Fungal Root Research Articles

Precipitation increased the proportion of non-mycorrhizal fungi in Plantathera chlorantha orchid roots

Orchids are endangered due to their extremely high ornamental and medicinal values, and their growth and development are closely related to root fungal communities. Therefore, the study of fungi in orchid roots helps in the protection and population restoration of orchids. This study compared the specificity and composition of the fungal community in the roots of the greater butterfly-orchid Platanthera chlorantha under three precipitation conditions (400–500 mm, L; 700–800 mm, M; and 1000–1100 mm, H). The results showed that non-mycorrhizal fungi accounted for >92% of the root fungal community of P. chlorantha. The proportion of non-mycorrhizal fungi Trichoderma in L (12.84%) and M (25.26%) conditions was significantly higher than that in H (2.57%), indicating that with an increase in precipitation, they play important roles in improving plant drought resistance and growth and development. The only mycorrhizal fungus Ceratobasidiaceae, which accounted for >1% of the total sequences, was significantly reduced under high precipitation habitats, indicating that it is more likely to survive in low precipitation habitats. Chao 1 and ACE index increased significantly with increased precipitation; however, there was no significant difference in Simpson and Shannon index, indicating that precipitation affects the structure of the root symbiotic fungal community of P. chlorantha, although the fungal community only revolves around some key species changes. This study provides a reference for the in-depth analysis of the relationship between fungal communities and environmental factors in orchid roots, and a theoretical basis for the protection and ecological restoration of orchid populations.

Mycorrhizal structures in mycoheterotrophic Thismia spp. (Thismiaceae): functional and evolutionary interpretations

Achlorophyllous, mycoheterotrophic plants often have an elaborate mycorrhizal colonization pattern, allowing a sustained benefit from external fungal root penetrations. The present study reveals the root anatomy and mycorrhizal pattern of eight mycoheterotrophic Thismia spp. (Thismiaceae), all of which show separate tissue compartments segregating different hyphal shapes of the mycorrhizal colonization, as there are intact straight, coiled and peculiarly knotted hyphae as well as degenerated clumps of hyphal material. Those tissue compartments in Thismia roots potentially comprise exo-, meso- and endoepidermae, and exo-, meso- and endocortices, although not all species develop all these root layers. Differences in details among species according to anatomy (number of root layers, cell sizes and shapes) and colonization pattern (hyphal shapes within cells) are striking and can be discussed as an evolutionary series towards increasing mycorrhizal complexity which roughly parallels the recently established phylogeny of Thismia. We suggest functional explanations for why the distinct elements of the associations can contribute to the mycorrhizal advantage for the plants and, thus, we emphasize the relevance of structural traits for mycorrhizae.

Contrasting community responses of root and soil dwelling fungi to extreme drought in a temperate grassland

Fungal communities inhabiting plant roots and the soil diverge because they are shaped by differences in abiotic environment and plant filtering. Therefore, these two communities will also likely respond differently to climate change. However, such responses are poorly understood, especially for climate extremes with increasing frequency and intensity. Based on a long-term field experiment that simulated two types of extreme drought (chronic/intense) of once-in-20-year occurrence in the temperate grassland, we studied the response of soil and root fungal communities to extreme drought in association with plant communities. The species richness, community composition, and network stability of the root fungi were sensitive to extreme drought and showed legacy effects during recovery; notably, these responses were independent of extreme drought types. The sensitivity of the root community was mainly driven by rare symbiotic and saprotrophic fungal species, with abundant species remaining stable. In contrast, except for species relative abundances, soil fungal communities were resistant to drought. Structural equation modelling revealed that plant communities mediate drought effects on root fungal communities but not soil communities. Our findings highlight the climate sensitivity of root fungal communities and their response asymmetry to soil communities, with potentially profound consequences for ecosystem stability and functionality.

Resorcylic acid lactones from the ginseng pathogen Ilyonectria mors-panacis

Ilyonectria mors-panacis, previously Cylindrocarpon destructans, is the main plant pathogen responsible for the fungal disease ginseng root rot. This economically important disease, also called disappearing root rot, reduces crop yields by an average of 30% at harvest. While the disease is well studied from ecological and genomic perspectives, the role of I. mors-panacis secondary metabolites in the disease process is not well understood. Our previous metabolomics study showed Ilyonectria strains that cause ginseng root rot produce mixtures of putative resorcylic acid lactones, whereas avirulent strains did not, and collectively synthesize fewer metabolites. To confirm these metabolomics findings, we isolated and characterized the secondary metabolites from I. mors-panacis DAOMC 251601, a strain that causes ginseng root rot. From its EtOAc soluble culture filtrate extract, eight resorcylic acid lactones (1-8), including chlorinated and non-chlorinated congeners, were characterized by HRMS and spectroscopic approaches (NMR, OR, UV). The structure of one new metabolite, named radicicol E (1), was elucidated and additional spectroscopic data for the known compound nordinonediol (2) are reported. Further, radicicol (9) production was confirmed by comparison to a standard. The roles that resorcylic acid lactones and the siderophore N,N′,N” triacetylfusarine C have in promoting Ilyonectria ginseng root rot are also discussed.

The Fiber Profile of Midrib Waste on Salak Sidempuan Fermented with Phanerochaete chrysosporium

Feed alternative is become the major concern for livestock industry in order to provide the continuously feeding. Feed technology system based on agriculture wastes were the modified strategy to gain the other sources of feed raw materials. Salak Sidempuan is performed similar with the Palm plantations which is produced the potential midrib waste. Nutritionally, the product will feed the animal to increase the performance. The research aims to evaluate the proximate profile especially the fiber contents of midrib waste of Salak Sidempuan fermented with white root fungi. The fifth experiments were evaluated after the measuring period by using the Phanerochaete chrysosporium and replicated in 4 times. Experiments were P0 (control), P1 (5%inoculant of P. chrysosporium), P2 (10%inoculant of P. chrysosporium), P3 (15%inoculant of P. chrysosporium), and P4 (20%inoculant of P. chrysosporium). A completely randomized design was used to determine the statistical effect on dry matter, organic matter, crude fiber and lignin. Results showed that the addition of inoculant about 20% signifantly effected the increasing on dry matter and organic matter while followed the decreasing of fiber contents. In conclusion, fermentation of midrib waste with Phanerochaete chrysosporium is potentially degradated the fiber content itselves.

Grass species identity shapes communities of root and leaf fungi more than elevation

Fungal symbionts can buffer plants from environmental extremes and may affect host capacities to acclimate, adapt, or redistribute under environmental change; however, the distributions of fungal symbionts along abiotic gradients are poorly described. Fungal mutualists should be the most beneficial in abiotically stressful environments, and the structure of networks of plant-fungal interactions likely shift along gradients, even when fungal community composition does not track environmental stress. We sampled 634 unique combinations of fungal endophytes and mycorrhizal fungi, grass species identities, and sampling locations from 66 sites across six replicate altitudinal gradients in the western Colorado Rocky Mountains. The diversity and composition of leaf endophytic, root endophytic, and arbuscular mycorrhizal (AM) fungal guilds and the overall abundance of fungal functional groups (pathogens, saprotrophs, mutualists) tracked grass host identity more closely than elevation. Network structures of root endophytes become more nested and less specialized at higher elevations, but network structures of other fungal guilds did not vary with elevation. Overall, grass species identity had overriding influence on the diversity and composition of above- and belowground fungal endophytes and AM fungi, despite large environmental variation. Therefore, in our system climate change may rarely directly affect fungal symbionts. Instead, fungal symbiont distributions will most likely track the range dynamics of host grasses.

Metabolomics and microbiome reveal potential root microbiota affecting the alkaloidal metabolome in Aconitum vilmorinianum Kom.

BackgroundThe plant microbiome is vital for plant health, fitness, and productivity. Interestingly, plant metabolites and the plant microbiome can influence each other. The combination of metabolomics and microbiome may reveal the critical links between the plant and its microbiome. It is of great significance to agricultural production and human health, especially for Chinese medicine research. Aconitum vilmorinianum Kom. is a herb with alkaloid activities, and its roots are the raw material for some Chinese medicines. Former studies have investigated alkaloidal metabolites and antibacterial activities of endophytes in A. vilmorinianum roots. However, there are limited reports on the root microbiota that can influence the alkaloidal metabolome of A. vilmorinianum.ResultsThis research used ultra performance liquid chromatography-tandem mass spectrometry technology and high-throughput sequencing to examine the alkaloidal metabolome, bacterial microbiota, and fungal microbiota in A. vilmorinianum roots at two different sites in China. The results revealed that the samples from the two sites were rich in distinct alkaloidal metabolites and recruited significantly different root microbiota. Based on bioinformatics analysis, we found the potential bacterial and fungal microbiota impacting the alkaloidal metabolome in A. vilmorinianum.ConclusionOur findings reveal the composition of the alkaloidal metabolome, bacterial root microbiota, and fungal root microbiota in A. vilmorinianum roots at two different sites. Potential root microbiota that can influence the alkaloidal metabolome of A. vilmorinianum are indicated. This study provides a strategy for the cultivation and research of A. vilmorinianum and other Chinese herbs.

Conservation agriculture practices drive maize yield by regulating soil nutrient availability, arbuscular mycorrhizas, and plant nutrient uptake

Conservation agriculture (CA) can sustainably increase crop productivity through improved soil chemical, physical, and biological properties, among others. However, the implementation of all its three main components (i.e., no-tillage, organic soil cover/mulch, and crop diversification) in southern Africa is often challenging, resulting in variable yield responses. Disentangling the contributions of CA practices is necessary to understand the drivers of maize grain yield within the region. Here we analysed two 6-year long component omission experiments, one at a sandy soil location and the other at a clay soil location. In these two experiments, soil chemical parameters, total plant nutrient uptake, rate of crop residue decomposition, and arbuscular mycorrhizal fungi (AMF) colonization of maize roots were assessed. Soil chemical properties only differed across systems at the sandy soil location with the mulched systems under no-tillage (NT) resulting in increased soil organic carbon levels, total nitrogen, and soil available phosphorus as compared to conventional tillage with no mulch or rotation (CT). Conventional tillage-based systems resulted in fastest decomposition of maize residues, while systems with NT and rotation resulted in highest AM fungal root colonization rate of maize at the clay soil location. Total plant N uptake was almost 2-fold higher in tilled and no-tilled systems with both mulch (M) and rotations (R) (i.e., NT+M+R and CT+M+R) as compared to CT. Structural equation modeling was used to disentangle the links between cropping systems, soil chemical and biological properties, plant nutrient uptake, and maize grain yield. Cropping systems had direct and indirect influences on yield at both locations. At both locations, cropping systems influenced yield via plant N uptake, with the NT+M+R and CT+M+R systems having more beneficial effects compared to other systems, as shown by their higher path coefficients. In conclusion, we recommend a more holistic approach to cropping system assessment that includes a higher number of abiotic and biotic determinants. This would allow for a more rigorous evaluation of the drivers of yield and increase our understanding of the effects and performance of practices under the prevailing agro-ecological conditions. • Mulching under no-tillage increase soil organic carbon (SOC) and total nitrogen (N) • No-tillage plus rotation improve symbiosis of arbuscular mycorrhizal fungi & maize • Conventional tillage enhances stover decomposition but reduces SOC and N build-up • Conservation agriculture influences maize yield positively via nitrogen uptake

Environmental stress determines the colonization and impact of an endophytic fungus on invasive knotweed

There is increasing evidence that microbes play a key role in some plant invasions. A diverse and widespread but little understood group of plant-associated microbes are the fungal root endophytes of the order Sebacinales. They are associated with exotic populations of invasive knotweed (Reynoutria ssp.) in Europe, but their effects on the invaders are unknown. We used the recently isolated Sebacinales root endophyte Serendipita herbamans to experimentally inoculate invasive knotweed and study root colonisation and effects on knotweed growth under different environmental conditions. We verified the inoculation success and fungal colonisation through immunofluorescence microscopy and qPCR. We found that S. herbamans strongly colonized invasive knotweed in low-nutrient and shade environments, but much less under drought or benign conditions. At low nutrients, the endophyte had a positive effect on plant growth, whereas the opposite was true under shaded conditions. Our study demonstrates that the root endophyte S. herbamans has the potential to colonize invasive knotweed fine roots and impact its growth, and it could thus also play a role in natural populations. Our results also show that effects of fungal endophytes on plants can be strongly environment-dependent, and may only be visible under stressful environmental conditions.

Dominance of arbuscular mycorrhizal fungi is key for Mongolian steppe management under livestock grazing, as indicated by ecosystem multifunctionality

Livestock grazing of drylands supports millions of livelihoods worldwide; however, overgrazing causes severe biodiversity loss and degrades ecosystem functions. Understanding the effects of grazing intensity, aridity, and soil microbes is required for sustainable management. Here, we focused on arbuscular mycorrhizal (AM) fungi in soils and roots and examined their relationship with ecosystem multifunctionality under livestock grazing of Mongolian grasslands with different aridity levels. Above- and below-ground plant biomass were used to measure ecosystem-service multifunctionality, excluding annual plants that are unfavorable for ecosystem function and rangeland management. In both mountain forest steppe (mean annual precipitation = 207.7 mm) and steppe–desert steppe transition zone (mean annual precipitation = 128.4 mm), ecosystem multifunctionality was decreased by livestock grazing, as indicated by palatable plant shoot biomass. In line with the multifunctionality, the dominant plant species, Stipa krylovii, and AM plant biomass were decreased by livestock grazing. The Berger–Parker dominance index of soil AM fungi and Simpson’s diversity had a positive and negative relationship with multifunctionality, respectively, indicating that dominant AM fungi rather than AM fungal diversity in soil are key for maintaining multifunctionality. Root and soil AM fungal communities were significantly different with dominance of Rhizophagus operational taxonomic units (OTUs) in roots and Claroideoglomus OTUs in soil. However, the similarity between soil and root AM fungal communities increased with livestock grazing. Correlation analysis between palatable plant biomass and relative abundance of dominant AM fungal OTUs identified indicator virtual taxa that decreased (VTX00325 in roots, and VTX00165, VTX00214, and VTX00222 in soil) or increased (VTX00100, VTX00130, and VTX00295 in soil) with grazing intensity. The OTUs that were increased by grazing may be r-selected, grazing-tolerant AM fungi that accept a low C supply and supply few nutrients to plants. Our results suggest that grassland management focusing on ecosystem-service multifunctionality via control of AM plants, including S. krylovii and their co-dominant dominant AM fungi, in ungrazed grasslands are key for sustainable rangeland management in Mongolia.

Alleviation of the adverse effects of drought stress using a desert adapted endophytic fungus and glucose in tomato

Beneficial interaction of plants with fungi is one strategy for adapting to environmental stresses like drought. Serendipita indica, an endophytic root fungus, promotes plant growth and enhances tolerance to abiotic stresses. The present study aimed to investigate the amelioration of drought stress in tomato (Solanum lycopersicum L.) upon S. indica and glucose application through morpho-physiological analysis. A completely randomized design was applied with two types of fungal inoculation (non-inoculated and S. indica), two glucose concentrations (0 and 20 mM), and three levels of drought stress (0, 10%, and 20% polyethylene glycol) with three replications per treatment. The plants were collected to analyze various growth and physiological parameters 6 weeks after inoculation. The results showed that S. indica enhances root and shoot biomass and also root volume of inoculated plants in all treatments. An increase in carbohydrate (76%), proline (3.77-fold), potassium (21%), phosphorous (2.62-fold), antioxidant enzymes (peroxidase, ascorbate peroxidase, catalase and superoxide dismutase), total chlorophyll (33%), and carotenoid (16%) content were also observed with S. indica treated plants over untreated plants under drought stress. Additionally, the endophyte decreased hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage (EL) by 20, 10 and 22%, respectively. The results showed that the level of carbohydrate (90%), proline (35%), potassium (7%), plant water status (3%), chlorophyll (11%) and carotenoid (6%), as well as the activities of antioxidant enzymes, were increased in glucose-treated plants. Moreover, glucose application decreases the levels of MDA, hydrogen peroxide (H2O2), and EL by 4, 7 and 13%, respectively. Overall, the interaction effect between fungal inoculation and glucose treatment with drought stress was significant in nearly all measured traits, which means both fungus and glucose promotes plant growth and can enhance drought stress tolerance. Hence, these indicate that S. indica and glucose co-application should be further investigated with field trials.

Intraspecific Variation in Responses of a Montane Grass, Festuca thurberi, to Simulated Biological Invasion

High elevation plant populations, such as those found in sub-alpine meadows, are at the forefront of climate change and likely to experience novel interactions with migrating plants from lower elevations, including non-native species. Some of these non-native plants, particularly members of the Brassicaceae, produce secondary metabolites that have been shown to inhibit root fungi in other ecosystems. We conducted a growth experiment with plant leachates in order to evaluate the degree to which the dominant high elevation grass species, Festuca thurberi would be affected by future novel interactions with the non-native mustard, Thlaspi arvense, relative to a native mustard (Noccaea fendleri). We assessed growth, chlorophyll content, biomass, mortality, and percent colonization of arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in different genotypes of F. thurberi exposed to leachates from native and non-native mustards as well as F. thurberi leachate and a deionized (DI) water control. New growth and mortality varied more by genotype than by treatment with leachate of F. thurberi, T. arvense, and N. fendleri. Treatment, genotype, and the treatment × genotype interaction all had significant effects on chlorophyll content, with N. fendleri treatments demonstrating higher relative greenness levels than control treatments. Percent of fine roots with dark septate endophytes was significantly affected by individual genotype and treatment × genotype interaction, but there were no effects of treatment, genotype, or their interaction on percent root colonization by arbuscules or vesicles. Overall, we show that performance of a dominant high-altitude grass species varies in its response to the presence of an expanding, non-native plant, which may become increasingly common due to climate change.

Regulation of Tomato Specialised Metabolism after Establishment of Symbiosis with the Endophytic Fungus Serendipita indica

Specialised metabolites produced during plant-fungal associations often define how symbiosis between the plant and the fungus proceeds. They also play a role in the establishment of additional interactions between the symbionts and other organisms present in the niche. However, specialised metabolism and its products are sometimes overlooked when studying plant-microbe interactions. This limits our understanding of the specific symbiotic associations and potentially future perspectives of their application in agriculture. In this study, we used the interaction between the root endophyte Serendipita indica and tomato (Solanum lycopersicum) plants to explore how specialised metabolism of the host plant is regulated upon a mutualistic symbiotic association. To do so, tomato seedlings were inoculated with S. indica chlamydospores and subjected to RNAseq analysis. Gene expression of the main tomato specialised metabolism pathways was compared between roots and leaves of endophyte-colonised plants and tissues of endophyte-free plants. S. indica colonisation resulted in a strong transcriptional response in the leaves of colonised plants. Furthermore, the presence of the fungus in plant roots appears to induce expression of genes involved in the biosynthesis of lignin-derived compounds, polyacetylenes, and specific terpenes in both roots and leaves, whereas pathways producing glycoalkaloids and flavonoids were expressed in lower or basal levels.

Comparative Secretome Analyses of Trichoderma/Arabidopsis Co-cultures Identify Proteins for Salt Stress, Plant Growth Promotion, and Root Colonization

Numerous Trichoderma strains are beneficial for plants, promote their growth, and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes the growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host without growth promotion. To understand the dynamics of plant-fungus interaction, we examined the secretome from both sides and revealed a substantial change under different salt regimes, and during co-cultivation. Stress-related proteins, such as a fungal cysteine-rich Kp4 domain-containing protein which inhibits plant cell growth, fungal WSC- and CFEM-domain-containing proteins, the plant calreticulin, and cell-wall modifying enzymes, disappear when the two symbionts are co-cultured under high salt concentrations. In contrast, the number of lytic polysaccharide monooxygenases increases, which indicates that the fungus degrades more plant lignocellulose under salt stress and its lifestyle becomes more saprophytic. Several plant proteins involved in plant and fungal cell wall modifications and root colonization are only found in the co-cultures under salt stress, while the number of plant antioxidant proteins decreased. We identified symbiosis- and salt concentration-specific proteins for both partners. The Arabidopsis PYK10 and a fungal prenylcysteine lyase are only found in the co-culture which promoted plant growth. The comparative analysis of the secretomes supports antioxidant enzyme assays and suggests that both partners profit from the interaction under salt stress but have to invest more in balancing the symbiosis. We discuss the role of the identified stage- and symbiosis-specific fungal and plant proteins for salt stress, and conditions promoting root colonization and plant growth.

Tembotrione combinations on enzyme activities and arbuscular mycorrhiza in maize planted soil

Tembotrione, a new generation low dose herbicide applied solely or in combination with atrazine or 2,4-D for controlling complex weed flora in maize field. Frequent use of herbicides at higher rate and in combinations might be a threat to soil biological health. Hence the effect of tembotrione applied at 120 and 240 g/ha and its combination with surfactant isoxadifen-ethyl, atrazine and or 2,4-D as tank mix on soil enzymes and arbuscular mycorrhiza fungi infection and sporulation was assessed in this study. The enzymes dehydrogenase and alkaline phosphatase and the arbuscular mycorrhizal fungi population and root colonization were hindered by tembotrione applied at higher dose and with surfactant and atrazine though significant weed control was achieved. Thus, the tembotrione with surfactant isoxadifen-ethyl should be applied at recommended rate to control weeds. Also, continuous monitoring is essential to avoid effect on non-target organisms and maintain soil biological health when applied with atrazine for broad spectrum weed control in irrigated maize.

Diversity of arbuscular mycorrhiza fungi in rhizosphere soil and roots in Vetiveria zizanioides plantation chronosequence in coal gangue heaps

Diversity of arbuscular mycorrhiza fungi in rhizosphere soil and roots in Vetiveria zizanioides plantation chronosequence in coal gangue heaps

Biodiversity of arbuscular mycorrhizal fungi in plant roots and rhizosphere soil from different arid land environment of Qatar.

Recently more attention has been observed toward the role of arbuscular mycorrhizal fungi (AMF) in plant growth. Qatar belongs to the Arabian Gulf region with hot and dry climatic conditions. The study aims to investigate the species composition and abundance of AMF in Qatar, rhizosphere soil samples, and roots of plants from 12 families and 8 different locations. The AMF were identified based on the sequencing of the polymerase chain reaction (PCR) product of the amplified conserved ITS region. The reported AMF infection rate was found to vary with location and plant species. Tamarix aphylla recorded the highest AMF infection rate (100%), followed by Blepharis ciliaris (98%) and Sporobolus ioclados (92%). AMF spore counts ranged from 29.3 spores in Blepharis ciliaris to 643 spores/100 g soil in Fagonia indica. No correlation was detected between colonization rate and spore counts. While all AMF identified at species levels were reported in other regions, new species are still expected since some were identified only at higher taxonomic levels. Claroideoglomus drummondii and Rhizophagus irregularis were the most widespread while Claroideoglomus claroideum and Diversispora aurantia were the least present. Our results fill the gap of knowledge of AMF in the region and opens new research toward its future applications for sustainable agriculture.

Cotton waste‐derived biochar and compost improve early growth and AMF association in cotton

AbstractImproving the sustainability of cotton (Gossypium hirusutum L.) production can be achieved by returning organic matter and nutrients to degraded soils. Amendment with biochar prepared from locally available feedstocks has been suggested as a pathway to sustainability. A greenhouse study collaboratively conducted by Malian and Texas A&M investigators evaluated the effect of biochar prepared from two feedstocks readily available in northwestern Africa: cotton field residue and rice (Oryza sativa L.) hulls, on cotton plants grown to 6 wk. A composted municipal biosolid was included for comparison with the more carbon (C)‐stable biochars. Four soils of contrasting properties were included in the study. Plant growth response variables were all affected by soil type (p < .0001). Shoot height was improved by biochars and composts in all soils. Root mass was improved by amendment only in the soil with the greatest clay content. Nitrogen (N) uptake was significantly depressed, and phosphorus (P) uptake was increased under biochar and compost amendment in the most coarsely textured soil. No effect on N and P uptake was observed in the soil with the greatest clay content. Ridge regression analysis showed that arbuscular mycorrhizal fungi (AMF) root colonization was positively related to the P content of the amendments (1.41*Pamend), negatively related to soil P (–0.49*Psoil) and positively related to both soil pH (2.15*pH) and clay content (1.130*clay%). Results indicate that degraded soils may be restored through amendment with biochar created from locally available feedstock to improve sustainability of cotton production. Soil properties will determine the degree of benefit.

Maize Fungal Root Pathogens as Affected by Rotation with Legumes and Fertilization

Maize Fungal Root Pathogens as Affected by Rotation with Legumes and Fertilization

Growth, leaf gas exchange and mycorrhizal colonization of three medicinal species submitted to different irradiance levels

ABSTRACT: This study o evaluated growth, leaf gas exchange and arbuscular mycorrhizal fungi root colonization in three medicinal plant species under different irradiance intensities. Fridericia chica (Bonpl.) L.G.Lohmann, Mikania laevigata Sch.Bip. ex Baker and Varronia curassavica Jacq. were propagated by cutting and cultivated for 120 days in artificially shaded environments using black shade-type screens, obtaining four irradiance levels: 100%, 70%, 50% and 30%. The experimental design was completely randomized in a 3 x 4 factorial scheme (three plant species and four irradiation levels) with seven replicates. The three medicinal species showed higher liquid assimilation, mass growth and arbuscular mycorrhizal fungi root colonization rates when exposed to environments with 70% light availability. In relation to physiological responses, V. curassavica presented higher photosynthetic rate, stomatal conductance and transpiration when submitted to 70% irradiance, being able to be cultivated in more open environments with higher irradiation levels. Conversely F. chica and M. laevigata presented shade tolerance characteristics. At the initial growth phase, the results obtained can be used as indicators to recommend the ideal cultivation environment for these species in agroforestry systems.