Mycorrhizal Fungi and Phosphorus Application

Aims: The effective use of companion trees in agroforestry systems could improve the health and productivity of cocoa trees by understanding the interactions they promote. This study aims to decipher the characteristics of arbuscular mycorrhizal communities in the roots and soil of cocoa trees and their companion trees to understand the interaction between these two types of trees. Methodology: Five mycorrhization parameters measured in cocoa trees and nearby companion trees were compared. These were, shared species diversity, number of spores, mycorrhization frequency, mycorrhization intensity and colonization intensity in the mycorrhized part of the root system. correlation tests between these parameters were also used to establish the link between the data. Results: The study identified 49 AMF species involved in the interactions between companion and cocoa trees. T. superba (64.28%) and B. mannii (62.5%) recorded the highest species diversity and spore numbers. The highest mycorrhization rates were found between T. ivorensis and cocoa. Statistical analysis revealed strong positive correlations for species diversity and spore numbers with specific companion trees. Based on the results, T. superba, B. mannii, and R. heudelotii are recommended for promoting mycorrhizal spore production, while T. ivorensis is suggested for high mycorrhization levels. Conclusion: The study of interactions thus disclosed strong links between all cocoa trees and companion trees on the basis of the 5 types of variables used to establish correlations. But, A. boonei, T. superba, T. ivorensis, T. heckelii, M excelsa, B. mannii, B. mannii and G. kola can be recommended in cocoa agroforestry systems as they have the most important mycorrhizal interactions with cocoa trees.

A field experiment was conducted to investigate the effect of phosphorus and boron on yield and yield attributes of black gram. Four levels of phosphorus (0, 25, 50, 75 kg ha-1) and four levels of boron (0, 0.5, 1.0, 1.5 kg ha-1) were laid in split plot design with three replications. . The native soil had a pH 4.99, E.C. 0.42 dS m-1, organic carbon 1.32%, available nitrogen 251.35 kg ha-1, available phosphorus 13.68 kg ha-1, available potassium 233.24 kg ha-1 and hot water soluble boron 0.054 ppm. The results revealed that application of phosphorus and boron have a synergistic effect on yield, content and uptake in seed and straw of black gram. Significant highest seed yield was found when 50 kg P2O5 ha-1 along with 1.5 kg B ha-1. Significant plant height at 30 DAS (20.04 cm) and 60 DAS (39.31 cm) was found with the application of P50B1.5 whereas at maturity, the plant height was recorded maximum (43.01 cm) at P50B0.5. Whereas, highest number of pods per plant was recorded with com...

Alternative substrates were evaluated for mycorrhizal inoculants production considering the beneficial effects of arbuscular mycorrhizal fungi (AMF) for plants and environment. The first step of the experiment aimed at evaluating the potential of substrates produced from sugarcane bagasse (SB), coconut fibre (CF) and urban waste compost (UWC) to produce AMF inoculants, by using Brachiaria decumbens as multiplier plant. The experiment has followed a randomized block design, at 7x3 factorial arrangement (seven substrates: SB, CF,

Plants respond differentially to different arbuscular mycorrhizal fungi (AMF) as well as to the different soil moisture levels. Based on this background, the present study was carried out to investigate the effects of different levels of soil moisture and AMF inoculations on mycorrhization and growth of important agroforestry plants, viz., Phaseolus mungo, Triticum aestivum, Eucalyptus tereticornis, and Albizia procera. The experiments consisted of main treatment, i.e., three levels of soil moisture [field capacity (FC016 %), half-field capacity (FC/208 %) and double-field capacity (2×FC032 %)] and four subtreatments (mycorrhizal inoculations), viz., Acaulospora scrobiculata, Glomus cerebriforme, Glomus intraradices, and un-inoculated (control). AMF inoculations significantly (P<0.05) increased growth and P uptake, in all tested plant species. In P. mungo, maximum AMF efficiency was observed at FC while in other plants, AMF were equally effective at FC/2 and 2×FC. Different inoculants were effective at different moisture levels. Furthermore, mycorrhization was the highest at FC. AMF inoculations were more important than soil moisture (explaining 33-97 % variation in growth) in P. mungo, T. aestivum, and A. procera (forward selection method), whereas soil moisture was more important for growth of E. tereticornis. Thus, it may be stated that depending upon soil moisture, inoculation of plants with suitable AMF consortium can be beneficial. Keywords Arbuscular mycorrhiza. Albizia procera. Eucalyptus tereticornis. Phaseolus mungo. Soil moisture. Triticum aestivum 2009). These situations (wet or dry) impose plants to a variety of stresses (Livesley et al. 2004). In such conditions, inoculation with arbuscular mycorrhizal fungi (AMF) can confer many benefits to the plants (Auge 2001; Entry et al. 2002; Mendoza et al. 2005). According to Garcia and Mendoza (2009), AMF are important in the ecology and physiology of plants, particularly for those living under abiotic stresses. They are the key factors in increasing tolerance to the drastic environmental conditions (Subramanian et al. 2006). These can cause changes in plant-water relations (Broadhead et al. 2003; Livesley et al. 2004; Boomsma and Vyn 2008). AM symbiosis protects plant from the adverse effects of drought and water logging (Miller and Bever 1999; Auge 2001; Mendoza et al. 2005) where a variety of mechanisms can be involved (Ruiz-Lozano and Azcon 1995). They increase plant growth by nutrient transportation, phytohormone production, and by augmentation of root surface (Al-Karaki and Al-Raddad 1997; Al-Karaki et al. 1998; Karasawa et al.

Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/23/2-3-1/12 The 23rd International Grassland Congress (Sustainable use of Grassland Resources for Forage Production, Biodiversity and Environmental Protection) took place in New Delhi, India from November 20 through November 24, 2015. Proceedings Editors: M. M. Roy, D. R. Malaviya, V. K. Yadav, Tejveer Singh, R. P. Sah, D. Vijay, and A. Radhakrishna Published by Range Management Society of India

Alternative substrates were evaluated for mycorrhizal inoculants production considering the beneficial effects of arbuscular mycorrhizal fungi (AMF) for plants and environment. The first step of the experiment aimed at evaluating the potential of substrates produced from sugarcane bagasse (SB), coconut fibre (CF) and urban waste compost (UWC) to produce AMF inoculants, by using Brachiaria decumbens as multiplier plant. The experiment has followed a randomized block design, at 7x3 factorial arrangement (seven substrates: SB, CF,

The low sufficiency of animal protein sources has elevated the need for alternative protein sources. Despite its food security potential, bambara groundnut ( Vigna subterranea (L.) Verdc) has remained an orphaned or neglected underutilized crop. The need to increase national output will necessitate its introduction into areas with no history of the crop. Two year field experiments were conducted at the Teaching and Research Farm of the University of Calabar, Nigeria to evaluate the effects of three planting densities (30 x 30, 30 x 40 and 30 x 50 cm) corresponding to 111,111; 83,333 and 69,400 plants ha -1 and four levels of P 2 O 5 (0, 45, 60 and 75 kg ha -1 ) on the yield performance of bambara nut, using a 3 x 4 factorial experiment. Treatments were dispersed using randomized complete block design with three replications. Results showed that the vegetative attributes were not significantly affected by the treatments. However, total dry matter, dry pod yield and the seed yield ha ...

SUMMARYFindings from multi-year, multi-site field trial experiments measuring maize yield response to inoculation with the phosphorus-solubilizing fungus,Penicillium bilaiaeChalabuda are presented. The main objective was to evaluate representative data on crop response to the inoculant across a broad set of different soil, agronomic management and climate conditions. A statistical analysis of crop yield response and its variability was conducted to guide further implementation of a stratified trial and sampling plan. Field trials, analysed in the present study, were conducted across the major maize producing agricultural cropland of the United States (2005–11) comprising 92 small (with sampling replication) and 369 large (without replication) trials. The multi-plot design enabled both a determination of how sampling area affects the estimation of maize yield and yield variance and an estimation of the ability of inoculation withP. bilaiaeto increase maize yield. Inoculation increase...

Abstract: A study was conducted to investigate the effect of soil moisture levels (field capacity [FC], half field capacity [HFC] and double field capacity [DFC]) on growth and arbuscular mycorrhizal (AM) colonization of two crops (Phaseolus mungo Roxb. var. PU-35 and Triticum aestivum L. var. WH-147) and seedlings of two multi purpose tree species (Eucalyptus tereticornis Sm.[Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.). Significant increase in plant growth parameters and phosphorus (P) uptake was recorded ...

A field experiment was conducted during kharif season 2014 at P.S.B. Agriculture farm, Visva-Bharati, Sriniketan West Bengal to study the effect of phosphate solubilizing bacteria on growth and productivity of transplanted rice laid out in RBD with three replications. The result revealed that at harvest, highest (1101.11 g) dry matter was accumulated with NPK+PSB which was statistically at par but 7.9%, 8.6%, 13.27% higher than NP 0 K, NP 0 K+PSB and NPK, respectively. NP 0 K+PSB gave the highest (442.22) number of panicle m-2 which was significantly 40.70% and 37.68% higher over N 0 P 0 K 0 +PSB and N 0 P 0 K 0 , respectively. NPK+PSB proved best in influencing growth and productivity, which however at par with NP 0 K, NPK, NP 0 K+PSB, and NP 0 K+PSB+RP except NP 0 K+PSB+RP for dry matter at harvest. NPK+PSB recorded highest (₹ 52750/-) gross returns but NP 0 K resulted maximum (₹ 19466/-) net returns.

Arbuscular mycorrhizal fungi (AMF) help to facilitate mobilization of nutrients from soil to plant. The study was carried out in humid Rubavu and semi-arid Bugesera districts in Rwanda. We hypothesized that the presence of tree species in farming systems enhances mycorrhizal fungal density. The occurrence and abundance of AMF in the soil around main agroforestry tree species in these regions was studied. Tree species in Rubavu included Alnus acuminata, Markhamia lutea, Grevillea robusta and Eucalyptus sp. and in Bugesera Acacia polyacantha, Senna spectabilis, Grevillea robusta and Eucalyptus sp. AMF spores were isolated from soil samples collected under and outside the trees canopies. Results show significant differences in spore density between species. The density of AMF spores was highest under A. acuminata and A. polyacantha and lowest in Eucalyptus sp. and G. robusta in Rubavu and Bugesera, respectively. Generally, the mean spore abundance (spores/g of soil) was significantly h...

Anyigba Soils (Lat 7 0 29' and Long 7 0 11'E) in Kogi State is deficient in Nitrogen and Phosphorus which retard growth and yield of cowpea crop. A field experiment was therefore conducted during the rainy seasons of years 2018 and 2019 respectively, at the student Research and Demonstration Farm, Faculty of Agriculture, Kogi State University, Anyigba. The aim of the trial was to evaluate the influence of Nitrogen-fertilizer-starter dose and phosphorus on growth, yield attributes, final Grain yi eld and Grain Crude Protein content of three varieties of cowpea in Anyigba. The N-fertilizer rates were-0, 10 and 20kg N/ha applied as urea, while the P rates were 0, 37.5 and 75.0 Kg P2O5/ha as single super phosphate (26. 0% P2O5). Factorial experiment was used and treatments were arranged and laid out in Split Plot Design (SPD) and replicated three times. The results indicated that for both years, Nitrogen and Phosphorus application resulted in significant (P < 0.05) increases in growth, some yield attributes and final Grain Yield of the three varieties of cowpea. One major significant outcome of the exp eriment was that while Nitrogen application significantl y (P<0.05) increased number of nodul es produced/plant for all the sampling periods and for both years, phosphorus application how ever had no significant (P>0.05) influence on the character (nodule) throughout the sampling periods and for both years. The highest grain yi eld of 0.93tonha-1 was obtained with application of 10 kg N and 37. 5 Kg P2O5/ha. Application of 10.0 Kg N ha-1 and 37.5 Kg P2O5 ha-1 of Phosphorus significantl y (P<0.05) yielded a Crude Protein Content of 20.83% and 23.31% over the control plot which gave 20. 54% and 19.17% Crude Protein respectively in 2018 trials. This trend was equally maintained in 2019 trials.

Abstract. Asmelash F, Bekele T, Belay Z, Kebede F. 2021. Cordia africana but not Juniperus procera and Podocarpus falcatus respond positively to arbuscular mycorrhizal fungi at the early stages of seedling development. Biodiversitas 22: 2971-2980. AMF (Arbuscular mycorrhizal fungi) inoculation could be an important technology to improve the growth and field survival of trees. Hence, we evaluated the mycorrhizal responsiveness of Cordia africana Lam., Juniperus procera (Hoechst. ex Endl.), and Podocarpus falcatus (Thumb.) Mirb. seedlings. Seedlings germinated on sterile sand were transplanted to 1-liter plastic pots filled with sterile and non-sterile degraded bulk soil. Rhizospheric soil from adult C. africana and J. procera were used as whole-soil AMF inocula. Cordia africana and J. procera received conspecific whole-soil AMF inocula while P. falcatus received J. procera inoculum. Hence, in the two-by-two factorial experiment, we also evaluated the growth effects of AMF inoculation...

We present findings from multi-year, multi-site field trial experiments measuring corn yield response to inoculation with the phosphorus-solubilizing fungus, Penicillium bilaiae Chalabuda. Our main objective was to evaluate representative data on crop response to the inoculant across a broad set of different agronomic management and climate conditions. Our research objective was to conduct a statistical analysis of crop yield response and its variability to guide further implementation of a stratified sampling plan. Field trials analyzed in this study were conducted across the major corn producing agricultural cropland of the United States (2005-11) comprising 92 small (with sampling replication) and 369 large (without replication) trials. Corn was selected given its particularly high demand for nutrients and associated fertilizer additions, and its economic importance to the agricultural sector. Our multi-plot design enabled both a determination of how sampling area affects the est...

A study of arbuscular mycorrhizal fungi in the rhizosphere of date palm was conducted in the palm groves of Tafilalet and Zagora (southeastern Morocco). The parameters considered are the root colonization of date palm, spore density and species richness. The average frequencies and intensities of colonization are 66% and 7.34% respectively. The spore density varies between 80% and 132 spores / 100 g of soil, according to the site. Nine species of arbuscular mycorrhizal fungi were identified in all study sites; their appearance frequency is from 1 to 6%. Species richness varies from 2 to 7 species depending on the sites.

The presence of indigenous mycorrhizal fungi may have significant effects on the growth and on the root morphology of plants, under arid and semi arid soil conditions. Lentil and wheat are the traditional crops grown in Southeastern Turkey. In this study soil samples from the Harran plain were collected from the 0-15 cm surface layer under wheat or lentil crop residues and used in a pot experiment carried out under greenhouse conditions with four levels of P fertilization: 0, 20, 40 and 80 mg kg-1 soil as Ca(H 2 PO 4) 2. Half of the soil batches were submitted to a heating treatment (80°C, 2 h). The maize variety PX-9540 was grown in the pots for 57 days. At harvest, plant dry weight, root length, P and Zn concentrations in plant tissues were measured and the extent of root colonization by arbuscular mycorrhizal fungi (AMF) was determined. Results showed that maize plants grown in soils where lentil had been previously cultivated grew better than those grown after wheat cultivation. In both cases, P concentration in plant tissues increased with increased P fertilization. There were no significant differences in root AMF colonization between soils with different crop sequences, nor with soils submitted to high temperature. Previous crops had a significant influence on the growth of plants that could be related to differences in the indigenous mycorrhiza inoculum potential and efficacy that can promote P uptake and benefit plant growth.

A field experiment was conducted at New Delhi in rainy (kharif) season of 2013 to study the effect of 2 sources of phosphorus, viz. rock phosphate (RP) and di-ammonium phosphate (DAP), 2 levels of phosphorus viz. 15 and 30 kgP/ha and 2 microbial inoculants viz. phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) in different combination along with control on growth, productivity and economics of aerobic rice (Oryza sa-tiva L.). Seed was inoculated with liquid formulation of PSB @ 250 ml/ha before sowing and AMF was applied @ 12 kg/ha in the furrows at the time of sowing. Recommended doses of N (120 kg/ha) and K (40 kg/ha) were applied in all the treatments. Results revealed that plant height, tillers/plant, dry-matter/plant, panicle/plant and yield (5.62 t/ha) of aerobic rice increased significantly due to application of 30 kg P/ha through RP + PSB + AMF. There was significant increase in plant height, tillers, dry-matter, number of panicles and grain yield of aerobic rice with increase in P application rate from 15 kg P/ha to 30 kg P/ha applied either through DAP or RP. The application of 30 kg P/ha through RP + PSB + AMF resulted in highest net return (139.0 × 10 3 /ha) of aerobic rice. Phosphorus (P) deficiency has been recognized as one of the main limiting factors in upland rice production in many parts of the world (Sahrawat et al., 1995). P deficiency can be rectified with supplying phosphate to the soils but a large portion of soluble inorganic phosphate applied to the soil as chemical fertilizer is immobilized rapidly and becomes unavailable to plants (Goldstein, 1986). Rock phosphate (RP) is cheapest P containing fertilizer but completely insoluble in soil hence, there is growing interest in manipulating RP by biological methods in order to enhance its solubilization and agronomic effectiveness (Whitelaw, 2000). Microorganisms especially phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) have the ability to solubilize P in soil and reduce burden of chemical fertilizers (Arpana and Bagyaraj, 2007). With this background, the present study was undertaken to investigate the effect of microbial inoculants with RP in supplying the P and find out the optimum application rate for higher plant growth and yield of aerobic rice. A field experiment was conducted during rainy (Kharif) season (June-November) of 2013 at the research field of ICAR-Indian Agricultural Research Institute, New Delhi. The soils of experimental field had 142.3 kg/ha alkaline permanganate oxidizable N, 13.46 kg/ha available P, 252.2 kg/ha 1N ammonium acetate exchangeable K and 7.7 pH. The experiment was laid out in randomized block design with fifteen treatments including P control, phosphate -solubilizing bacteria (PSB), arbuscular mycorrhizal fungi (AMF), PSB + AMF, 15 kg P/ha through rock phosphate (RP), 30 kg P/ha through RP, 15 kg P/ha through di-ammonium phosphate (DAP), 30 kg P/ha through DAP, 15 kg P/ha through RP + PSB, 15 kg P/ha through RP + AMF, 15 kg P/ha through RP + PSB + AMF, 30 kg P/ha through RP + PSB, 30 kg P/ha through RP + AMF, 30 kg P/ha through RP + PSB + AMF and P on soil test basis. The rice variety 'Pusa Basmati 1509' was sown at 20 cm row to row spacing on 26 June, 2013. Seed rate of 40 kg/ ha was used. Liquid formulation of PSB was inoculated with seed at 250 ml/ha before sowing and AMF was applied in the furrows at the time of sowing at 12 kg/ha. N (120 kg/ha) and K (40 kg/ha) were applied in all treatments Research Communication

Arbuscular mycorrhizal (AM) symbiosis is established between the roots/rhizoids of ca 70% of extant plant species, including some of the most important crops, and specialized soil fungi. The AM fungi provide a direct interconnection between roots and soil as well as between root systems of different plant individuals belonging to the same or different plant species. AM fungi exert several direct (e.g., enhanced nutrient acquisition, pollutant immobilization/detoxification, plant carbon reallocation, induced pathogen tolerance, signal transfer), and indirect (e.g., photosynthesis stimulation, drought tolerance, soil physical and microbial conditioning) effects on the plants, with possible consequences to yield and agricultural product quality, multitrophic interaction (e.g., pollinator) networks, and soil quality. Besides having a finely tuned molecular dialogue with their plant hosts, the fungi also interact with soil microbes fulfilling important ecosystem functions, such as organic nutrient mineralization or stabilization of soil organic matter, and these interactions are further modulated by environmental (soil, climatic, ecosystem management) contexts. The goal of this Research Topic is to provide a holistic view on the functioning of AM symbiosis in natural and anthropogenic systems, with special emphasis on metabolic and genetic reprogramming of the plants. In addition, this topic aims to promote mechanistic understanding of the formation, extent, and dynamics of the AM fungal hyphal networks and associated microbes in the soil, particularly with respect to agricultural production and feedback between human interventions and ecosystem functioning across various plant species/genotypes, soil types, climatic regions, and management systems (considering factors such as land-use intensity, tillage, crop rotation, and various kinds of inputs, among others). Knowledge should be synthesized from natural systems to build more sustainable agroecosystems for the future striving to improve resource recycling upon food/feed production, maintain/improve soil and plant quality, and satisfy human demands for various ecosystem services in a globalized and rapidly changing world. The collection of articles should provide quantitative answers, feeding the ongoing debate as to whether AM symbiosis should be included in crop breeding programs, considered in soil quality testing, and/or assigned any monetary value-or whether humans should not care much about this hidden soil resource in their future visions, which is the current state of the art. We welcome a broad range of formats such as Original Research Articles, Reviews/meta-analyses, Hypotheses and Opinions, Letters and Commentaries relevant to AM symbiosis functioning in ecosystems (relevant but not necessarily restricted to agroecosystems), all being scientifically rigorous and always backed up with relevant references to previous research/scientific evidence. The following topics are particularly welcomed:  Physiological and metabolic reprogramming of plants by AM fungi/symbiosis  Molecular dialogue between plant, associated AM fungi, and hyphosphere microbes  Interaction of AM fungi and soil bacteria/fungi/animals/protists in soil, and consequences of such interactions for plant responses to biotic and abiotic stresses  Each article should be including the human dimension of the tackled research, relevance to society and future agriculture  Socioeconomic aspects of AM symbiosis and its contributions to current and future (agro)ecosystem functioning, stability, resilience, and sustainability Studies from genetics and genomics, transcriptomics, proteomics, metabolomics, and ionomics areas are all welcome. However, purely descriptive studies using-omics approaches will only be considered for review/ inclusion into this Research Topic if they provide justified insights into (demonstrated or theoretical) functions of the molecular pathways described.

The aim of this study was to reduce food insecurity by improving the yield of Bambara groundnut with phosphorus fertilizer. The experiment was carried out in the field at the University of Yaounde I. The experimental design was a split plot with three factors; landraces (V1 and V2), single superphosphate doses (0, 50, 100, 150 and 200 kg P2O5.ha-1) and AMF inoculum (M0:-AMF and M1: +AMF). P2O5 doses and AMF (composites Gigaspora margarita, Acaulospora tuberculata and Glomus intraradices) significantly boosted growth (number of branches, shoot height) and yield of Bambara groundnut. The dose 150 kg P2O5.ha-1 significantly increased the yield by 100% compared to the control (0 kg P2O5.ha-1 +M0) in V1. AMFs significantly increased the yield by 87.5% compared to the control in V2. P2O5 and AMF independently improved the grain yield. However, low doses of P2O5 (100 kg.ha-1) may be associated with AMF to maximize grain yield of Bambara groundnut.

The phytoremedial potential of three halophytes and the role of arbuscular mycorrhizal fungi (AMF) isolated from heavy metal contaminated soil under cadmium stress were studied. The plants were treated with different Cd concentrations (0, 50, 200, and 400 µM) with and without AMF inoculation. On the plant growth, AMF inoculation to all species resulted in increased biomass, shoots and roots length, and leave number compared to control (non-inoculated) plants, especially in Limbarda crithmoides, where no mortality was detected neither in controls nor inoculants. Furthermore, L. crithmoides and Atriplex canescens recorded higher values of relative mycorrhizal dependency and water content. The arbuscular mycorrhizal association was observed in all host plants and was not affected by cadmium. Our results indicate that studied halophytes can tolerate high Cd concentrations due to the support of AMF, particularly in Atriplex halimus association with AMF in pot experiment which was recorded for the first time.

Wheat production (Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha À1 during the last 5 years, and 164 kg P ha À1 applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot À1 ), and nitrogen (N) fertilization (0 and 150 mg N pot À1 ). A range of soil P between 6 and 60 mg P kg À1 was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content (r 2 = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0-27 mg P kg À1 (a decrease of 2.8% mg P À1 kg À1 ). Above 27 mg P kg soil À1 , AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil À1 . The soil P range that ensures high wheat production without deterring indigenous AMC is discussed. #

Wheat production (Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha À1 during the last 5 years, and 164 kg P ha À1 applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot À1 ), and nitrogen (N) fertilization (0 and 150 mg N pot À1 ). A range of soil P between 6 and 60 mg P kg À1 was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content (r 2 = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0-27 mg P kg À1 (a decrease of 2.8% mg P À1 kg À1 ). Above 27 mg P kg soil À1 , AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil À1 . The soil P range that ensures high wheat production without deterring indigenous AMC is discussed. #

Wheat production (Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha À1 during the last 5 years, and 164 kg P ha À1 applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot À1 ), and nitrogen (N) fertilization (0 and 150 mg N pot À1 ). A range of soil P between 6 and 60 mg P kg À1 was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content (r 2 = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0-27 mg P kg À1 (a decrease of 2.8% mg P À1 kg À1 ). Above 27 mg P kg soil À1 , AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil À1 . The soil P range that ensures high wheat production without deterring indigenous AMC is discussed. #

BACKGROUND: In a field experiment conducted in a Mediterranean area of inner Sicily, durum wheat was inoculated with plant growth–promoting rhizobacteria (PGPR), with arbuscular mycorrhizal fungi (AMF), or with both to evaluate their effects on nutrient uptake, plant growth, and the expression of key transporter genes involved in nitrogen (N) and phosphorus (P) uptake. These biotic associations were studied under either low N availability (unfertilised plots) and supplying the soil with an easily mineralizable organic fertiliser. Regardless of N fertilisation, at the tillering stage, inoculation with AMF alone or in combination with PGPR increased the aboveground biomass yield compared to the uninoculated control. Inoculation with PGPR enhanced the aboveground biomass yield compared to the control, but only when N fertiliser was added. At the heading stage, inoculation with all microorganisms increased the aboveground biomass and N. Inoculation with PGPR and AMF+PGPR resulted in significantly higher aboveground P compared to the control and inoculation with AMF only when organic N was applied. The role of microbe inoculation in N uptake was elucidated by the expression of nitrate transporter genes. NRT1.1, NRT2, and NAR2.2 were significantly upregulated by inoculation with AMF and AMF+PGPR in the absence of organic N. A significant down-regulation of the same genes was observed when organic N was added. The ammonium (NH4+) transporter genes AMT1.2 showed an expression pattern similar to that of the NO3- transporters. Finally, in the absence of organic N, the transcript abundance of P transporters Pht1 and Pht2;1 was increased by inoculation with AMF+PGPR, and inoculation with AMF upregulated Pht2 compared to the uninoculated control. These results indicate the soil inoculation with AMF and PGPR (alone or in combination) as a valuable option for farmers to improve yield, nutrient uptake, and the sustainability of the agro-ecosystem.

Four vesicular arbuscular mycorrhizal (VAM) fungi (Glomus spp.) isolates namely VAM-O, VAM-B, VAM-S and VAM-M were isolated from onion, broad bean, swiss cheese and maize roots, respectively, used to produce in vitro inocula which were evaluated under field conditions. The VAM isolates were grown in vitro on barely modified (BM) cultures to produce their applicable inocula. The in vitro inocula were used at low (2.5/g ridge), medium (5.0/g ridge) and high levels (10.0/g ridge) equivalent to 10, 15 and 20 kg/feddan, respectively. Two field experiments were carried out during 2002 and 2003 growing seasons to evaluate the effect of VAM inoculation treatments compared to P-fertilizer and VAM inoculation + N-fertilization compared to N-fertilizer alone on the seed germination, percentage of smutted and stunted plants, fresh and dry weight/plant, ear weight, grain yield/plant and weight of 100-kernels. Response of maize to VAM inoculation was greatly varied depending on the VAM isolate, inoculum level and growing season. The aforementioned maize growth parameters were significantly enhanced by VAM inoculation than P-fertilization, whereas most VAM treatments + N-fertilization showed similar response when compared with the N-fertilizer alone.

Pongamia pinnata (L.) Pierre, a fast-growing oil-seed-producing tree legume, has the ability to grow on wastelands. It can be utilized for biofuel plantation on such lands. The preconditioning of young seedlings during the early stage of development with efficient arbuscular mycorrhizal fungi (AMF) confers several benefits enhancing the possibility of their establishment in fields after outplanting from nurseries. However, before recommending these fungi for inoculation, the suitable AMF species must be identified. Therefore, to determine the potential AMF species, 9 purified fungi (isolated from different sites) were tested for their growth promotion activity. The inoculated fungi were not able to increase seedling growth. Some fungi reduced growth, which was attributed to more utilization of carbon by fungal symbiont. Development of fine roots was delayed up to 30 days after sowing and hence their colonization by AMF
inoculants. This could be due to the large amount of nutrients stored in cotyledons of large P. pinnata seeds. Removal of cotyledons significantly reduced seedling growth and plants showed some extent of dependency on AMF inoculants. Thus, it was concluded that AMF inoculations should enhance biomass of P. pinnata only after depletion of metabolic reserves in its cotyledons and such mycorrhizal
seedlings can be utilized for biofuel plantation.

Abstract: A study was conducted to investigate the effect of soil moisture levels (field capacity [FC], half field capacity [HFC] and double field capacity [DFC]) on growth and arbuscular mycorrhizal (AM) colonization of two crops (Phaseolus mungo Roxb. var. PU-35 and Triticum aestivum L. var. WH-147) and seedlings of two multi purpose tree species (Eucalyptus tereticornis Sm.[Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.).

In tree-based intercropping system (agroforestry), the role of perennial trees in maintaining active populations and mycelial networks of arbuscular mycorrhizal fungi (AMF) is well documented. Agroforestry positively influences the AMF community, but complete studies regarding mycorrhization in such systems are scarce. The present study was conducted to assess the effect of tree introduction in agriculture fields on mycorrhization. In particular, we investigated the effect of trees on AMF colonization of intercrops and vice versa, the effect of canopy management of trees on their root colonization, and the cross-infectivity of AMF isolated from tree rhizosphere in intercrops and vice versa. The results of the field study suggest that in agroforestry systems, trees acted as AMF inoculum reservoir for intercrops, especially during the rainy season. Intercropping (Phaseolus mungo and Triticum aestivum in the rainy and winter seasons, respectively) increased mycorrhization, i.e., root colonization and spore population in the rhizosphere of Albizia procera and Eucalyptus tereticornis. Canopy management, i.e., shoot pruning, reduces root colonization in A. procera, Anogeissus pendula, Dalbergia sissoo, Hardwickia binata, and Tectona grandis, especially in April 2005 (late spring), but during subsequent periods, differences among the treatments were at par. Results from greenhouse suggest that AMF are nonspecific in their selection of host since species isolated from tree rhizosphere could colonize the roots of crops and vice versa.

Jatropha curcas L. and Pongamia pinnata Pierre are gaining importance as bio-diesel crop in India. J. curcas is a member of the family Euphorbiacea and P. pinnata, a member of the family Leguminoseae. A study was conducted to identify common arbuscular mycorrhizal fungi present in its rhizosphere from different regions of India viz., Jodhpur (Rajasthan), Hissar (Haryana), Jhansi and Lalitpur (Uttar Pradesh) and Hyderabad (Andhra Pradesh). The results showed that different AM fungal species were present at different locations. A total of five Acaulospora species were recorded from different locations of India. The highest frequency of occurrence was recorded for Acaulospora scrobiculata Trappe (100%), minimum frequency of occurrence was observed in A. mellea in J. curcas. The highest frequency of occurrence was recorded for Acaulospora scrobiculata Trappe (75%), moderate frequency of occurrence was observed in A. mellea in P. pinnata. Maximum species richness was recorded at Jodhpur, followed by Jodhpur, Hissar, Hydrabad, Jhansi, Lalitpur, and Pantnagar. Isolation of five species of Acaulospora species (A. dilatata (Morton), A. denticulata (Sieverding & Toro), A. longula (Spain & Schenck), A. mellea (Spain & Schenck), and Spores formed singly in the soil, borne or in sporocarps, spores are globose and subglobose, borne laterally on subtending hypha of large, terminal, relatively thin walled, sporogenous saccule. Spore composed to essentially two distinct, separable wall groups: at least part of outer is continuous with wall of subtending stalk, may be pigmented, laminated or composed distinct wall, and variously ornamented; inner is composed of one or more walls that are usually membranous, hyaline, may be laminated, ornamented, and stain pink, red, or purple in Melzer’s-reagent.

A study was conducted (during 2004-05) to access the effect of trees on colonization of intercrops by vesicular arbuscular mycorrhizae in agroforestry systems under and outside tree canopy in 43 tree crop combinations. Trees acted as vesicular arbuscular mycorrhizal inoculum reservoir for intercrops in most of the combinations. During rainy (kharif) season colonization index of intercrops was significantly more under tree canopy in all 24 tree-crop combinations as compared to respective values outside tree canopy. During winter (rabi) season colonization index of intercrops was significantly more under tree canopy only in 5 combinations viz., ber (Zizyphus rnauritiarla L.) + wheat (Triticurlz aestivum L. emend. Fiori & Paol), neem (Azadirachta indica A. Juss.) + wheat, neem + gram (Cicer arietinum L.), neem + pea (Pisurn sativum L.) and teak (Tectona grandis L.E) + gram, than outside tree canopy. The index of the intercrops was at par under and outside tree canopy in remaining 14 combinations. A net-house study under different shade levels showed that heavy shade reduced vesicular arbuscular mycorrhizal colonization in wheat when winter was at its peak. Results on effect of different shading conditions on microclimate of net house indicated that with increase in per cent shade, soil moisture increased and soil surface temperature, sub soil temperature at 10 cm depth and lux meter reading at 12 noon decreased.

The study was conducted to investigate the effects of different light intensities (25, 50, 67, and 100% of full sun [open]) on arbuscular mycorrhizal (AM) colonization and growth of two intercrops (a rainy season crop, Phaseolus mungo Roxb. var. PU-35 and a winter crop, Triticum aestivum L. var. WH-147) and seedlings of two multipurpose tree species (Eucalyptus tereticornis Sm. [Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.) of Central India. The results showed that various plant growth parameters viz., shoot length, dry weight and phosphorus (P) uptake were adversely affected by low light intensity. Inoculations with AM fungi (Acaulospora scrobiculata Trappe, Glomus intraradix Schenck & Smith and an unidentified Glomus species) increased the plant growth on account of all measured parameters under tested light conditions. Mycorrhizal
efficiency of different AM fungi varied in narrow range. AM inoculants were more efficient at higher light intensity in above mentioned plant species, except wheat. Data on colonization of P. mungo, T. aestivum, E. tereticornis and A. procera showed that formation of arbuscules, vesicles and sporocarp was delayed by lower light intensity. Colonization index of host roots and spore counts increased with increase in light intensity during successive months after inoculation. Data on effect of light regimes on microclimate of net house showed that lux meter reading decreased as per grades of shading nets used during both rainy and winter seasons. With increase in light intensity, ambient temperature, soil surface temperature and sub
surface temperature at 15 cm depth increased, except that the ambient and soil surface temperature in control (open) were slightly lower than net house observations during January and February. Value of ambient temperature varied in narrow range, with in treatments as compared to soil surface and sub soil
surface temperature at 15 cm depth. Soil surface temperature at 25% of full sunlight was less than respective control values by 2–11C and sub soil temperature at 15 cm depth was less by 4–12 C. The values of different microclimate parameters varied in narrower range during winter season as compared to rainy season. While ranking the importance of two factors studied—light and AM fungi—for their effect on the growth and P uptake by different plant species, inoculations with AM fungi came in the first place (explained 50–82% variation) and light substantially increased the values of R2 in stepwise regression
analysis (forward selection). The results suggest that AM inoculation may enhance the growth and P uptake of intercrops under tree shade and the tree canopy management is likely to increase the efficiency of AM inoculants in agroforestry systems. Use of excessive shading (25% of full sun or more) in nurseries may be avoided and PAR (photosynthetically active radiation) lamps may be used to increase growth and colonization index of tree seedlings.

The study was conducted to investigate the effect of phosphorus (P) concentrations (0, 5, 10, 20, 50, and 100 μg g−1) on growth and arbuscular mycorrhizal (AM) colonization of two crops (a rainy season crop, Phaseolus mungo Roxb. var. PU-35 and a winter crop, Triticum aestivum L. var. WH-147) and seedlings of two multipurpose tree species (Eucalyptus tereticornis Sm. [Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.). Plant growth parameters (shoot length, dry weight) and P uptake increased significantly after inoculations with AM fungi (Acaulospora scrobiculata Trappe, Glomus cerebriforme McGee, and Glomus intraradices Schenck and Smith) in P. mungo, T. aestivum, E. tereticornis, and A. procera. Best results were obtained with G. cerebriforme in P. mungo and A. procera, and A. scrobiculata in T. aestivum, and G. intraradices in E. tereticornis. Results on effect of P application on mycorrhizal dependency (MD) of studied crop and tree species showed that decrease in MD with increase in P concentrations in non-nitrogen-fixing species (T. aestivum and E. tereticornis) was higher than in nitrogen-fixing species (P. mungo and A. procera). Threshold P concentrations for maximum benefits from the AM symbiosis in above-mentioned plant species varied from 5 to 20 μg g−1 and corresponding peaks of arbuscules, vesicles, sporocarp formation, colonization index, and spore count per 100 g sand were noticed. Thus, the results showed that the recorded plant growth peaks were due to AM colonization of crops and tree rhizosphere. Inoculations with AMF were more important than P application (explaining 14–78% variation in plant growth) for P. mungo, T. aestivum, and A. procera (forward selection method), whereas P application was more important for growth in E. tereticornis. Therefore, inoculating plants with a suitable AM inoculant could result in a benefit comparable to high P input and lead to a significant saving of inorganic P fertilizer.