Increase Plant Performance Research Articles

Native soil amendments combined with commercial arbuscular mycorrhizal fungi increase biomass of Panicum amarum

Coastal dune restorations often fail because of poorly performing plants. The addition of beneficial microbes can improve plant performance, though it is unclear if the source of microbes matters. Here, we tested how native soil amendments and commercially available arbuscular mycorrhizal (AM) fungi influenced performance of Panicum amarum, a dominant grass on Texas coastal dunes. In a greenhouse experiment, we manipulated the identity of native soil amendments (from P. amarum, Uniola paniculata, or unvegetated areas), the presence of soil microbes in the native soil amendments (live or sterile), and the presence of the commercial AM fungi (present or absent). Native soils from vegetated areas contained 149% more AM fungal spores than unvegetated areas. The commercial AM fungi, when combined with previously vegetated native soils, increased aboveground biomass of P. amarum by 26%. Effects on belowground biomass were weaker, although the addition of any microbes decreased the root:shoot ratio. The origin of native soil amendments can influence restoration outcomes. In this case soil from areas with vegetation outperformed soil from areas without vegetation. Combining native soils with commercial AM fungi may provide a strategy for increasing plant performance while also maintaining other ecosystem functions provided by native microbes.

Effect of Salt, Nutrients, and Native Microbe Additions on Common Dune Restoration Grasses

Clark, G.S.; Busch, M.H., and Crawford, K.M., 2021. Effect of salt, nutrients, and native microbe additions on common dune restoration grasses. Journal of Coastal Research, 37(5), 1025–1034. Coconut Creek (Florida), ISSN 0749-0208. Sand dunes are a valuable resource that shelters coastal communities and wildlife. Unfortunately, their survival is threatened by commercial development and erosion accelerated by climate change. Restoring sand dunes is challenging because of the difficulty in establishing vegetation in such a hostile environment. Restoration practitioners have responded by choosing stress-tolerant native species, adding nutrients, or incorporating native microbial communities into transplanted soils, but little is known about how these practices interact. In other systems, native microbes sometimes increase plant performance and salt tolerance. Nutrient additions promote growth but may inhibit development of beneficial fungi and disproportionately benefit some plant species at the expense of community diversity. To explore these interactions, two grasses commonly used in dune restorations—Panicum amarum and Uniola paniculata—were grown in a greenhouse and exposed to soil with and without native microbiota and to a range of nutrient and salinity treatments. Native microbial additions had little impact on live, aboveground biomass or the salt tolerance of the nursery-grown plants. Nutrient additions did not inhibit beneficial fungi. In fact, the density of extraradical hyphae in the soil increased by an average of 31% across all plants subject to a balanced, slow-release fertilizer. The two grasses responded differently to the salinity and nutrient treatments. Under a 2.5% salinity treatment, average live aboveground biomass for P. amarum fell 52%, compared with a 5.5% increase for U. paniculata. None of the nutrient additions affected U. paniculata; however, a combination of nitrogen and phosphorus increased P. amarum live, aboveground biomass by 356%. The strong response of P. amarum to fertilization offers a path to rapid growth of dune vegetation, but it may foster that species' dominance, which could lower the plant community's aggregate resistance to salinity.

Influence of Tall Fescue Epichloë Endophytes on Rhizosphere Soil Microbiome.

Tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire) often forms a symbiotic relationship with fungal endophytes (Epichloë coenophiala), which provides increased plant performance and greater tolerance to environmental stress compared to endophyte-free tall fescue. Whether this enhanced performance of tall fescue exclusively results from the grass–fungus symbiosis, or this symbiosis additionally results in the recruitment of soil microbes in the rhizosphere that in turn promote plant growth, remain a question. We investigated the soil bacterial and fungal community composition in iron-rich soil in the southeastern USA, and possible community shifts in soil microbial populations based on endophyte infection in tall fescue by analyzing the 16s rRNA gene and ITS specific region. Our data revealed that plant-available phosphorus (P) was significantly (p < 0.05) influenced by endophyte infection in tall fescue. While the prominent soil bacterial phyla were similar, a clear fungal community shift was observed between endophyte-infected (E+) and endophyte-free (E−) tall fescue soil at the phylum level. Moreover, compared to E− soil, E+ soil showed a greater fungal diversity at the genus level. Our results, thus, indicate a possible three-way interaction between tall fescue, fungal endophyte, and soil fungal communities resulting in improved tall fescue performance.

Drought effects on montane grasslands nullify benefits of advanced flowering phenology due to warming

AbstractWarming due to climate change is generally expected to lengthen the growing season in areas of seasonal climate and to advance plant phenology, particularly the onset of leafing and flowering. However, a reduction in aboveground biomass production and reproductive output may occur when warming is accompanied by drought that crosses critical water deficit thresholds. Tracking warmer temperatures has been shown to be species‐specific with unknown impacts on community composition and productivity. The variability in species’ ability to leverage earlier leaf unfolding and flowering into increased aboveground net primary production (ANPP) or increased investments into reproductive organs has heretofore been poorly explored. We tested whether phenological sensitivity to temperature, as a result of experimental warming, directly translated into increased plant performance, as measured by ANPP and flower abundance. In order to experimentally simulate climate warming, we translocated a total of 45 intact soil–plant communities downslope along an elevational gradient of 900 m within the European Alps from 1260 to 350 m asl and weekly recorded flower abundance and total green cover as well as cumulative biomass production at peak growing season. We found that advanced phenology at lower elevations was related to increased reproductive performance and conditional on whether they experienced drought stress. While a temperature increase of +1K had positive effects on the amount of reproductive organs for species with accelerated phenology, temperature increase going along with drier conditions resulted in plants being unable to sustain early investment in reproduction as measured by flower abundance. This finding highlights that the interaction of two climate change drivers, warming and drought, can push communities’ past resistance thresholds. Moreover, we detected biotic competition mechanisms and shifts toward forb‐depressed states with graminoids best taking advantage of experimentally altered increased temperature and reduced precipitation. Our results suggest that while species may track warmer future climates, concurrent drought events post a high risk for failure of temperature‐driven improvement of reproductive performance and biomass production in the European Alps.

Commercial arbuscular mycorrhizal fungal inoculant failed to establish in a vineyard despite priority advantage

BackgroundArbuscular mycorrhizal (AM) fungi associate with most plants and can increase nutrient uptake. As a result, commercial inoculants called “biofertilizers” containing AM fungi have been developed and marketed to increase plant performance. However, successful establishment of these inoculants remains a challenge, and may be negatively impacted by competition with fungi already present (priority effects). Perennial agriculture may be more amenable if inoculants can be successfully established on crops prior to field planting.MethodsHere, we inoculate grapevine (Vitis vinifera) with a commercial inoculant in three treatments designed to manipulate the strength and direction of priority effects and quantified the abundance of the fungal strain before and after introduction using droplet digital PCR (ddPCR).ResultsWe found that the introduced strain did not establish in any treatment, even with priority advantage, and inoculated vines did not differ in performance from non-inoculated vines. Fungal abundance was not greater than in pre-inoculation soil samples during any of the five years sampled and may have been impaired by high available phosphorus levels in the soil. This study highlights the need to understand and evaluate how the management of the agricultural system will affect establishment before introduction of “biofertilizers”, which is often unpredictable.

Mathematical structure of mosaic disease using microbial biostimulants via Caputo and Atangana–Baleanu derivatives

In this research collection, we analysed two different fractional non-linear mathematical models of a well-known mosaic epidemic of plants, which is underlying by begomoviruses and is distributed to plants by whitefly. We included the role of natural microbial biostimulants which are used to increase plant performance and protects them against mosaic infection. Cause of the big expansion of the mosaic epidemic in various geographical areas, and its large privative economic and societal impacts, it is of major consequence to define dominant optimal control means of this disease. In this paper, we used Caputo (singular type kernel) and Atangana–Baleanu (Mittag-Leffler type kernel) fractional derivatives to define the structure of the proposed mosaic model. We performed some important existence and uniqueness analyses for both models by the applications of fixed point theory and the Picard–Lindelof technique. We derived the numerical solution of the Caputo fractional model by the application of the fourth-order Runge–Kutta method and the Atangana–Baleanu model by the Predictor–Corrector algorithm. A long-term discussion on the graphical interpretations of both models with different infection transmission rate and application proportion rate of MBs (microbial biostimulants) at different fractional-order values have established. We exemplified that under the case of the Mittag-Leffler kernel, the effects of different fractional-order values are much clear as compared to the singular type kernel. The main contribution of this paper is to study the dynamics of mosaic disease at different transmission rates and MBs application rates in the sense of two different kernel types.

Targeting Nitrogen Metabolism and Transport Processes to Improve Plant Nitrogen Use Efficiency.

In agricultural cropping systems, relatively large amounts of nitrogen (N) are applied for plant growth and development, and to achieve high yields. However, with increasing N application, plant N use efficiency generally decreases, which results in losses of N into the environment and subsequently detrimental consequences for both ecosystems and human health. A strategy for reducing N input and environmental losses while maintaining or increasing plant performance is the development of crops that effectively obtain, distribute, and utilize the available N. Generally, N is acquired from the soil in the inorganic forms of nitrate or ammonium and assimilated in roots or leaves as amino acids. The amino acids may be used within the source organs, but they are also the principal N compounds transported from source to sink in support of metabolism and growth. N uptake, synthesis of amino acids, and their partitioning within sources and toward sinks, as well as N utilization within sinks represent potential bottlenecks in the effective use of N for vegetative and reproductive growth. This review addresses recent discoveries in N metabolism and transport and their relevance for improving N use efficiency under high and low N conditions.

Trophic interactions as determinants of the arbuscular mycorrhizal fungal community with cascading plant-promoting consequences

BackgroundThe soil mycobiome is composed of a complex and diverse fungal community, which includes functionally diverse species ranging from plant pathogens to mutualists. Among the latter are arbuscular mycorrhizal fungi (AMF) that provide phosphorous (P) to plants. While plant hosts and abiotic parameters are known to structure AMF communities, it remains largely unknown how higher trophic level organisms, including protists and nematodes, affect AMF abundance and community composition.ResultsHere, we explored the connections between AMF, fungivorous protists and nematodes that could partly reflect trophic interactions, and linked those to rhizosphere P dynamics and plant performance in a long-term manure application setting. Our results revealed that manure addition increased AMF biomass and the density of fungivorous nematodes, and tailored the community structures of AMF, fungivorous protists, and nematodes. We detected a higher abundance of AMF digested by the dominant fungivorous nematodes Aphelenchoides and Aphelenchus in high manure treatments compared to no manure and low manure treatments. Structural equation modeling combined with network analysis suggested that predation by fungivorous protists and nematodes stimulated AMF biomass and modified the AMF community composition. The mycorrhizal-fungivore interactions catalyzed AMF colonization and expression levels of the P transporter gene ZMPht1;6 in maize roots, which resulted in enhanced plant productivity.ConclusionsOur study highlights the importance of predation as a key element in shaping the composition and enhancing the biomass of AMF, leading to increased plant performance. As such, we clarify novel biological mechanism of the complex interactions between AMF, fungivorous protists, and nematodes in driving P absorption and plant performance.3Rct2UgWKJzaMmE1q1nvDRVideo

The involvement of gamma-aminobutyric acid shunt in the endoplasmic reticulum stress response of Arabidopsis thaliana

The endoplasmic reticulum (ER) is the main site of secretory protein production and folding and its homeostasis under environmental stress is vital for the maintenance of the protein secretory pathway. The loss of homeostasis and accumulation of unfolded proteins in the ER is referred to as ER stress. Although, γ-aminobutyric acid (GABA) is an important regulator of stress response in plants, its roles during ER stress remains unclear. This study investigated the involvement of GABA in the ER stress response of plants. For this, changes in GABA metabolism under ER stress was analysed in Arabidopsis thaliana, then to study the response of the ER-folding machinery, plants were treated with exogenous GABA under ER stress. The antibiotic tunicamycin, which inhibits N-glycosylation was used to specifically induce ER stress. This stress up-regulated the expression of five glutamate decarboxylase (GAD) genes except GAD2 and GABA content of A. thaliana plants increased with an increasing concentration of tunicamycin (0.1 μg ml−1 and 0.25 μg ml−1). Moreover, expressions of genes involved in the conversion of GABA to succinate was also induced, while genes involved in transport across plasma and mitochondrial membrane showed no response to ER stress. The exogenous treatment of plants with 1-and 5-mM GABA increased plant performance under ER stress but 0.1 mM proved ineffective. Plants treated with GABA under ER stress had decreased expression of ER stress marker genes such as BIP1, BIP3 or CNX, but the expression of genes related to ER stress perception or ER-associated protein degradation showed no changes with respect to GABA treatments.

The effect of Frankia and multiple ectomycorrhizal fungil species on Alnus growing in low fertility soil

Plant interactions with single symbionts of nitrogen fixing bacteria or mycorrhizal fungi are well studied. However, less is known about how plants interact with multiple symbiont species. The aim of this study was to assess whether multiple symbionts had a synergistic effect on host plant performance compared with a single symbiont and whether increasing the number of non-specific fungal species would increase plant performance due to niche complementarity. Green alder (Alnus viridis ssp. crispa) were inoculated with non-specific ectomycorrhizal fungi (Lactarius torminosus, Lactarius theiogalus, Hebeloma crustuliniforme) alone or in combination, with and without Frankia, and grown in nutrient-poor soil. Frankia significantly increased plant growth by 48.5%, doubled the proportion of plants forming ectomycorrhizae, as well as increased root extracellular phosphatase activity by 8.8% compared to non-Frankia treatments. However, increasing number of fungal species decreased nodulated plant biomass. Plants that formed a Hartig net had reduced nodule number and nodule biomass allocation, as well as total nodule activity compared with plants with no Hartig net. Our results indicated that Frankia inoculation provided benefit for both host plants and ectomycorrhizal fungi in the nutrient-poor soil, while ectomycorrhizal fungi did not. These negative effects of mycorrhizal fungi are likely dependent on soil nutrient P availability.

AMF inoculation of green roof substrate improves plant performance but reduces drought resistance of native dry grassland species

Standard extensive green roofs (EGRs) with their shallow substrate layers represent extreme sites for plant growth and therefore are planted mostly with drought-resistant species, including non-native plant species. As standard EGR substrates often lack potentially mutualistic soil microorganisms, it has been stated that inoculation with arbuscular mycorrhizal fungi (AMF) might increase plant performance and drought resistance. Aiming to support native biodiversity on EGRs, we tested whether AMF inoculation into standard green roof substrate can enhance plant performance and drought resistance of regionally occurring native dry grassland species.The results of a pot experiment with 11 native plant species growing with and without AMF inoculation showed considerable differences in fitness-relevant plant traits. Over 88 days of moderate drought conditions, inoculated plants produced 2.5 times more above-ground biomass than control plants. In addition, the number of inflorescences on inoculated plants was significantly higher in 5 out of 7 flowering species. Under severe drought stress created by stopping the water supply, however, inoculated plants wilted on average 2.38 days earlier than control plants.Although the underlying mechanisms of the observed results remain unresolved, AMF inoculation might help to enhance an earlier and higher seed set, facilitating the establishment of a soil seed bank, which is necessary for a self-sustaining plant population in drought-governed habitats such as EGRs.

Biochar Effects on Two Tropical Tree Species and Its Potential as a Tool for Reforestation

Research Highlights: We find that biochar plus fertilizer has synergistic and positive effects on seedling growth and robustness, but slightly lowers early seedling survival. Biochar plus fertilizer has the potential to greatly decrease costs associated with afforestation as compared to traditional fertilization and gives better results. Background and Objectives: Biochar can improve soil fertility and plant yield in crops. However, there is little information regarding the effects of biochar on trees, even though reforestation/afforestation projects are increasing and are often unsuccessful due to soil fertility limitations. This study aims to increase knowledge of biochar use as a reforestation tool. Materials and Methods: We measured survival and growth in an early ((Guazuma crinita Mart. [n = 240])) and a late (Terminalia amazonia (J.F. Gmel.) Exell. [n = 240]) successional species under 6 different biochar treatments in a 6-month nursery experiment. Results: (i) Survival was highest in the 1 t/ha biochar treatment, while treatments containing fertilizers or biochar at 5 t/ha lowered the survival rate of both species compared to the control; (ii) simultaneous addition of biochar and fertilizer lead to significant increases in height, diameter, total number of leaves, and aboveground and belowground biomass of both species as compared to other treatments; (iii) biochar treatment containing 1 t/ha with and without fertilizer showed significantly better results than applications of 5 t/ha; and (iv) Guazuma crinita responded more strongly to treatments containing biochar and fertilizers compared to Terminalia amazonia, which is suggestive of greater synergetic effects of biochar and fertilizer addition on early successional tree species. Conclusions: Applying biochar and fertilizer is synergistic and outperforms any single treatment, as well as the control, in terms of plant performance. This case study suggests that biochar can greatly improve reforestation/afforestation projects by increasing plant performance while substantially reducing fertilizer and labor maintenance costs. Field experiments and testing of additional species is needed to generalize the findings.

Cyanobacteria and Glutathione Applications Improve Productivity, Nutrient Contents, and Antioxidant Systems of Salt-Stressed Soybean Plant

Salt stress restricts plant performance by disrupting various physio-biochemical processes like photosynthesis. Plants growing in saline substrates show deficiencies in absorption of some essential elements due to the presence of excessive sodium (Na+) in the rhizosphere, which antagonizes beneficial cations and causing toxicity in metabolism. Cyanobacteria (CB; a natural biofertilizer) play a fundamental role in building-up soil fertility, thus increasing plant performance. Glutathione (GSH) is a well-known antioxidant, which contributes to increase salt tolerance in the plant. This work was conducted as a pot experiment (sand culture) in 2017 to study the combined effect of CB, applied as seed inoculation, and GSH, applied as foliar spray, on growth, pods and seed yields, the contents of antioxidants, osmoprotectants, and nutrients, and the antioxidative enzymes activities of soybean (Glycine max L., cv. Giza 111) plants grown under saline conditions. At fourth leaf stage (21 days after sowing; DAS), CB-pretreated seedlings were supplemented with NaCl (150 mM) along with Hoagland′s nutrient solution, and at the same time seedlings were sprayed with 1 mM GSH. Samples were taken at 60 DAS to assess morphological, physio-biochemical and antioxidant defense systems attributes. Results showed that the integrative application of CB and GSH under saline conditions was effective in improving significantly the growth characteristics, yield components, photosynthetic efficiency (pigments contents and chlorophyll fluorescence), membrane stability index, relative water content, contents of soluble sugars, free proline, ascorbic acid, glutathione, α-tocopherol, and protein, and activities of superoxide dismutase, catalase, and guaiacol peroxidase. The contents of macronutrients (N, P, K+, and Ca2+) were also increased significantly in Glycine max plants compared to the stressed control. In contrast, Na+ content and electrolyte leakage were significantly reduced. Our results recommend using the combined CB (as seed inoculation) and GSH (as foliar spray) application for soybean plantss to grow well under saline conditions.

Cyanobacteria and Glutathione Applications Improve Productivity, Nutrient Contents, and Antioxidant Systems of Salt-Stressed Soybean Plant

Salt stress restricts plant performance by disrupting various physio-biochemical processes like photosynthesis. Plants growing in saline substrates show deficiencies in absorption of some essential elements due to the presence of excessive sodium (Na+) in the rhizosphere, which antagonizes beneficial cations and causing toxicity in metabolism. Cyanobacteria (CB; a natural biofertilizer) play a fundamental role in building-up soil fertility, thus increasing plant performance. Glutathione (GSH) is a well-known antioxidant, which contributes to increase salt tolerance in the plant. This work was conducted as a pot experiment (sand culture) in 2017 to study the combined effect of CB, applied as seed inoculation, and GSH, applied as foliar spray, on growth, pods and seed yields, the contents of antioxidants, osmoprotectants, and nutrients, and the antioxidative enzymes activities of soybean (Glycine max L., cv. Giza 111) plants grown under saline conditions. At fourth leaf stage (21 days after sowing; DAS), CB-pretreated seedlings were supplemented with NaCl (150 mM) along with Hoagland′s nutrient solution, and at the same time seedlings were sprayed with 1 mM GSH. Samples were taken at 60 DAS to assess morphological, physio-biochemical and antioxidant defense systems attributes. Results showed that the integrative application of CB and GSH under saline conditions was effective in improving significantly the growth characteristics, yield components, photosynthetic efficiency (pigments contents and chlorophyll fluorescence), membrane stability index, relative water content, contents of soluble sugars, free proline, ascorbic acid, glutathione, α-tocopherol, and protein, and activities of superoxide dismutase, catalase, and guaiacol peroxidase. The contents of macronutrients (N, P, K+, and Ca2+) were also increased significantly in Glycine max plants compared to the stressed control. In contrast, Na+ content and electrolyte leakage were significantly reduced. Our results recommend using the combined CB (as seed inoculation) and GSH (as foliar spray) application for soybean plantss to grow well under saline conditions.

Identification and Characterization of the Core Rice Seed Microbiome

The use of microbes in agriculture for enhancing crop production is an emerging alternative to chemical fertilizers and pesticides; however, their effectiveness is often limited by factors such as host genotype and variability in geographic location. To address this issue, the microbiomes of six different rice (Oryza sativa) seeds, sourced from two locations in Arkansas, U.S.A. of two different genotypes and two harvest years, were characterized. The bacterial and fungal communities were identified in each of four seed compartments (grain, outer grain, husk, and outer husk) using high throughput Illumina MiSeq sequencing. More unique amplicon sequence variants were identified in the outer seed husk and least in the grain compartment for both the fungal and bacterial microbiomes, however this only resulted in a decrease in diversity for the fungal communities. Principal component analysis indicated that each tissue compartment harbored relatively distinct bacterial and fungal communities for the three innermost compartments. A bacterial and fungal core microbiome shared among the six seed types for each compartment was identified. Key bacterial genera in the core across all compartments were Sphingomonas, Methylobacterium, and taxa in the family Enterobacteriaceae, members of which have been reported to support rice growth. Compared with the bacterial core, more fungal taxa were identified, possibly resulting from the more abundant reads after filtering, and key genera identified were Alternaria, Hannaella, and members of the order Pleosporales. These core members represent valuable candidates for manipulating the rice microbiome, decreasing the use of chemicals while increasing plant performance.

Soil Microbial Resources for Improving Fertilizers Efficiency in an Integrated Plant Nutrient Management System.

Tomorrow’s agriculture, challenged by increasing global demand for food, scarcity of arable lands, and resources alongside multiple environment pressures, needs to be managed smartly through sustainable and eco-efficient approaches. Modern agriculture has to be more productive, sustainable, and environmentally friendly. While macronutrients such as nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) supplied by mineral fertilizers are vital to crop production, agriculturally beneficial microorganisms may also contribute directly (i.e., biological N2 fixation, P solubilization, and phytohormone production, etc.) or indirectly (i.e., antimicrobial compounds biosynthesis and elicitation of induced systemic resistance, etc.) to crop improvement and fertilizers efficiency. Microbial-based bioformulations that increase plant performance are greatly needed, and in particular bioformulations that exhibit complementary and synergistic effects with mineral fertilization. Such an integrated soil fertility management strategy has been demonstrated through several controlled and non-controlled experiments, but more efforts have to be made in order to thoroughly understand the multiple functions of beneficial microorganisms within the soil microbial community itself and in interaction with plants and mineral resources. In fact, the combined usage of microbial [i.e., beneficial microorganisms: N2-fixing (NF), P-solubilizing, and P mobilizing, etc.] and mineral resources is an emerging research area that aims to design and develop efficient microbial formulations which are highly compatible with mineral inputs, with positive impacts on both crops and environment. This novel approach is likely to be of a global interest, especially in most N- and P-deficient agro-ecosystems. In this review, we report on the importance of NF bacteria and P solubilizing/mobilizing microbes as well as their interactions with mineral P fertilization in improving crop productivity and fertilizers efficiency. In addition, we shed light on the interactive and synergistic effects that may occur within multi-trophic interactions involving those two microbial groups and positive consequences on plant mineral uptake, crop productivity, and resiliency to environmental constraints. Improving use of mineral nutrients is a must to securing higher yield and productivity in a sustainable manner, therefore continuously designing, developing and testing innovative integrated plant nutrient management systems based on relevant biological resources (crops and microorganisms) is highly required.

Genetic resources of the millet collection of the Ustymivka experimental station and their value for breeding practice

The results of studying, evaluating and describing 637 accessions of the millet collection of Ustymivka Experimental Station of Plant Production in terms of performance and adaptability traits in 2011–2015 are presented. Our objective was to select a group of promising accessions from the changing gene pool of the National collection of millet, basing on previous studies, and to comprehensively assess them for a set of economic and breeding-valuable traits. Material and methods. Ustymivka Experimental Station of Plant Production investigated the assortment of breeding varieties, which were generated in different years, landraces and local forms differing by harvest site and time, resistance to diseases and pests, suitability for mechanized harvesting, grain and groat quality and by other traits. Results and discussion. The comprehensive study using field and laboratory assessments made it possible to identify sources of economically- and breeding-valuable traits: 46 accessions with increased yield (over 500 g/m 2 ), 62 accessions with large grains (1000-grain weight >8.0), 40 accessions with increased plant performance (7–10 g), 33 accessions with increased panicle performance (>6.0 g), 38 accessions with increased grain number per panicle (> 800–1,000), 27 accessions with resistance to panicle drooping, 20 accessions with lodging resistance, and 24 accessions with shedding resistance (after maturation, during transportation and threshing). Ten accessions were recognized as the most suitable for direct mechanized harvesting (the maximum sum of points from lodging resistance, panicle drooping and post-maturation grain shedding scores). Seven accessions with the maximum sum of points from resistance to biotic factors scores were also identified. Conclusions. The millet gene pool accessions were comprehensively studied under various weather conditions by field and laboratory assessments, which allowed us to select material with increased parameters. The valuable accessions are recommended to develop new millet varieties.

Does local isolation allow an invasive thistle to escape enemy pressure?

Enemy release often is invoked to explain the success of invasive plants: an invader benefits from reduced attack as it escapes specialized enemies through the invasion process. Enemy release typically is thought of as occurring at large geographic scales, but local-scale interactions may also be important for invader establishment and success. Furthermore, most tests of local enemy release have been conducted over a single year even though release may be a transient phenomenon, especially at small scales. In this study, we used a multi-year field experiment to investigate whether locally isolated populations of the noxious non-native weed Cirsium arvense benefit from reduced levels of aboveground damage, and whether any initial advantage is lost over subsequent growing seasons. Populations of C. arvense were grown in plots at set distances from established source populations for 4years. In the first year of the experiment, folivory significantly declined with host isolation, but damage from specialist stem gallers and seed predators did not. However, in subsequent years of observation, folivores began colonizing isolated C. arvense populations while stem gallers exhibited very slow colonization of more isolated plots; seed predation showed no pattern with distance in any year. Local enemy escape did not result in increased plant performance, which instead negatively correlated with degree of isolation. Nonetheless, our results stress the importance of multi-year observations in tests of enemy release, since the herbivory patterns initially observed often changed within subsequent years depending on the dispersal ability and biology of the causal organism involved.

Arbuscular Mycorrhizal Fungi Negatively Affect Nitrogen Acquisition and Grain Yield of Maize in a N Deficient Soil.

Arbuscular mycorrhizal fungi (AMF) play a crucial role in enhancing the acquisition of immobile nutrients, particularly phosphorus. However, because nitrogen (N) is more mobile in the soil solution and easier to access by plants roots, the role of AMF in enhancing N acquisition is regarded as less important for host plants. Because AMF have a substantial N demand, competition for N between AMF and plants particularly under low N condition is possible. Thus, it is necessary to know whether or not AMF affect N uptake of plants and thereby affect plant growth under field conditions. We conducted a 2-year field trial and pot experiments in a greenhouse by using benomyl to suppress colonization of maize roots by indigenous AMF at both low and high N application rates. Benomyl reduced mycorrhizal colonization of maize plants in all experiments. Benomyl-treated maize had a higher shoot N concentration and content and produced more grain under field conditions. Greenhouse pot experiments showed that benomyl also enhanced maize growth and N concentration and N content when the soil was not sterilized, but had no effect on maize biomass and N content when the soil was sterilized but a microbial wash added, providing evidence that increased plant performance is at least partly caused by direct effects of benomyl on AMF. We conclude that AMF can reduce N acquisition and thereby reduce grain yield of maize in N-limiting soils.

Performance of Quercus suber L. at nursery stage\u2014application of two bio-inoculants under two distinct environments

Key messageDespite the fact that the technique of application of bioinoculants improved the quality ofQuercus suberL. seedlings produced in nurseries, these benefits are dependent on the ecological conditions of the site and the composition of the applied inoculum, which interferes with the profile of the local fungal community.ContextQuercus suber L. plays a key ecological and socio-economical role in the Iberian Peninsula. Symbiotic ectomycorrhizal fungi-ECM are crucial partners of several tree species, and assessing the efficacy of bioinoculants at nursery stage helps devising tools to increase plant resilience.AimsThe aim of this study was to compare the effects of two inocula formulations of mixed ECM fungi and bacteria on the quality of seedlings produced in two forest nurseries, differing in environmental conditions and forest embedment.MethodsQuercus suber L. seedlings were inoculated with a commercial product containing Pisolithus tinctorius (Pers) Coker & Couch, Scleroderma sp., and six bacterial species and with a non-commercial fungal and bacterial dual inoculum (Suillus granulatus (L.) Roussel + Mesorhizobium sp.). Biometric and nutritional parameters and morphological quality indexes were determined on seedlings. The ECM community was assessed by denaturing gradient gel electrophoresis and cloning-sequencing.ResultsIn both nurseries, the seedling quality index in inoculated was up to 2-fold higher than in non-inoculated seedlings. Plant biomass differed significantly among nurseries. The inoculum influenced the profile of the fungal community. S. granulatus and P. tinctorius persisted for 6 months in the inoculated seedlings.ConclusionThe nursery ecosystem influenced plant growth. Inoculation treatments increased plant performance; however, the dual inoculum resulted in more consistent improvements of Q. suber at nursery stage, highlighting the importance of inocula selection.