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Introduction: Optimizing fruit quality and yield in agriculture requires accurately monitoring leaf nitrogen (N) status spatially and temporally throughout the growing season. Standard remote sensing approaches for assessing leaf N rely on proxies like vegetation indices or leaf chlorophyll a + b (Cab) content. However, limitations exist due to the Cab-N relationship’s saturation and early nutrient deficiency insensitivity. Methods: The study utilized Sentinel-2 satellite imagery to estimate a set of plant biochemical traits in large almond orchards in a two-year study. These traits, including leaf dry matter, leaf water content, and leaf Cab retrieved from the radiative transfer model, were used to explain the observed variability of leaf N. Airborne hyperspectral imagery-derived leaf N using Cab and solar-induced fluorescence served as a benchmark for validation. Results: Results demonstrate that plant traits quantified from Sentinel-2 were strongly associated with leaf N variability across the orchard, with a strong contribution from the estimated leaf Cab content and leaf dry matter biochemical constituent, outperforming the consistency of vegetation indices. The Sentinel-2 model explaining leaf N variability yielded r2 = 0.82 and nRMSE = 13% in a two-year dataset, obtaining consistent performance and trait contribution across both years. Conclusion: This study highlights the potential application of Sentinel-2 satellite imagery for monitoring leaf N variability in almond tree orchards. Incorporating plant biochemical traits allows for a more consistent and reliable prediction of leaf N compared to traditional vegetation indices over two years, making it a promising method for precision agriculture applications. [ABSTRACT FROM AUTHOR]

Summary: Leaf economic spectrum (LES) relationships have been studied across many different plant lineages and at different organizational scales. However, the temporal stability of the LES relationships is largely unknown. We used the wild blueberry system with high genotypic diversity to test whether trait–trait relationships across genotypes demonstrate the same LES relationships found in the global database (GLOPNET) and whether they are stable across years.We studied leaf structure, photosynthesis, and leaf nutrients for 16 genotypes of two wild blueberry species semi‐naturally grown in a common farm in Maine, USA, across 4 yr.We found substantial variation in leaf structure, physiology, and nutrient traits within and among genotypes, as well as across years in wild blueberries. The LES trait–trait relationships (covariance structure) across genotypes were not always found in all years. The trait syndrome of wild blueberries was shifted by changing environmental conditions over the years. Additionally, traits in 1 yr cannot be used to predict those of another year.Our findings show that LES generally holds among genotypes but is temporally unstable, stressing the significant influence of trait plasticity in response to fluctuating environmental conditions across years, and the importance of temporal dimensions in shaping functional traits and species coexistence. [ABSTRACT FROM AUTHOR]

Soil salinity is a significant abiotic stress and poses risks to environmental sustainability. Thus, the improvement of the time for recovering the salt-affect soil is crucial for the phytoextraction process using halophytes plants, especially regarding on nutritional management. We evaluated the responses of Atriplex nummularia Lindl. to nitrogen (N) and phosphorus (P) under different salinity levels. The treatments comprised doses of N (N1 = 80 kg ha−1) and P (P1 = 60 kg ha−1): (1) without N and P (N0P0) (control); (2) with N and without P (N1P0); (3) without N and with P (N0P1); and (4) with N and P (N1P1) and five levels of electrical conductivity from irrigation water: 0.08, 1.7, 4.8, 8.6, and 12.5 dS m−1. The. We evaluated dry biomass of leaves, stems, and roots 93 days after transplantation. We also assessed the leaf and osmotic water potential, the osmotic adjustment, and the nutrient contents (N, P, Na, and K). N application increased 22.3, 17.8, and 32.8% the leaf biomass, stem biomass, and osmotic adjustment, respectively; and consequently, boosts Na extraction in 27.8%. Thus, the time of the phytoextraction process can be improved with N fertilizer at a rate of 80 kg ha−1. NOVELTY STATEMENT: Very few studies have investigated the nutrient dynamics responses in Atriplex species in salt-affected soils; thus, this study represents a novelty. We tested the management of nitrogen (N) and phosphate (P) fertilizers to increase crop yield and optimize the phytoextraction process in salt-affected soils. We believe our results contribute to the improvement of the knowledge of this relevant topic, mainly in terms of the recovery of areas degraded by salinity. There is a paucity of studies associating salinity and nutritional management of soils worldwide. [ABSTRACT FROM AUTHOR]

Land-use changes and anthropogenic disturbances are major threats to biodiversity, affecting ecosystem function and recovery. In boreal Alberta, Canada, petroleum development has led to extensive landscape fragmentation, notably through linear clearings created for seismic exploration that remove surface vegetation and microtopography. Despite partial recovery on forested seismic lines, peatland recovery is often arrested, impacting wildlife and carbon dynamics. Restoration efforts employ silviculture techniques to create microtopography and foster tree growth, but the efficacy of restoration treatments in restoring peatland plant diversity remains uncertain. We compared taxonomic, phylogenetic, and functional diversity of understory plant communities across treated and untreated seismic lines, alongside reference sites in treed bogs and fens. Treated lines generally had a twofold increase in plant height, leaf dry matter content, and foliar nitrogen and phosphorus contents compared to reference sites. In bogs, treated lines differed from reference conditions driven by increases in herbaceous taxa, while fens displayed disparities mainly in taxonomic and phylogenetic diversity. Differential responses of bogs and fens underline the necessity for tailored management strategies. Changes in plant diversity away from restoration targets have implications for ecosystem recovery, emphasizing the importance of long-term monitoring to evaluate the effectiveness of silviculture techniques in restoring boreal peatland plant communities. [ABSTRACT FROM AUTHOR]

To maximize their fitness, plants have to adjust their allocation strategy according to their abiotic and biotic environments. Plants can use the ratio of red to far‐red light (R:FR) to sense neighbours, allowing them to modify their growth in response to aboveground competition.In this study, we used supplemental FR light to artificially lower the R:FR of the lower leaves of common sunflowers (Helianthus annuus) to examine how plants change their growth in response to the threat of neighbours. We combined this treatment with a nitrogen fertilization treatment to investigate how responses to neighbour‐detection interact with nitrogen limitation.Plants grown in low R:FR increased in height at the expense of root growth, resulting in nitrogen limitation that restricted leaf growth. However, we found that plants reduced their nitrogen investment into leaves in low R:FR. By weakening the nitrogen sink strength of these lower leaves before they experienced low photosynthetically active radiation, plants were able to preemptively allocate nitrogen to leaves higher in the canopy.Plants responded to the perception of neighbours by simultaneously diverting resources from root growth to stem elongation and from leaves threatened by neighbours to leaves that would pose a threat to neighbours. This whole‐plant response to neighbour‐detection enables plants to change their allocation in a way that simultaneously manages their limited nitrogen and prepares them for future light competition. Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) stoichiometry in plant leaves plays an important role in linking plant physiological processes with community assemblage and species distribution. Studies have revealed that temperature is a major driver of leaf stoichiometry, however, whether current global warming will alter leaf N and P stoichiometry on a local scale remain poorly understood. Taking advantage of an unique data set on leaf element concentrations of 122 plant species in the Xilingol Grassland National Reserve (established in 1979), we addressed this issue by resampling plant leaves of the same 121 species in 2018, and compared the leaf N, P, and N:P ratio between the 2 years. We found that leaf N, P, and N:P ratio of the 121 species all exhibited large variation, with a magnitude of 4.5‐fold for N, 5.8‐fold for P, and 6.3‐fold for N:P ratio, respectively. However, the mean leaf N, P, and N:P ratio of the 121 species, as well as for each family, each life form and each habitat type, did not significantly change over 40 years (1979 vs. 2018), though a 2°C increase in annual mean temperature occurred. We identified that taxonomic difference was the primary driver for variations in leaf N, P, and N:P ratio in this grassland reserve, which is different from those on the regional and global scales. These results suggest that controls over leaf stoichiometry are likely scale‐dependent. Thus, using leaf stoichiometry to explain community assemblage and species distribution should take into account the scale‐dependent drivers. Plain Language Summary: Nitrogen (N) and phosphorus (P) are important elements in terrestrial biogeochemical cycles. Disentangling the controls over leaf N, P, and N:P ratio at different spatial scales (i.e., local, regional and global) is of great significance for understanding the N and P cycles in terrestrial ecosystems, especially in the face of current global changes. Previous studies have revealed some global‐ and regional‐scale controls over leaf N, P, and N:P ratio, but the local‐scale controls remain inconsistent. By a field investigation on leaf N, P, and N:P ratio of 121 species in a grassland reserve, we showed that leaf N, P, and N:P ratio all exhibited large variation. We identified that taxonomic difference was the primary driver for leaf N and P stoichiometry, different from the major drivers on a regional or a global scale. Moreover, a 2°C‐increase in temperature over 40 years (1979–2018) did not alter the leaf N, P, and N:P ratio of the same 121 plant species, suggesting that the current magnitude of global warming does not necessarily alter local‐scale leaf stoichiometry. Key Points: Taxonomic difference plays a critical role in driving local‐scale leaf N and P stoichiometryA 2°C increase in annual mean temperature over 40 years does not alter leaf N, P, and N:P ratioLocal‐scale controls over leaf stoichiometry are different from those on the regional and global scales [ABSTRACT FROM AUTHOR]

Premise: With the global atmospheric CO2 concentration on the rise, developing crops that can thrive in elevated CO2 has become paramount. We investigated the potential of hybridization as a strategy for creating crops with improved growth in predicted elevated atmospheric CO2. Methods: We grew parent accessions and their F1 hybrids of Arabidopsis thaliana in ambient and elevated atmospheric CO2 and analyzed numerous growth traits to assess their productivity and underlying mechanisms. Results: The heterotic increase in total dry mass, relative growth rate and leaf net assimilation rate was significantly greater in elevated CO2 than in ambient CO2. The CO2 response of net assimilation rate was positively correlated with the CO2 response of leaf nitrogen productivity and with that of leaf traits such as leaf size and thickness, suggesting that hybridization‐induced changes in leaf traits greatly affected the improved performance in elevated CO2. Conclusions: Vegetative growth of hybrids seems to be enhanced in elevated CO2 due to improved photosynthetic nitrogen‐use efficiency compared with parents. The results suggest that hybrid crops should be well‐suited for future conditions, but hybrid weeds may also be more competitive. [ABSTRACT FROM AUTHOR]

Premise: With the global atmospheric CO2 concentration on the rise, developing crops that can thrive in elevated CO2 has become paramount. We investigated the potential of hybridization as a strategy for creating crops with improved growth in predicted elevated atmospheric CO2. Methods: We grew parent accessions and their F1 hybrids of Arabidopsis thaliana in ambient and elevated atmospheric CO2 and analyzed numerous growth traits to assess their productivity and underlying mechanisms. Results: The heterotic increase in total dry mass, relative growth rate and leaf net assimilation rate was significantly greater in elevated CO2 than in ambient CO2. The CO2 response of net assimilation rate was positively correlated with the CO2 response of leaf nitrogen productivity and with that of leaf traits such as leaf size and thickness, suggesting that hybridization‐induced changes in leaf traits greatly affected the improved performance in elevated CO2. Conclusions: Vegetative growth of hybrids seems to be enhanced in elevated CO2 due to improved photosynthetic nitrogen‐use efficiency compared with parents. The results suggest that hybrid crops should be well‐suited for future conditions, but hybrid weeds may also be more competitive. [ABSTRACT FROM AUTHOR]

IntroductionIn recent decades, the introduction of high-yielding cultivars under optimal conditions has been the main focus of grain research programs. The identification of wheat cultivars that have acceptable yields on different planting dates has been taken into account.Materials and MethodsThe present split-plot test was performed with three replications in two cropping years, 2016-2017 and 2017-2018. The main factor included three planting dates (October 20, November 20, and December 20 as early, normal, and delayed planting dates), and the sub-factor included six wheat cultivars (Zare with winter growth habits, Heidari, Pishgam, and Alvand with facultative growth habits, and Sirvan and Pishtaz with spring growth habits). The soil was sampled from a depth of 0 to 30 cm before the experiment, and the physical and chemical traits of the soil were determined. Land preparation steps were performed before the experiment. For this purpose, a land area of 1500 m2 was plowed by a reversible plow and then leveled. Fertilizer application was performed based on the soil experiment results as 100 kg.ha-1 of triple superphosphate, 100 kg.ha-1 of potassium sulfate, and 100 kg.ha-1 of urea before planting. The rest of the urea fertilizer (200 kg.ha-1) was applied at the stage of stem emergence and the beginning of anthesis wheat. Iron, zinc, and manganese fertilizers were also used from their sulfate sources at the rate of 0.2%, which were sprayed in two stages at the beginning of stalking and spiking. Each plot was 5 m long and 2 m wide and consisted of 8 planting rows at a distance of 25 cm. A distance of 50 cm was considered between the two sub-plots and 1 m between the two main plots. The required seed for each experimental plot was determined and distributed based on the density of 400 seeds per m2 based on the weight of 1000 seeds of each cultivar. Irrigation was performed immediately after planting. Agricultural care was applied uniformly, including pest, disease, and weed control. In each subplot, 50 cm from the beginning and end of the rows was considered as the margin. All data were subjected to ANOVA using the GLM procedure of SAS (SAS 9.1) and means were compared by using the Duncan test at 5% probability level.Results and DiscussionThe results showed that delayed planting reduced nutrient uptake and increased the extinction coefficient. Radiation use efficiency on the planting date of December 20 showed a reduction of 27% and 25%, compared to the planting date of October 20 in 2016-2017 and 2017-2018, respectively. Also, on December 20, Sirvan and Pishtaz cultivars with spring growth habits showed lower extinction coefficients and higher photosynthesis rates than winter and facultative cultivars. On October 20 and November 20, the highest grain yield was obtained in cultivars with winter and facultative growth habits. On December 20, the grain yield was higher in cultivars with facultative and spring growth habits than in winter cultivars. Late planting of wheat cultivars with winter growth type, which must receive low temperatures for Vernalization, is very risky. Because delaying planting may lead to a sharp decrease in yield. These negative consequences of the delay in planting may have occurred through disruption of absorption of water, nutrients, and absorption of active photosynthetic radiation. Late cultivation shortens the vegetative growth period and the plant enters the reproductive stage prematurely, and then the plant faces a lack of photosynthetic resources. Also, the grain filling period is faced with drought and heat stress at the end of the season and this final stress causes a sharp decrease in yield.ConclusionIn general, the delayed planting significantly reduced grain yield, especially in cultivars with winter growth habits. Therefore, it is recommended to use intermediate and spring cultivars for delayed cultivation.

Nitrogen (N)‐fixing trees are thought to break a basic rule of leaf economics: higher leaf N concentrations do not translate into higher rates of carbon assimilation. Understanding how leaf N affects photosynthesis and water use efficiency (WUE) in this ecologically important group is critical.We grew six N‐fixing and four non‐fixing tree species for 4–5 years at four fertilization treatments in field experiments in temperate and tropical regions to assess how functional type (N fixer vs. non‐fixer) and N limitation affected leaf N and how leaf N affected light‐saturated photosynthesis (Asat), stomatal conductance (gsw) and WUE (WUEi and δ13C).Asat, WUEi and δ13C, but not gsw, increased with higher leaf N. Surprisingly, N‐fixing and non‐fixing trees displayed similar scaling between leaf N and these physiological variables, and this finding was supported by reanalysis of a global dataset. N fixers generally had higher leaf N than non‐fixers, even when non‐fixers were not N‐limited at the leaf level. Leaf‐level N limitation did not alter the relationship of Asat, gsw, WUEi and δ13C with leaf N, although it did affect the photosynthetic N use efficiency. Higher WUE was associated with higher productivity, whereas higher Asat was not.Synthesis: The ecological success of N‐fixing trees depends on the effect of leaf N on carbon gain and water loss. Using a field fertilization experiment and reanalysis of a global dataset, we show that high leaf‐level photosynthesis and WUE in N fixers stems from their higher average leaf N, rather than a difference between N fixers and non‐fixers in the scaling of photosynthesis and WUE with leaf N. By clarifying the mechanism by which N fixers achieve and benefit from high WUE, our results further the understanding of global N fixer distributions. [ABSTRACT FROM AUTHOR]

In response to increasing global warming, extreme heat stress significantly alters photosynthetic production. While numerous studies have investigated the temperature effects on photosynthesis, factors like vapour pressure deficit (VPD), leaf nitrogen, and feedback of sink limitation during and after extreme heat stress remain underexplored. This study assessed photosynthesis calculations in seven rice growth models using observed maximum photosynthetic rate (Pmax) during and after short‐term extreme heat stress in multi‐year environment‐controlled experiments. Biochemical models (FvCB‐type) outperformed light response curve‐based models (LRC‐type) when incorporating observed leaf nitrogen, photosynthetically active radiation, temperatures, and intercellular CO2 concentration (Ci) as inputs. Prediction uncertainty during heat stress treatment primarily resulted from variation in temperatures and Ci. Improving FVPD (the slope for the linear effect of VPD on Ci/Ca) to be temperature‐dependent, rather than constant as in original models, significantly improved Ci prediction accuracy under heat stress. Leaf nitrogen response functions led to model variation in leaf photosynthesis predictions after heat stress, which was mitigated by calibrated nitrogen response functions based on active photosynthetic nitrogen. Additionally, accounting for observed differences in carbohydrate accumulation between panicles and stems during grain filling improved the feedback of sink limitation, reducing Ci overestimation under heat stress treatments. Summary statement: The predictions of rice leaf photosynthesis during and after heat stress were improved by modifying the effects of temperature, VPD, nitrogen, and feedback of sink limitation, based on multi‐model comparison approach. [ABSTRACT FROM AUTHOR]

The spatial and temporal distribution of sunlight around plants is constantly changing in natural and farmland environments. Previous studies showed that the photosynthesis of crops responds significantly to heterogeneous light conditions in fields. However, the underlying mechanisms remain unclear. In the present study, soybean plants were treated by heterogeneous light after a pre-shading (SH-HL) to simulate the light condition in relay strip intercropping. Gas exchange and nitrogen (N) of leaves were measured to evaluate the photosynthetic performance, as well as photosynthetic N- and water-use efficiency (PNUE and PWUE). Chlorophylls (Chl) and Rubisco were analyzed as representative photosynthetic N components. Results suggest that SH-HL treated soybean exhibited evident photosynthetic compensation as the net photosynthetic rate (Pn) increased significantly in unshaded leaves, from which the export of photosynthates was enhanced. Under SH-HL, leaf N concentration remained relatively stable in unshaded leaves. While Chl concentration decreased but Rubisco concentration increased in unshaded leaves, indicating preferential allocation of leaf N for CO2 fixation. Results also showed that PNUE increased and PWUE decreased in unshaded leaves under SH-HL. Therefore, we suggest that within-leaf N allocation for CO2 fixation in unshaded leaves rather than within-plant N distribution to unshaded leaves drives the photosynthetic compensation under heterogeneous light after a pre-shading. However, enhanced water loss from unshaded leaves is a cost for efficient N-use under these conditions. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of wood vinegar and humic acid on morphological and biochemical traits, antioxidant enzymes, and peppermint essential oil under water deficit stress conditions, an experiment was conducted as split plot based on randomized complete block design with three replications in the research farm of the Faculty of Agriculture of the Tarbiat Modares University. The experimental treatments were irrigation regimes at three levels (irrigation up to the field capacity and after depletion 25 (optimal irrigation), 40 (moderate water deficit stress), and 55 (severe water deficit stress) % of plant available water in the root zone, respectively) as main plots and foliar application at seven levels (humic acid (1, 2, and 3%), wood vinegar (5, 10, and 15%) and no foliar application (control)) as sub plots. The highest plant height (38.63 cm) was obtained from the treatment of using wood vinegar 15% under optimal irrigation conditions, while, the maximum leaf area index (3.01) was observed in the treatment using wood vinegar 15% under moderate water deficit stress conditions. The maximum essential oil yield was observed in the foliar application of humic acid 3% under optimal irrigation conditions with 37.48 kg h-1, and with the treatments of humic acid 2% under optimal irrigation conditions with 34.34 kg ha-1 and foliar application of 15% of wood vinegar under optimal irrigation conditions with 36.11 kg ha-1 was placed in a statistical group. An increase in water deficit stress caused a decrease in essential oil yield, so that in moderate and severe water deficit stress, 9.37% and 40.17% of essential oil yield decreased, respectively. The use of wood vinegar and humic acid increased the yield of peppermint essential oil, so that by increasing the foliar concentration of wood vinegar from 0 to 15%, the yield of essential oil increased by 81.29%, and increasing the concentration of humic acid foliar application from 0 to 3% increased the yield of essential oil by 69.28%. Considering the water limitation, the use of acid humic 3% is recommended in optimal irrigation conditions and moderate water deficit stress, and wood vinegar 15% in severe water deficit stress conditions is recommended. [ABSTRACT FROM AUTHOR]

ABSTRACT Brazil is the largest Coffea arabica L. producer and exporter in the world market. In view of the need for nitrogen fertilization, the objective of this work was to evaluate the use of digital images of coffee leaves as a function of nitrogen concentration and cultivars, as well as to evaluate the most adequate sampling of this technique to predict leaf nitrogen. The experiment was set in a greenhouse, at UNESP - Experimental Campus of Registro-SP, using 12L pots with medium sand. A completely randomized design was adopted, in a 4 x 2 factorial scheme, with four concentrations of N (0, 50, 100 and 200 mg dm-3), and two coffee cultivars (Mundo Novo and Obatã), with ten replications. The variables evaluated were: hue, dark green color index (DGCI), leaf area and leaf nitrogen content. The hue and DGCI were influenced by N concentration, cultivar and are dependent on the day after treatment application and the number of leaves used. The use of five leaves per replication was more adequate to estimate leaf N content. Hue, DGCI and leaf area were higher in Obatã depending on the day after application of the treatment and N concentration.

There is increasing awareness that plant community functional properties can be an important driver of ecosystem functioning. However, major knowledge gaps exist about how environmental factors, especially climate and soil abiotic properties, shape plant functional diversity at a regional scale. Furthermore, at those scales the relationships between plant functional and taxonomic diversity have rarely been considered. Here, we used a large database of plant species and functional trait data from 180 temperate grasslands across England, covering a broad range of grassland types, climatic conditions and management intensities, the last having a strong influence on multiple soil variables. Our specific aims were to: (1) identify the dominant environmental factors explaining variation in different facets of plant community functional properties, including community weighted means (CWMs) of functional traits and various multi-trait functional diversity indices; and (2) test whether the relationship between plant functional and taxonomic diversity is mediated by environmental factors at a regional scale. We found that soil abiotic properties (pH and nutrient stocks), but not climate, were the main environmental factors explaining grassland plant functional diversity at a regional scale, with a significant contribution of soil nutrient stoichiometry (N/P ratio). Two indices of plant community functional properties, namely CWMs of specific leaf area and relative growth rate, were explained by interactions between soil pH and N and mean annual precipitation, soil pH soil N and soil N/P ratio. These indices were also negatively related to taxonomic diversity under certain soil abiotic conditions, specifically high soil clay content, pH and N/P. Together, our results indicate that soil abiotic properties rather than climate factors shape plant functional diversity across temperate grassland plant communities at a regional scale. They also suggest that interactions between environmental factors play a significant role in shaping patterns of plant community functional properties. Our findings are of importance for the design and interpretation of future studies using trait and diversity measures as proxies of ecosystem services at regional scales. [ABSTRACT FROM AUTHOR]

Plant traits are useful for predicting how species may respond to environmental change and/or influence ecosystem properties. Understanding the extent to which traits vary within species and across climatic gradients is particularly important for understanding how species may respond to climate change. We explored whether climate drives spatial patterns of intraspecific trait variation for three traits (specific leaf area (SLA), plant height, and leaf nitrogen content (Nmass)) across 122 grass species (family: Poaceae) with a combined distribution across six continents. We tested the hypothesis that the sensitivity (i.e. slope) of intraspecific trait responses to climate across space would be related to the species' typical form and function (e.g. leaf economics, stature and lifespan). We observed both positive and negative intraspecific trait responses to climate with the distribution of slope coefficients across species straddling zero for precipitation, temperature and climate seasonality. As hypothesized, variation in slope coefficients across species was partially explained by leaf economics and lifespan. For example, acquisitive species with nitrogen‐rich leaves grew taller and produced leaves with higher SLA in warmer regions compared to species with low Nmass. Compared to perennials, annual grasses invested in leaves with higher SLA yet decreased height and Nmass in regions with high precipitation seasonality (PS). Thus, while the influence of climate on trait expression may at first appear idiosyncratic, variation in trait–climate slope coefficients is at least partially explained by the species' typical form and function. Overall, our results suggest that a species' mean location along one axis of trait variation (e.g. leaf economics) could influence how traits along a separate axis of variation (e.g. plant size) respond to spatial variation in climate. [ABSTRACT FROM AUTHOR]

Aim: Leaf traits are central to plant function, and key variables in ecosystem models. However recently published global trait maps, made by applying statistical or machine‐learning techniques to large compilations of trait and environmental data, differ substantially from one another. This paper aims to demonstrate the potential of an alternative approach, based on eco‐evolutionary optimality theory, to yield predictions of spatio‐temporal patterns in leaf traits that can be independently evaluated. Innovation: Global patterns of community‐mean specific leaf area (SLA) and photosynthetic capacity (Vcmax) are predicted from climate via existing optimality models. Then leaf nitrogen per unit area (Narea) and mass (Nmass) are inferred using their (previously derived) empirical relationships to SLA and Vcmax. Trait data are thus reserved for testing model predictions across sites. Temporal trends can also be predicted, as consequences of environmental change, and compared to those inferred from leaf‐level measurements and/or remote‐sensing methods, which are an increasingly important source of information on spatio‐temporal variation in plant traits. Main conclusions: Model predictions evaluated against site‐mean trait data from > 2,000 sites in the Plant Trait database yielded R2 = 73% for SLA, 38% for Nmass and 28% for Narea. Declining species‐level Nmass, and increasing community‐level SLA, have both been recently reported and were both correctly predicted. Leaf‐trait mapping via optimality theory holds promise for macroecological applications, including an improved understanding of community leaf‐trait responses to environmental change. [ABSTRACT FROM AUTHOR]

Climate change, including both increasing temperatures and changing snow regimes, is progressing rapidly in the Arctic, leading to changes in plant phenology and in the seasonal patterns of plant properties, such as tissue nitrogen (N) content and community aboveground biomass. However, significant knowledge gaps remain over how these seasonal patterns vary among Arctic plant functional groups (i.e., shrubs, grasses, and forbs) and across large geographical areas. We used three years of in situ field vegetation sampling from an 80,000‐km2 area in Arctic Alaska, remotely sensed vegetation data (daily normalized difference vegetation index [NDVI]), and modeled output of snow‐free date to determine and model the seasonal trends and primary controls on leaf percent nitrogen and biomass (in grams per square meter) among Arctic vegetation functional groups. We determined relative vegetation phenology stage at a 500‐m spatial scale resolution, defined as the number of days between the date of the seasonal maximum NDVI and the vegetation field sampling date, and relative snow phenology stage (90‐m spatial scale) was determined as the number of days between the date of snow‐free ground and the sampling date. Models including relative phenology stage were particularly important for explaining seasonal variability of %N in shrubs, graminoids, and forbs. Similarly, vegetation and snow phenology stages were also important for modeling seasonal biomass of shrubs and graminoids; however, for all functional groups, the models explained only a small amount of seasonal variability in biomass. Relative phenology stage was a stronger predictor of %N and biomass than geographic position, indicating that localized controls on phenology, acting at spatial scales of 500 m and smaller, are critical to understanding %N and biomass. [ABSTRACT FROM AUTHOR]

The carbon, nitrogen and water cycles of terrestrial ecosystems are important biogeochemical cycles. Addressing the relationship of leaf nitrogen (N) and carbon isotope discrimination (Δ) will enhance the understanding of the links between these three cycles in plant leaves because Δ can reflect time-integrated leaf-level water-use efficiency (WUE) over the period when the leaf material is produced. Previous studies have paid considerable attention to the relationship. However, these studies have not effectively eliminated the interference of environmental factors, inter-species, and inter-individual differences in this relationship, so new research is necessary. To minimize these interferences, the present work explored the relationship at the three levels of community, population, and plant individual. Three patterns of positive, negative and no relationship were observed across communities, populations, and individuals, which is dependent on environmental conditions, species, and plant individuals. The results strongly suggested that there is no general pattern for the relationship between leaf N and Δ. Furthermore, the results indicated that there is often no coupling between leaf-level long-term WUE and leaf N in the metabolic process of carbon, N and water in leaves. The main reason for the lack of this relationship is that most plants do not invest large amounts of nitrogen into photosynthesis. In addition, the present study also observed that, for most plant species, leaf N was not related to photosynthetic rate, and that variations in photosynthetic rates are mainly driven by stomatal conductance. [ABSTRACT FROM AUTHOR]

Main conclusion: Cultivated tomato presented lower constitutive volatiles, reduced morphological and chemical defenses, and increased leaf nutritional quality that affect its resistance against the specialist herbivore Tuta absoluta compared to its wild relatives. Plant domestication process has selected desirable agronomic attributes that can both intentionally and unintentionally compromise other important traits, such as plant defense and nutritional value. However, the effect of domestication on defensive and nutritional traits of plant organs not exposed to selection and the consequent interactions with specialist herbivores are only partly known. Here, we hypothesized that the modern cultivated tomato has reduced levels of constitutive defense and increased levels of nutritional value compared with its wild relatives, and such differences affect the preference and performance of the South American tomato pinworm, Tuta absoluta—an insect pest that co-evolved with tomato. To test this hypothesis, we compared plant volatile emissions, leaf defensive (glandular and non-glandular trichome density, and total phenolic content), and nutritional traits (nitrogen content) among the cultivated tomato Solanum lycopersicum and its wild relatives S. pennellii and S. habrochaites. We also determined the attraction and ovipositional preference of female moths and larval performance on cultivated and wild tomatoes. Volatile emissions were qualitatively and quantitatively different among the cultivated and wild species. Glandular trichomes density and total phenolics were lower in S. lycopersicum. In contrast, this species had a greater non-glandular trichome density and leaf nitrogen content. Female moths were more attracted and consistently laid more eggs on the cultivated S. lycopersicum. Larvae fed on S. lycopersicum leaves had a better performance reaching shorter larval developmental times and increasing the pupal weight compared to those fed on wild tomatoes. Overall, our study documents that agronomic selection for increased yields has altered the defensive and nutritional traits in tomato plants, affecting their resistance to T. absoluta. [ABSTRACT FROM AUTHOR]

Introduction: Drip irrigation is an efficient water-saving system used to improve crop production worldwide. However, we still lack a comprehensive understanding of maize plant senescence and its association with yield, soil water, and nitrogen (N) utilization under this system. Methods: A 3-year field experiment in the northeast plains of China was used to assess four drip irrigation systems: (1) drip irrigation under plastic film mulch (PI); (2) drip irrigation under biodegradable film mulch (BI); (3) drip irrigation incorporating straw returning (SI); and (4) drip irrigation with the tape buried at a shallow soil depth (OI), and furrow irrigation (FI) was used as the control. The plant senescence characteristic based on the dynamic process of green leaf area (GLA) and live root length density (LRLD) during the reproductive stage, and its correlation with leaf N components, water use efficiency (WUE), and N use efficiency (NUE) was investigated. Results: PI followed by BI achieved the highest integral GLA and LRLD, grain filling rate, and leaf and root senescence rate after silking. Greater yield, WUE, and NUE were positively associated with higher N translocation efficiency of leaf protein responding for photosynthesis, respiration, and structure under PI and BI; whereas, no significant differences were found in yield, WUE, and NUE between PI and BI. SI effectively promoted LRLD in the deeper 20- to 100-cm soil layers, prolonged the GLA and LRLD persistent durations, and reduced the leaf and root senescence rates. The remobilization of non-protein storage N was stimulated by SI, FI, and OI, which made up for the relative inadequacy of leaf N. Discussion: Instead of persistent GLA and LRLD durations and high translocation efficiency of non-protein storage N, fast and large protein N translocation from leaves to grains under PI and BI was found to facilitate maize yield, WUE, and NUE in the sole cropping semi-arid region, and BI was recommend considering that it can reduce plastic pollution. [ABSTRACT FROM AUTHOR]

Abstract Climate change, including both increasing temperatures and changing snow regimes, is progressing rapidly in the Arctic, leading to changes in plant phenology and in the seasonal patterns of plant properties, such as tissue nitrogen (N) content and community aboveground biomass. However, significant knowledge gaps remain over how these seasonal patterns vary among Arctic plant functional groups (i.e., shrubs, grasses, and forbs) and across large geographical areas. We used three years of in situ field vegetation sampling from an 80,000‐km2 area in Arctic Alaska, remotely sensed vegetation data (daily normalized difference vegetation index [NDVI]), and modeled output of snow‐free date to determine and model the seasonal trends and primary controls on leaf percent nitrogen and biomass (in grams per square meter) among Arctic vegetation functional groups. We determined relative vegetation phenology stage at a 500‐m spatial scale resolution, defined as the number of days between the date of the seasonal maximum NDVI and the vegetation field sampling date, and relative snow phenology stage (90‐m spatial scale) was determined as the number of days between the date of snow‐free ground and the sampling date. Models including relative phenology stage were particularly important for explaining seasonal variability of %N in shrubs, graminoids, and forbs. Similarly, vegetation and snow phenology stages were also important for modeling seasonal biomass of shrubs and graminoids; however, for all functional groups, the models explained only a small amount of seasonal variability in biomass. Relative phenology stage was a stronger predictor of %N and biomass than geographic position, indicating that localized controls on phenology, acting at spatial scales of 500 m and smaller, are critical to understanding %N and biomass.

Ontogenic changes in soybean radiation use efficiency (RUE) have been attributed to variation in specific leaf nitrogen (SLN) based only on data collected during seed filling. We evaluated this hypothesis using data on leaf area, absorbed radiation (ARAD), aboveground dry matter (ADM), and plant nitrogen (N) concentration collected during the entire crop season from seven field experiments conducted in a stress-free environment. Each experiment included a full-N treatment that received ample N fertilizer and a zero-N treatment that relied on N fixation and soil N mineralization. We estimated RUE based on changes in ADM between sampling times and associated ARAD, accounting for changes in biomass composition. The RUE and SLN exhibited different seasonal patterns: a bell-shaped pattern with a peak around the beginning of seed filling, and a convex pattern followed by an abrupt decline during late seed filling, respectively. Changes in SLN explained the decline in RUE during seed filling but failed to predict changes in RUE in earlier stages and underestimated the maximum RUE observed during pod setting. Comparison between observed and simulated RUE using a process-based crop simulation model revealed similar discrepancies. The decoupling between RUE and SLN during early crop stages suggests that leaf N is above that needed to maximize crop growth but may play a role in storing N that can be used in later reproductive stages to meet the large seed N demand associated with high-yielding crops. [ABSTRACT FROM AUTHOR]

Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars.

IntroductionCamelina [Camelina sativa (L.) Crantz] oilseed is a low-input crop that grows and yields well in semiarid regions with low-fertility or saline soils in comparison with other crops. Camelina seeds contain 30–40 percent oil. Camelina is an annual plant from the Brassicaceae family that has short and fast growth. Camelina is well adapted to cool temperate and semi-arid climates, it is more tolerant of drought and spring freezing than rapeseed (Brassica napus L.). Also, Resistance to some diseases and pests of other members of Brassicaceae plants is another important features of this plant. Research-based information is lacking to provide basic agronomic recommendations for Camelina. In general, yield and yield components of Camelina seeds depends on nitrogen fertilization, planting time and climatic conditions. Camelina responds differently to fertilizer management and planting date in different climatic and soil conditions. Selection of crop managements such as planting date and fertilization can increase the quantitative and the qualitative yield of this plant.Materials and MethodsIn order to evaluate the effects of nitrogen fertilizer on agronomic characteristics in Camelina under different planting dates, a study was conducted in split-plot based on randomized complete blocks design with three replications at the research field of Agricultural College, the Shahid Chamran University of Ahvaz, located in the southwest of Ahvaz and the western bank of the Karun River with 31°19׳ʹ N; 48° 41׳ʹ an altitude of 22 meters above sea level during 2018-19 growth season. Experimental factors included planting date in three times (November 6, December 6 and January 5) as the main plots and nitrogen fertilizer at four levels (0, 23, 46 and 69 kg.ha-1) as the subplots. The plant material (seed) of this research was Camelina sativa cultivar Soheil which was prepared from the Biston Shafa Knowledge Foundation Company. Half of the nitrogen fertilizer was spread with phosphorus and potassium in the surface of each experimental unit and mixed with soil before planting. The other half of nitrogen fertilizer used in three sections during three stages of plant phenology included True four leaves, beginning of stem elongation and beginning of silicle emergence.Results and DiscussionAnalysis of variance of traits showed a significant difference between nitrogen levels at each level of planting date in terms of all traits studied, including grain yield, biological yield, harvest index, plant height, percentage and oil yield, etc. Generally, based on the results of the analysis of variance, in all three planting dates. The highest grain yield (2653.8 kg.ha-1) was obtained from the first planting date and 46 kgN.ha-1 treatment and the highest harvest index in second planting date and 46 kg nitrogen treatment was measured. The highest oil yield (737.9 kg.ha-1) belonged to the first planting date and the level of 23 kgN.ha-1. However, the highest protein percentages (28.53) was obtained in the second planting date and 69 kg nitrogen treatment. Regarding to the other traits, it was observed that the optimal use of nitrogen fertilizer led to the improvement of the studied traits such as the number of sub-branches, silicle per plant, seed per silicle and 1000-grain weight, but delay in planting date caused the mean of these traits decreased significantly.ConclusionIn general, the results of this study showed a significant response of Camelina to the amount of nitrogen used and planting date, so that in early planting (November 6) was obtained the highest grain yield, yield components, biological yield, oil yield and protein percentage. But in late planting, especially the third planting date, all the studied traits were reduced due to the collision of the plant reproductive stage with the high temperature at the end of Khuzestan growth season and the reduction of the plant growth cycle. Under three planting dates, nitrogen fertilizer application up to 46 kgN.ha-1 increased grain yield, oil yield and some yield components. Based on the results of this experiment, in order to obtain maximum grain and oil yield of Camelina, it is important to consider planting date and optimum nitrogen use.

Leaf dry mass per unit area (LMA), carboxylation capacity (Vcmax) and leaf nitrogen per unit area (Narea) and mass (Nmass) are key traits for plant functional ecology and ecosystem modelling. There is however no consensus about how these traits are regulated, or how they should be modelled. Here we confirm that observed leaf nitrogen across species and sites can be estimated well from observed LMA and Vcmax at 25°C (Vcmax25). We then test the hypothesis that global variations of both quantities depend on climate variables in specific ways that are predicted by leaf‐level optimality theory, thus allowing both Narea to be predicted as functions of the growth environment.A new global compilation of field measurements was used to quantify the empirical relationships of leaf N to Vcmax25 and LMA. Relationships of observed Vcmax25 and LMA to climate variables were estimated, and compared to independent theoretical predictions of these relationships. Soil effects were assessed by analysing biases in the theoretical predictions.LMA was the most important predictor of Narea (increasing) and Nmass (decreasing). About 60% of global variation across species and sites in observed Narea, and 31% in Nmass, could be explained by observed LMA and Vcmax25. These traits, in turn, were quantitatively related to climate variables, with significant partial relationships similar or indistinguishable from those predicted by optimality theory. Predicted trait values explained 21% of global variation in observed site‐mean Vcmax25, 43% in LMA and 31% in Narea. Predicted Vcmax25 was biased low on clay‐rich soils but predicted LMA was biased high, with compensating effects on Narea. Narea was overpredicted on organic soils.Synthesis. Global patterns of variation in observed site‐mean Narea can be explained by climate‐induced variations in optimal Vcmax25 and LMA. Leaf nitrogen should accordingly be modelled as a consequence (not a cause) of Vcmax25 and LMA, both being optimized to the environment. Nitrogen limitation of plant growth would then be modelled principally via whole‐plant carbon allocation, rather than via leaf‐level traits. Further research is required to better understand and model the terrestrial nitrogen and carbon cycles and their coupling. [ABSTRACT FROM AUTHOR]

Brazil is the largest Coffea arabica L. producer and exporter in the world market. In view of the need for nitrogen fertilization, the objective of this work was to evaluate the use of digital images of coffee leaves as a function of nitrogen concentration and cultivars, as well as to evaluate the most adequate sampling of this technique to predict leaf nitrogen. The experiment was set in a greenhouse, at UNESP - Experimental Campus of Registro-SP, using 12L pots with medium sand. A completely randomized design was adopted, in a 4 x 2 factorial scheme, with four concentrations of N (0, 50, 100 and 200 mg dm-3), and two coffee cultivars (Mundo Novo and Obatã), with ten replications. The variables evaluated were: hue, dark green color index (DGCI), leaf area and leaf nitrogen content. The hue and DGCI were influenced by N concentration, cultivar and are dependent on the day after treatment application and the number of leaves used. The use of five leaves per replication was more adequate to estimate leaf N content. Hue, DGCI and leaf area were higher in Obatã depending on the day after application of the treatment and N concentration. [ABSTRACT FROM AUTHOR]

As an important part of the forest ecosystem, the litter is an important link in the material cycle of the ecosystem. In this paper, the functional traits of leaves and stems and the litter standing crop of 28 common tree species in the subtropical artificial young forests were selected as the research objects, in order to explore the relationship between the functional traits of tree species and litter standing crop in the subtropical artificial young forests. The results showed that, the evergreen broad-leaved tree species had the highest litter standing crop (mean 123. 73 g • m-2), followed by the deciduous broadleaved tree species (mean 57. 08 g • m-2) and the evergreen needle-leaved tree species (mean 54. 61 g • m-2). The deciduous tree species such as Hovenia acerba, Ormosia hosiei, and Alnus trabeculosa had the characteristics of high true leaf area, leaf nitrogen concentration, low leaf tannin content and wood density, indicating that these tree species exhibited the acquisitive strategies in resource utilization, while the evergreen tree species such as Osmanthus fra grans, Lithocarpus glaber, Michelia maudiae and Castanopsis sclerophylla had the opposite characteristics, showing the conservative strategy in resource utilization. There was a significant negative correlation between the litter standing crop and leaf nitrogen content and leaf non-structural carbohydrates in the subtropical artificial young forests. The results showed that, the functional traits of plants not only affected the plant growth rate, but also affected the litter standing crop through the decomposition rate. Therefore, the leaf functional traits of tree species should be considered in the selection of tree species for afforestation. [ABSTRACT FROM AUTHOR]

One metric of peatland restoration success is the re‐establishment of a carbon sink, yet considerable uncertainty remains around the time‐scale of carbon sink trajectories. Conditions post‐restoration may promote the establishment of vascular plants such as graminoids, often at greater density than would be found in undisturbed peatlands, with consequences for carbon storage. Although graminoid species are often considered as a single plant functional type (PFT) in land‐atmosphere models, our understanding of functional variation among graminoid species is limited, particularly in a restoration context.We used a traits‐based approach to evaluate graminoid functional variation and to assess whether different graminoid species should be considered a single PFT or multiple types. We tested hypotheses that greenhouse gas fluxes (CO2, CH4) would vary due to differences in plant traits among five graminoid species in a restored peatland in central Alberta, Canada. We further hypothesized that species would form two functionally distinct groupings based on taxonomy (grass, sedge).Differences in gas fluxes among species primarily reflected variation in leaf physiology related to photosynthetic efficiency and resource‐use, and secondarily by plant size. Multivariate analyses did not reveal distinct functional groupings based on taxonomy or environmental preferences. Rather, we identified functional groups defined by plant traits and carbon fluxes that are consistent with ecological strategies related to differences in growth rate, resource‐acquisition and leaf economics, representing plants with either a strategy to grow quickly and invest in resource capture or to prioritize structural investment and resource conservation. These functional groups displayed larger average carbon fluxes compared to graminoid PFTs currently used in modelling.Synthesis. Existing PFT designations in peatland models may be more appropriate for pristine or high‐latitude systems than those under restoration. Although replacing PFTs with plant traits remains a challenge in peatlands, traits related to leaf physiology and growth rate strategies offer a promising avenue for future applications. [ABSTRACT FROM AUTHOR]

Improving the accuracy of estimates of forest carbon exchange is a central priority for understanding ecosystem response to increased atmospheric CO2 levels and improving carbon cycle modelling. However, the spatially continuous parameterization of photosynthetic capacity (Vcmax) at global scales and appropriate temporal intervals within terrestrial biosphere models (TBMs) remains unresolved. This research investigates the use of biochemical parameters for modelling leaf photosynthetic capacity within a deciduous forest. Particular attention is given to the impacts of seasonality on both leaf biophysical variables and physiological processes, and their interdependent relationships. Four deciduous tree species were sampled across three growing seasons (2013-2015), approximately every 10 days for leaf chlorophyll content (ChlLeaf ) and canopy structure. Leaf nitrogen (NArea ) was also measured during 2014. Leaf photosynthesis was measured during 2014-2015 using a Li-6400 gas-exchange system, with A-Ci curves to model Vcmax. Results showed that seasonality and variations between species resulted in weak relationships between Vcmax normalized to 25°C (Vcmax25) and NArea (R2  = 0.62, P

A plant’s photosynthetic capacity is typically reflected by its maximum carboxylation rate (Vcmax), which varies with time and plant functional type. In what way Vcmax in a xerophytic-shrub species changes in response to variation in its desert habitat remains poorly understood. In this study, Vcmax was continuously monitored in a common desert-shrub species, Artemisia ordosica, with a portable photosynthetic system over seven growing seasons from 2013 to 2019. Vcmax’s annual and interannual variations were subsequently assessed in conjunction with a meta-analysis carried out as a separate study. Vcmax in the species did not show a distinct seasonal pattern over the seven growing seasons. It rather displayed extensive year-to-year variations in the seasonal peak and its associated timing, exhibiting greater plasticity as compared with other plant functional types. Seasonal variation in Vcmax was primarily controlled by leaf nitrogen content per area (Narea) in a positive, linear manner, with the relationship’s sensitivity varying as a function of soil volumetric water content (VWC). Interannual variation in Vcmax was regulated by annual mean VWC, also in a positive, linear manner. The effect of Narea on Vcmax was amplified during the leaf-expanding stage of the shrub. Given severe drought anticipated under continued climate change, xerophytic shrubs are believed sufficiently malleable to acclimatize to ongoing environmental change in deserts.

Foliar traits such as specific leaf area (SLA), leaf nitrogen (N), and phosphorus (P) concentrations play important roles in plant economic strategies and ecosystem functioning. Various global maps of these foliar traits have been generated using statistical upscaling approaches based on in-situ trait observations. Here, we intercompare such global upscaled foliar trait maps at 0.5° spatial resolution (six maps for SLA, five for N, three for P), categorize the upscaling approaches used to generate them, and evaluate the maps with trait estimates from a global database of vegetation plots (sPlotOpen). We disentangled the contributions from different plant functional types (PFTs) to the upscaled maps and quantified the impacts of using different plot-level trait metrics on the evaluation with sPlotOpen: community weighted mean (CWM) and top-of-canopy weighted mean (TWM). We found that the global foliar trait maps of SLA and N differ drastically and fall into two groups that are almost uncorrelated (for P only maps from one group were available). The primary factor explaining the differences between these groups is the use of PFT information combined with remote sensing-derived land cover products in one group while the other group mostly relied on environmental predictors alone. The maps that used PFT and corresponding land cover information exhibit considerable similarities in spatial patterns that are strongly driven by land cover. The maps not using PFTs show a lower level of similarity and tend to be strongly driven by individual environmental variables. Upscaled maps of both groups were moderately correlated to sPlotOpen data aggregated to the grid-cell level (R = 0.2–0.6) when processing sPlotOpen in a way that is consistent with the respective trait upscaling approaches, including the plot-level trait metric (CWM or TWM) and the scaling to the grid cells with or without accounting for fractional land cover. The impact of using TWM or CWM was relevant, but considerably smaller than that of the PFT and land cover information. The maps using PFT and land cover information better reproduce the between-PFT trait differences of sPlotOpen data, while the two groups performed similarly in capturing within-PFT trait variation. Our findings highlight the importance of explicitly accounting for within-grid-cell trait variation, which has important implications for applications using existing maps and future upscaling efforts. Remote sensing information has great potential to reduce uncertainties related to scaling from in-situ observations to grid cells and the regression-based mapping steps involved in the upscaling. [Display omitted] • Analyses revealed two fundamentally different categories of upscaled trait maps. • Differences between categories mainly driven by use of plant functional types (PFT). • Additional differences due to whole community vs. top-of-canopy trait metrics. • Upscaling without PFT does not capture the observed trait differences between them. • Accounting for within-grid-cell trait variation crucial for upscaling and evaluation. [ABSTRACT FROM AUTHOR]

In many invaded grasslands, dominant exotic species can produce large amounts of litter that modify local abiotic conditions and species' interactions. These novel conditions can reduce native species abundance and promote the persistence of exotic species, yet the strength of this disparity may be influenced by how consumer pressure interacts with litter accumulation. Consumers may exacerbate this disparity by preferentially targeting native species or by promoting heterogeneity in microhabitats due to their movement and small‐scale ground disturbances that favours fast growing exotic species. How species respond to litter accumulation and consumer pressure may depend on either evolutionary differences, whereby exotics species may benefit from a lack natural predators, or by functional differences, in which species' physiological traits may confer fitness advantages to low‐light conditions or herbivory or granivory pressure.We examined the impact of litter presence and small mammal herbivory on the establishment and reproduction of functionally diverse exotic versus native species seeded across sites that naturally vary in resource availability in an annual invaded California grassland. We assessed whether seed mass and leaf nitrogen content (LNC) were predictive of successful establishment and reproduction.Litter accumulation affected exotic and native species differently, with litter significantly decreasing native recruitment and reproduction, while exotics were largely unaffected. Small mammals had a slight positive effect on the establishment of native species when litter was present but did not influence exotic species. Regardless of species provenance, larger seeded species established at a higher density while species with lower leaf nitrogen content had a higher density of reproductive individuals. Native species that successfully established and reproduced were functionally different in LNC than the resident community, while successful exotic species were functionally more similar to the resident community in LNC.Our study demonstrates that exotic species outperformed native species regardless of the presence of litter or herbivory pressure. Without the removal or thinning of litter, it is likely that exotic species will continue to dominate, resulting in positive feedback that further favours the persistence of exotic species within this invaded grassland system. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The links between internal nitrogen recycling through the process of resorption from senescing leaves, whole‐plant resource‐use strategies and performance remain elusive. Indeed, tests of such potential linkages are hampered by the classical evaluation of plant nitrogen resorption efficiency (REN) based on 'snapshots' of leaf nitrogen concentration from adult and senescent leaves.We significantly increased the resolution for measuring leaf nitrogen resorption by non‐destructively tracking time courses of nitrogen concentration in leaves of 137 natural Arabidopsis thaliana genotypes native to a wide range of climates across Europe, grown in a greenhouse. In addition to the classical measurement of resorption efficiency, we computed the relative maximum resorption rate of nitrogen (RRN), that is, the amount of nitrogen remobilized by a leaf per unit time and per unit nitrogen, together with slow–fast syndrome traits at the leaf and whole‐plant levels.Across genotypes, high rates and efficiencies of nitrogen resorption were associated with low specific leaf area and late flowering. The RRN showed significant heritability, genetic associations and was negatively correlated with the mean annual temperature of the native populations. By contrast, despite the evidence of a correlation with temperature, REN showed lower heritability and no evidence of genetic association, questioning the mechanisms of nitrogen resorption.Overall, our results suggest a much stronger adaptive role for leaf nitrogen resorption than previously uncovered. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Improving the model-based predictions of plant species under a projected climate is essential to better conserve our biodiversity. However, the mechanistic link between climatic variation and plant response at the species level remains relatively poorly understood and not accurately developed in Dynamic Vegetation Models (DVMs). We investigated the acclimation to climate of Cedrus atlantica (Atlas cedar), an endemic endangered species from northwestern African mountains, in order to improve the ability of a DVM to simulate tree growth under climatic gradients. Our results showed that the specific leaf area, leaf C:N and sapwood C:N vary across the range of the species in relation to climate. Using the model parameterized with the three traits varying with climate could improve the simulated local net primary productivity (NPP) when compared to the model parameterized with fixed traits. Quantifying the influence of climate on traits and including these variations in DVMs could help to better anticipate the consequences of climate change on species dynamics and distributions. Additionally, the simulation with computed traits showed dramatic drops in NPP over the course of the 21st century. This finding is in line with other studies suggesting the decline in the species in the Rif Mountains, owing to increasing water stress. [ABSTRACT FROM AUTHOR]

The carbon, nitrogen and water cycles of terrestrial ecosystems are important biogeochemical cycles. Addressing the relationship of leaf nitrogen (N) and carbon isotope discrimination (Δ) will enhance the understanding of the links between these three cycles in plant leaves because Δ can reflect time-integrated leaf-level water-use efficiency (WUE) over the period when the leaf material is produced. Previous studies have paid considerable attention to the relationship. However, these studies have not effectively eliminated the interference of environmental factors, inter-species, and inter-individual differences in this relationship, so new research is necessary. To minimize these interferences, the present work explored the relationship at the three levels of community, population, and plant individual. Three patterns of positive, negative and no relationship were observed across communities, populations, and individuals, which is dependent on environmental conditions, species, and plant individuals. The results strongly suggested that there is no general pattern for the relationship between leaf N and Δ. Furthermore, the results indicated that there is often no coupling between leaf-level long-term WUE and leaf N in the metabolic process of carbon, N and water in leaves. The main reason for the lack of this relationship is that most plants do not invest large amounts of nitrogen into photosynthesis. In addition, the present study also observed that, for most plant species, leaf N was not related to photosynthetic rate, and that variations in photosynthetic rates are mainly driven by stomatal conductance.

Plants make leaf-level trade-offs between photosynthetic carbon assimilation and water loss, and the optimal balance between the two is dependent, in part, on water availability. "Conservative" water-use strategies, in which minimizing water loss is prioritized over assimilating carbon, tend to be favored in arid environments, while "aggressive" water-use strategies, in which carbon assimilation is prioritized over water conservation, are often favored in mesic environments. When derived from foliar carbon isotope ratios, intrinsic water-use efficiency (iWUE) serves as a seasonally integrated indicator of the balance of carbon assimilation to water loss at the leaf level. Here, we used a multi-decadal record of annual iWUE, growth, and flowering from a single population of Encelia farinosa in the Mojave Desert to evaluate the effect of iWUE on plant performance across interannual fluctuations in water availability. We identified substantial variability in iWUE among individuals and found that iWUE interacted with water availability to significantly influence growth and flowering. However, the relationships between iWUE, water availability, and plant performance did not universally suggest that "conservative" water-use strategies were advantageous in dry years or that "aggressive" strategies were advantageous in wet years. iWUE was positively related to the odds of growth regardless of water availability and to the odds of flowering in dry years, but negatively related to growth rates in dry years. In addition, we found that leaf nitrogen content affected interannual plant performance and that an individual's iWUE plasticity in response to fluctuations in aridity was negatively related to early life drought survival and growth. [ABSTRACT FROM AUTHOR]

Motivation: Leaf traits represent an important component of plant functional strategies, and those related to carbon fixation and nutrient acquisition form the leaf economics spectrum. However, observations of functional leaf traits are underrepresented in tropical regions in comparison with those in temperate areas. Brazil, a country with continental scale and vast biodiversity is a timely example, where many biomes are impacted by human activities and climate change. However, leaf traits relevant to understand vegetation responses to these impacts remain poorly quantified for many species found in the country. We compiled an extensive data set of four functional leaf traits for native woody species occurring in the Brazilian territory. In addition to trait observations, sampling dates and geo‐references were compiled and climatic parameters and soil properties of each sampling site were extracted from several databases. Main types of variables contained: The LT‐Brazil data set contains 3,479, 1,216, 775 and 775 clean observations of leaf mass per area, leaf nitrogen (N) concentration per unit mass, leaf phosphorus (P) concentration per unit mass, and leaf N : P ratio, respectively, from native woody species, encompassing information of biome, vegetation, taxonomic data, geographical coordinates, climatic parameters, as well as soil properties. Spatial location and grain: We compiled trait observations from 223 sites under native vegetation distributed in all main biomes (i.e., Amazônia, Caatinga, Cerrado, Mata Atlântica, Pampa and Pantanal) across the Brazilian territory. Time period and grain: The data represent information published and/or sampled during the last 25 years. Major taxa and level of measurement: Our compilation was focused on trait data observed for native woody species, excluding monocots, palm trees, herbs, and hemiparasitic plants. Thus, 108, 478 and 1,321 botanical families, genera and species were included, covering c. 9% of the woody angiosperm flora of Brazil. Software format: Data are provided as comma‐separated value (.csv) files. [ABSTRACT FROM AUTHOR]

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Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars. [ABSTRACT FROM AUTHOR]

Climate change has intensified drought conditions, aiding the spread of some invasive plant species. However, the impact of drought on invasion control, such as clipping, remains largely unexplored. Therefore, we conducted a greenhouse experiment to investigate the growth of an invasive non-native grass, Johnsongrass (Sorghum halepense), under drought and non-drought conditions, coupled with clipping and non-clipping treatments. We measured above- and belowground biomass and eco-physiological parameters of photosynthesis, plant water and nutrient status, and arbuscular mycorrhizal (AM) fungi-related factors. We also developed a theoretical model simulating the population dynamics of a hypothetical invasive grass species, enabling us to generalize the effects of clipping across a broad gradient of drought conditions. We found that: (1) The differences in aboveground biomass between clipped and non-clipped grasses were significant under the condition of non-drought, but became non-significant under drought; (2) Our model also showed a decrease in the clipping-caused population difference with increasing drought severity; (3) The clipped grasses exhibited a higher carbon assimilation rate and lower water stress compared to non-clipped ones under drought, but these differences were non-significant without drought; (4) The difference in leaf phosphorus concentration and AM fungal abundances between the clipped and non-clipped grasses were consistent across both drought levels. Taken together, the clipping efficacy was diminished under drought likely due to the low water stress experienced by clipped grasses. Furthermore, the AM fungi-related factors are unlikely to drive the reduced clipping efficacy. Therefore, the implementation of control treatment could consider climate conditions to improve the control efficacy. [ABSTRACT FROM AUTHOR]

Summary: Plant morphology and physiology change with growth and development. Some of these changes are due to change in plant size and some are the result of genetically programmed developmental transitions. In this study we investigate the role of the developmental transition, vegetative phase change (VPC), on morphological and photosynthetic changes.We used overexpression of microRNA156, the master regulator of VPC, to modulate the timing of VPC in Populus tremula × alba, Zea mays, and Arabidopsis thaliana to determine its role in trait variation independent of changes in size and overall age.Here, we find that juvenile and adult leaves in all three species photosynthesize at different rates and that these differences are due to phase‐dependent changes in specific leaf area (SLA) and leaf N but not photosynthetic biochemistry. Further, we found juvenile leaves with high SLA were associated with better photosynthetic performance at low light levels.This study establishes a role for VPC in leaf composition and photosynthetic performance across diverse species and environments. Variation in leaf traits due to VPC are likely to provide distinct benefits under specific environments; as a result, selection on the timing of this transition could be a mechanism for environmental adaptation. [ABSTRACT FROM AUTHOR]

The dynamics of organic and inorganic nutrient sources in diverse input systems can affect physiological processes of rice. Understanding these nutrient dynamics and their relation to final yields are important to devise optimum nutrient management strategies. This experiment was conducted to evaluate the relationships between nutrient availability from different sources, and growth physiology and crop yield of rice during 2019 Yala and 2019/20 Maha seasons. The Department of Agriculture (DOA) recommended inorganic fertilizer application (conventional system), 50% of DOA recommended inorganic fertilizer with organic manure mixture (integrated system), and 100% organic manure mixture application (organic system) were used as three treatments. Organic manure mixture was added to equalize the nitrogen supply through DOA rate. The systems were arranged in a randomized complete block design with six replicates and Bg 300 rice variety was used. The conventional and integrated systems were similar, while the organic system was weak in canopy light interception, photosynthetic rate, and leaf chlorophyll content at panicle initiation and heading stages. The treatment effect was significant (P<0.05) in 2019 Yala (dry season) but not in 2019/20 Maha (wet season). The correlations between leaf nitrogen concentration and yield were observed with respect to input systems. Most physiological parameters showed no robust correlation to biomass and crop yield. Crop yields were higher in the conventional and integrated systems compared to the organic system. However, the differences are expected to be narrowed down with the development of long-term nutrient status in the organic system as this study was conducted during the first year of the transition. [ABSTRACT FROM AUTHOR]

Questions: Human activities are increasing the density of domestic grazers and global nutrient loads, modifying the main determinants of vegetation community dynamics. Grazing (top‐down control) and nutrient availability (bottom‐up control) may interactively modify plant biomass, which is particularly important in grasslands devoted to livestock production. Here, we aim to understand the interactive effects of grazing and fertilization on grassland plant biomass. We hypothesized that the joint effects of nutrient addition and domestic grazing on above‐ground plant biomass are not additive, but they modify each other through changes in ground‐level light, leaf nutritional quality, above‐ground net primary productivity (ANPP), and below‐ground plant allocation. Location: Flooding Pampa (Buenos Aires, Argentina). Methods: We carried out a factorial experiment of grazing exclusion and fertilization with nitrogen, phosphorus, and potassium + micronutrients during ​several years in a mesic grassland devoted to livestock production. Results: After four years, grazing reduced live above‐ground plant biomass by 52%, and when combined with fertilization this reduction was 70%. Nutrient addition in the grazed grassland increased ANPP and leaf nutrient concentration. These changes in turn intensified grazing pressure and cattle’s plant consumption. By contrast, fertilization did not produce any significant effect on plant biomass or ANPP inside the exclosures, where ground‐level light was low. A structural equation model revealed that the increase in ANPP fostered above‐ground and reduced below‐ground plant biomass. Conclusions: This is the first study conducted in the Pampas grasslands that evaluated the effect of cattle grazing and fertilization on plant communities under field conditions over several years. Grazing and nutrient addition synergistically controlled grassland plant biomass, as the reduction in above‐ground biomass by cattle consumption was greater in fertilized plots. Our results provided empirical evidence that leaf nitrogen and ANPP modulated plant biomass dynamics in grasslands devoted to livestock production in the context of increased nutrient loads in terrestrial ecosystems.Grassland ecosystems are used for livestock production and are exposed to the global alteration of nutrient budgets. We found that grazing reduced above‐ground plant biomass, but this reduction was greater when combined with nutrient addition. The observed changes in plant biomass across experimental plots were mainly accounted for by differences in plant quality and rates of above‐ground plant biomass production. [ABSTRACT FROM AUTHOR]