT FROM AUTHOR]