Using arbuscular mycorrhiza to alleviate the stress of soil compaction on wheat (Triticum aestivum L.) growth

Since large areas of agricultural fields in the world become compacted every year, much effort has been made to reduce the adverse effects of soil compaction on plant growth. Mechanical methods to control soil compaction may be laborious and expensive; however, biological methods such as using arbuscular mycorrhiza (AM) may be more useful, economically and environmentally. The objectives of this study were: (1) to evaluate the effects of soil compaction on wheat (Triticum aestivum L.) growth, and (2) to evaluate if using AM of different origin can reduce the stressful effects of soil compaction on wheat growth. Unsterilized and sterilized soils, different levels of compaction and three species of arbuscular mycorrhiza were applied in four replicates. The experiments were conducted in the Soil and Water Research Institute, Karaj, Iran. Soil physical and chemical properties were determined. The AM increased wheat growth in both soils at different levels of soil compaction in both experiments. For root, shoot (P=0.1) and grain (P=0.05) dry weights increases were significant. AM enhanced root growth more than shoot growth under compaction (AM resulted in significant increase in root/shoot ratios, P=0.1). Due to its unique characteristics, AM may reduce the stressful effects of soil compaction on wheat growth, though its effectiveness may decrease with increasing compaction.     

帽儿山地区黄檗根际丛枝菌根真菌资源的调查

通过对自然状态下黄檗根际土壤的丛枝菌根真菌资源进行取样调查,共发现4属23种丛枝菌根真菌的孢子,分别为无梗囊霉属、球囊霉属、盾巨孢囊霉属和原囊霉属。从出现频度看以无梗囊霉属和球囊霉属占优势;其中无梗囊霉属的细凹无梗囊霉、刺无梗囊霉和球囊霉属的聚丛球囊霉、悬钩子状球囊霉,以及盾巨孢囊霉属的美丽盾巨孢囊霉是出现频度较高的5个种。     

四川桉树内生菌根真菌的研究

四川省桉树内生菌根资源菌较丰富，共14种，隶属接合菌亚门内囊霉科的3个属。其中以球囊霉属（Glomus)的近明球囊霉（G.claroideum Schenck and Smith)，缩球囊霉（G.constrictum Trappe)，地表球囊霉（G.versiforme(Karsren)Berch)，摩西球囊霉（G.mosseae)，有较广泛的宿主，为优势菌群，小果球囊霉，大果球囊霉，微丛球囊霉为零星出现，感染宿主相对较窄。通过5种桉树固定标准地的调查，我们发现不同桉树树种内生菌化率有显著差异，且内生菌根真菌随林分年龄增加而增多。     

Influence of Soil Water Regimes on VA Mycorrhiza

A greenhouse trial was conducted with cassava inoculated with seven different VAM fungal species, i.e. Acaulospora longula, A. myriocarpa, Entrophospora colombiana, Glomus fasciculatum, G. manihotis, G. occultum and Scutellospora heterogama. A wet and a dry soil water regime was established to study the effect of water stress on performance of these fungi with a drought tolerant cassava clone. At harvest, N, P and K concentration was analysed in leaves, petioles, stems and roots.
In unstressed plants, five endophytes were effective whereas in stressed plants only three fungi improved growth beyond the non-mycorrhizal control. These were E. colombiana, G. manihotis and G. occultum which were most effective for P uptake under stress. Differential effects of VAM fungal species on root length and K. uptake were found. A. myriocarpa caused the greatest increase in length of feeder roots and G. occultum was one of the most effective for K uptake under both water regimes even though these fungi were not the most effective for dry matter production. Under each water regime, the concentration of N, P and K in leaves, petioles, stems and roots was influenced by the fungal species. Mycorrhizal endophytes differed in tolerance to dry soil conditions as found by root infection ratings. From the results it can be concluded that in addition to the improved P nutrition the enhanced root length and K uptake by VAM fungi may be important for drought tolerance of cassava.     

Chitinase andβ1,3-glucanase isoforms expressed in pea roots inoculated with arbuscular mycorrhizal or pathogenic fungi

Chitinases were studied in an endomycorrhiza-resistant mutant and wild type pea (Pisum sativum L. cv. Frisson) in order to characterize plant hydrolases specific to pathogenic (Aphanomyces euteiches andChalara elegans) or mycorrhizal (Glomus mosseae) root interactions. Stimulation of constitutive and induction of new chitinase activities was detected by native PAGE for acidic proteins in both pea genotypes inoculated with pathogenic fungi. In contrast, a different additional chitinase isoform was induced inG. mosseae-colonized roots. This isoform was also not elicited in chemically-stressed roots, confirming its mycorrhiza-specificity. Investigations of basic chitinase and-1,3-glucanase activities provided further evidence for differential pea responses during pathogenic and symbiotic interactions.     

3种球囊霉属真菌对盆栽木薯生长影响

应用盆栽试验法,单独接种球囊霉属Glomus菌种：根内球囊霉G．intraradices（Gi）、木薯球囊霉Gmanihotis（Gm）和幼套球囊霉Getunicatum（Ge）菌剂及混合菌剂（2G）,检测不同接种条件下对盆栽木薯Manihot esculenta根系的侵染能力及其对木薯生长的影响．3个试验菌种均可与木薯形成疆南星型（Arum—type）丛枝菌根（arbuscular mycorrhiza,AM）,其中Gi和Gm均可在菌根内形成根内孢子．2G和Gi均显示较强的侵染能力,Gm在早期的侵染较慢,但在后期的感染率较高,Ge侵染能力最差．2G、Gi和Gm处理组木薯的高度生长均比非接种处理的对照组好,但只有2G处理组无论株高生长还是生物积累均达到显著水平,其他处理组差异不显著,Ge处理组木薯在叶部和根部生物量的积累有负向影响．     

Behaviour of arbuscular-mycorrhizal fungi on Vigna luteola growth and its effect on the exchangeable (32P) phosphorus of soil

 The effect of the inoculation of Glomus mosseae and Scutellospora fulgida, singly or in mixed inocula, was tested on the growth and mycorrhizal characteristics of Vigna luteola. Soil depletion by mycorrhizal inoculation was determined as exchangeable ³²PO₄. Five treatments were performed: non-inoculated control (C); inoculated with a suspension of microorganisms free of mycorrhizae (M); inoculated with S. fulgida plus microorganisms (Sf+M); inoculated with G. mosseae plus microorganisms (Gm+M) and a treatment inoculated with both S. fulgida and G. mosseae plus microorganisms (Sf+Gm+M). G. mosseae was the most efficient fungus in promoting growth of V. luteola. This fungus produced higher shoot dry weight, P uptake in shoots (P_shoot) and P_shoot/arbuscules ratio than the S. fulgida inoculum, even though percent arbuscular-mycorrhizal (AM) colonization was similar for the two single AM-inoculated treatments. The highest value of isotopically exchangeable P was recorded for treatment M (P<0.05). In comparison with M, Gm+M treatment reduced the different P pools more than Sf+M treatment. C_p values were reduced to half by Gm+M and Sf+M treatments and were minimum for the combined treatment. Pools A (exchangeable phosphate between 1 min and 1 day) and B (exchangeable phosphate between 1 day and 3 months) were reduced by Gm+M treatment in contrast to Sf+M, which left them unchanged. The depression of isotopically exchangeable P for all pools obtained for the Sf+Gm+M treatment suggested that specific characteristics of fungi caused differences in P absorption, which in addition was altered by the possible interactions among them, when multiple inocula were used in a soil low in native P. Received: 29 January 1999     

Influences of Potassium Chloride Fertilization on Mycorrhizal Formation in a Tropical Alfisol

This study examines the influence of different amounts of potassium chloride (KCl) fertilization on plant growth, nutrient accumulation and content, nutrient ratios, and root colonization by indigenous arbuscular mycorrhizal (AM) fungi in maize (Zea mays L.). KCl was applied at the rate of 0, 0.25, 0.50, 1.00, 1.50, and 1.75 mg/kg of soil. Effect of KCl on indigenous AM formation and function was evaluated in terms of the extent of root length colonization, plant growth, and nutrient uptake. Increasing concentration of KCl fertilization proportionately limited the total root length colonized by AM fungi as well as the root length with different AM fungal structures. Maize plants raised on soils amended with different concentrations of KCl were significantly taller than those raised on unamended soils. KCl application also significantly increased the total root length and root dry weight. Nevertheless, KCl fertilization did not significantly alter the root/shoot ratios. Higher concentrations of nitrogen (N), phosphorus (P), and potassium (K) were evident in shoot and root tissues of maize (except shoot N) raised on KCl-amended soils. Phosphorus concentrations in shoots and roots significantly influenced mycorrhization and root length colonized by different AM fungal structures, and such an effect was evident for root N. KCl fertilization increased the efficiency of N and P accumulation. No significant change was evident in the K:N ratios of shoots or roots, whereas the K:P ratios were significantly altered in shoots or roots in response to KCl application.     

中国牡丹主栽培区根围土壤中的丛枝菌根真菌的分离鉴定

对中国牡丹主栽培区河南洛阳和山东菏泽栽培牡丹(Paeonia suffruticosa)根围土壤中丛枝菌根(arbuscularmycorrhizae,AM)真菌资源状况进行了调查,共分离鉴定出AM真菌35种:Acaulospora属12种,Archaespora属1种,Glomus属17种,Gigaspora属2种,Scutellospora属3种。其中Glomus lacteum和Scutellospora arenicola为国内新记录种。     

Comparative Performance of Geographical Isolates of Glomus mosseae in Field Crops under Low-Input Intensive P-Deficient Acid Alfisol

Comparative performance of five geographical isolates of Glomus mosseae screened from maize fields, soybean fields, vegetable fields, tea orchard, and citrus orchard was assessed in three major field crops (wheat, maize, and soybean) under low-input management in three glass-house pot experiments in a phosphorus (P)–deficient acid Alfisol. These geographical isolates of Glomus mosseae varied with respect to vesicular arbuscular mycorrhizal (VAM) spore count and root colonization in these crops with greatest spore count (240 per 250 g soil) and root colonization (28–34%) using previously screened local Glomus mosseae culture (VAM_L) of CSK Himachal Pradesh Agricultural University, Palampur, India, followed in order by VAM isolate from vegetable-based cropping system, Glomus mosseae isolate from soybean fields, and Glomus mosseae isolate from tea farm. Glomus mosseae isolate from vegetable-based cropping system remaining at par with local VAM culture (VAM_L), resulting in significantly greatest grain productivity in these field crops under low-input management. There was a considerable reduction in soil fertility with respect to NPK status over the control and initial status in pot soils inoculated with Glomus mosseae isolate from vegetable-based cropping system followed by local VAM strain (VAM_L), thereby indicating greater nutrient mobilization and productivity as well through this efficient Glomus mosseae strain in P-deficient acid Alfisol. In addition, Glomus mosseae isolates from different farming situations resulted in differential productivity and soil fertility under these field crops. Overall, Glomus mosseae isolate from vegetable-based cropping system proved its superiority in realizing greater productivity and nutrient mobilization compared to local Glomus mosseae VAM culture under low-input management in P-deficient acid Alfisol.