Application Of Arbuscular Mycorrhizal Fungi Research Articles

The application of arbuscular mycorrhizal fungi and mycorrhizae helper bacteria combined with compost to reduce the Pratylenchus coffeae population in an Arabica coffee plantation

The application of arbuscular mycorrhizal fungi and mycorrhizae helper bacteria combined with compost to reduce the Pratylenchus coffeae population in an Arabica coffee plantation

The reduction of abiotic stress in food crops through climate-smart mycorrhiza-enriched biofertilizer.

Climate change enhances stress in food crops. Recently, abiotic stress such as metalloid toxicity, salinity, and drought have increased in food crops. Mycorrhizal fungi can accumulate several nutrients within their hyphae through a symbiotic relationship and release them to cells in the root of the food crops under stress conditions. We have studied arbuscular mycorrhizal fungi (AMF)-enriched biofertilizers as a climate-smart technology option to increase safe and healthy food production under abiotic stress. AMF such as Glomus sp., Rhizophagus sp., Acaulospora morrowiae, Paraglomus occultum, Funneliformis mosseae, and Claroideoglomus etunicatum enhance growth and yield in food crops grown in soils under abiotic stress. AMF also works as a bioremediation material in food crops grown in soil. More precisely, the arsenic concentrations in grains decrease by 57% with AMF application. In addition, AMF increases mineral contents, and antioxidant activities under drought and salinity stress in food crops. Catalase (CAT) and ascorbate peroxidase (APX) increased by 45% and 70% in AMF-treated plants under drought stress. AMF-enriched biofertilizers are used in crop fields like precision agriculture to reduce the demand for chemical fertilizers. Subsequently, AMF-enriched climate-smart biofertilizers increase nutritional quality by reducing abiotic stress in food crops grown in soils. Consequently, a climate resilience environment might be developed using AMF-enriched biofertilizers for sustainable livelihood.

Silicon and arbuscular mycorrhizal fungi alleviate chromium toxicity in Brassica rapa by regulating Cr uptake, antioxidant defense expression, the glyoxalase system, and secondary metabolites

The potential contribution of silicon (Si) (300 mg kg−1 potash silica) or arbuscular mycorrhizal fungi (AMF) (Rhizophagus irregularis) to reduce chromium toxicity (Cr; 0 and 300 mg kg−1) in Brassica rapa was examined in this work. Under Cr stress, Si and AMF were used separately and in combination (no Si, or AMF, Si, AMF, and Si + AMF). Brassica rapa growth, colonization, photosynthesis, and physio-biochemical characteristics decreased under Cr stress. Oxidative stress was a side effect of Cr stress and was associated with high levels of methylglyoxal (MG), hydrogen peroxide (H2O2), lipid peroxidation (MDA), and maximum lipoxygenase activity (LOX). On the other hand, quantitative real-time PCR analyses of gene expression showed that under Cr stress, the expression of genes for secondary metabolites and antioxidant enzymes was higher than that under the control. The co-application of Si and AMF activated the plant defense system by improving the antioxidative enzymes activities, the potassium citrate and glutathione pool, the glyoxalase system, metabolites, and genes encoding these enzymes under Cr stress. Under the influence of Cr stress, oxidative stress was reduced by the coordinated control of the antioxidant and glyoxalase systems. However, the restricted Cr uptake and root and shoot accumulation of Si and AMF co-applied to only Cr-stressed plants was more significant. In summary, Si and AMF applied together successfully counteract the deleterious effects of Cr stress and restore growth and physio-biochemical characteristics. As a result, the beneficial effects of the combined Si and AMF application may be attributed to mycorrhizae-mediated enhanced Si absorption and metal resistance.

Effects of Humic Substances and Mycorrhizal Fungi on Drought-Stressed Cactus: Focus on Growth, Physiology, and Biochemistry.

Utilizing water resources rationally has become critical due to the expected increase in water scarcity. Cacti are capable of surviving with minimal water requirements and in poor soils. Despite being highly drought-resistant, cacti still faces limitations in realizing its full potential under drought-stress conditions. To this end, we investigated the interactive effect of humic substances (Hs) and arbuscular mycorrhizal fungi (AMF) on cactus plants under drought stress. In the study, a cactus pot experiment had three irrigation levels (W1: no irrigation, W2: 15% of field capacity, and W3: 30% of field capacity) and two biostimulants (Hs soil amendment and AMF inoculation), applied alone or combined. The findings show that the W1 and W2 regimes affected cactus performance. However, Hs and/or AMF significantly improved growth. Our results revealed that drought increased the generation of reactive oxygen species. However, Hs and/or AMF application improved nutrient uptake and increased anthocyanin content and free amino acids. Furthermore, the soil's organic matter, phosphorus, nitrogen, and potassium contents were improved by the application of these biostimulants. Altogether, using Hs alone or in combination with AMF can be an effective and sustainable approach to enhance the tolerance of cactus plants to drought conditions, while also improving the soil quality.

Arbuscular mycorrhizal fungi enhanced the drinking water treatment residue-based vertical flow constructed wetlands on the purification of arsenic-containing wastewater

Arsenic (As) is a toxic metalloid that poses a potential risk to the environment and human health. In this study, drinking water treatment residue (DWTR) and ceramsite-based vertical flow constructed wetlands (VFCWs) were built to purify As-containing wastewater. As a method of bioaugmentation, arbuscular mycorrhizal fungi (AMF) was inoculated to Pteris vittata roots to enhance the As removal of the VFCWs. The results showed that the As removal rates reached 87.82–94.29% (DWTR) and 33.28–58.66% (ceramsite). DWTR and P. vittata contributed 64.33–72.07% and 7.57–29% to the removal of As, while AMF inoculation intensified the As accumulation effect of P. vittata. Proteobacteria, the main As3+ oxidizing bacteria in the aquatic systems, dominated the microbial community, occupying 72.41 ± 7.76%. AMF inoculation increased As-related functional genes abundance in DWTR-based wetlands and provided a reliable means of arsenic resistance in wetlands. These findings indicated that the DWTR-based VFCWs with AMF inoculated P. vittata had a great purification effect on As-containing wastewater, providing a theoretical basis for the application of DWTR and AMF for As removal in constructed wetlands.

Arbuscular mycorrhizal colonization of pioneer mangrove species in Mahakam Delta, East Kalimantan

Arbuscular mycorrhizal fungi (AMF) are symbiotic, with more than 80% of plant species in terrestrial and mangrove ecosystems. This study aimed to determine the level of AMF colonization on Avicennia lanata and its correlation with soil chemical properties. Sampling was conducted in Sepatin Village, located in Mahakam Delta. There are four sampling locations, three were mangrove rehabilitation areas (A, B, and C), and one was a mangrove natural forest (MNF). Root samples were taken from four A. lanata seedlings purposively selected at each location. The roots were stained with 0.05% trypan blue, and the mycorrhizal structures of the roots were observed using a compound microscope. The results showed that the percentage of AMF colonization with A. lanata in MNF was higher (97%) than in other locations. Internal hyphae were the dominant structure found in the root of A. lanata in all locations, with a percentage of 76.61%. AMF root colonization negatively correlated with N-total, C-organic, and available P. In contrast, Ca, Mg, K, Na, and CEC positively correlated with AMF root colonization. The colonization of AMF in the root of A. lanata may promote the early growth of seedlings, and the application of AMF can support rehabilitating mangrove degraded.

The Effect of AMF-Cacao Association on Varying Physicochemical, Nutrient, and Biological Soil Parameters in an Agroforest System

The increasing interest in sustainable methods in agroforestry directs the attention of many to arbuscular mycorrhizal fungi (AMF) for their role in maintaining or improving overall plant health and nutrition of many plants including cacao (Theobroma cacao L.) trees. The effects of different treatments of AMF and other soil amendments applied singly or in combination on physicochemical properties, nutrient levels, spore count, and rhizosphere microbial counts, were investigated and compared across different sampling periods of varying climatological conditions in an agroforest system. Results showed that there was a significant effect on the N content using the different treatments. The treatment using AMF from MR (MYKORICH) alone has the highest N level (%) (0.587 ± 0.024, p < 0.001). Levels of P (ppm) and K (cmolc/kg) and soil physicochemical properties were not significantly affected by AMF applications. N levels were highest in January (1.772 ± 0.018, p = 0.004) which was the same month recorded with the lowest P content (0.0163 ± 2.228, p < 0.0001). Soil physicochemical properties did not significantly vary between sampling periods except for organic matter (OM) which was highest in October (2.883 ± 0.151, p = < 0.001), and with water-holding capacity (WHC) in March (80.429 ± 1.775, p < 0.001). Mycorrhizal spore counts were significantly higher in treatments with AMF (p > 0.0001) and between the sampling months (p < 0.0001). Results showed that the effect of season on spore count was not the same for each of the treatments used and vice versa (p = 0.001). Microbial counts on nitrogen-fixing bacteria and phosphate-solubilizing bacteria showed no variability between treatments (p = 0.134). These findings guide cacao farmers in directing future interventions for improving soil conditions and yield in cacao agroforests.

Co-inoculation of mycorrhizal fungi and plant growth-promoting rhizobacteria improve growth, biochemical and physiological attributes in Dracocephalum kotschyi Boiss. under water deficit stress.

Because of swift climate change, drought is a primary environmental factor that substantially diminishes plant productivity. Furthermore, the increased use of chemical fertilizers has given rise to numerous environmental problems and health risks. Presently, there is a transition towards biofertilizers to enhance crops' yield, encompassing medicinal and aromatic varieties. This study aimed to explore the impacts of plant growth-promoting rhizobacteria (PGPR), both independently and in conjunction with arbuscular mycorrhizal fungi (AMF), on various morphological, physiological, and phytochemical characteristics of Dracocephalum kotschyi Boiss. This experimentation took place under different irrigation conditions. The irrigation schemes encompassed well watering (WW), mild water stress (MWS), and severe water stress (SWS). The study evaluated the effects of various biofertilizers, including AMF, PGPR, and the combined application of both AMF and PGPR (AMF + PGPR), compared to a control group where no biofertilizers were applied. The findings of the study revealed that under water-stress conditions, the dry yield and relative water content of D. kotschyi Boiss. experienced a decline. However, the application of AMF, PGPR, and AMF + PGPR led to an enhancement in dry yield and relative water content compared to the control group. Among the treatments, the co-application of AMF and PGPR in plants subjected to well watering (WW) exhibited the tallest growth (65 cm), the highest leaf count (187), and the most elevated chlorophyll a (0.59 mg g-1 fw) and b (0.24 mg g-1 fw) content. Regarding essential oil production, the maximum content (1.29%) and yield (0.13 g plant -1) were obtained from mild water stress (MWS) treatment. The co-application of AMF and PGPR resulted in the highest essential oil content and yield (1.31% and 0.15 g plant-1, respectively). The analysis of D. kotschyi Boiss. essential oil identified twenty-six compounds, with major constituents including geranyl acetate (11.4-18.88%), alpha-pinene (9.33-15.08%), Bis (2-Ethylhexyl) phthalate (8.43-12.8%), neral (6.80-9.32%), geranial (9.23-11.91%), and limonene (5.56-9.12%). Notably, the highest content of geranyl acetate, geranial, limonene, and alpha-pinene was observed in plants subjected to MWS treatment following AMF + PGPR application. Furthermore, the co-application of AMF, PGPR, and severe water stress (SWS) notably increased the total soluble sugar (TSS) and proline content. In conclusion, the results indicate that the combined application of AMF and PGPR can effectively enhance the quantity and quality of essential oil in D. kotschyi Boiss., particularly when the plants are exposed to water deficit stress conditions.

Combined use of seaweed extract and arbuscular mycorrhizal fungi for alleviating salt stress in bell pepper (Capsicum annuum L.)

Salinity is the most catastrophic abiotic stress that aggravating its detrimental effects on productivity of horticultural crop especially bell pepper that might be alleviated through judicious application of seaweed extract (SWE) and arbuscular mycorrhizal fungi (AMF). Therefore, the present study was focused on the interactive effects of SWE and AMF to improve growth, physiological responses and yield performance of bell pepper grown under salt stress. Factorial experiment consisted of three factors namely SWE dose (non-treated control, 2.5 g L–1, 5.0 g L–1 and 7.5 g L–1 designated as SWE0, SWE2.5, SWE5.0 and SWE7.5, respectively); water salinity levels (control- 0.54, 4, 8 and 12 dS m–1) and two levels of AMF inoculation (with AMF [+AMF] and without AMF [–AMF]). Factorial experiment was laid out where treatment combinations were assigned completely randomized design (CRD) with three replications. SWE treated plants upgraded leaf relative water content, leaf greenness and membrane stability index 16 %, 19 % and 13 %, respectively with lower electrolyte leakage (15 %) at 12 dS m–1 water salinity compared to non-treated plants. In addition, higher proline content (79 %) was observed at SWE5.0 in AMF inoculated plants over control (non-inoculated plants. Marketable fruit yields were higher (31 %) with the combined application of SWE and AMF at extreme salt stress conditions (12 dS m–1). Apart from that, SWE7.5 treated plants exhibited more accumulation of potassium (26 %) and phosphorous (32 %) while less accumulation of sodium (16 %) was displayed at higher salinity level (12 dS m–1) compared to control plants. Moreover, SWE and AMF treated plants showed better postharvest quality (pH, Brix) performance during storage condition compared with control. Taken together, it might be inferred that integrated application of SWE and AMF had boosted up morpho-physiological traits, yield and ion homeostasis to ameliorate the baleful effects of salt stress on bell pepper.

Is there space for arbuscular mycorrhizal fungi in the production chain of photoprotective cosmetics?

Many plant species are used in cosmetics and have the potential to compose suncare products. An alternative to standardizing and improving the quality of the phytomass supplied is the application of arbuscular mycorrhizal fungi (AMF), which form a mutualistic symbiosis with most plants and can offer better uptake and concentration of compounds to the host. However, research verifying the efficiency of these fungi in favoring cosmetic properties is still scarce. Thus, in this opinion paper, we outlined what makes AMF biotechnology important for supplying high-quality phytomass to companies that produce sun care products and the challenges to be faced. Finally, it is worth highlighting that despite the drawbacks, mycorrhizal technology has the potential to integrate the chain production of plant-based cosmetics.

Boosting Drought Resistance in Pepper (Capsicum annuum L.) with the Aid of Arbuscular Mycorrhizal Fungi and Key Phytohormones

Drought is a primary abiotic stressor that markedly impairs pepper growth and quality. This study aimed to investigate the effects of foliar applications of phytohormones, including salicylic acid (SA), jasmonic acid (JA), and root application of arbuscular mycorrhizal fungi (AMF), on severe and moderate drought stress of 38-day-old ‘Anemon F1’ pepper plants. The results showed that drought stress led to a considerable decrease in plant growth parameters, nutrient uptake, leaf water content, and chlorophyll content, and it increased leaf temperature, phenolic and flavonoid contents, and antioxidant enzyme activity. Nevertheless, the combined application of AMF with SA and JA demonstrated substantial synergistic effects, resulting in a notable improvement in the ability to alleviate the detrimental impacts of drought stress. Furthermore, the combined application of AMF and phytohormones exhibited a stronger effect on drought stress compared with the individual application of AMF or phytohormones alone. The application of AMF+SA and AMF+JA not only improves the availability of essential nutrients but also leads to an increase in fresh shoot weight, relative water content, leaf area, and chlorophyll and antioxidant capacity. Consequently, the combined application of SA and JA with mycorrhiza emerged as a promising treatment for enhancing pepper growth under drought-stress conditions. The positive results observed in pepper cultivation through the combined use of phytohormones and mycorrhizae in regions with limited water availability emphasize the importance of investigating the effectiveness of similar approaches in other agricultural crops.

The Effect of Pruning and Growing Media Composition on Arbuscular Mycorrhizal Propagation

The symbiosis of arbuscular mycorrhizal fungi with plants is the oldest symbiosis in the world. The obligate nature of mycorrhizal fungi in symbiotic relationships is believed to underlie its enduring presence to this day. The application of arbuscular mycorrhizal fungi (AMF) based fertilizers has become increasingly common. Spores are the most important organs that determine the quality of AMF-based fertilizers, along with AMF colonization in the roots. The production of AMF spores is greatly influenced by plant physiology, including photosynthesis processes affected by canopy abundance, as well as the type of planting medium, which determines plant root growth and AMF habitat. This study was conducted to investigate the effect of pruning and planting medium composition on AMF infection and spore production in AMF propagation using sorghum as the host plant. The pruning levels tested were at one, two, and three months after germination, and thereafter, each plant was maintained for 136 days after planting (DAP). The tested planting medium composition was the ratio between zeolite and compost in five different compositions: (v/v) 1) 100:0, 2) 90:10, 3) 70:30, and 4) 50:50. The chemical characteristic of compost used was contained 15.5% C, 1.49% N, 2.54% P2O5, 1.49% K2O, pH 6.6, and some microelements such as Cr, Fe, Zn, and Mn at 5.2 ppm, 5961 ppm, 294 ppm, and 199 ppm, respectively. The Sukabumi‘s zeolite used had a size of 2-3 mm. Propagation of AM fungal spores was carried out using polybags containing 10 kg of medium according to the treatment. Plant maintenance was carried out by alternating between watering with water and Johnson nutrient solution. Watering was performed until the plants were 120 days old, and subsequently, no watering was done until 136 days after planting. The observed parameters were the development of AMF spore numbers until a 4.5-month incubation period. The results showed that pruning time can affect spore production if the plant has reached a certain vegetative age, which is three months for sorghum. Additionally, adding 10% compost to zeolite medium can enhance spore formation, even though sorghum growth may not be at its maximum in this medium composition.

Application of Arbuscular Mycorrhizal Fungi to Increasing N-total and P- Available Soil for Eggplant (Solanum melongena l.) Growth on Ultisol Soil

Ultisol land is a physically and chemically poor piece of land because it needs special handling that must be done with extreme caution. Arbuscular mycorrhizal fungi (AMF) is one biological fertilizer technique to get around this issue. One of the tiny soil creatures that can coexist with the roots of land plants is the arbuscular mycorrhizal fungi. In order to support plant development and make it simpler for plants to absorb nutrients and maintain soil moisture, AMF can symbiose with plant roots and form hifa around young roots. The purpose of this study is: (1) to determine the effect of the application of the AMF on increasing N-total and P-available on ultisol soil, (2) to determine the effect of the best AMF application on the growth of eggplant in Ultisol. This research was conducted on experimental land II and the Laboratory of AMI branch of Sultra. The study was conducted in November 2022- January 2023. This study used a group of randomized groups. Arbuscular mycorrhizal fungi consists of 5 levels, namely M0 = without treatment (control), M1 = 5 g , M2 = 10 g , M3 = 15 g , and M4 = 20 g polybag-1. The results of the study show that the AMF affected the total increase in N and P-available ultisol soil, the results of the initial analysis of 0.03% increased to 0.13% and P available from 9.00 ppm increased to 17.50 ppm. AMF with a dose of 20 g polybag-1 provides better eggplant plant growth.

Soil-borne microbes, natural stimulants, and post-harvest treatments alter quality and phytochemicals of tomato fruit

ABSTRACT Various approaches have been used to improve the quality of tomato (Solanum lycopersicum. L.) fruit. Studies on the impact of soil-born microbe and natural stimulant inoculum on tomato fruit are limited. Concentrations of arbuscular mycorrhizal fungi (AMF) and licorice root extract (LRE) were applied to the soil under greenhouse conditions. How post-harvest period affected quality of tomato fruit was tested by storing fruit after harvest. All treatments reduced weight loss compared to the control. The LRE applications increased fruit hardness, cohesiveness, and total sugar. Integrated AMF with LRE treatments improved fruit hardness, springiness, and cohesiveness increased. Overall, pH, total soluble solids, total sugar, total phenol, and chlorophyll contents of the fruit were increased, however, total acidity and vitamin C decreased. The AMF and LRE applications can be used to improve tomato fruit quality and yield.

Synergistic effect of silicon and arbuscular mycorrhizal fungi reduces cadmium accumulation by regulating hormonal transduction and lignin accumulation in maize

Cadmium (Cd) stress causes serious damage to plants, inducing various physiological and biochemical disruptions that lead to reduced plant biomass and compromised growth. The study investigated the combined effects of silicon (Si) and arbuscular mycorrhizal fungi (AMF) on mitigating Cd stress in plants, revealing promising results in enhancing plant tolerance to Cd toxicity. Under Cd stress, plant biomass was significantly reduced (−33% and −30% shoot and root dry weights) as compared to control. However, Si and AMF application ameliorated this effect, leading to increased shoot and root dry weights (+47% and +39%). Furthermore, Si and AMF demonstrated their potential in reducing the relative Cd content (−43% and −36% in shoot and root) in plants and positively influencing plant colonization (+648%), providing eco-friendly and sustainable strategies to combat Cd toxicity in contaminated soils. Additionally, the combined treatment in the Cd-stressed conditions resulted in notable increases in saccharide compounds and hormone levels in both leaf and root tissues, further enhancing the plant's resilience to Cd-induced stress. Si and AMF also played a vital role in positively regulating key lignin biosynthesis genes and altering lignin-related metabolites, shedding light on their potential to fortify plants against Cd stress. These findings underscore the significance of Si and AMF as promising tools in addressing Cd toxicity and enhancing plant performance in Cd-contaminated environments.

The effect of Arbuscular Mycorrhizal Fungi (AMF) on agronomic characteristics of clove seedlings of superior local variety of East Halmahera

Cloves (Syzygium aromaticum L.) have taproots but during the dry season the plants suffer from drought. Increasing the surface area of plant roots in the nursery is very important to produce clove plants with roots that have a high absorption of water and nutrients from the soil. The aim of this study was to determine the effect of arbuscular mycorrhizal fungi (AMF) on the growth of clove seedlings in the nursery and their nursery business. The research was conducted at a clove nursery in Telaga Jaya Village, South Wasile District, East Halmahera Regency, North Maluku from May to October 2020. The study used a Completely Randomized Block Design consisting of 4 treatments and three replications. The treatments were AMF doses: 0 g, 25 g, 50 g, and 75 g on each polybag. The results showed that the application of AMF increased plant height, number of branches, number of leaves, stem diameter, root length, and fresh weight of roots. East Halmahera clove nursery business had higher profits when using AMF than without AMF application.

The effect of Arbuscular Mycorrhizal Fungi (AMF) on agronomic characteristics of clove seedlings of superior local variety of East Halmahera

Cloves (Syzygium aromaticum L.) have taproots but during the dry season the plants suffer from drought. Increasing the surface area of plant roots in the nursery is very important to produce clove plants with roots that have a high absorption of water and nutrients from the soil. The aim of this study was to determine the effect of arbuscular mycorrhizal fungi (AMF) on the growth of clove seedlings in the nursery and their nursery business. The research was conducted at a clove nursery in Telaga Jaya Village, South Wasile District, East Halmahera Regency, North Maluku from May to October 2020. The study used a Completely Randomized Block Design consisting of 4 treatments and three replications. The treatments were AMF doses: 0 g, 25 g, 50 g, and 75 g on each polybag. The results showed that the application of AMF increased plant height, number of branches, number of leaves, stem diameter, root length, and fresh weight of roots. East Halmahera clove nursery business had higher profits when using AMF than without AMF application.

Research Progress of Arbuscular Mycorrhizal Fungi Promoting Citrus Growth

Citrus, the world’s most common fruit, boasts an abundance of resources and varieties and possesses a high commodity value. Arbuscular mycorrhizal fungi (AMF) and citrus roots can form a symbiotic relationship, promoting citrus growth, improving its disease resistance, and increasing the quality of the fruits. However, the literature lacks a detailed understanding of the symbiotic citrus–AMF relationship in cultivation. In this study, we reviewed the diversity (different citrus species and habitats), stress resistance (disease, drought, saline-alkali, temperature stresses), expression of defense genes, and underlying mechanisms of symbiotic AMF in citrus. Our aim was to provide a robust reference point and offer valuable insights to guide future studies on citrus symbiotic AMF and their applications in citrus planting. This review could help to facilitate AMF applications in citrus biological control (particularly in the citrus Huanglongbing) and sustainable development.

Effects of AMF inoculation on the growth, photosynthesis and root physiological morphology of root-pruned Robinia pseudoacacia seedlings.

Root pruning hinders the absorption and utilization of nutrients and water by seedlings in the short term. Arbuscular mycorrhizal fungi (AMF) are an important source of nutrient and water for seedlings except for the root system. However, the mechanism by which AMF affect the physiological growth of seedlings after root pruning has rarely been studied. In this study, a pot experiment was conducted through a three-compartment partition system to clarify the effects of Funneliformis mosseae (F. mosseae) strain BGC XJ07A on the physiological growth of root-pruned Robinia pseudoacacia seedlings. Five root pruning treatments (zero, one-fifth, one-fourth, one-third and one-half of the taproot length were removed) were applied to noninoculated seedlings and those inoculated with F. mosseae. The results showed that the presence of F. mosseae significantly increased the shoot and root biomasses, leaf photosynthetic rate, stomatal conductance and transpiration rate. The root projected area, root surface area, average root diameter, root density, root volume and number of root tips of the inoculated seedlings were higher than those without inoculation in all root pruning treatments. The root cytokinin, gibberellins and indole-3-acetic acid concentrations, but root abscisic acid concentration, were higher than those measured in the absence of inoculation in all root pruning treatments. Moreover, the changes in the root endogenous hormone concentrations of the seedlings were closely related to the root morphological development and seedling biomass. The AMF increased the soil available nitrogen, soil available phosphorus, soil available potassium and soil organic matter concentrations compared with the noninoculated treatment. These results indicate that AMF can alleviate the adverse effects of root pruning on the physiological growth of R. pseudoacacia and soil properties, and can provide a basis for AMF application to forest cultivation and the sustainable development of forest ecosystems.

AM fungus promotes wheat grain filling via improving rhizospheric water & nutrient availability under drought and low density

Arbuscular mycorrhizal fungi (AMF) are widely considered as ecosystem engineers to positively affect the adaptation of plants to adverse environments, but whether AMF can commonly promote root-soil relationships and reproductive allocation is unclear in dryland crops. It is crucial to reveal if AMF can promote grain filling via mediating rhizosphere interactions regardless of soil water regimes and planting densities in dryland crops for the application of AMF regarding more precise management. To address this issue, Funneliformis mosseae was inoculated in pot-cultured wheat to examine the inoculation effects on wheat growth, yield formation, rhizospheric moisture and nutrient status across four planting densities under the drought and well-watered conditions. As expected, under drought stress, wheat grain filling, shoot biomass, rhizospheric soil water content (SWC), water use efficiency (WUE), soil organic carbon (SOC) content and the ratio of SOC to soil total nitrogen (TN) contents were significantly lowered in the soils without AMF inoculation across four planting densities. Under well-watered conditions, the SWC ranged from 10.30 % to 16.64 %, while under water stress conditions, the values ranged from 5.77 % to 9.61 %. Soil mineralized nitrogen (NO3−-N and NH4+-N) contents were decreased with AMF regardless of soil water status and planting densities. Under drought stress, AMF inoculation increased wheat productivity, WUE, SWC, SOC content, the ratio of SOC to TN, and promoted the absorption of mineralized nitrogen. Particularly, AMF inoculation substantially promoted the soil easily oxidizable organic carbon (EOC) content by 58.5 % and 55.6 % in the two highest densities, respectively. The soil microbial biomass carbon (MBC) content was totally >50 mg kg−1, whereas that of the non-AMF group was <40 mg kg−1. AMF inoculation significantly promoted grain yield up to 28.5 % under drought stress. Such a trend was tightly associated with higher WUE, rhizosphere C/N ratio and labile SOC (EOC and MBC) content owing to the enhanced absorption of soil mineralized nitrogen under drought stress with AMF. The above trend tended to become weaker with increasing densities. However, under a sufficient water supply, AMF inoculation had no such significant effect on the above parameters in low densities, and turned to generate negative effects under high densities (P < 0.05). For example, compared with well-watered, AMF inoculation reduced wheat grain yield and shoot weight by 9.78 % and 4.83 % in high planting density treatment (HC), respectively. Therefore, the inoculation effects of AMF were highly dependent on planting density and soil moisture, and the mechanism was that AMF optimized the rhizospheric interactions for better water and nutrient status under drought and low density. Our findings may provide novel insights into the application of AMF regarding agricultural sustainability under climate change.