Arbuscular Mycorrhizal Fungi Plants Research Articles

Alleviation of drought stress of Chile ancho pepper ( Capsicum annuum L. cv. San Luis) with arbuscular mycorrhiza indigenous to Mexico

Selecting indigenous mycorrhizal fungi that enhance plant water status is important in Mexico for sustainable production systems of Chile ancho pepper ( Capsicum annuum L. cv. San Luis). To determine mycorrhizal enhancement of drought resistance, plants were either non-inoculated (NonAMF), or inoculated with arbuscular mycorrhizal fungi (AMF): Glomus fasciculatum and a mixed Glomus spp. from Mexico (ZAC-19). Plants were then exposed to a 20-day drought cycle. To equalize growth and minimize tissue-P differences, NonAMF plants received higher P than AMF plants. Drought reduced leaf water potential ( Ψ leaf), tissue relative water content (RWC), stomatal conductance ( g s), whole plant transpiration (mg H 2O m −2 s −1), leaf transpirational surface area and plant biomass. Only plants colonized with ZAC-19 had enhanced drought resistance, as indicated by higher Ψ leaf and fewest plants with visible wilting during peak drought stress. A higher root/shoot ratio occurred with ZAC-19 plants (despite equal total plant biomass among droughted plants), which may have also contributed to drought resistance. Drought enhanced arbuscule formation and hyphae development of ZAC-19, while reducing colonization of G. fasciculatum. Tissue P was not a contributing factor to drought resistance. AMF did not enhance water-use efficiency (WUE) as-determined gravimetrically on a whole plant basis (g carbon/kg H 2O) or by carbon isotope discrimination ( Δ).

Shoot δ15N and δ13C values of non-host Brassica rapa change when exposed to ±Glomus etunicatum inoculum and three levels of phosphorus and nitrogen

Glasshouse experiments were conducted to study the response of non-host Brassica rapa and host Sorghum bicolor to inoculation with the arbuscular mycorrhizal fungus (AMF) Glomus etunicatum when given different levels of N (0.9mmol kg(-1) sand, 2.7mmol kg(-1) sand, 8.1mmol kg(-1) sand) and P (3.6µmol kg(-1) sand, 10.7µmol kg(-1) sand, 32.0µmol kg(-1) sand) fertiliser. On both plant species, the presence of G. etunicatum inoculum (+AMF) was associated with significant changes of shoot δ(15)N values, with +AMF plants having larger average δ(15)N values than uninoculated plants (-AMF). These values are the largest average differences in shoot δ(15)N yet recorded for AMF and nutrient effects. B. rapa shoot δ(15)N average differences ranged from 1.67‰ to 2.70‰, while for S. bicolor they range between 2.07‰ and 4.40‰. For shoot δ(13)C only the non-host B. rapa responded to ±AMF and added N. Although the harvested dry weight biomass (-35.2% B. rapa; +39.8% S. bicolor) of both plant species responded to AMF inoculation, no direct relationship was observed between isotopic discrimination and growth inhibition for the non-host B. rapa. In this paper we discuss some implications regarding AMF inocula on the basis of our findings and current literature.

MAIZE RESPONSE TO PHOSPHATE ROCK AND ARBUSCULAR MYCORRHIZAL FUNGI IN ACIDIC SOIL

Plants grown in acidic soils often have reduced productivity because of limited mineral nutrients. For plants to obtain adequate nutrients under these conditions, some source of fertilizer is commonly added or a method to make nutrients more available to plants, such as mycorrhiza, is needed. Maize (Zea mays L.) was grown in acidic soil (pHW 4.7, soilwater, 1:1) with added phosphate rock (PR) and the arbuscular mycorrhizal fungus (AMF) Glomus clarum to determine the effectiveness of AMF and PR for supplying nutrients, especially P. Plants were grown in a growth chamber and harvested when plants had grown in treated soil 15, 22, 29, and 36 d. Plant dry matter (DM) was greatly enhanced by PR, and even more at each harvest when roots were colonized with AMF (AMF+PR). Shoot DM increased more than root DM with PR (PR and AMF+PR) treatments. Total root length (RL) was greater for plants grown with PR and AMF+PR compared to the Control (no added P or AMF) and AMF plants. Colonization of roots by AMF was higher for AMF+PR than for AMF plants. Acquisition of P followed the sequence of AMF+PR > PR >> AMF > Control. Other nutrients commonly limiting in acidic soil [e.g., calcium (Ca), magnesium (Mg), and potassium (K)] were greatly enhanced in AMF compared to nonmycorrhizal (nonAMF) plants. The AMF plants had 2-3-fold greater inflow rates [inflow = μg nutrient m−1 RL day−1] of Ca, Mg, copper (Cu), zinc (Zn), and boron (B) than nonAMF plants. The application of PR and/or AMF colonization decreased the concentrations of iron (Fe), manganese (Mn), and aluminum (Al) in the shoots. The lower specific accumulation rate [SAcR = μg nutrient g−1 shoot DM day−1] of Fe, Mn, and Al in the shoots indicated a possible precipitation or/and formation of metal-organic complexes in the roots. Application of PR to this acidic soil did not inhibit maize response to AMF, and both PR and AMF were important for optimal growth of maize in this acidic soil.

Phosphorus source, organic matter, and arbuscular mycorrhiza effects on growth and mineral acquisition of chickpea grown in acidic soil

Plants grown in acidic soil usually require relatively high amounts of available phosphorus (P) to optimize growth and productivity, and sources of available P are often added to meet these requirements. Phosphorus may also be made available at relatively high rates in native soil when roots are colonized with arbuscular mycorrhizal fungi (AMF). Addition of P to soil usually reduces root‐AMF colonization and decreases beneficial effects ofAMF to plants. In glasshouse experiments, soil treatments of P [0 P (Control), 50 mg soluble‐P kg−1 as KH2PO4 (SP), and 200 mg P kg−1 as phosphate rock (PR)], organic matter (OM) at 12.5 g kg−1, AMF (Glomus darum), and various combinations of these (OM+SP, OM+PR, AMF+SP, AMF+PR, AMF+OM, AMF+OM+SP, and AMF+OM+PR) were added to steam treated acidic Lily soil (Typic Hapludult, pHw=5.8) to determine treatment effects on growth and mineral acquisition by chickpea (Cicer areitinum L.). The various treatment applications increased shoot dry matter (DM) above the Control, but not root DM. Percentage AMF‐root colonization increased 2‐fold or more when mycorrhizal plants were grown with AMF, OM+SP, and OM+PR. Regardless of P source, plant acquisition of P, sulfur (S), magnesium (Mg), calcium (Ca), and potassium (K) was enhanced compared to the Control, and mineral enhancement was greater in PR compared to SP plants. Mycorrhizal plants also had enhanced acquisition of macronutrients. OM+SP and OM+PR enhanced acquisition of P, K, and Mg, but not Ca. Concentrations of Fe, Mn, Cu, and Al were generally lower than Controls in SP, RP, AMF+PR, AMF+SP, and OM plants, and mycorrhizal plants especially had enhanced micronutrients. Relative agronomic effectiveness values for shoot DM and shoot P, Ca, and Mg contents were considerably higher for PR, including OM+PR, AMF+PR, and AMF+OM+PR, than for SP. PR and OM applications to AMF plants are low‐cost attractive and ecologically sound alternatives to intensive use of P fertilizers for crops grown in acidic soils.

Arbuscular mycorrhizal fungal isolate effectiveness on growth and root colonization of Panicum virgatum in acidic soil

Arbuscular mycorrhizal fungi (AMF) can enhance plant ability to grow and withstand acidic soil induced stresses. Panicum virgatum L. (switchgrass) was grown in pH Ca 4 and 5 (soil:10 mM CaCl 2, 1:1) soil (typic Hapludult) inoculated with eight isolates of AMF [ Glomus ( G.) clarum, G. diaphanum, G. etunicatum, G. intraradices, Gigaspora ( Gi.) albida, Gi. margarita, Gi. rosea and Acaulospora ( A.) morrowiae] to determine the effects of these isolates on plant growth and root colonization. Compared to nonmycorrhizal (nonAMF) plants, mycorrhizal (AMF) plants had as high as 52-fold increases in dry matter (DM) in pH Ca 4 soil and as high as 26-fold increases in DM in pH Ca 5 soil; G. clarum and G. diaphanum plants had the highest DM and Gi. rosea plants had the lowest DM. The AMF plants grown in pH Ca 4 soil had higher DM than in pH Ca 5 soil. Root DM decreased more than shoot DM for plants grown in pH Ca 5 compared to pH Ca 4 soil, which was reflected in shoot-to-root DM ratio changes. Total root length (RL) was similar for plants grown in pH Ca 4 and 5 soil and varied considerably depending on AMF isolate. Specific RL was higher for AMF plants grown in pH Ca 5 than in pH Ca 4 soil. Root colonization [determined as vesicles or arbuscules in root cells (VA), roots with hyphal infections (HI) and total colonization (VA or HI)] varied extensively with AMF isolate. Although percentage root colonization was not directly related to amount of DM, good enhancement of DM did not occur unless total colonization was >20%. Some AMF isolates were highly effective in overcoming acidic soil constraints and good growth of switchgrass in acidic soil may depend on root-AMF symbiosis.

Effectiveness of arbuscular mycorrhizal colonization at nursery-stage on growth and nutrition in wetland rice (Oryza sativaL.) after transplanting under different soil fertility and water regimes

Abstract In order to analyze the effectiveness of colonization by arbuscular mycorrhizal fungi (AMF) at the nursery stage on the growth and nutrient concentration of wetland rice after transplanting, the experiments were conducted under glasshouse conditions using two types of soil, namely (i) sterilized paddy soil (PS) and (ii) sterilized paddy soil diluted with sterilized Andosol subsoil 5 times (DS) under two water regimes, (i) flooded conditions changed to non-flooded conditions 30 d before harvest (F-NF) and (ii) continuous flooding (CF) up to harvest. Treatments consisting of mycorrhizal inoculation (+AMF) and non-inoculation ( — AMF) were applied only at the nursery stage when the seedlings were produced under dry nursery (60% moisture of maximum water holding capacity) conditions. Seedlings grown in PS showed a significantly higher biomass yield and nutrient concentrations than in DS. At 90 and 105 d after transplanting, the mycorrhizal plants showed a higher biomass than non-mycorrhizal plants in PS whereas there were no differences in DS except for roots. Mycorrhizal colonization at the transplanting stage was higher in DS than in PS. However, after transplanting opposite results were obtained, the level in PS being relatively higher than in DS. Grain yield and P concentration of unhulled grain and shoots in PS were higher in the +AMF treatments than in the -AMF treatments under both water regimes. Contents of micronutrients (Zn, Cu, Fe, and Mn) were higher in the +AMF plants than in the -AMF ones at all growth stages up to maturation irrespective of soil fertility and water regimes. These results suggest that AMF inoculation at the nursery-stage was beneficial for wetland rice after transplanting to flooded conditions in terms of growth promotion and increase of nutrient concentrations.