Fungal Root Research Articles

Synthetic growth by self-lubricated photopolymerization and extrusion inspired by plants and fungi

Many natural organisms, such as fungal hyphae and plant roots, grow at their tips, enabling the generation of complex bodies composed of natural materials as well as dexterous movement and exploration. Tip growth presents an exemplary process by which materials synthesis and actuation are coupled, providing a blueprint for how growth could be realized in a synthetic system. Herein, we identify three underlying principles essential to tip-based growth of biological organisms: a fluid pressure driving force, localized polymerization for generating structure, and fluid-mediated transport of constituent materials. In this work, these evolved features inspire a synthetic materials growth process called extrusion by self-lubricated interface photopolymerization (E-SLIP), which can continuously fabricate solid profiled polymer parts with tunable mechanical properties from liquid precursors. To demonstrate the utility of E-SLIP, we create a tip-growing soft robot, outline its fundamental governing principles, and highlight its capabilities for growth at speeds up to 12 cm/min and lengths up to 1.5 m. This growing soft robot is capable of executing a range of tasks, including exploration, burrowing, and traversing tortuous paths, which highlight the potential for synthetic growth as a platform for on-demand manufacturing of infrastructure, exploration, and sensing in a variety of environments.

Landscape scale ecology of Tetracladium spp. fungal root endophytes

BackgroundThe genus Tetracladium De Wild. (Ascomycota) has been traditionally regarded as a group of Ingoldian fungi or aquatic hyphomycetes—a polyphyletic group of phylogenetically diverse fungi which grow on decaying leaves and plant litter in streams. Recent sequencing evidence has shown that Tetracladium spp. may also exist as root endophytes in terrestrial environments, and furthermore may have beneficial effects on the health and growth of their host. However, the diversity of Tetracladium spp. communities in terrestrial systems and the factors which shape their distribution are largely unknown.ResultsUsing a fungal community internal transcribed spacer amplicon dataset from 37 UK Brassica napus fields we found that soils contained diverse Tetracladium spp., most of which represent previously uncharacterised clades. The two most abundant operational taxonomic units (OTUs), related to previously described aquatic T. furcatum and T. maxilliforme, were enriched in roots relative to bulk and rhizosphere soil. For both taxa, relative abundance in roots, but not rhizosphere or bulk soil was correlated with B. napus yield. The relative abundance of T. furcatum and T. maxilliforme OTUs across compartments showed very similar responses with respect to agricultural management practices and soil characteristics. The factors shaping the relative abundance of OTUs homologous to T. furcatum and T. maxilliforme OTUs in roots were assessed using linear regression and structural equation modelling. Relative abundance of T. maxilliforme and T. furcatum in roots increased with pH, concentrations of phosphorus, and increased rotation frequency of oilseed rape. It decreased with increased soil water content, concentrations of extractable phosphorus, chromium, and iron.ConclusionsThe genus Tetracladium as a root colonising endophyte is a diverse and widely distributed part of the oilseed rape microbiome that positively correlates to crop yield. The main drivers of its community composition are crop management practices and soil nutrients.

Orchid mycorrhizal fungi and ascomycetous fungi in epiphytic Vanda falcata roots occupy different niches during growth and development.

Epiphytic orchids are commonly found in exposed environments, which plausibly lead to different root fungal community structures from terrestrial orchids. Until recently, few studies have been conducted to show the fungal community structure during the growth of a photosynthetic and epiphytic orchid in its natural growing site. In this study, the Vanda falcata (commonly known as Neofinetia falcata), one of Japan's ornamental orchids, was used to characterize the fungal community structure at different developmental stages. Amplicon sequencing analysis showed that all development stages contain a similar fungal community: Ascomycota dominate half of the community while one-third of the community belongs to Basidiomycota. Rhizoctonia-like fungi, a polyphyletic basidiomycetous fungal group forming mycorrhizas in many orchids, exist even in a smaller portion (around one-quarter) compared to other Basidiomycota members. While ascomycetous fungi exhibit pathogenicity, two Ceratobasidium strains isolated from young and adult plants could initiate seed germination in vitro. It was also found that the colonization of mycorrhizal fungi was concentrated in a part of the root where it directly attaches to the phorophyte bark, while ascomycetous fungi were distributed in the velamen but never colonized cortical cells. Additionally, the root parts attached to the bark have denser exodermal passage cells, and these cells were only colonized by mycorrhizal fungi that further penetrated into the cortical area. Therefore, we confirmed a process that physical regulation of fungal entry to partition the ascomycetes and mycorrhizal fungi results in the balanced mycorrhizal symbiosis in this orchid.

Arbuscular vesicular mycorrhizae in olive tree (Olea europaea L.)

The objective of the work was to determine the general and sanitary condition of olive seedlings (Olea europaea L.). For which the presence of the main microbial group that colonizes the roots of the seedlings of this crop was investigated. To determine and assess fungal root infection, colonization by native fungal organisms in roots of olive trees produced in a nursery in the Central Valley of the province of Catamarca (Argentina) was studied. The studies were carried out by microscopic observation of stained fungal structures within the root, using clarification and staining methodologies. Typical structures of endomycorrhizae such as hyphae, arbuscules and vesicles (MVA), and dark septate endophytic fungi (ESO) with septate, melanized hyphae and numerous microsclerotia were observed. This first condition is desirable in all plants due to its ability to promote plant growth of mycorrhizal-forming fungi

ANALISA PRODUKTIVITAS TANAMAN KARET (Havea brasiliensis Muell. Arg) KLON PB 260 DENGAN MENGGUNAKAN BERBAGAI SISTEM SADAP DI AFDELING I KEBUN BANGUN PT. PERKEBUNAN NUSANTARA III

The productivity of rubber plantations is determined by the type of clone, the age of the plant, the level of land suitability, and the exploitation system applied. The exploitation system applied determines the productivity of the rubber plantation because it is related to the use of the skin and the physiological process of latex. Implementing the right exploitation system can ensure high and sustainable productivity. On the other hand, the implementation of the wrong exploitation system can result in low productivity and shorten the economic life of the plant. This study aims to determine the productivity of rubber plants in clone PB 260 with various tapping systems. This research was conducted at Afdeling I Kebun Bangun PT. Perkebunan Nusantara III using a descriptive analysis method by collecting secondary data on the productivity of the PB 260 clone rubber plant from 2016 – 2020. The parameters observed were the production data of the PB 260 clone rubber plant with various tapping systems. The results of this study indicate that the analysis of rubber plant productivity data in 2016 – 2020 had the highest production in 2017 with a planting year of 2009 and the lowest in 2020 with a planting year of 2000. Meanwhile, overall, the highest production was in 2018 and the lowest was in 2016. The factors that influence the high and low productivity are caused by the tapping system that is not permanent or changing, the lack of application of fertilization, the reduction in the number of trees in the field caused by being attacked by JAP (White Root Fungus), KAS (Dry Alur Sadap), Moldy Road, fallen trees due to strong winds, and the age of the plants. The relationship between production and cost of goods/kg is that the greater the production obtained, the lower the cost of goods/kg.

ANALISA PRODUKTIVITAS TANAMAN KARET (Havea brasiliensis Muell. Arg) KLON PB 260 DENGAN MENGGUNAKAN BERBAGAI SISTEM SADAP DI AFDELING I KEBUN BANGUN PT. PERKEBUNAN NUSANTARA III

The productivity of rubber plantations is determined by the type of clone, the age of the plant, the level of land suitability, and the exploitation system applied. The exploitation system applied determines the productivity of the rubber plantation because it is related to the use of the skin and the physiological process of latex. Implementing the right exploitation system can ensure high and sustainable productivity. On the other hand, the implementation of the wrong exploitation system can result in low productivity and shorten the economic life of the plant. This study aims to determine the productivity of rubber plants in clone PB 260 with various tapping systems. This research was conducted at Afdeling I Kebun Bangun PT. Perkebunan Nusantara III using a descriptive analysis method by collecting secondary data on the productivity of the PB 260 clone rubber plant from 2016 – 2020. The parameters observed were the production data of the PB 260 clone rubber plant with various tapping systems. The results of this study indicate that the analysis of rubber plant productivity data in 2016 – 2020 had the highest production in 2017 with a planting year of 2009 and the lowest in 2020 with a planting year of 2000. Meanwhile, overall, the highest production was in 2018 and the lowest was in 2016. The factors that influence the high and low productivity are caused by the tapping system that is not permanent or changing, the lack of application of fertilization, the reduction in the number of trees in the field caused by being attacked by JAP (White Root Fungus), KAS (Dry Alur Sadap), Moldy Road, fallen trees due to strong winds, and the age of the plants. The relationship between production and cost of goods/kg is that the greater the production obtained, the lower the cost of goods/kg.

Mycorrhiza-mediated potassium transport in Medicago truncatula can be evaluated by using rubidium as a proxy

Arbuscular mycorrhizal (AM) fungi considerably improve plant nutrient acquisition, particularly phosphorus and nitrogen. Despite the physiological importance of potassium (K+) in plants, there is increasing interest in the mycorrhizal contribution to plant K+ nutrition. Yet, methods to track K+ transport are often costly and limiting evaluation opportunities. Rubidium (Rb+) is known to be transported through same pathways as K+. As such our research efforts attempt to evaluate if Rb+ could serve as a viable proxy for evaluating K+ transport in AM symbiosis. Therefore, we examined the transport of K+ in Medicago truncatula colonized by the AM fungus Rhizophagus irregularis isolate 09 having access to various concentrations of Rb+ in custom-made two-compartment systems. Plant biomass, fungal root colonization, and shoot nutrient concentrations were recorded under sufficient and limited K+ regimes. We report that AM plants displayed higher shoot Rb+ and K+ concentrations and a greater K+:Na+ ratio relative to non-colonized plants in both sufficient and limited K+ conditions. Consequently, our results indicate that Rb+ can be used as a proxy to assess the movement of K+ in AM symbiosis, and suggest the existence of a mycorrhizal uptake pathway for K+ nutrition in M. truncatula.

The Clean Water Act and biosolids: A 45‐year chronological review of biosolids land application research in Colorado

The 1972 U.S. Clean Water Act set forth the generation of biosolids. In Colorado, biosolids land application research began in 1976 and continues today. Pastureland research suggested that sewage effluent could effectively be land applied to benefit aboveground plant growth and to polish water prior to reaching receiving waters. Forest wildfire-affected ecosystems can also benefit from biosolids applications; application rates of up to 80 Mg ha-1 can lead to greater plant establishment, soil microbial activity, and nutrient turnover and reduced nutrient and heavy metal concentrations in runoff below livestock and USEPA drinking water standards. Long-term (24-yr) observations in oil shale-mined lands showed that biosolids (up to 224 Mg ha-1 ) can have a positive effect on microbial-mediated nutrient cycling and, in turn, on aboveground plant community structure. Biosolids applications of up to 40 Mg ha-1 in high-elevation shrubland ecosystems, dominated by Mo-containing shale deposits, can aid in reducing imbalances between Mo and Cu in soils and plants; excessive plant Mo, when consumed by ruminants, can lead to molybdenosis. Biosolids and lime applications (both at 224 Mg ha-1 ) have been shown to improve long-term reclamation success on acid-generating, heavy metal-containing fluvial mine tailings. Thirty years of grazing land research, focused on soil and aboveground plant benefits, illustrate that soil health and plant productivity can be improved to the greatest extent at biosolids application rates close to 10 Mg ha-1 . Finally, 40 yr of dryland agroecosystem research (a) have helped identify biosolids N fertilizer equivalency (∼8kg N Mg-1 ) and thus dryland winter wheat application rates (e.g., 4.5-6.7 dry Mg ha-1 ); (b) have identified first-year mineralization rates of 25-32%; (c) dispute the "time bomb" theory by showing that plant metal uptake follows an exponential rise to a maximum; (d) showcase economic return to producers via increased wheat grain protein content; (e) suggest that biosolids-borne proteins and their degradation products are labile C and N sources; (f) have led to long-term tracking of micronutrients and heavy metals in soils and revealed that plants-soil concentrations will not lead to groundwater degradation and that plants are safe for human consumption; and (g) have shown that biosolids provide Zn, helping to overcome soil deficiencies and enhancing Zn biofortification in wheat grain. This latter point is important because ∼2 billion people globally suffer from Zn deficiencies. Forty-five years of research in Colorado have proven that biosolids can enhance environmental quality, improve soil health, and produce healthy food products.

Greater chemical signaling in root exudates enhances soil mutualistic associations in invasive plants compared to natives.

Invasive plants can change soil properties resulting in improved growth. Although invaders are known to alter soil chemistry, it remains unclear if chemicals secreted by roots facilitate invasive plant-soil mutualisms. With up to 19 confamilial pairs of invasive and native plants, and most of which were congeners, we explored the root exudate-induced changes in plant-arbuscular mycorrhizal (AM) fungal mutualisms. We found that, relative to natives, invaders had greater AM colonization, greater biomass and their root exudates contained higher concentrations of two common chemical signals - quercetin and strigolactones - which are known to stimulate AM fungal growth and root colonization. An exudate exchange experiment showed that root exudates from invaders increased AM colonization more than exudates from natives. However, application of activated carbon led to greater reduction in AM colonization and plant biomass for invaders than natives, suggesting stronger effects of chemical signals in root exudates from invaders. We show that nonnative plants promote interactions with soil mutualists via enhancing root exudate chemicals, which could have important implications for invasion success.

Drought Stress Exacerbates Fungal Colonization and Endodermal Invasion and Dampens Defense Responses to Increase Dry Root Rot in Chickpea.

Drought plays a central role in increasing the incidence and severity of dry root rot (DRR) disease in chickpea. This is an economically devastating disease, compromising chickpea yields particularly severely in recent years due to erratic rainfall patterns. Macrophomina phaseolina (formerly Rhizoctonia bataticola) is the causal agent of DRR disease in the chickpea plant. The infection pattern in chickpea roots under well-watered conditions and drought stress are poorly understood at present. This study provides detailed disease symptomatology and the characteristics of DRR fungus at morphological and molecular levels. Using microscopy techniques, the infection pattern of DRR fungus in susceptible chickpea roots was investigated under well-watered and drought-stress conditions. Our observations suggested that drought stress intensifies the progression of already ongoing infection by weakening the endodermal barrier and overall defense. Transcriptomic analysis suggested that the plant's innate immune defense program is downregulated in infected roots when subjected to drought stress. Furthermore, genes involved in hormonal regulation are differentially expressed under drought stress. These findings provide hints in terms of potential chickpea genes to target in crop improvement programs to develop climate-change-resilient cultivars.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Endophytic Fungal and Bacterial Microbiota Shift in Rice and Barnyardgrass Grown under Co-Culture Condition

Although barnyardgrass (Echinochloa crus-galli L.) is more competitive than rice (Oryza sativa L.) in the aboveground part, little is known about whether barnyardgrass is still competitive in recruiting endophytes and the root microbiota composition variation of rice under the barnyardgrass stress. Here, by detailed temporal characterization of root-associated microbiomes of rice plants during co-planted barnyardgrass stress and a comparison with the microbiomes of unplanted soil, we found that the bacterial community diversity of rice was dramatically higher while the fungal community richness was significantly lower than that of barnyardgrass at BBCH 45 and 57. More importantly, rice recruited more endophytic bacteria at BBCH 45 and 57, and more endophytic fungi at BBCH 17, 24, 37 to aginst the biotic stress from barnyardgrass. Principal coordinates analysis (PCoA) showed that rice and barnyardgrass had different community compositions of endophytic bacteria and fungi in roots. The PICRUSt predictive analysis indicated that majority of metabolic pathways of bacteria were overrepresented in barnyardgrass. However, eleven pathways were significantly presented in rice. In addition, rice and barnyardgrass harbored different fungal trophic modes using FUNGuild analysis. A negative correlation between bacteria and fungi in rice and barnyardgrass roots was found via network analysis. Actinobacteria was the vital bacteria in rice, while Proteobacteria dominated in barnyardgrass, and Ascomycota was the vital fungi in each species. These findings provided data and a theoretical basis for the in-depth understanding of the competition of barnyardgrass and endophytes and have implications relevant to weed prevention and control strategies using root microbiota.

Black Root Rot of Strawberry: A Disease Complex

Historically, root diseases have been a production-limiting problem for the strawberry industry worldwide. Even though this disease is of great economic importance, the etiology remains unresolved. However, soilborne fungal root pathogens, particularly Pythium and Rhizoctonia spp. have been implicated as major role players. Presence of nematodes in soil and favourable environmental conditions also play significant role in the disease development. Development of integrated disease management strategies is dependent upon a more complete understanding of the etiology, biology and ecology of the disease complex.

Secondary metabolites produced by Macrophomina phaseolina, a fungal root endophyte of Brugmansia aurea, using classical and epigenetic manipulation approach.

Endophytic fungi are rich sources of structurally complex chemical scaffolds with interesting biological activities. However, their metabolome is still unknown, making them appealing for novel compound discovery. To maximize the number of secondary metabolites produced from a single microbial source, we used the "OSMAC (one strain-many compounds) approach." In potato dextrose medium, M. phaseolina produced phomeolic acid (1), ergosterol peroxide (2), and a volatile compound 1,4-benzene-diol. Incorporating an epigenetic modifier, sodium valproate, affected the metabolite profile of the fungus. It produced 3-acetyl-3-methyl dihydro-furan-2(3H)-one (3) and methyl-2-(methyl-thio)-butyrate (4), plus volatile chemicals: butylated hydroxy toluene (BHT), di-methyl-formamide, 3-amino-1-propanol, and 1,4-benzenediol, 2-amino-1-(O-methoxyphenyl) propane. The structure of compounds 1-4 was established with the help of spectroscopic data. This study revealed first-time compounds 1-4 in the fungus M. phaseolinausing a classical and epigenetic manipulation approach.

Habitat Protection Approaches Facilitate Conservation of Overlooked Fungal Diversity - A Case Study From the Norwegian Coastal Heathland System.

European coastal heathlands are distinct ecosystems shaped by land use tradition and they have experienced an 80% area reduction from their historical maximum. These mosaics of mires and wind exposed patches have ericaceous shrub dominated vegetation, and soils within coastal heathlands are characterized by low pH and high levels of recalcitrant debris. Using a culture-based approach with molecular identification of isolates, we characterized root-associated fungal communities of six ericaceous species in eight heathland localities along Norway's western coast. Site-level alpha diversity ranged from 21-38 OTUs, while the total estimated gamma diversity for culturable heathland root fungi was 190-231 OTUs. Most species recovered are previously reported at low abundance in Norway, suggesting the biodiversity in this community is underreported, rather than novel for science. The fungi recovered were primarily Ascomycota, specifically endophytic Phialocephala, and Pezicula, and no host specificity was observed in the communities. The fungal communities exhibited high turnover and low nestedness, both between ericaceous hosts and across heathland sites. We observed no spatial patterns in fungal betadiversity, and this heterogeneity may be a product of the unique historic land use practices at each locality creating a distinct mycofloral "fingerprint". Robust diversity estimates will be key for managing fungal biodiversity in coastal heathlands. Our results indicate that sampling schemes that maximize the number of host plants sampled per site, rather than the number of cultures per plant yield improved alpha diversity estimates. Similarly, gamma diversity estimates are improved by maximizing the total number of localities sampled, rather than increasing the number of plants sampled per locality. We argue that while the current protected status of coastal heathland habitats and restoration efforts have knock-on effects for the conservation of fungal biodiversity, fungi have a vital functional role in the ecosystem and holistic conservation plans that consider fungal biodiversity would be beneficial.

Dancing with Douglas‐fir: Determinism dominates fungal community assembly processes

Abstract Fungal communities can influence the productivity, composition and survival of trees through cycling nutrients, providing resources and altering pathogens. Thus, shifts in fungal communities could impact forests by altering interactions between trees and their environments. Fungal community composition may be shaped by stochastic and deterministic processes such as dispersal limitation, environmental filtering and partner specificity between trees and fungi. For tree species with large geographical ranges, we expect fungal assembly processes to change with environmental variation across the range of the tree partner. Due to specificity between trees and symbiotic fungi, we expect deterministic to outweigh stochastic processes in root compared with soil fungi. As some tree species have exceptional longevity, we also expected tree age to influence fungal community assembly. We surveyed fungi in four stands of Pseudotsuga menziesii with tree ages up to 800 years along an 1,800 km transect. We sampled roots and soil around 12 P. menziesii in each stand, aged the trees, and sequenced fungal rDNA to determine composition and richness from which we calculated the relative role of deterministic and stochastic assembly processes. We used null models to evaluate the relative importance of deterministic variable and homogenizing selection, and stochastic dispersal limitation, drift and homogenizing dispersal in fungal community assembly. We detected 7,280 amplicon sequence variants with 5,270 associated with soil, 3,887 with roots and 1,877 found across both roots and soils. Deterministic processes dominated root and soil fungal communities at all sites except one where stochastic processes (i.e. dispersal limitation and drift) controlled root fungi. Despite the dominance of determinism in fungal community assembly, the proportion of processes differed by site. Assembly processes did not vary with tree age. Synthesis. Taken together, we suggest that the local environment, water limitation and partner‐preference between trees and their associated fungi, influence fungal community composition across the range of P. menziesii. We conclude that while fungal communities occurring near P. menziesii are dominated by homogenizing selection, the role of neutral processes still has a minor influence on community assembly and may be important in spatially isolated communities and those with strong gradients of fungal diversity.

Fungal association and root morphology shift stepwise during ontogenesis of orchid Cremastra appendiculata towards autotrophic nutrition.

The chlorophyllous, terrestrial orchid Cremastra appendiculata from East Asia is unique concerning its fungal mycorrhiza partners. The initially mycoheterotrophic protocorms exploit rather specialized non-rhizoctonia saprotrophic Psathyrellaceae. Adult individuals of this orchid species are either linked to Psathyrellaceae being partially mycoheterotrophic or form mycorrhiza with fungi of the ubiquitous saprotrophic rhizoctonia group. This study provides new insights on nutrition mode, subterranean morphology and fungal partners across different life stages of C. appendiculata. We compared different development stages of C. appendiculata to surrounding autotrophic reference plants based on multi-element natural abundance stable isotope analyses (δ13C, δ15N, δ2H, δ18O) and total N concentrations. Site- and sampling-time-independent enrichment factors of stable isotopes were used to reveal trophic strategies. We determined mycorrhizal fungi of C. appendiculata protocorm, seedling and adult samples using high-throughput DNA sequencing. We identified saprotrophic non-rhizoctonia Psathyrellaceae as dominant mycorrhizal fungi in protocorm and seedling rhizomes. In contrast, the roots of seedlings and mature C. appendiculata were mainly colonized with fungi belonging to the polyphyletic assembly of rhizoctonia (Ceratobasidium, Thanatephorus and Serendipitaceae). Mature C. appendiculata did not differ in isotopic signature from autotrophic reference plants suggesting a fully autotrophic nutrition mode. Characteristic of orchid specimens entirely relying on fungal nutrition, C. appendiculata protocorms were enriched in 15N, 13C and 2H compared to reference plants. Seedlings showed an intermediate isotopic signature, underpinning the differences in the fungal community depending on their subterranean morphology. In contrast to the suggestion that C. appendiculata is a partially mycoheterotrophic orchid species, we provide novel evidence that mature C. appendiculata with rhizoctonia mycobionts can be entirely autotrophic. Besides an environmentally driven variability among populations, we suggest high within-individual flexibility in nutrition and mycobionts of C. appendiculata, which is subject to the ontogenetic development stage.

Effect of Biofertilizer, Organic and Inorganic Fertilizers on the Growth Parameters and Root Colonization of Pennisetum Typhoides (Burm F.) under Greenhouse Conditions

Soil fertility remains a major driving force in plant growth and performance. In recent times, there has been an increase in demand for fertilizers to augment the fertility of marginal soils. However, the high cost of inorganic fertilizer has made farmers search for a cost-effective alternative. This study was carried out to investigate the effects of Arbuscular mycorrhizal fungi (AMF) as an alternative biofertilizer, and its effect was compared with that of organic manure (OM) and inorganic fertilizer (NPK) on the growth parameters of Pearl millet. The experiment employed a randomized complete block design (RCBD), and the treatments were replicated four times each under experimental greenhouse conditions. The shoot heights of the plants ranged from 38.06 cm to 83.45 cm, which was significantly higher (P<0.05) in OM-treated plants than those in the remaining treatments. The plants’ number of leaves and leaf area (cm2 ) differed significantly from the NPK treated plants, which out-competed the remaining treatments. The AMF significantly increased fungal root colonization by 30%, which was higher than in plants with NPK, OM, and the control (0.71% each). Although AMF did not significantly improve the plant’s growth, it was better at supporting shoot girth, root elongation, and overall root biomass than unfertilized plants. Inoculation with AMF was more efficient as it was positively reflected in colonized roots and other plant growth traits than non-biofertilized plants. Although the AMF was unable to compete with conventional fertilizers favorably, its potential to support millet growth has been established. Therefore, further investigations channeled towards the search for better mycorrhizal species under different experimental conditions are necessary.

Individual and combined effects of beneficial fungal root endophytes Piriformospora indica and Glomus fasciculatum on growth, nutrient uptake and IAA production in small cardamom

Individual and combined effects of beneficial fungal root endophytes Piriformospora indica and Glomus fasciculatum on growth, nutrient uptake and IAA production in small cardamom

Agronomic practices and mycorrhizal development and function in maize: Root fungal interactions may affect early nutrition and yield

Efficient management of soil biota and fertilization to reduce environmental impacts of agriculture requires understanding of functional soil biota-crop relationships and how they interact with management practices. An experiment was conducted to examine functional interactions between native arbuscular mycorrhizal (AM) fungi and maize nutrition, development and yield, for understanding and capturing most mycorrhizal benefits in the field. Soil tillage, fertilization and fungicide treatments were used to manipulate early AM development and functioning and test the hypothesis that the rapid root colonization and preservation of AM networks in soil would increase early P uptake and biomass, and later increase the yield and nutritional quality of the grain in comparison with treatments reducing early mycorrhizal development and function. The treatments succeeded in modulating mycorrhizal development and achieved up to 95% reductions in early root colonization. Tillage generally had few significant effects on most variables. Furthermore, the fungicide improved early nutrition and yield, and fertilization increased the nutrition, biomass, yield and grain quality. Early functional AM-maize relationships were positive at the third leaf (V3) stage but became negative at the sixth (V6) and tenth (V10) leaf stages, when root colonization by AM fungi and by other fungi increased, especially in treatments without fungicide. The abundance of AM fungi and other fungi in roots was negatively related to early shoot N and P, and some treatments did not reach the critical concentrations of N or P at V6. The shoot N and P reductions did not significantly affect the biomass during vegetative growth, but the yield was reduced by 10% in treatments without fungicide. Fertilization, which increased the yield by 30%, compensated for yield depression in treatments without fungicide. Close monitoring of early events in the development and functioning of AM-maize symbiosis suggested that early reductions in maize shoot N and P, and later the yield, were related to the combined effects of root colonization by mycorrhizal and non-mycorrhizal fungi. These results provide new evidence for the involvement of other root fungi in maize's early nutrition and yield depressions already reported in low fertility soils, which had been overlooked and attributed solely to AM fungi.

Long Term Effects of Tillage–Crop Rotation Interaction on Soil Organic Carbon Pools and Microbial Activity on Wheat-Based System in Mediterranean Semi-Arid Region

Conservation agriculture based on no-tillage (NT) and crop rotation allows to enhance soil health. Based on data collected from long-term trials in a semi-arid region of Tunisia, results showed that NT increased significantly soil organic carbon stock (SOCS), soil microbial biomass carbon (SMBC), arbuscular mycorrhizal fungal (AMF) root colonization, and soil microbial respiration (CO2) at 0–20 cm topsoil layer compared to conventional tillage (CT). Moreover, triennial rotation (TRI), based on annual succession of Faba bean-Durum wheat-Barley, and biennial rotation (BI), based on annual succession of Faba bean-Durum wheat, increased significatively SMBC, AMF, and CO2. Likewise, a significant benefit of the two-way interactions Tillage × Rotation was observed. Furthermore, NT combined with TRI recorded the highest SOCS (2181 g C m−2), SMBC (515 mg C kg−1 soil), AMF (14%), and CO2 which is an indicator of soil microbial respiration (1071 mg CO2 kg−1 soil). The current results highlight the benefit adoption of minimum or (NT)combined with crop diversification on soil health.