In view of future changes in climate, it is important to better understand how different plant functional groups (PFGs) respond to warmer and drier conditions, particularly in temperate regions where an increase in both the frequency and severity of drought is expected. The patterns and mechanisms of immediate and delayed impacts of extreme drought on vegetation growth remain poorly quantified. Using satellite measurements of vegetation greenness, in-situ tree-ring records, eddy-covariance CO2 and water flux measurements, and meta-analyses of source water of plant use among PFGs, we show that drought legacy effects on vegetation growth differ markedly between forests, shrubs and grass across diverse bioclimatic conditions over the temperate Northern Hemisphere. Deep-rooted forests exhibit a drought legacy response with reduced growth during up to 4 years after an extreme drought, whereas shrubs and grass have drought legacy effects of approximately 2 years and 1 year, respectively. Statistical analyses partly attribute the differences in drought legacy effects among PFGs to plant eco-hydrological properties (related to traits), including plant water use and hydraulic responses. These results can be used to improve the representation of drought response of different PFGs in land surface models, and assess their biogeochemical and biophysical feedbacks in response to a warmer and drier climate.

• Klíčová slova
• drought legacy effect *, drought resilience *, ecohydrological responses *, extreme drought *, plant functional groups *, rooting system *, stomatal conductance *, vegetation growth *,
• MeSH
• hydrologie MeSH
• klimatické změny * MeSH
• lesy * MeSH
• období sucha * MeSH
• stromy růst a vývoj   MeSH
• voda fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• voda MeSH

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought.

• Klíčová slova
• Drought-Net, International Drought Experiment, climate extreme, productivity,
• MeSH
• ekosystém * MeSH
• klimatické změny MeSH
• koloběh uhlíku MeSH
• období sucha * MeSH
• pastviny MeSH
• tyrosinkinasové receptory MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• tyrosinkinasové receptory MeSH

The present work is aimed to hypothesize that fungal endophytes associated with wheat (Triticum aestivum L.) plants can play a variety of roles in biotechnology including plant growth. Out of 67 fungal isolates, five maximum drought-tolerant isolates were used to check their various plant growth-promoting traits, antioxidants, and antifungal activities under secondary screening. Fungal isolate #8TAKS-3a exhibited the maximum drought tolerance capacity and potential to produce auxin, gibberellic acid, ACC deaminase, phosphate, zinc solubilization, ammonia, siderophore, and extracellular enzyme activities followed by #6TAKR-1a isolate. In terms of antioxidant activities, #8TAKS-3a culture also showed maximum DPPH scavenging, total antioxidant, and NO-scavenging activities. However, #6TAKR-1a exhibited maximum total flavonoid content, total phenolic content, and Fe-reducing power and also the highest growth inhibition of Aspergillus niger (ITCC 6152) and Colletotrichum sp. (ITCC 6152). Based on morphological characters and multi-locus phylogenetic analysis of the nuc rDNA internal transcribed spacer region (ITS1-5.8S-ITS2 = ITS), β-tubulin (TUB 2), and RNA polymerase II second largest subunit (RPB2) genes, potent fungal isolate #8TAKS-3a was identified as Talaromyces purpureogenus. Under the in vitro conditions, T. purpureogenus (#8TAKS-3a) was used as a bioinoculant that displayed a significant increase in various physio-biochemical growth parameters under normal and stressed conditions (p < 0.05). Our results indicate that drought stress-tolerant T. purpureogenus can be further used for field testing as a growth promoter.

• Klíčová slova
• Bioinoculant, Drought, Endophytic fungi, Plant-growth promoter, Wheat,
• MeSH
• antioxidancia MeSH
• endofyty MeSH
• fylogeneze MeSH
• období sucha MeSH
• pšenice MeSH
• semenáček * MeSH
• Talaromyces * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH

BACKGROUND: Arbuscular mycorrhizal fungi (AMF) have a positive effect on drought tolerance of plants after establishing reciprocal resymbiosis with roots, while the underlying mechanism is not deciphered. Metabolomics can explain the mechanism of plant response to environmental stress by analyzing the changes of all small molecular weight metabolites. The purpose of this study was to use Ultra High Performance Liquid Chromatography Q Exactive Mass Spectrometer to analyze changes in root metabolites of walnut (Juglans regia) after inoculation with an arbuscular mycorrhizal fungus Diversispora spurca under well-watered (WW) and drought stress (DS). RESULTS: Sixty days of soil drought significantly inhibited root mycorrhizal colonization rate, shoot and root biomass production, and leaf water potential in walnut, while AMF inoculation significantly increased biomass production and leaf water potential, accompanied by a higher increase magnitude under DS versus under WW. A total of 3278 metabolites were identified. Under WW, AMF inoculation up-regulated 172 metabolites and down-regulated 61 metabolites, along with no changes in 1104 metabolites. However, under DS, AMF inoculation up-regulated 49 metabolites and down-regulated 116 metabolites, coupled with no changes in 1172 metabolites. Among them, juglone (a quinone found in walnuts) as the first ranked differential metabolite was up-regulated by AMF under WW but not under DS; 2,3,5-trihydroxy-5-7-dimethoxyflavanone as the first ranked differential metabolite was increased by AMF under DS but not under WW. The KEGG annotation showed a large number of metabolic pathways triggered by AMF, accompanied by different metabolic pathways under WW and DS. Among them, oxidative phosphorylation and phenylalanine metabolism and biosynthesis were triggered by AMF in response to WW and DS, where N-acetyl-L-phenylalanine was induced by AMF to increase under DS, while decreasing under WW. CONCLUSION: This study provides new insights into the metabolic mechanisms of mycorrhiza-enhanced drought tolerance in walnuts.

• Klíčová slova
• Juglone, Metabolite, Nut fruits, Phenylalanine, Symbiosis, Walnut, Water deficit,
• MeSH
• Juglans * MeSH
• metabolomika MeSH
• mykorhiza * MeSH
• období sucha MeSH
• odolnost proti suchu MeSH
• Publikační typ
• časopisecké články MeSH

Belowground niche partitioning presents a key mechanism for maintaining species coexistence and diversity. Its importance is currently reinforced by climate change that alters soil hydrological conditions. However, experimental tests examining the magnitude of its change under climate change are scarce. We combined measurements of oxygen stable isotopes to infer plant water-uptake depths and extreme drought manipulation in grasslands. Belowground niche partitioning was evidenced by different water-uptake depths of co-occurring species under ambient and extreme drought conditions despite an increased overlap among species due to a shift to shallower soil layers under drought. A co-occurrence of contrasting strategies related to the change of species water-uptake depth distribution was likely to be key for species to maintain some extent of belowground niche partitioning and could contribute to stabilizing coexistence under drought. Our results suggest that belowground niche partitioning could mitigate negative effects on diversity imposed by extreme drought under future climate.

• Klíčová slova
• belowground niche partitioning, climate change, extreme drought, grasslands, hydrological niche segregation, oxygen stable isotopes, rainout shelter, water-uptake depth,
• MeSH
• klimatické změny MeSH
• období sucha * MeSH
• pastviny MeSH
• půda MeSH
• rostliny * MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• půda MeSH
• voda MeSH

• Klíčová slova
• Brassicaceae, Classification & Regression Tree, Heliophila, Random Forests, climatic seasonality, drought regime, life history, phylogenetic tree,
• MeSH
• Brassicaceae * MeSH
• klimatické změny MeSH
• lesy MeSH
• období sucha * MeSH
• stromy MeSH
• Publikační typ
• dopisy MeSH

Floodplain forests are very complex, productive ecosystems, capable of storing huge amounts of soil carbon. With the increasing occurrence of extreme events, they are today among the most threatened ecosystems. Our study's main goal was to assess the productivity of a floodplain forest located at Lanžhot in the Czech Republic from two perspectives: carbon uptake (using an eddy covariance method) and stem radius variations (using dendrometers). We aimed to determine which conditions allow for high ecosystem production and what role drought plays in reducing such production potential. Additionally, we were interested to determine the relative soil water content threshold indicating the onset and duration of this event. We hypothesized that summer drought in 2018 had the most significant negative effects on the overall annual carbon and water budgets. In contrast with our original hypothesis, we found that an exceptionally warm spring in 2018 caused a positive gross primary production (GPP) and evapotranspiration (ET) anomaly that consequently led in 2018 to the highest seasonal total GPP and ET from all of the investigated years (2015-2018). The results showed ring-porous species to be the most drought resistant. Relative soil water content threshold of approximately 0.45 was determined as indicating the onset of drought stress. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

• Klíčová slova
• drought, eddy covariance, floodplain forest, gross primary production, radial stem variations, tree water deficit,
• MeSH
• klimatické změny * MeSH
• koloběh uhlíku * MeSH
• lesy * MeSH
• období sucha * MeSH
• roční období MeSH
• stromy růst a vývoj   MeSH
• uhlík metabolismus   MeSH
• voda metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• uhlík MeSH
• voda MeSH

BACKGROUND: Plant growth and development can be greatly impacted by drought stress. Suitable plant growth promoting rhizobacteria (PGPR) or biochar (BC) application has been shown to alleviate drought stress for plants. However, their co-application has not been extensively explored in this regard. METHODS: We isolated bacterial strains from rhizospheric soils of plants from arid soils and characterized them for plant growth promoting characteristics like IAA production and phosphate solubilization as well as for drought tolerance. Three bacterial strains or so called PGPRs, identified as Bacillus thuringiensis, Bacillus tropicus, and Bacillus paramycoides based on their 16S rRNA, were screened for further experiments. Wheat was grown on normal, where soil moisture was maintained at 75% of water holding capacity (WHC), and induced-drought (25% WHC) stressed soil in pots. PGPRs were applied alone or in combination with a biochar derived from pyrolysis of tree wood. RESULTS: Drought stress substantially inhibited wheat growth. However, biochar addition under stressed conditions significantly improved the wheat growth and productivity. Briefly, it increased straw yield by 25%, 100-grain weight by 15% and grain yield by 10% compared to the control. Moreover, co-application of biochar with PGPRs B. thuringiensis, B. tropicus and B. paramycoides further enhanced straw yield by 37-41%, 100-grain weight by 30-36%, and grain yield by 22-22.57%, respectively. The co-application also enhanced soil quality by increasing plant-available phosphorus by 4-31%, microbial biomass by 33-45%, and soil K+/Na+ ratio by 41-44%. CONCLUSION: Co-application of PGPRs and biochar alleviated plant drought stress by improving nutrient availability and absorption. Acting as a nutrient reservoir, biochar worked alongside PGPRs, who solubilized nutrients from the former and promoted wheat growth. We recommend that the co-application of suitable PGPRs and biochar is a better technology to produce wheat under drought conditions than using these enhancers separately.

• Klíčová slova
• Biochar, Drought, Grain yield, PGPR, Plant available phosphorus, Soil enzymatic activity,
• MeSH
• Bacillus fyziologie   MeSH
• dřevěné a živočišné uhlí * farmakologie   chemie   MeSH
• období sucha * MeSH
• pšenice * růst a vývoj   MeSH
• půda * chemie   MeSH
• půdní mikrobiologie * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biochar MeSH Prohlížeč
• dřevěné a živočišné uhlí * MeSH
• půda * MeSH

Under climate change, extreme droughts will limit water availability for plants. However, the species-specific responses make it difficult to draw general conclusions. We hypothesized that changes in species' abundance in response to extreme drought can be best explained by a set of water economic traits under ambient conditions in combination with the ability to adjust these traits towards higher drought resistance. We conducted a 4-year field experiment in temperate grasslands using rainout shelters with 30% and 50% rainfall reduction. We quantified the response as the change in species abundance between ambient conditions and the rainfall reduction. Abundance response to extreme drought was best explained by a combination of traits in ambient conditions and their functional adjustment, most likely reflecting plasticity. Smaller leaved species decreased less in abundance under drought. With increasing drought intensity, we observed a shift from drought tolerance, i.e., an increase in leaf dry matter content, to avoidance, i.e., a less negative turgor loss point (TLP) in ambient conditions and a constancy in TLP under drought. We stress the importance of using a multidimensional approach of variation in multiple traits and the importance of considering a range of drought intensities to improve predictions of species' response to climate change.

• Klíčová slova
• climate change, climate extremes, drought intensity, drought resistance strategies, grasslands, leaf area, leaf dry matter content, rainout shelters, turgor loss point,
• MeSH
• klimatické změny * MeSH
• listy rostlin fyziologie   MeSH
• období sucha * MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• voda MeSH

Severe drought events are known to cause important reductions of gross primary productivity (GPP) in forest ecosystems. However, it is still unclear whether this reduction originates from stomatal closure (Stomatal Origin Limitation) and/or non-stomatal limitations (Non-SOL). In this study, we investigated the impact of edaphic drought in 2018 on GPP and its origin (SOL, NSOL) using a dataset of 10 European forest ecosystem flux towers. In all stations where GPP reductions were observed during the drought, these were largely explained by declines in the maximum apparent canopy scale carboxylation rate VCMAX,APP (NSOL) when the soil relative extractable water content dropped below around 0.4. Concurrently, we found that the stomatal slope parameter (G1, related to SOL) of the Medlyn et al. unified optimization model linking vegetation conductance and GPP remained relatively constant. These results strengthen the increasing evidence that NSOL should be included in stomatal conductance/photosynthesis models to faithfully simulate both GPP and water fluxes in forest ecosystems during severe drought. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

• Klíčová slova
• drought, eddy covariance, forest, model, photosynthesis, stomatal conductance,
• MeSH
• atmosféra analýza   MeSH
• klimatické změny * MeSH
• lesy * MeSH
• období sucha * MeSH
• průduchy rostlin fyziologie   MeSH
• stromy fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH