丛枝菌根对酸枣实生苗耐盐性的影响

本文研究了在土中加入不同量NaCl条件下 (0、1 5、3 0、4 5gkg-1干土 )接种丛枝菌根真菌 (AMF)Glomusmosseae对盆栽酸枣 (ZizyphusspinosusHu)实生苗生长及耐盐性的影响。结果表明 ,无论接种与否 ,植株的高度、根茎叶的干鲜重均随土壤NaCl浓度的增加而降低 ,而根、茎、叶和整株的Na浓度及Na全量均随土壤NaCl浓度的增加而增大。在土壤盐浓度相同的条件下 ,接种AMF植株的生长量 (株高、鲜重、干重等 )和叶片的叶绿素含量显著高于不接种植株。接种AMF的植株茎、叶中Na浓度低于不接种植株 ,而根中Na浓度、植株Na总量显著高于不接种植株。盐浓度最大的接种处理 ,其植株生长量和叶片叶绿素含量均高于不加盐不接菌处理。播种时进行盐胁迫处理和播种后 4 0d开始进行盐胁迫处理对菌根的侵染率、植株生长的影响差异不显著。上述四种盐浓度播种时进行盐处理的接种AMF植株的总干重比不接种植株分别提高 16 4 %、14 9%、4 8%、35 % ,在播种后 4 0d进行盐处理的接种AMF的植株比不接种植株分别提高 194 %、12 7%、72 %、4 6 %。结果证明 ,酸枣实生苗具有较强的耐盐性 ,其生长对菌根真菌有很强的依赖性 ,接种菌根真菌提高了其耐盐能力。     

Arbuscular Mycorrhizal Fungi Contribute to Resistance of Upland Rice to Combined Metal Contamination of Soil

A greenhouse pot experiment was conducted to investigate heavy metal [copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd)] uptake by two upland rice cultivars, ‘91B3’ and ‘277’, grown in a sterilized field soil contaminated by a mixture of Cu, Zn, Pb, and Cd. Rice plants were inoculated with each of three arbuscular mycorrhizal fungi (AMF), Glomus versiforme (GV), Glomus mosseae (GM), and Glomus diaphanum (GD), or remained noninoculated (NM). Both rice cultivars could be colonized by the three AMF used in this experiment. The percentage of mycorrhizal colonization by the three AMFs on the two rice cultivars ranged from 30% to 70%. Mycorrhizal colonization of both upland rice cultivars had a large influence on plant growth by increasing the shoot and root biomass compared with non-inoculated (NM) plants. The results indicate that mycorrhiza exert some protective effects against the combined toxicity of Cu, Zn, Pb, and Cd in the contaminated soil. This conclusion is supported by the partitioning of heavy metals (HMs) in the two cultivars. In the two cultivars, colonization by AMF reduced the translocation of HMs from root to shoot (except that the colonization of AMF increased the Cu translocation of HMs in cultivar ‘277’). Immobilization of the HMs in roots can alleviate the potential toxicity to shoots induced by the mixture of Cu, Zn, Pb, and Cd. The two rice cultivars showed significant differences in uptake of Cu, Zn, Pb, and Cd when uninoculated. GM inoculation gave the most protective effects on the two cultivars under the combined soil contamination.     

Modulation of the ROS‐scavenging system in salt‐stressed wheat plants inoculated with arbuscular mycorrhizal fungi

Although there is evidence for a positive involvement of the antioxidant defense system in plant response to salt stress, there is poor information regarding the influence of mycorrhizal symbiosis on enzymatic and nonenzymatic antioxidant defense in wheat under saline conditions. The present article focuses on the contribution of mycorrhizae to antioxidant defense in salt‐stressed wheat plants. Two wheat (Triticum aestivum L.) cultivars, Sids 1 and Giza 168, were grown under nonsaline or two saline conditions (4.7 and 9.4 dS m^–1) with and without arbuscular mycorrhizal fungi (AMF) inoculation. Salt stress considerably decreased root colonization and plant productivity, particularly in Giza 168. Interestingly, mycorrhizal colonization alleviated the adverse effect of salt stress and significantly enhanced plant productivity, especially in Sids 1. The concentration of glycinebetaine, the activities of antioxidative enzymes (superoxide dismutase, peroxidase, catalase, and glutathione reductase) and the concentrations of antioxidant molecules (glutathione and ascorbate) were increased under saline conditions; these increases were more significant in salt‐stressed mycorrhizal plants, especially in Sids 1. Salt stress induced oxidative damage through increased lipid peroxidation, electrolyte leakage, and hydrogen peroxide concentration, particularly in Giza 168. Mycorrhizal colonization altered plant physiology and significantly reduced oxidative damage. Elimination of reactive oxygen species (ROS) can be one of the mechanisms how AMF improve wheat adaptation to saline soils and increase its productivity.     

Responses of directly seeded wetland rice to arbuscular mycorrhizal fungi inoculation

The mycorrhizal enhancement of plant growth is generally attributed to increased nutrients uptake. A greenhouse experiment was conducted to investigate the effect of arbuscular mycorrhizal fungi (AMF) inoculation on the growth and nutrient uptake of directly seeded wetland rice. Seeds were germinated and inoculated with arbuscular mycorrhizal fungi or left uninoculated. The plants were grown at 60% of ‐0.03 MPa to establish the mycorrhizas. After 5 weeks, half of the pots were harvested and the rest were flooded with deionized water to maintain 3–5 cm of standing water until harvesting (122 days after sowing). Mycorrhizal fungal colonization of rice roots was 36.2% at harvest. Mycorrhizal fungi inoculated rice seedlings grew better compared to uninoculated seedlings and had increased grain yield (10%) at the harvesting stage. Shoot and root growth were effectively increased by AMF inoculation at the harvesting stage. The nitrogen (N) and phosphorus (P) acquisition of direct seeding wetland rice were significantly increased by AMF inoculation. The AMF enhanced N and P translocation through the hyphae from soils to roots/shoots to grains effectively.     

Arbuscular mycorrhizal fungus and rhizobacteria affect the physiology and performance of Sulla coronaria plants subjected to salt stress by mitigation of ionic imbalance

Salt stress has become a major menace to plant growth and productivity. The main goal of this study was to investigate the effect of inoculation with the arbuscular mycorrhizal fungi (AMF; Rhizophagus intraradices) in combination or not with plant growth‐promoting rhizobacteria (PGPR; Pseudomonas sp. (Ps) and Bacillus subtilis) on the establishment and growth of Sulla coronaria plants under saline conditions. Pot experiments were conducted in a greenhouse and S. coronaria seedlings were stressed with NaCl (100 mM) for 4 weeks. Plant biomass, mineral nutrition of shoots and activities of rhizosphere soil enzymes were assessed. Salt stress significantly reduced plant growth while increasing sodium accumulation and electrolyte leakage from leaves. However, inoculation with AMF, whether alone or combined with the PGPR Pseudomonas sp. alleviated the salt‐induced reduction of dry weight. Inoculation with only AMF increased shoot nutrient concentrations resulting in higher K⁺: Na⁺, Ca²⁺: Na⁺, and Ca²⁺: Mg²⁺ ratios compared to the non‐inoculated plants under saline conditions. The co‐inoculation with AMF and Pseudomonas sp. under saline conditions lowered shoot sodium accumulation, electrolyte leakage and malondialdehyde (MDA) levels compared to non‐inoculated plants and plants inoculated only with AMF. The findings strongly suggest that inoculation with AMF alone or co‐inoculation with AMF and Pseudomonas sp. can alleviate salt stress of plants likely through mitigation of NaCl‐induced ionic imbalance, thereby improving the nutrient profile.     

The role of arbuscular mycorrhizal fungi and cattle manure in the establishment of Tocoyena selloana Schum. in mined dune areas

In mined dune areas, revegetation with manured seedlings of native species is a common practice. Establishment of mycorrhized Tocoyena selloana seedlings in the mined coastal sand dunes of Northeast Brazil was tested. In greenhouse, seedlings were grown in substrates with 0, 5, 10, 15 or 20% cattle manure proportions and inoculated with Acaulospora longula, a mixture of native arbuscular mycorrhizal fungi (AMF) or uninoculated. The seedlings responded positively to the inoculation, but growth was limited in the absence of manure, independently of inoculation, and was higher with fertilizing doses ≥10%. The seedlings transplanted to the field were grown in a substrate with 16.5% manure and inoculated with A. longula or Gigaspora albida. After 13 months, 19 AMF species were identified in the rhizosphere and the inoculated plants were more colonized than those uninoculated. Plants associated to G. albida were taller and those associated to A. longula had a tendency of higher biomass than the uninoculated ones. Even though this tendency was not statistically significant, considering the effect on height and the low cost of inoculation it may be a feasible practice to maximize environment restoration.     

长期施肥黑土微生物区系及功能多样性的变化

Black soil （Mollisol） is one of the main soil types in northeastern China. Biolog and polymerase chain reactiondenaturing gradient gel electrophoresis （PCR-DGGE） methods were used to examine the influence of various fertilizer combinations on the structure and function of the bacterial community in a black soil collected from Harbin, Heilongjiang Province. Biolog results showed that substrate richness and catabolic diversity of the soil bacterial community were the greatest in the chemical fertilizer and chemical fertilizer＋manure treatments. The metabolic ability of the bacterial community in the manure treatment was similar to the control. DGGE fingerprinting indicated similarity in the distribution of most 16S rDNA bands among all treatments, suggesting that microorganisms with those bands were stable and not influenced by fertilization. However, chemical fertilizer increased the diversity of soil bacterial community. Principal com- ponent analysis of Biolog and DGGE data revealed that the structure and function of the bacterial community were similar in the control and manure treatments, suggesting that the application of manure increased the soil microbial population, but had no effect on the bacterial community structure. Catabolic function was similar in the chemical fertilizer and chemical fertilizer＋manure treatments, but the composition structure of the soil microbes differed between them. The use of chemical fertilizers could result in a decline in the catabolic activity of fast-growing or eutrophic bacteria.     

铅锌矿区分离丛枝菌根真菌对万寿菊生长与吸镉的影响

盆栽试验研究了土壤不同施Cd水平(0、20、50 mg kg-1)下,接种矿区污染土壤中丛枝菌根真菌对万寿菊根系侵染率、植株生物量及Cd吸收与分配的影响。结果表明:接种丛枝菌根真菌显著提高了Cd胁迫下万寿菊的根系侵染率和植株生物量;随着施Cd水平提高,各处理植株Cd浓度和Cd吸收量显著增加。各施Cd水平下万寿菊地上部Cd吸收量远远高于根系Cd吸收量,尤其在20 mg kg-1施Cd水平下,接种处理地上部Cd吸收量是根系的3.90倍,对照处理地上部Cd吸收量是根系的2.33倍;同一施Cd水平下接种处理地上部Cd吸收量要显著高于对照。总体上,试验条件下污染土壤中分离的丛枝菌根真菌促进了万寿菊对土壤中Cd的吸收,并增加了Cd向地上部分的运转,表现出植物提取的应用潜力。     

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.     

丛枝菌根真菌与植物共生影响植物水分状态的研究进展

丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)能与宿主植物形成共生体,广泛存在于陆地生态系统中。大量研究表明,不同水分条件下,植物通过接种AMF比未接种AMF的植物具有更强的水分吸收能力和更高的水分利用效率。在干旱、盐胁迫下,接种AMF能有效提高宿主植物的耐旱性与耐盐性。本文综述了不同水分条件下,与植物共生的AMF通过扩大植物根系吸收面积、改善根系结构,增强植物根系吸收水分能力的相关研究进展。土壤中根外菌丝网络的形成,不但为植物增加了水分吸收途径(菌根途径),还通过改善植物体内的矿质营养来调节植物对水分的吸收,进而影响植物的水分吸收状况；不同水分条件下,根系被AMF侵染后植物的光合作用、蒸腾作用以及气孔导度都得到增强,植物蒸腾作用的增强能够直接有效的提升植物的蒸腾拉力,因此植物对水分的吸收能力得以提升。同时,被AMF侵染的植物的水分利用率、蒸腾速率以及净光合速率得以提升从而提高了植物的水分利用能力。进一步总结了缺水胁迫(干旱胁迫、盐胁迫)严重影响植物体内的水分状况,通过接种AMF可以有效调节植物在缺水胁迫下植物体内渗透调节物质的含量、抗氧化酶的活性,平衡植物体内离子平衡,提升植物光合、蒸腾作用水平,从而提高植物的耐胁迫能力。本文通过综述不同水分条件下,接种AMF对植物的影响及机制,期望为未来新型菌剂的研发与菌根互作对植物水分状况的改善提供支撑。     

Varied rates of mycorrhizal inoculum on growth and nutrient acquisition by barley grown with drought stress

Effectiveness of arbuscular mycorrhizal fungi (AMF) is crucial for maximum plant growth and acquisition of mineral nutrients under drought. The objective of this research was to determine effects of varied rates of AMF inoculum on plant growth and acquisition of phosphorus (P), zinc (Zn), copper (Cu), and manganese (Mn) by barley (Hordeum vulgare L. cv. SLB‐6) grown with and without drought stress (WS and nonWS). Plants inoculated with four inoculum rates [control (M₀), 120 (M₁), 240 (M₂), and360 (M₃) spores per 100 g dry soil] of Glomus mosseae were grown in a low P silty clay (Typic Xerochrept) soil (pH=8.0) mix in a greenhouse for 45 days. Root AMF colonization increased as inoculum rate increased in plants grown with WS and nonWS. Leaf area and shoot and root dry matter (DM) increased as inoculum rate increased up to M₂ regardless of soil moisture. Shoot concentrations of P, Cu, and Mn were generally higher for mycorrhizal (AMF) than for nonmycorrhizal (nonAMF) plants grown with both WS and nonWS. Shoot contents of P, Zn, Cu, and Mn were higher for AMF than for nonAMF plants grown with nonWS, and shoot contents of P were higher for AMF than for nonAMF plants with WS. For plants grown with WS and nonWS, contents of P, Zn, Cu, and Mn were generally higher for plants inoculated with M₂ compared to other rates of inoculum. The results of this study indicated that plant responses to root colonization with AMF were dependent on AMF rate and soil moisture. Based on enhancements in plant DM and mineral acquisition traits, M₂ inoculum was the most effective rate of inoculation for this AMF isolate.     

Response of a wild-type and modern cowpea cultivars to arbuscular mycorrhizal inoculation in sterilized and non-sterilized soil

Cowpea is an important crop that serves as a legume and vegetable source to many smallholder farmers in sub-Saharan Africa. Soil fertility is a significant limitation to its production thus; inoculation with beneficial soil biota such as arbuscular mycorrhizal fungi (AMF) could improve its performance. However, plant–AMF interaction could vary based on crop cultivar hence affecting overall crop production. The present study aimed at determining the effect of AMF inoculation and soil sterilization on root colonization and growth of a wild-type and three modern cowpea cultivars grown by smallholder farmers in Kenya. Potted cowpea plants were inoculated with a commercial AMF inoculum comprising of Rhizophagus irregularis, Funneliformis mosseae, Glomus aggregatum and Glomus etunicatum and maintained in a greenhouse for 40 days. After harvesting, mycorrhizal colonization, nodule number and dry weight, root and shoot dry weights, nitrogen (N,) phosphorus (P) and potassium (K) content were determined. Interestingly, the modern cultivars showed significantly (p < 0.001) higher root colonization, nodulation, shoot P and N compared to the wild-type cultivar. Moreover, a strong positive correlation between AMF root colonization and shoot P (r² = 0.73, 0.90, p < 0.001), AMF root colonization and shoot N (r² = 0.78; 0.89, p < 0.001) was observed in both sterilized and non-sterilized soil, respectively. Soil sterilization affected root colonization and growth parameters with plants grown in non-sterilized soil performing better than those grown in sterilized soil. This study provides major evidence that modern cowpea cultivars are still responsive to mycorrhizal inoculation suggesting that modern breeding programs are not deleterious AMF symbiosis.     

Arbuscular mycorrhizal fungi respond to rhizobial inoculation and cropping systems in farmers' fields in the Guinea savanna

 It has been difficult to explain the rotation effect based solely on N availability in maize-soybean cropping systems in the moist savanna zone of sub-Saharan Africa. Although arbuscular mycorrhizal fungi (AMF) can contribute to plant growth by reducing stresses resulting from other nutrient deficiencies (mainly P) and drought, their role in the maize/soybean rotation cropping systems in the Guinea savanna has not yet been determined. Pot and field experiments were conducted for 2 years using 13 farmers' fields with different cropping histories in two agroecological zones (Zaria, northern Guinea savanna and Zonkwa, southern Guinea savanna) in Nigeria. We quantified the influence of cropping systems and rhizobial inoculation on plant growth, mycorrhizal colonization and diversity of promiscuous soybean and maize grown in rotation. The relationships between these variables and selected soil characteristics in farmers' fields were also examined. Percentage mycorrhizal colonization in promiscuous soybean roots ranged from 7% to 36%, while in maize it varied between 17% and 33%, depending on fields and the previous cropping history. A large variation was also observed for mycorrhizal spores, but these were not correlated with mycorrhizal colonization and did not appear to be influenced by rotation systems. Soybean mycorrhizal colonization was higher (13% increase) in Zonkwa, but not in Zaria, if the preceding crop was maize and not soybean. These differences were related to the soil P concentration, which was positively related to mycorrhizal colonization in Zonkwa but negatively to this parameter in Zaria. The previous crop did not affect mycorrhizal colonization of maize in both locations. Soybean cultivars inoculated with rhizobia had a higher mycorrhizal colonization rate (25%) and more AMF species than maize or uninoculated soybean (19%). Maize grown in plots previously under inoculated soybean also had higher percentage mycorrhizal colonization than when grown after uninoculated soybean and maize. Four AMF genera comprising 29 species were observed at Zaria and Zonkwa. Glomus was the dominant genus (56%) followed by Gigaspora (26%) and Acaulospora (14%). The genus Sclerocystis was the least represented (4%). Received: 28 October 1998     

STUDIES ON DIFFERENCES OF NITROGEN EFFICIENCY AND ROOT CHARACTERISTICS OF OILSEED RAPE (BRASSICA NAPUS L.) CULTIVARS IN RELATION TO NITROGEN FERTILIZATION

Differences of nitrogen efficiency of oilseed rape (Brassica napus L.) cultivars and their physiological properties were studied in a pot experiment, and the ratio of seed yield with no nitrogen supplied to that with normal nitrogen supply was adopted as a nitrogen efficiency coefficient. Results showed that the nitrogen efficiency coefficient determined for eight oilseed rape cultivars varied from 0.37 to 0.69, the ratio of nitrogen uptake amounts per plant, nitrogen transfer velocity from stems and leaves to seeds, and nitrogen physiological efficiency of oilseed rape cultivars under nitrogen stressed condition differed from with normal nitrogen supply. The higher the nitrogen efficiency of a cultivar, the higher the ratio of N uptake in no nitrogen to with N supplied. Under low nitrogen-supplying conditions, high nitrogen efficiency cultivars had longer roots, more lateral roots, higher amounts of reuse of nitrate from stem and leaves, and higher nitrate reductase activities in leaves.     

大棚土壤接种丛枝菌根真菌增强黄瓜枯萎病抑制水平

A pot experiment was conducted to study the plant growth and fruit yields of cucumber (Cucumis sativus L.) on a greenhouse soil with or without inoculation of arbuscular mycorrhizal fungi (AMFs) and Fusarium oxysporum f. sp. cucumerinum under unsterilized conditions. Two AMF inocula were tested: only one AMF strain Glomus caledonium 90036 and an AMF consortium mainly consisting of Glomus spp. and Acaulospora spp. There were four treatments including no inoculation (control), inoculation with F. oxysporum but without mycorrhizae (FO), inoculation with F. oxysporum and G. caledonium (FO+M1), and inoculation with F. oxysporum and the AMF consortium (FO+M2). Cucumber plants were harvested at weeks 3 and 9 after transplanting. Compared with the control, the FO treatment without AMF inoculation had less biomass both at weeks 3 and 9 (P < 0.05) and had higher incidence of Fusarium wilt and produced no cucumber fruit at week 9. Both FO+M1 and FO+M2 treatments had higher mycorrhizal colonization than the treatments which received no AMF inoculation at week 3 (P < 0.05), but only the FO+M2 treatment elevated plant biomass, decreased the incidence of Fusarium wilt, and improved cucumber yields to the same level as the control at week 9. The results indicated that the AMF consortium could suppress Fusarium wilt of cucumber and, therefore, showed potential as a biological control agent in greenhouse agroecosystems.     

Use of mycorrhizal seedlings on recovery of mined dunes in northeastern Brazil

The exploitation of minerals from coastal dunes in northeastern Brazil requires subsequent revegetation for ecosystem recovery. In mined dunes areas, we have compared the growth of Guazuma ulmifolia and Tabebuia roseo-alba seedlings using substrates containing 10 or 15% of cattle manure, uninoculated or inoculated with a mixture of native arbuscular mycorrhizal fungi (AMF) or exotic AMF (Acaulospora longula). The inoculated plants had a higher percentage of colonization than those that were uninoculated. Plants of G. ulmifolia had the highest growth when inoculated with native AMF and fertilized with 10% manure or inoculated with A. longula and fertilized with 15% manure. In general, fertilization with 15% manure did not produce greater seedling development and had a negative effect on the effectiveness of the symbiosis. Twenty one AMF species were recorded in the planting areas at the end of the experiments, with a predominance of species that form acaulosporoid spores in areas with T. roseo-alba and gigasporoid spores in areas with G. ulmifolia plants. The incorporation of 10% cattle manure and native AMF in the substrate of T. roseo-alba and G. ulmifolia seedlings contributes to the initial establishment of plants in the field and to the incorporation of AMF propagules in the soil of the revegetated mined dunes.     

Fertilizer Concentration Affects Growth Response and Leaf Color of Tradescantia virginiana L.

ABSTRACT

A pot experiment was conducted out to investigate the yield and pungency of spring onion (Allium fistulosum L.) as affected by inoculation with arbuscular mycorrhizal (AM) fungi and addition of nitrogen (N) and sulfur (S) fertilizers. Plants were inoculated with either Glomus mosseae or Glomus intraradices or grown as uninoculated controls. Two levels of N and S were applied to the soil in factorial combinations of 50 and 250 mg N kg^?1 soil and 0 and 60 mg S kg^?1 soil. Plants were grown in a greenhouse for 25 weeks and then harvested. Mycorrhizal colonization resulted in increased shoot dry weight, shoot-to-root ratio, shoot length, sheath diameter, and phosphorus (P) concentrations. Shoot dry-matter yield was significantly affected by added N, but not by S. Shoot dry weight increased with increasing N supply (except for non-mycorrhizal controls without additional S fertilizer). Shoot total S concentration (TSC), enzyme-produced pyruvate (EPY), and organic sulfur concentration (OSC) in plants inoculated with Glomus mosseae were significantly lower than those of non-mycorrhizal controls, while these parameters in plants inoculated with Glomus intraradices were comparable to or higher than in the controls. Neither N nor S supply affected shoot EPY or OSC, whereas shoot TSC (except in plants inoculated with Glomus mosseae) and SO₄ ^2? concentrations were usually significantly increased by S supply. In soil of high S and low P availability, mycorrhizal colonization had a profound influence on both the yield and the pungency of spring onion.     

The Effect of Mycorrhiza Inoculation and Phosphorus Application on Phosphorus Efficiency of Wheat Plants

The effect of indigenous soil and selected mycorrhizal inoculation and phosphorus (P) applications on wheat yield, root infection and nutrient uptake was monitored for two successive years under field conditions. In addition, phosphorus efficiency and inoculation effectiveness (IE) were determined. Wheat (Triticum aestivum L.) plants were used as host plants in a Menzilat soil series (Typic Xerofluvents) in the Mediterranean coastal region of Turkey. Three levels of phosphorus were applied with Glomus mosseae to wheat plants over two successive years. Mycorrhizal inoculation significantly increased root colonization. G. mosseae-inoculated plants in both years exhibited a two-fold higher root colonization than the indigenous mycorrhizal colonization. Compared with non-inoculated plants, mycorrhizal inoculation increased wheat yield for both years. In addition, increasing P fertilizer levels enhanced the wheat grain yield. In both years, the inoculum efficiency (IE) decreased with increasing P level addition. Phosphorus efficiency is higher under low P application than the higher P application. However, with mycorrhizal inoculation P efficiency is higher than the non-inoculated treatment.

The effects of mycorrhizal inoculation on plant nutrient concentrations were determined: mycorrhiza-inoculated plants exhibited a higher zinc (Zn), manganese (Mn), copper (Cu), iron (Fe) nutrients concentration than non-inoculated plants. After two years of field experiments, it is concluded that mycorrhizal inoculation can be used in large arable areas; however, it is also very important to manage the indigenous mycorrhiza of arable land.     

Mycorrhizal inoculation affects arbuscular mycorrhizal diversity in watermelon roots,but leads to improved colonization and plant response under water stress only

Horticultural crops in the Mediterranean basin have to cope with severe drought conditions. The effect of inoculating watermelon plants grown under limited water availability conditions with AM fungi on the fruit yield, water use efficiency (WUE), root-N and -P content was examined. We focused on the impact of watering level and inoculation with allochthonous AM fungi on the diversity and presence of AM fungi in the watermelon roots using molecular techniques. An open field experiment was conducted and plants were grown with (M) and without AM fungal inoculum (NM), subjected to water stress (NW) and no stress conditions (W). Suboptimal water application (NW) resulted in significant reduction of fruit yield, root-N and -P content. Inoculation of plants grown under water stress resulted in a significant increase of WUE (19%), fruit yield (19%), root-N (27%) and -P (40%). However, only root-P responded to AM inoculation under non water stress conditions demonstrating 23% increase in M plants. DNA extracted from root samples was subjected to PCR–DGGE analysis. The native mycorrhizal population colonized watermelon roots, as indicated by DGGE bands in NM treatments. Some members of this colonizer community appear sensitive to the introduction of allochthonous inocula and to water stress conditions. Cloning and sequencing of AM fungi revealed that watermelon roots were colonized by Glomus and Paraglomus species. A TaqMan real-time PCR assay was also carried out targeting the 18S rRNA gene for the quantification of AM nucleic acids. The 18S rRNA copy numbers of AM fungi were significantly increased in M plants compared to NM plants under water stress. On the contrary, under non stress conditions M and NM plants did not show significant differences, indicating that inoculation with AM fungi was related to the response of plants to water stress conditions. Principle coordinate analysis of the DGGE banding patterns showed that the diversity of AM fungal colonizers was strongly affected (i) by inoculation and (ii) by water stress in the inoculated plants. Inoculation affected fungal presence under water limitation conditions only. The latter was in line with the significant beneficial effect of inoculation on both WUE and yield only under water limitation.     

Influence of mycorrhizal inoculation and different pruning regimes on fresh root yield of alley and sole cropped cassava (manihot esculenta crantz) in Nigeria

The effect of mycorrhizal fungus inoculation on fresh root yield of cassava (Manihot esculenta crantz) cv TMS 4 (2) 1425 as influenced by two hedgerow tree species and their mixtures, subjected to 2- and 3-month pruning regimes were investigated in alley cropping experiments at three different sites within the same eco-climatic region in Nigeria. Mixture of the prunings of the two hedgerow tree species (Gliricidia sepium and Senna siamea) with mycorrhiza gave higher fresh root yield than the sole hedgerow tree with mycorrhizal inoculation. Gliricidia sepium prunings were found to give higher fresh root yield than the prunings from the Senna siamea. The 2-month prunings of G. sepium recorded higher yield than its 3-month prunings while 2-month prunings of Senna siamea recorded higher yield than its 3-month prunings. However, mycorrhiza inoculation with 2- and 3-month prunings in the two hedgerow species used were found higher than their counterparts without mycorrhizal inoculation in all the three sites. Mycorrhizal inoculation without the hedgerow prunings recorded the lowest fresh root yield but was still higher than the fresh root yield from the sole without mycorrhizal inoculation. Thus, inoculation with mycorrhiza increased alley-cropped cassava fresh root yield over uninoculated plants under both pruning regimes. Generally, this study shows that inoculation of cassava with mycorrhiza alone without mulching with prunings significantly increased cassava fresh root yield.