DO MAIZE AND PEPPER PLANTS DEPEND ON MYCORRHIZAE IN TERMS OF PHOSPHORUS AND ZINC UPTAKE?

Nutrient deficiency, especially zinc (Zn) and phosphorus (P), is a common nutritional problem for the production of some crops in Turkey. This problem results in the application of increasing amounts of several fertilizers. Mycorrhizal inoculation or the indigenous potential of mycorrhizae in the soil is a critical factor in crop production under low supply of Zn and P. The effects of selected mycorrhizal inoculation on growth and Zn and P uptake of maize and green pepper were investigated in Zn- and P-deficient calcareous soils from Central Anatolia. Soils were sterilized by autoclaving and plants were grown for 7 weeks in pots under greenhouse conditions with inoculation of two selected arbuscular mycorrhizal (AM) species (Glommus moseea and G. etunicatum) at three rates of P (0, 25, 125 mg P kg^?1 soil) and two rates of Zn (0 and 5 mg Zn kg^?1soil). Without mycorrhizal inoculation, shoot and root dry matter production were severely affected by P and Zn deficiencies, and supply of adequate amounts of P and Zn significantly enhanced plant growth. When the soil was inoculated with mycorrhizal inoculation, the increasing effects of P and Zn fertilization on plant growth remained less pronounced. In accordance with growth data, mycorrhizae inoculation enhanced P and Zn concentration of plants, especially under low supply of P and Zn. The results obtained indicate that maize and green pepper are highly mycorrizal–dependent (MD) plant species under both low P and Zn supply and mycorrhizae play an essential role in P and Zn nutrition of plants in P and Zn-deficient soils. Although addition of P and Zn increased plant growth and plants are mycorrhizal dependent on P and Zn nutrition however dependence is much more dependent on P nutrition.     

EFFECTS OF ELEMENTAL SULFUR AND MYCORRHIZAE ON THE YIELD OF WHEAT IN DIFFERENT SOILS

Yield responses of wheat (Triticum aestivum L.) to elemental sulfur (S), mycorrhizae (mycorrhizal fungus, Glomus mosseae), and phosphorus (P) alone and collectively in two different soils were investigated. Plants were grown on calcareous sterilized Karaburun and Menek?e soils (sub-group of Typic Xerorthent). In the all treatments mycorrhizae inoculation alone compared to the control treatment increased shoot and root yields. The yield responses to S alone, P alone, and combined application of S and P in mycorrhizal and non-mycorrhizal treatments in two different soils were interestingly fluctuating. The findings obtained in this study indicated that S tended to increase the efficiency of mycorrhizae in the well aerated Karaburun soil in comparison to a less aerated (heavier textured) Menek?e soil. This potential to increase the efficiency of mycorrhizae on the root growth indicate that yield increase of shoot and grain can occur being an important finding for ecological agriculture.     

Effects of Arbuscular Mycorrhizal Colonization on Microbial Community in Rhizosphere Soil and Fusarium Wilt Disease in Tomato

Fusarium wilt is caused by soil-borne pathogen Fusarium oxysporum. Tomato (Lycopersicon esculentum Mill.) is susceptible to Fusarium oxysporum f. sp. lycopersici race 1 and was infected with wilt disease. A pot experiment was conducted to investigate effects of inoculating arbuscular mycorrhizal (AM) fungus (Glomus etunicatium) on the microbial community in the rhizosphere soil and Fusarium wilt in tomato (cv. Oogatafukuju). The results indicated that AM fungal inoculation suppressed the Fusarium number in the rhizosphere soil of tomato and decreased the Fusarium wilt disease index. Compared to the control, AM fungal inoculation increased the actinomycete number but increased bacterial number. Bacterial and fungal numbers were high but actinomycetes number was low when tomato basal stems became discolored brown. Fusarium inoculation significantly suppressed development of AM colonization and decreased polyphenol oxidase (PPO) activity in leaves and roots of tomato. Inoculation with AM fungi and Fusarium maintained high PPO activity in leaves and roots. The AM colonization increased root growth of tomato, whereas Fusarium inoculation had no significant effect on tomato growth. These findings suggest that because AM fungal inoculation changes microbial communities and enhances PPO activity, it should suppress occurrence of Fusarium wilt in tomato.     

Mycorrhizal inoculation increases genes associated with nitrification and improved nutrient retention in soil

The effects of arbuscular mycorrhizal (AM) inoculation on prokaryote abundance within the maize rhizosphere and hyphosphere, and retention of nutrients were investigated. Maize plants were grown in pots with a membrane located at a soil depth of approximately 16 cm that allowed growth of fungal hyphae above and below the membrane, but did not allow growth of roots below the membrane. As expected, mycorrhizal inoculation significantly increased the contents of soil organic matter, Total Kjeldahl Nitrogen (primarily organic N), and Mehlich 1 phosphorus relative to the non-inoculated control. Copy numbers of 16S rRNA genes were significantly higher in the mycorrhizal compartments relative to non-mycorrhizal controls. Bacterial ammonia monooxygenase (AOB) genes, but not archaeal monooxygease genes (AOA), were significantly higher in planted treatments with and without addition of mycorrhizae, indicating that mycorrhizae stimulate prokaryotic growth and bacterial nitrification. The ecological relevance of increased NOx-N resulting from the growth of AOB in inoculated soils is not clear; however, increased mobility of NOx-N over NH₄ ⁺ could result in a competition between leaching loss and increased uptake by mycorrhizae.     

Response of Mycorrhizal Infection to Glyphosate Applications and P Fertilization in Glyphosate-Tolerant Soybean,Maize, and Cotton

Glyphosate and phosphorus (P) fertilizer may alter arbuscular mycorrhizal (AM) fungal infection rates of glyphosate-tolerant cotton, maize, and soybean in low-P soil. Microbial biomass, water soluble P, Mehlich-3 P, and acid and alkaline phosphatase activities were not significantly impacted by glyphosate or P in the greenhouse. Phosphorus fertilization decreased mycorrhizal infection rates in cotton and maize and increased shoot biomass and shoot P in soybean in 2005, and decreased mycorrhizal infection in soybean and increased shoot biomass in cotton and maize and shoot P in all three crops in 2006. In pasteurized soil, glyphosate decreased percent mycorrhizal infection in maize, increased infection in cotton, and did not significantly affect infection in soybean. When soil was not pasteurized, glyphosate did not significantly alter mycorrhizal infection in any crop. The potential for glyphosate to alter AM fungal infection in glyphosate-tolerant plants may depend on whether soil microbial communities are compromised by other factors.     

Effect of mixing soil saprophytic fungi with organic residues on the response of Solanum lycopersicum to arbuscular mycorrhizal fungi

The effect of the dual inoculation with arbuscular mycorrhizal (AM) and saprophytic fungi and a combination of wheat straw and sewage sludge residues were studied by determining their effect on dry weight of tomato and on chemical and biochemical properties of soil. Incubation of organic residue (sewage sludge combined with wheat straw) with saprophytic fungi and plant inoculation with mycorrhizal fungi was essential to study plant growth promotion. Soil application of organic residues increased the dry weight of tomato inoculated with Rhizophagus irregularis. The greatest shoot dry mass was obtained when the organic residues were incubated with Trichoderma harzianum and applied to AM plants. However, the greatest percentage of root length colonized with AM in the presence of the organic residues was obtained with inoculation with Coriolopsis rigida. The relative chlorophyll was greatest in mycorrhizal plants regardless of the presence of either saprophytic fungus. The presence of the saprophytic fungi increased soil pH as the incubation time increased. Soil nitrogen and phosphorus contents and acid phosphatase were stimulated by the addition of organic residues, and contents of N and P. Total N and P content in soil increased when the organic residue was incubated with saprobe fungi, but this effect decreased as the incubation period of the residue with saprobe fungi increased. The same trend was observed for soil β‐glucosidase and fluorescein diacetate activities. The application of organic residues in the presence of AM and saprophytic fungi seems to be an interesting option as a biofertilizer to improve plant growth and biochemical parameters of soils.     

Influence of arbuscular mycorrhizal fungi and salinity on growth,biomass, and mineral nutrition of<Emphasis Type="Italic"> Acacia auriculiformis</Emphasis>

The effect of salinity on the efficacy of two arbuscular mycorrhizal fungi, Glomus fasciculatum and G. macrocarpum, alone and in combination was investigated on growth, development and nutrition of Acacia auriculiformis. Plants were grown under different salinity levels imposed by 0.3, 0.5 and 1.0 S m^-1 solutions of 1 M NaCl. Both mycorrhizal fungi protected the host plant against the detrimental effect of salinity. The extent of AM response on growth as well as root colonization varied with fungal species, and with the level of salinity. Maximum root colonization and spore production was observed with combined inoculation, which resulted in greater plant growth at all salinity levels. AM fungal inoculated plants showed significantly higher root and shoot weights. Greater nutrient acquisition, changes in root morphology, and electrical conductivity of soil in response to AM colonization was observed, and may be possible mechanisms to protect plants from salt stress.     

蚯蚓菌根互作对土壤酶活、 甘薯根系生长及养分吸收的影响

【目的】蚯蚓和丛枝菌根真菌处于不同的营养级,但在促进植物生长和提高土壤肥力等方面却都发挥着积极作用。单独对土壤微生物或土壤动物的研究较多,但对土壤微生物与土壤动物之间相互作用的研究很少。因此研究它们对土壤和植物生长的作用可为挖掘土壤生物的潜力和提高土壤生物肥力提供依据。【方法】采用盆栽试验,研究了蚯蚓(Eisenia fetida)与丛枝菌根真菌(Rhizophagus irregularis)互作对甘薯生长和养分吸收的影响。试验采用两因素完全随机试验设计,分为接种和不接种菌根真菌及添加和不添加蚯蚓。试验共4个处理: 不加菌根和蚯蚓(CK); 接种菌根真菌(AM); 添加蚯蚓(E); 添加蚯蚓和菌根真菌(E+AM),每个处理4次重复。调查了甘薯养分吸收、 根系形态及土壤养分变化,采用Canoco4.5软件对土壤生物与植物对应关系进行RDA (redundancy analysis)分析。【结果】接种菌根真菌显著提高了甘薯地上和地下部生物量(P0.05),而添加蚯蚓的处理仅提高了甘薯地上部生物量。同时添加蚯蚓和菌根的处理显著提高了甘薯地上地下部生物量,并且高于其他三个处理(P0.05)。与对照相比,接种菌根真菌显著提高了土壤磷酸酶活性(P0.01),增幅近一倍; 同时提高了土壤磷的植物有效性,土壤有效磷含量下降了30%左右。添加蚯蚓后土壤脲酶活性从5.45 mg NH+4-N/g显著增加到8.71 mg NH+4-N/g,土壤碱解氮的含量从5.82 mg/kg显著增加到6.89 mg/kg (P0.05)。RDA分析表明蚯蚓菌根互作对甘薯地上和地下部氮磷含量、 根表面积、 根体积、 根平均直径和根尖数均存在显著的正交互效应。蚯蚓菌根互作通过调控土壤酶和改变土壤养分有效性促进甘薯对土壤氮磷养分的吸收。【结论】蚯蚓(Eisenia fetida)通过调控土壤脲酶和碱性磷酸酶增加了土壤中氮磷的有效性从而促进甘薯地上部生长。丛枝菌根真菌(Rhizophagus irregularis)通过调控土壤磷酸酶和增加植株地上地下部吸磷量从而促进甘薯生长。添加蚯蚓或接种菌根真菌均能增加根系吸收面积和根体积从而促进甘薯对养分的吸收。蚯蚓和菌根真菌相互作用通过调控土壤酶和改变土壤养分有效性以及促进根系发育从而互补的促进甘薯养分吸收和生长。     

Mycorrhizal inoculation enhances growth and nutrition of cotton plant

Arbuscular Mycorrhizae Fungi (AMF) inoculations may improve growth and nutrient uptake of cotton (Gossypium hirsutum L.) plant. Although the importance of mycorrhizal symbioses for growth and nutrient acquisition of cotton plant is known, less is known about mycorrhizal dependency on P and Zn nutrition under low Zn fertile soil conditions. A greenhouse experiment was conducted to investigate the effect of different of P and Zn fertilizer addition on cotton plant growth as well as Zn and P uptake. Sterilized and non-sterilized low Zn fertile Konya series soil was treated with different levels of P and Zn. Soils were inoculated with two mycorrhizae species like Funneliformis mosseae and Claroideoglomus etunicatum after sterilization. Results showed that mycorrhizal inoculation on plant growth and nutrient uptake has significant effect when soil was sterilized. Cl. etunicatum mycorrhizae species has greater effect than Fu. mosseae mycorrhizae species. Root colonization increased 23–65% due to mycorrhizal amendment. The shoot: root ratio increased by 13 and 22% for non-sterile and sterile condition respectively in mycorrhiza amended soil. Mycorrhizal dependency varies 1–55% and 3–64% for non-sterile and sterile soil respectively on mycorrhizae, P and Zn amended soil. Mycorrhizal dependency analysis showed that cotton plant in both sterile and non-sterile soil conditions depends on mycorrhizae species, P nutrition, however is less depend on Zn nutrition. This study concluded that the inoculation of cotton plant with selected mycorrhizae is necessary under both sterile and non-sterile soil conditions.     

Impact of soil nitrogen concentration on Glomus spp.-Sinorhizobium interactions as affecting growth, nitrate reductase activity and protein content of Medicago sativa

Our objective was to evaluate how increasing levels of N in the medium (0, 4, 8 and 16 mmol N added kg^-1 soil) affect the interaction between Sinorhizobium and arbuscular mycorrhiza (AM) fungi in the tripartite symbiosis with Medicago sativa. Growth response, nutrient acquisition, protein content, and nitrate reductase (NR) activity were measured both in plant shoots and roots. Results showed that N levels in soil did not affect mycorrhizal colonization but they strongly influenced nodulation, particularly of mycorrhizal plants. Mycorrhizal colonization was required for a proper nodulation when no N was applied to soil. In contrast, the addition of 4 mmol N kg^-1 soil reduced nodulation only in mycorrhizal plants and 8 mmol N added kg^-1 soil allowed nodule formation only in non-mycorrhizal plants. Nodulation was totally inhibited in all treatments with the addition of 16 mmol N added kg^-1 soil. N addition enhanced NR activity in all the treatments, while AM colonization increased the proportion of NR allocated to roots. This effect was more pronounced under the lowest N levels in the medium. The two AM fungal species showed different distribution pattern of enzymatic activities in plant tissues indicating specific physiological traits. Protein content as well as the relative proportion of protein in roots were greatly increased after mycorrhizal colonization. Glomus intraradices-colonized plants had the highest protein content in shoot and root. Mycorrhizal effects on growth, N acquisition and biochemical variables cannot be interpreted as an indirect P-mediated effect since P content was lower in mycorrhizal plants than in those which were P fertilized. Mycorrhizal colonization increased the N content in plants irrespective of the N level, but the effectiveness of AM fungi on plant N acquisition depended on the AM fungus involved, G. intraradices being the most effective, particularly at the highest N rate. N₂ fixation, enhanced by AM colonization, contributed to N acquisition when a moderate N quantity was available in the soil. Nevertheless, under a high N amount the nodulating process and/or fixing capacity by Sinorhizobium was reduced in AM plants. In contrast, the AM fungal mycelium from a particular mycorrhizal fungus may continue to contribute efficiently to the N uptake from the soil even at high N levels. These results demonstrate the particular sensitivity of AM fungal species in terms of their growth and/or function to increasing N amounts in the medium. A selection of AM fungi used to address specific environmental conditions, such as N fertilization regimes comparable to those used in agronomic practices, is required for a better use of N applied to soil.     

Response of neem (Azadirachta indica A. Juss) to indigenous arbuscular mycorrhizal fungi, phosphate-solubilizing and asymbiotic nitrogen-fixing bacteria under tropical nursery conditions

Neem (Azadirachta indica A. Juss) seedlings were inoculated with arbuscular mycorrhizal (AM) fungi, Glomus intraradices Schenck and Smith and G. geosporum (Nicol. and Gerd.) Walker, Azospirillum brasilense, and phosphate-solubilizing bacteria (PSB) individually or in various combinations in unsterile soil under nursery conditions. Seedlings were harvested at 60 and 120 days after transplantation. Microbial inoculation resulted in increased mycorrhizal colonization, greater plant height, leaf area and number, root collar diameter, biomass, phosphorus, nitrogen and potassium content, and seedling quality. Inoculated seedlings also had low root/shoot ratios and low nutrient utilization efficiencies. Populations of PSB declined with seedling growth; contrarily populations of A. brasilense increased. A. brasilense and PSB populations were related to each other and influenced root colonization by AM fungi. Microbial inoculation effects were greatest when seedlings were inoculated with a combination of microbes rather than individually. This clearly indicates that these microorganisms act synergistically when inoculated simultaneously, with maximum response being when both AM fungi were coinoculated with A. brasilense and PSB. The results emphasize the importance of microbial inoculations for the production of robust, rapidly growing seedlings in nurseries and illustrate the advantage of inoculating soils of a low microbial population with indigenous microbes.     

Effects of Mycorrhizae and Fertilization on Soybean Yield and Nutrient Uptake

Soybean (local variety Ar?soy) was grown for 45 days on calcareous Karaburun and Menek?e soils. Mycorrhizal inoculation significantly increased both shoot and root yields in the soils. Sulfur (S) fertilization alone did not affect the shoot and root yields in Karaburun soil, whereas there was a great increase in the shoot yield and relatively smaller increase in the root yield for nonmycorrhizal treatments in Menek?e soil. The combination of mycorrhizae and S in Menek?e soil resulted in a yield less than that obtained for mycorrhizae treatments alone. There was a fluctuation in shoot and root yield upon S and/or phosphorus (P) fertilization. There was an accumulation of magnesium (Mg) and zinc (Zn) in the mycorrhizal treatments, whereas there was a dilution of those elements upon yield increases in the nonmycorrhizal treatments. Apart from those, co-application of mycorrhizae, P, and S, resulted in the greatest root yields in both soils, indicating the potential to increase the shoot yield, too, in a longer growth period.     

Interactions between phosphorus availability and an AM fungus (Glomus intraradices) and their effects on soil microbial respiration, biomass and enzyme activities in a calcareous soil

The interactions between soil P availability and mycorrhizal fungi could potentially impact the activity of soil microorganisms and enzymes involved in nutrient turnover and cycling, and subsequent plant growth. However, much remains to be known of the possible interactions among phosphorus availability and mycorrhizal fungi in the rhizosphere of berseem clover (Trifolium alexandrinum L.) grown in calcareous soils deficient in available P. The primary purpose of this study was to look at the interaction between P availability and an arbuscular mycorrhizal (AM) fungus (Glomus intraradices) on the growth of berseem clover and on soil microbial activity associated with plant growth. Berseem clover was grown in P unfertilized soil (−P) and P fertilized soil (+P), inoculated (+M) and non-inoculated (−M) with the mycorrhizal fungus for 70 days under greenhouse conditions. We found an increased biomass production of shoot and root for AM fungus-inoculated berseem relative to uninoculated berseem grown at low P levels. AM fungus inoculation led to an improvement of P and N uptake. Soil respiration (SR) responded positively to P addition, but negatively to AM fungus inoculation, suggesting that P limitation may be responsible for stimulating effects on microbial activity by P fertilization. Results showed decreases in microbial respiration and biomass C in mycorrhizal treatments, implying that reduced availability of C may account for the suppressive effects of AM fungus inoculation on microbial activity. However, both AM fungus inoculation and P fertilization affected neither substrate-induced respiration (SIR) nor microbial metabolic quotients (qCO₂). So, both P and C availability may concurrently limit the microbial activity in these calcareous P-fixing soils. On the contrary, the activities of alkaline phosphatase (ALP) and acid phosphatase (ACP) enzymes responded negatively to P addition, but positively to AM fungus inoculation, indicating that AM fungus may only contribute to plant P nutrition without a significant contribution from the total microbial activity in the rhizosphere. Therefore, the contrasting effects of P and AM fungus on the soil microbial activity and biomass C and enzymes may have a positive or negative feedback to C dynamics and decomposition, and subsequently to nutrient cycling in these calcareous soils. In conclusion, soil microbial activity depended on the addition of P and/or the presence of AM fungus, which could affect either P or C availability.     

Humus-Rich Compost Increases Lettuce Growth, Nutrient Uptake, Mycorrhizal Colonisation, and Soil Fertility

Sandy soils, typical of Australia's west, either have little or no habitat protection for microbes including arbuscular mycorrhizal (AM) fungi, which are essential for nutrient cycling. To minimize this problem, the application of organic matter, such as humus-rich composts, is necessary during vegetable crop production. This study aimed at determining the effects of humus-rich composts on either indigenous or inoculated AM fungal colonisation in roots, lettuce (Lactuca sativa L. var. Quechua) growth, and soil fertility improvement. Four different humus-rich composts with varying humus contents were applied at the same standard rate to lettuce grown under glasshouse conditions for 10 weeks after sowing and compared with two low-humus composts and non-amended soil (control). Humus-rich composts significantly increased lettuce shoot growth, root growth, and AM fungal colonisation in roots. Humus contents in the composts were also correlated with lettuce shoot and root growth. Soil dissolved organic carbon, microbial biomass carbon, and fertility were increased with the application of humus-rich composts. These humus-rich composts, especially the compost of higher humic acid with and without AM inoculation, might have a significant role in sustainable vegetable production, for example lettuce growth. Overall, the results indicate that supplementation with humus-rich compost is highly beneficial to enhance soil fertility and potentially maintain the sustainability of vegetable production.     

Effect of Superphosphate and Arbuscular Mycorrhizal Fungus Glomus mosseae on Phosphorus and Arsenic Uptake in Lentil (Lens culinaris L.)

Arsenic (As)-contaminated irrigation water is responsible for high As levels in soils and crops in many parts of the world, particularly in the Bengal Delta, Bangladesh and West Bengal, India. While arbuscular mycorrhizal (AM) fungi markedly improve phosphorus (P) uptake, they can also alleviate metal toxicity. In this study, the effects of superphosphate and inoculation with the AM fungus Glomus mosseae on P and As uptake of lentil were investigated. Plant height, shoot dry weight, shoot/root P concentration, and shoot P content increased due to mycorrhizal inoculation. However, As concentration in roots/shoots and root As content were reduced, plant height, shoot dry weight, shoot/root P concentration/content, and root As concentration and content increased due to superphosphate application. Root P concentration decreased with increasing As concentration. It was apparent that As concentration and content in shoots/roots increased with increasing As concentration in irrigation water. Superphosphate interaction with G. mosseae reduced the role of mycorrhizal infection in terms of enhancing P nutrition and reducing uptake of potentially toxic As into plant parts. The role and relationship of mycorrhizal in respect of P nutrition and As remediation efficiency in plant parts was established. In conclusion, it was worth alluding to that lentil with AM fungal inoculation can reduce As uptake and improve P nutrition. However, in retrospect superphosphate increased P and As uptake and decreased the role of the mycorrhizal association. This resulted in stimulating increased P uptake while decreasing As uptake in lentil.     

Under filed conditions,mycorrhizal inoculum effectiveness depends on plant species and phosphorus nutrition

Abstract

The cultivation of horticultural crops, such as green peppers, tomatoes, eggplants and bell peppers is very common in semi-arid Mediterranean climate conditions. Two field experiments were performed to determine the effect of mycorrhizal species, plant species and phosphorus levels on mycorrhizal effectiveness and phosphorus (P) and zinc (Zn) nutrient uptake. In the first experiment, under field conditions, four plants species were inoculated with five arbuscular mycorrhizae (AM) species. In the second field experiment, under the same soil conditions, the same plant species were treated with three levels of phosphorus (P), i.e., control; 50?kg and 100?kg P₂O₅ ha^?1. The most effective mycorrhiza species Claroideoglomus etunicatum selected in the first experiment was used in the second field first experiment. In the first experiment, fruit yield enhancement, yield increase, inoculation effectiveness and nutrient concentration in the plant leaves were analyzed. Under field conditions, plant species growth is strongly dependent on the species of AM fungi. Tomato and green pepper plants were inoculated with Cl. etunicatum, eggplants were inoculated with Funneliformis mosseae and bell peppers were inoculated with Rhizophagus clarus, which are high fruit-yielding plant species. In general, Fu. mosseae and Cl. etunicatum increased the yield of the tomatoes, green peppers and eggplants. It seems mycorrhiza species specific to plant species. In the second experiment, mycorrhizal inoculation with P fertilizer application, in particular a moderate amount of P (50?kg ha^?1 P₂O₅) fertilizer increased the green pepper, bell pepper and tomato fruit yield compared with non-inoculated plants and non-P fertilizer application treatments. Increasing the application of P level reduced the mycorrhizal inoculation effectiveness (MIE). The results indicate that for all four solanaceae family plants 50?kg ha^?1 P₂O₅ is a P level threshold for mycorrhizal development, which enhanced plant growth and addition of fertilizer over 50?kg ha^?1 P₂O₅ reduced MIE. P and Zn uptake were significantly increased with mycorrhizal inoculation. These findings are supported by our hypothesis that mycorrhiza inoculation can reduce mycorrhizal dependent horticultural plants P fertilizer requirement.     

DEHP污染的两种土壤中接种丛枝菌根对豇豆生长和DEHP降解的影响

A 60-day pot experiment was carried out using di-(2-ethylhexyl) phthalate (DEHP) as a typical organic pollutant phthalic ester and cowpea (Vigna sinensis) as the host plant to determine the effect of arbuscular mycorrhizal inoculation on plant growth and degradation of DEHP in two contaminated soils, a yellow-brown soil and a red soil. The air-dried soils were uniformly sprayed with different concentrations of DEHP, inoculated or left uninoculated with an arbuscular mycorrhizal (AM) fungus, and planted with cowpea seeds. After 60 days the positive impact of AM inoculation on the growth of cowpea was more pronounced in the red soil than in the yellow-brown soil, with significantly higher (P < 0.01) mycorrhizal colonization rate, shoot dry weight and total P content in shoot tissues for the red soil. Both in the yellow-brown and red soils, AM inoculation significantly (P < 0.01) reduced shoot DEHP content, implying that AM inoculation could inhibit the uptake and translocation of DEHP from roots to the aboveground parts. However, with AM inoculation no positive contribution to the degradation of DEHP was found.     

Effects of indigenous and introduced arbuscular mycorrhizal fungi on the growth of Allium fistulosum under field conditions

ABSTRACT

Enhanced phosphorus (P) uptake from the soil and increased plant growth related to arbuscular mycorrhizal (AM) fungi in pot culture, using sterilized soil, are well-known phenomena. However, these enhancements are not widely observed under field conditions because field sterilization is difficult. The aim of this study was to investigate the effects of AM fungi on P uptake and the growth of Allium fistulosum in non-fumigated and fumigated fields, under different levels of P availability. Plants were inoculated with the AM fungus Glomus R-10 and grown in fumigated soil. For the uninoculated treatment, a sterilized inoculum was applied directly. The field was fumigated using dazomet. Superphosphate was applied to the field at the rates of 0 (P0) or 500 (P500) kg P₂O₅ ha^?1. The inoculated and uninoculated plants were transplanted into the fields and sampled three times to measure AM fungal colonization, shoot P concentration, and shoot dry weight of the plants. At the transplanting stage, AM fungal colonization was observed in the inoculated plants (>70%) but not in the uninoculated plants. At the third sampling, irrespective of P treatment, AM fungal colonization was observed both in the uninoculated and inoculated plants in the non-fumigated field, and there was no difference in shoot P content and shoot dry weight between the inoculated and uninoculated plants. AM fungal colonization in the fumigated field was higher in the inoculated than uninoculated plants, irrespective of P treatment; shoot P content and shoot dry weight were both higher in the inoculated plants than in the uninoculated plants with P0. These results suggest that the responses of A. fistulosum to AM fungal inoculation under the low-P and fumigated conditions are similar to those observed in sterilized pot culture conditions.     

Fermentation of sugar beet waste by Aspergillus niger facilitates growth and P uptake of external mycelium of mixed populations of arbuscular mycorrhizal fungi

Sugar beet waste has potential value as a soil amendment and this work studied whether fermentation of the waste by Aspergillus niger would influence the growth and P uptake of arbuscular mycorrhizal (AM) fungi. Plants were grown in compartmentalised growth units, each with a root compartment (RC) and two lateral root-free compartments (RFC). One RFC contained untreated soil while the other RFC contained soil, which was uniformly mixed with sugar beet waste, either untreated (SB) or degraded by A. niger (ASB) in a rock phosphate (RP)-supplied medium. The soil in each pair of RFC was labelled with ³³P and ³²P in order to measure P uptake by the AM fungal mycelium, of which length density was also measured. Whole cell fatty acid (WCFA) signatures were used as biomarkers of the AM fungal mycelium and other soil microorganisms. The amount of biomarkers of saprotrophic fungi and both Gram-positive and Gram-negative bacteria was higher in SB than in ASB treatments. Whilst ASB increased growth and activity of AM mycelium, SB had the opposite effect. Moreover, shoot P content was increased by the addition of ASB, and by inoculation with AM fungi. Modification of soil microbial structure and production of exudates by A. niger, as a consequence of fermentation process of sugar beet waste, could possibly explain the increase of AM growth in ASB treatments. On the other hand, the highest P uptake was a result of the solubilisation of rock phosphate by A. niger during the fermentation.     

The Effect of Different Compost Compositions on Arbuscular Mycorrhizal Colonization and Nutrients Concentration of Leek (allium Porrum L.) Plant

ABSTRACT

Plant residue material produced compost is an organic fertilizer source and it is commonly used for soil amendments. Also in order to reduce the amount of chemical fertilizers need mycorrhizal inoculation can be used as an agricultural strategy. Thus, the aim of the research is to examine the effect of several residue materials produced compost and mycorrhizae fungi with two growth media on leek plant growth, nutrient uptake, and mycorrhizae spores’ production.

Eight different row organic materials and animal manures were used as compost production during 8 months. Leek (Allium porrum L.) plants were inoculated with Funneliformis mosseae and Claroideoglomus etunicatum with a level of 1000-spore per pot. The leek plant was analyzed for determination of nutrient concentration, root colonization, spore production, and shoot/root dry weight.

The composts were made from domestic waste, animal manure (bovine animal), animal manure (ovine animal), and different plant materials were determined to be the most suitable compost material for plant growth and mycorrhizal spore production compared to the rest of compost material. Mycorrhizal inoculation significantly increased leek plant growth and nutrient uptake especially phosphorus (P), potassium (K), copper (Cu) and zinc (Zn). Plants grown in 5:3:2 (volume/volume) growth media was responded better to the mycorrhizal inoculation than grown in 1:1:1 (v/v) growth media. Funneliformis mosseae inoculated plants have higher plant growth and nutrient uptake than that of Claroideoglomus etunicatum inoculation.