Trap Cultures Research Articles

Mycorrhizal fungi in Annona muricata L. rhizosphere in two agricultural production systems in Nayarit, Mexico

Mycorrhizal symbiosis is the association between the roots of several plant species and soil fungi of the Glomeromycotina subphylum. This symbiosis plays a crucial role in plant growth, development, and defense; therefore, understanding the abundance and diversity of arbuscular mycorrhizal fungi (AMF) species associated with plants of economic importance is of utmost concern. The objective of this study was to compare the abundance and composition of AMF communities in two Annona muricata cultivation sites, and in propagated soil, under different agricultural practices. The first cultivation site is under technified management with periodic fertilization and irrigation (TS), while the second cultivation site is under agroecological management without fertilization, irrigation, and with the presence of livestock (non-technified site; NTS). The extracted spores from the collected samples and the trap cultures were taxonomically identified based on their morphology. 13 species associated with A. muricata belonging to seven genera were identified in soil samples. The most abundant species were Funneliformis geosporum, Acaulospora kentinensis and Rhizophagus intraradices with a relative abundance of 45.9, 19.0 and 15.8%, respectively. In the propagation substrates, only 69% of the AMF species found in the field were identified. 11 species of AMF were found in the site with non-technified agronomic management, while only five species were found in the technified site.

Arbuscular Mycorrhizal Fungi and Soil Enzyme Activities in Different Fonio Millet (Digitaria exilis Stapf.) Agroecosystems in Senegal

In plant roots, arbuscular mycorrhizal fungi (AMF) are the most prevalent microsymbionts, and thereby provide many key ecosystem services to natural and agricultural ecosystems. Despite AMF’s significance for the environment and the economy, little is known about the mycorrhizal inoculum potential and diversity of AMF associated with orphan African cereal crops, specially fonio millet (Digitaria exilis stapf.) under field conditions. We hypothesized that the type of fonio millet agroecosystem influences the AMF density and distribution in soils. We therefore, assessed the inoculum potential, density and diversity of AMF spores and soil enzyme activities in five fonio millet agroecosystems belonging to three climatic zones (Sudanian, Sudano-Sahelian and Sudano-Guinean). By combining AMF spore identification from field-collected soils and trap culture, 20 species belonging to 8 genera (Acaulospora, Ambispora, Dendiscutata, Gigaspora, Glomus, Racocetra, Sclerocystis and Scutellospora) were identified. Glomus was the most represented genus with 8 species, followed by Gigaspora (5 species) and Acaulospora (2 species); the remaining genera were each represented by one species. Except for Ambispora which was not found in the Sudanian area, all genera occurred in the three climatic zones. The abundance and diversity of AMF species and FDA-hydrolytic and phosphatase activities varied between fonio millet agroecosystems as well as between climatic zones. Soil pH and soil texture were the variables that best explained the density and distribution of AMF spores. Our results contribute to paving the way towards the development of microbial engineering approaches for agronomic improvement of fonio millet.

Vineyard management systems influence arbuscular mycorrhizal fungi recruitment by grapevine rootstocks in New Zealand.

Arbuscular mycorrhizal fungi (AMF) can perform significant functions within sustainable agricultural ecosystems, including vineyards. Increased AMF diversity can be beneficial in promoting plant growth and increasing resilience to environmental changes. To effectively utilize AMF communities and their benefits in vineyard ecosystems, a better understanding of how management systems influence AMF community composition is needed. Moreover, it is unknown whether AMF communities in organically managed vineyards are distinct from those in conventionally managed vineyards. In this study, vineyards were surveyed across the Marlborough region, New Zealand to identify the AMF communities colonizing the roots of different rootstocks grafted with Sauvignon Blanc and Pinot Noir in both conventional and organic systems. The AMF communities were identified based on spores isolated from trap cultures established with the collected grapevine roots, and by next-generation sequencing technologies (Illumina MiSeq). The identified AMF species/genera belonged to Glomeraceae, Entrophosporaceae, and Diversisporaceae. The results revealed a significant difference in AMF community composition between rootstocks and in their interaction with management systems. These outcomes indicated that vineyard management systems influence AMF recruitment by rootstocks and some rootstocks may therefore be more suited to organic systems due to the AMF communities they support. This could provide an increased benefit to organic systems by supporting higher biodiversity.

Characterization of arbuscular mycorrhizal fungal species associating with Zea mays.

Taxonomic identification of arbuscular mycorrhizal (AM) fungal spores extracted directly from the field is sometimes difficult because spores are often degraded or parasitized by other organisms. Single-spore inoculation of a suitable host plant allows for establishing monosporic cultures of AM fungi. This study aimed to propagate AM fungal spores isolated from maize soil using single spores for morphological characterization. First, trap cultures were established to trigger the sporulation of AM fungal species. Second, trap cultures were established with individual morphotypes by picking up only one spore under a dissecting microscope and transferring it to a small triangle of sterilized filter paper, which was then carefully inoculated below a root from germinated sorghum seeds in each pot and covered with a sterile substrate. All pots were placed in sunbags and maintained in a plant growth room for 120 days. Spores obtained from single spore trap cultures from each treatment, maize after oats (MO), maize after maize (MM), maize after peas (MP), and maize after soybean (MS), were extracted using the sieving method. Healthy spores were selected for morphological analysis. Direct PCR was conducted by crushing spores in RNAlater and applying three sets of primer pairs: ITS1 × ITS4, NS31 × AML2, and SSUmcf and LSUmBr. Nucleotide sequences obtained from Sanger sequencing were aligned on MEGA X. The phylogenetic tree showed that the closest neighbors of the propagated AM fungal species belonged to the genera Claroideoglomus, Funneliformis, Gigaspora, Paraglomus, and Rhizophagus. The morphological characteristics were compared to the descriptive features of described species posted on the INVAM website, and they included Acaulospora cavernata, Diversispora spurca, Funneliformis geosporus, Funneliformis mosseae, Gigaspora clarus, Gigaspora margarita, Glomus macrosporum, Paraglomus occultum, and Rhizophagus intraradices. These findings can provide a great contribution to crop productivity and sustainable management of the agricultural ecosystem. Also, the isolate analyzed could be grouped into efficient promoters of growth and mycorrhization of maize independent of their geographical location.

Populasi dan Keanekaragaman Fungi Mikoriza Arbuskular pada Rizosfer Tanaman Lada (Piper nigrum L.) Monokultur dan Polikultur

Arbuscular mycorrhizal fungi (AMF) is a type of fungus that comes from the endomycorrhizal group, these fungi have the ability to form symbiosis with almost 90% of higher plant species. Population and diversity of AMF are influenced by biotic factors and abiotic factors. This research aims to determine the differences in population, diversity and dominant types of AMF in the rhizosphere of pepper planted in monoculture and pepper in polyculture. The soil samples were taking from monoculture and polyculture pepper plantations in Air Naningan District, Tanggamus Regency. The AMF population was tested using the One way Annova test. Culture trapping was done using a factorial treatment with the first factor being the origin of the soil sample (K) and the second actor being the type of host plant (T). Treatments design used was randomize design (CRD). The results showed that the AMF population in polyculture pepper plantation soil samples was higher than monoculture pepper, based on the Shannon-Wiener Diversity Index, AMF diversity in monoculture pepper and coffee intercropping pepper plantations was higher than in cocoa intercropping pepper plantations, and the type of AMF was dominant. from the results of trapping culture with monoculture pepper garden soil samples, namely spores of the species code S7, in samples of coffee intercropping pepper plantations the code S7 is dominant, while in cocoa intercropping pepper plantations it is dominated by code S6. Keywords: Arbuscular mycorrhizal fungi, diversity, population.

Uncovering the complex relationship between plant diversity, soil properties, and mycorrhizal inoculum potential in threatened Miombo woodlands

AbstractArbuscular mycorrhizal fungi (AMF) are key members of soil microbial communities and play a key role in regulating ecosystem processes. However, the mutual interdependence of plants and AMF in threatened Miombo woodlands has not yet been fully elucidated. In this study, we investigated the relationship between plant ecological indicators and soil mycorrhizal inoculum potential (MIP) in the Miombo forest fallow of Haut‐Katanga, Democratic Republic of Congo, and identified plant species that positively influence soil MIP. We conducted a floristic inventory on 32 plots and collected soil cores for physicochemical and AMF characterization. Trap cultures using Crotalaria juncea seedlings were performed to determine the soil MIP. We also tested the AMF colonization status of randomly collected living roots of mature woody and dominant herbaceous species to identify explanatory variables for MIP. Our results showed that MIP was twice as high in silty clay soils (63.13%) than in clay soils (30%). Furthermore, MIP increased accordingly with the relative abundance of a group of woody and herbaceous species (e.g., Albizia adianthifolia, Baphia bequaertii, and Setaria pumila) and decreased with others (e.g., Combretum collinum, Harungana madagascariensis and Hyparrhenia diplandra). Linear regressions showed that MIP increased significantly with the specific richness of woody species identified as indicators and with the amount of annual herbs. Woody legumes with high root colonization by AMF appeared to be refuge plants, and primary AMF dispersal vectors, increasing soil MIP. This study provides baseline data that can be used to formulate ecological restoration strategies, including soil and vegetation protection.

Long-Term Monitoring Studies of the Mycorrhizal Colonization of Aesculus hippocastanum L. Roots and the Vitality of Soil Microorganisms in Urban and Non-Urban Environments

Stress factors typical in urban environments adversely affect the productivity and vigor of trees and may limit the development of tree roots with associated soil fungi and bacteria. Studies on mycorrhizal symbiosis and the activity of soil microorganisms are important in monitoring the adaptation of trees to urban conditions. We compared the symbiotic activity of arbuscular mycorrhizal fungi (AMF) living in the rhizosphere of mature white chestnut trees (Aesculus hippocastanum L.) in an urban ecosystem at sites with varying degrees of anthropopressure and in a rural area. We used two methods: (1) direct analysis of the root samples, (2) assessment of the colonization of trap plants grown in the soil taken from under selected white horse chestnut trees. The seasonality of mycorrhizal colonization and soil microbial respiration based on the enzyme activity of nonspecific dehydrogenase (DHA) was studied over several growing seasons. The concentrations of macronutrients in the soil from all study sites were in the ranges accepted as normal for the upper soil layer. However, the C/N ratio indicated carbon limitation in the soil at urban and rural study sites. The results showed that arbuscular mycorrhizal fungi indigenous in the rhizosphere of A. hippocastanum developed a functioning mycorrhizal symbiosis at all research sites, including at highly disturbed urban locations, and that the mycorrhizal colonization varied between the study sites and the research term. The trap culture method confirmed the high biological potential of the soil microbial community, including AMF in urban ecosystems, which was comparable to that at the reference site in the rural environment. Soil moisture strongly affected the overall soil microbial vitality. This research showed that the mycorrhizal status of A. hippocastanum is more strongly influenced by climatic conditions and seasonal rhythms of trees than by urban/non-urban locations.

Synergic effect of Arbuscular mycorrhizal fungi and potassium fertilizer improves biomass-related characteristics of cocoa seedlings to enhance their drought resilience and field survival

Abstract Drought is the most widespread threat to cocoa production. We assessed the combined effect of arbuscular mycorrhizal fungi (AMF) and potassium fertilizer on cocoa drought resilience and survival at the nursery to 2 years after transplanting to field. Nursery and field experiments were conducted at the FRNR farm (6°43N and 1°36W), Ghana, from 2020 to 2022. A 3 × 3 × 2 factorial experiment in a RCBD with three varieties of cocoa (CRG8914 × \times PA150; AMAZ315–15 × \times EQX78; PA150 × \times CRG 0314: V1; V2; V3 respectively), potassium (0, 2, and 4 g/plant), and mycorrhizal spore treatment (non-AMF and AMF inoculated) was used. Soil from the cocoa rhizosphere was collected and the wet sieving, decantation, and sucrose centrifugation techniques were used for the isolation of AMF. Rhizophagus irregularis was identified using the morphological method. The identified inoculum was prepared using the trap culture technique. K levels with AMF recorded the highest plant height (50.27 cm) than the non-AMF seedlings (41.4 cm). 2 g K × AMF in V1 and V2 had the highest (p < 0.05) above-ground (5.13 g) and below-ground (2.81 g) biomass, respectively. At 24 months, V1 × 0 g and V3 × 4 g without AMF had mortality of 60% and 50%, respectively, while V1 × 4 g and V2 × 2 g with AMF had 2% mortality rate. In conclusion, this has implications for cocoa nutrient management, yield, and climate-smart strategies for the attainment of Sustainable Development Goal 13 (climate Action).

Influence of Soil Type, Land Use, and Rootstock Genotype on Root-Associated Arbuscular Mycorrhizal Fungi Communities and Their Impact on Grapevine Growth and Nutrition

Soil characteristics, land management practices, and plant genotypes influence arbuscular mycorrhizal fungi (AMF) communities, leading to the proliferation of AMF taxa with different growth and nutritional outcomes in their hosts. However, the specific patterns driving these relationships are still not well understood. This study aimed to (1) evaluate the influence of soil characteristics, land use, and rootstock on AMF diversity and community structure and (2) assess the effect of those AMF communities on grapevine growth and nutrition. Soil samples were collected from vineyard and non-agricultural areas in Lisbon and Pegões, Portugal, and trap cultures established using Richter 110 and 1103 Paulsen rootstocks. After 3.5 months growth under greenhouse conditions, root-associated AMF communities were assessed by amplicon metagenomic sequencing using AMF-specific primers. Alpha diversity was only influenced by the soil type, while in β-diversity, an interaction was found between the soil type and land use. Both diversity measures were positively correlated with foliar K and negatively with leaf Mn and Mg. Notably, the concentrations of these nutrients were highly correlated with the relative abundance of operational taxonomic units (OTUs) within the genera Glomus, Rhizophagus, and Claroideoglomus. These results are valuable for supporting AMF selection for improved plant nutrition based on varying soil types and land uses.

Potential use of indigenous arbuscular mycorrhizal fungi to improve soil productivity in tailing of tin mining: a greenhouse study scale

Tin mining is as a critical factor destroying ecosystems and challenging for reclamation. Indigenous arbuscular mycorrhizal fungi (AMF) are well-known for assisting plants growing in harsh environments. This study aimed to (1) isolate indigenous AMF; (2) screen AMF for nutrient uptake and plant biomass; (3) investigate the screened AMF in supporting plant growing in tin tailing. Soils were collected from natural forest and post-tin mining in Bangka. Wet sieving was conducted to obtain spore of AMF. Collected AMF were propagated and screened for phosphorus uptake and plant biomass of tested Sorghum bicolor growing in sterilized sand at greenhouse. Eight best-screened AMF was evaluated using Piper nigrum growing in sterilized tin tailing+10% compost at greenhouse. The new leaf number, phosphorus uptake, and flowering emergence were measured. Trap culture obtained 16 Acaulospora sp., 1 Glomus sp., and 1 Scutelospora sp, in post-tin mining, and 9 Acaulospora sp. in natural forest. Screening of AMF resulted in higher shoot P uptake and biomass than controls. Application of screened AMF on tin-talling showed that four AMF had higher new leaf number, phosphorus uptake, and flower emergence of P. nigrum. These results imply that selected indigenous AMF are potential for future land productivity of post-tin mining area.

Selection of Salinity-Adapted Endorhizal Fungal Consortia from Two Inoculum Sources and Six Halophyte Plants.

Soil salinity is a limiting factor in crop productivity. Inoculating crops with microorganisms adapted to salt stress is an alternative to increasing plant salinity tolerance. Few studies have simultaneously propagated arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSF) using different sources of native inoculum from halophyte plants and evaluated their effectiveness. In alfalfa plants as trap culture, this study assessed the infectivity of 38 microbial consortia native from rhizosphere soil (19) or roots (19) from six halophyte plants, as well as their effectiveness in mitigating salinity stress. Inoculation with soil resulted in 26-56% colonization by AMF and 12-32% by DSF. Root inoculation produced 10-56% and 8-24% colonization by AMF and DSF, respectively. There was no difference in the number of spores of AMF produced with both inoculum types. The effective consortia were selected based on low Na but high P and K shoot concentrations that are variable and are relevant for plant nutrition and salt stress mitigation. This microbial consortia selection may be a novel and applicable model, which would allow the production of native microbial inoculants adapted to salinity to diminish the harmful effects of salinity stress in glycophyte plants in the context of sustainable agriculture.

Exploration and culture of arbuscular mycorrhizal fungi from wild sago

The sago palm (Metroxylon sagu Rottb.) contains significant potential for carbohydrates. When harvested, the plant produces more than 300kg of dry starch per plant. Arbuscular mycorrhizal fungi (AMF, Glomeromycota) are known to often form symbiotic associations with the majority of higher plants, but there are limited studies on their interaction with Sago. Therefore, this study aims to obtain information on the presence of arbuscular mycorrhizal fungi from the rhizosphere of sago palms as well as to prepare pure cultures of the dominant species. Samples were collected from the test plant’s rhizosphere by exploring the West Papua region with a shallow peat area as a base. The soil bulk density in the region was 0.11-0.20 g cm−3 with a low pH (H2O) of 4.1. At the initial stage, a trapping culture was prepared from the rhizosphere soil sample, and a pure culture was then made from the dominant spore using telang (Clitoria ternatea.L) as the host. The observation results of spore morphology revealed that they belonged to Acaulosporaceae, Gigasporaceae, and Glomeraceae. The low abundance and diversity of AMF were caused by abiotic factors, including soil physicochemical properties.

Engineering Approach for Production of Arbuscular Mycorrhizal Inoculum Adapted to Saline Soil Management

(1) Background: Soil salinity impacts plant growth and productivity in steppic regions. Thus, the current study aims at producing, at low cost, an inoculum composed of native arbuscular mycorrhizal fungi (AMF) strains adapted to saline soil management. (2) Methods: The propagation of the native AMF strains was carried out in three natural saline soils presenting increasing salinity levels (4.5, 8.5 and 9.3 dS·m−1 in Boughzoul (BG), Salt Rocket (SR) and Zaafrane (ZA) sites, respectively). Three host plant species (alfalfa, clover and leek) were tested as trap cultures. AMF spore richness and diversity, the quantification of soil microbial biomass and the determination of the most probable number (MPN) were carried out before and after 24 months culture. Moreover, the mycorrhizal rates of the host plant species were assessed. (3) Results: The moderate saline soil (SR) planted with alfalfa was found to be the most suitable for AMF inoculum production with a maximum of 650 spores, 10 g−1 of soil, a mycorrhizal rate of 86%, 70 propagules·g−1 of soil and the highest microbial biomass content. (4) Conclusion: This study points out the best combination for the production of a more adapted AMF biofertilizer for saline soil management and proposes several indicators for biofertilizer quality evaluation.

Trap Culture and Colonization of Arbuscular Mycorrhizal Fungi from Corn Roots in Tidal Swamps Using Several Host Plants

Arbuscular mycorrhizal fungi (AMF) are mycorrhizal from the endomycorrhizal group. The fungi live on higher plants' roots by performing symbiotic mutualism. This study aimed to identify AMF spores after trapping in corn roots and the degree of root infection by AMF in several host plants. The study was conducted using tidal swamps soil samples taken from Mulyasari Tanjung Lago Village, Banyuasin Regency, South Sumatra. The experiment used a randomized block design and three replicates with four host plants as a treatment: corn, soybean, sugarcane (monoculture) and sugarcane-soybean (combination). The results showed that AMF spores found on corn roots after trapping were from the <em>Acaulospora</em> sp. and <em>Glomus</em> sp. groups. Hyphae, vesicles, arbuscules and spores are AMF structures found in the roots of host plants infected by AMF. The percentage of AMF infection in host plant roots ranged from 1.11% to 77.44% where the highest was in maize host plant roots at 77.44% in the form of internal hyphae. The maize host plant has a high potential to be colonized by AMF compared to a mixture of soybean, sugarcane and sugarcane-soybean.

MYCORRHIZAL DEVELOPMENT IN EUCALYPTUS CAMALDULENSIS DEHNH

Effects of arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) inoculation on mycorrhiza formation and development in E. camaldulensis seedlings were assessed in this study. Two experiments, the first with AM fungi and the second with EM fungi, were set up successively using vermiculite-peat (VP) as growth medium, and 2.5 mg l-1, 5.0 mg l-1, 10 mg l-1 and 20 mg l-1 phosphorus (P) Ingestad's nutrient solution in each experiment. The AM experiment using three AM inocula (including Glomus clarum Nicolson and Schenck. (isolate BR148-1) and Gigaspora rosea Nicolson and Schenck. (isolate FL105-5) and one from a trap culture of Bangladeshi soil) resulted in 30-50% colonisation; most colonisation was by G. clarum BR148-1 and was the highest at 10 mg l-1 P (>50%). In a similar experiment using five isolates of Pisolithus tinctorius (Pers.) Coker and Couch., only isolate K55 resulted in colonisation >15% most of which occurred at 2.5 mg l-1 P (>25%) while the other isolates resulted in <1% colonisation. This study showed that E. camaldulensis tended to be colonised more readily by arbuscular- than ecto-mycorrhizal fungi in the initial period of seedling growth. There were indications that the species could become ectomycorrhizal after 16 weeks of growth in glasshouse, but that proper care should be taken to select appropriate and compatible EM inoculants.

Impact of Mycorrhizal Fungi from Different Rhizospheric Soils on Fungal Colonization, Growth, and Chlorophyll Contents of Cenchrus ciliaris

Mycorrhizae are symbiotic associations between fungi and plants and are primarily responsible for nutrient transfer and survival of both partners. The present study was conducted to explore the diversity of mycorrhizal fungi in the rhizospheric soil of perennial grass species (Saccharum spontaneum, Saccharum bengalense, Setaria verticillata, Cymbopogon jwarancusa, and Typha angustata) around the district Layyah. In the subsequent experiment, the rhizospheric soils were used as inoculants, and their impact on mycorrhizal colonization in the plant and soil, and growth and physiological attributes, of Cenchrus ciliaris were investigated. The maximum hyphal, vesicles, arbuscules, dark septate endophytic and ectomycorrhizal colonization, and spore percentage were observed in the case of R-S5, i.e., rhizospheric soil, collected from Saccharum bengalense. However, the maximum (0.9310) Simpson’s index of diversity was observed in the case of R-S4, i.e., rhizospheric soil collected from Setaria verticillata. Different mycorrhizal fungal morphotypes scattered over three genera, i.e., Acaulospora, Glomus, and Scutellospora, were recorded both from rhizosphere and trap cultures. The application of spores from rhizospheric soil collected from S. bengalense (R-S5) caused the maximum increase in plant height (19.5%), number of leaves plant−1 (17.6%), leaf area (108.0%), and chlorophyll contents (29.4%) of Cenchrus ciliaris, compared to other treatments. In conclusion, the inoculation of mycorrhizal fungi significantly improves the mycorrhizal characteristics of Cenchrus ciliaris and its rhizospheric soil and ultimately enhances the growth and physiological parameters of Cenchrus ciliaris.

Dry-Season Soil and Co-Cultivated Host Plants Enhanced Propagation of Arbuscular Mycorrhizal Fungal Spores from Sand Dune Vegetation in Trap Culture.

The use of arbuscular mycorrhizal fungi (AMF) as biofertilizer in agriculture is a sustainable approach to fertilization. The first step in the production of AMF biofertilizer is inoculation of mycotrophic plants with a composite of soil and native plant roots, containing potentially viable AMF spores from natural habitats, to a trap culture. A single host plant or a consortium of host plants can be used to propagate AMF spores. However, the difference in the comparative efficiency of mono- and co-cultivated host plants used for the production of AMF spores and the maintenance of original AMF community composition has not been well elucidated. Here, we prepared trap culture with nutrient-poor soil from coastal sand dune vegetation collected during the dry season when the AMF spore density and relative abundance of Glomeromycota ITS2 sequences were significantly higher (p = <0.05) than in the wet season. The AMF communities in the soil were mainly composed of Glomus spp. Maize (Zea mays L.) and/or Sorghum (Sorghum bicolor (L.). Moench) were grown in trap cultures in the greenhouse. Our results demonstrated that co-cultivation of the host plants increased the production of AMF spores but, compared to mono-cultivation of host plants, did not better sustain the native AMF community compositions in the coastal sand dune soil. We propose that the co-cultivation of host plants in a trap culture broadens AMF-host plant compatibilities and thus sustains the symbiotic association of the natively diverse AMF. Therefore, the results of this study suggest that further research is needed to confirm whether the co-culturing of more than one host plant is as efficient a strategy as using a monoculture of a single host plant.

On farm inoculation of native arbuscular mycorrhizal fungi improves efficiency in increasing sugarcane productivity in the field

The objective of this study was to evaluate the effect of inoculation of native arbuscular mycorrhizal fungi (AMF) multiplied on farm in the productivity and quality of different cultivars of sugarcane (Saccharum ssp.) in field conditions by three ratoons. The experimental design was of randomized blocks, in factorial scheme 6 × 2: six cultivars (CTC 1, CTC 7, CTC 9, CTC 16, SP89-1115 and RB925345), with and without AMF inoculation, in three ratoons. The AMF species mix, used to compose the inoculant, were collected from the experimental area, multiplied in trap culture, and applied to the sugarcane planting line. To assess the effectiveness of establishing mycorrhizal symbiosis, root mycorrhizal colonization (MC), spore density (SD), and AMF diversity were quantified. Sugarcane productivity and quality were also obtained by quantifying of the vegetative and technological characteristics. With the inoculation and the increase of viable AMF propagules in the soil resulted in higher MC and SD. Acaulospora scrobiculata and Glomus sp. were the species with the highest frequency of occurrence. Sugarcane productivity and quality were also significantly higher in inoculated treatments, with average increases in the three ratoons of 20% in sugarcane productivity and 30% in sugar production. The increase in sugarcane productivity and quality after AMF inoculation is a positive indicator of the effectiveness this biotechnology has over the production of this commodity.

Early Growth Performance of In Vitro Raised Melia volkensii Gürke Plantlets in Response to Beneficial Microorganisms under Semi-Arid Conditions.

Before in vitro propagated Melia volkensii plants can be used for mass planting, the transition phase to in vivo conditions needs to be better controlled because too many plants are lost during acclimatization and in the field. Two experiments were set up to evaluate the effects of biological agents on the establishment of M. volkensii in vitro plantlets. The biological agents consisted of Trichotech®, Bio-cure B®, Rhizatech®, Bacillus subtilis, a Trichoderma isolate and self-isolated native arbuscular mycorrhizal fungi (AMF). Regarding the latter, in soil from the nursery, the number of AMF spores increased from six spores to 400 per 100 g of soil using a trap culture, in which thirteen AMF morphotypes were identified and root colonization assessed through observation of hyphae, vesicles, coils and appressoria. The first experiment was set up in the greenhouse to investigate the efficacy of the biological agents on the hardening off. In the second, a field experiment was set up to study their effect on the early establishment of the plantlets in the field compared to seedlings. All biological agents significantly (p ≤ 0.05) improved in vitro plant survival and growth compared to the control. The highest plant height and number of leaves per plant were recorded in plants treated with Rhizatech®, Native AMF, Bio-cure B® and Trichoderma isolate. The treatments with Rhizatech®, Bio-cure B® and native mycorrhiza recorded a significantly wider stem. The root diameter of the plants treated with Rhizatech® and Bio-cure B® was the largest, but the plants inoculated with the native AMF had the longest roots. Moreover, the inoculated plants generally developed multiple secondary roots. After two months, AMF had clearly colonized the acclimatized plantlets. In the field experiment, the biologicals made no difference in survival rate but did produce a significantly larger leaf area after two months, with the largest leaves recorded with Rhizatech®, native AMF and Trichotech®. They also increased the quality index of the plants from 0.21 to 0.52. The performance of in vitro grown M. volkensii plants six months after planting in semi-arid conditions in Kiambere was better than that of seedlings. Inoculation of plants increased plant height and diameter. Thus, inoculation of biological agents is an efficient approach for improving the early growth of in vitro propagated M. volkensii plants.

Cultivation, identification, and application of arbuscular mycorrhizal fungi associated with date palm plants in Drâa-Tafilalet oasis

Arbuscular mycorrhizal fungi (AMF) have been frequently reported as effective tools for alleviating environmental stresses and promoting plant growth and yield. In this study, we aimed to isolate, culture, and identify molecular and morphological AMF species associated with date palms and spontaneous plants present at eight sites in the arid agroecosystem of the Drâa-Tafilalet oasis of Morocco. We tested the capacity of AMF to colonize micropropagated date palm seedlings at their first acclimatization stage. Soil and root samples were collected to propagate indigenous AMF strains using trap culture techniques under greenhouse conditions and, at the same time, their root colonization potential was evaluated. We used freshly propagated spores to establish a collection of single spore-derived cultures. Morphological, microscopic, and molecular approaches were adopted to quantify AMF communities in the roots and rhizosphere and identify the recovered AMF species present at the eight sites. In an inoculation experiment, a micropropagated date palm was inoculated with a consortium of four cultured AMF strains, alone or in combination with synthetic fertilizer or compost. Our results showed that after two cycles of trap culturing, the frequency and intensity of AMF colonizing host plant roots significantly increased, exceeding 91% and 50%, respectively. Using three trap plant species and favorable growing conditions helped increase root colonization rates and AMF proliferation. AMF propagation resulted in the cultivation of 13 AMF strains. Molecular and morphological analyses revealed six different AMF species within our cultures: Pervetustus simplex, Claroideoglomus etunicatum, Albahypha drummondii, Septoglomus xanthium, Funneliformis mosseae, and Rhizoglomus irregulare. Results of the inoculation experiment revealed that root colonization was higher in treatments augmented with synthetic fertilizers than those supplemented with compost with 84.4% as against 46.7% and 26.1% as against 12.3%, respectively, for colonization frequency and intensity. In contrast, shoot length and stem diameter of date palms were significantly higher in treatments augmented with compost and AMF than that with synthetic fertilizers. Synthetic fertilizers might have been partially immobilized directly after application, limiting availability and resulting in lower growth performance of date palms. These findings indicated that date palm groves are a niche for efficient indigenous AMF strains that can colonize and enhance date palm growth at the early stages.