Glycine–Glomus–Phosphate Solubilizing Bacteria Interactions Lead to Fertilizer Phosphorus Economy in Soybean in a Himalayan Acid Alfisol

Effects of Glycine–Glomus–phosphate solubilizing bacteria (PSB) interactions were studied on productivity, nutrient dynamics, and root colonization in soybean in a phosphorus (P)–deficient Himalayan acidic Alfisol in a greenhouse experiment. Treatments consisted of three vesicular arbuscular mycorrhizae (VAM) cultures, VAM_L [VAM culture, Glomus mosseae, developed by CSK Himachal Pradesh Agricultural University, Palampur, India], VAM_T [VAM culture, Glomus intraradices, developed by Centre for Mycorrhizal Research, The Energy and Resources Institute (TERI), New Delhi, India], and VAM_I [VAM culture, Glomus mosseae, developed by Indian Agricultural Research Institute (IARI), New Delhi, India], and a local PSB culture (Pseudomonas striata) alone or in combination with or without 75% of recommended phosphorus pentoxide (P₂O₅) dose based on targeted yield concept following the soil-test crop response (STCR) precision model. Sole application of PSB or either of the above VAM cultures considerably enhanced VA-mycorrhizal root colonization and root weight besides crop productivity and nutrient uptake over control. A similar stimulatory effect with significant enhancement on mycorrhizal root colonization and root weight was observed with coinoculation of PSB and VAM cultures over the control. Dual inoculation of VAM and PSB cultures also resulted in significant improvement in grain and straw yield besides grain protein content, thereby revealing a synergistic interaction between VAM and PSB. Coinoculation with either of VAM_T (Glomus intraradices) or VAM_I (Glomus mosseae) + PSB + 75% P₂O₅ dose remained at par with sole application of 100% P₂O₅ dose with respect to crop productivity, nutrient content, nutrient uptake, and soil fertility status besides the greatest root colonization and root weight at flowering, indicating that Glycine–Glomus–PSB interactions in combination with 75% P₂O₅ dose based on STCR precision model lead to economization of fertilizer P by about one-fourth without impairing crop productivity and soil fertility in soybean in a Himalayan acidic Alfisol.     

Effect of Vesicular Arbuscular–Mycorrhizal Fungi and Phosphorus Application through Soil-Test Crop Response Precision Model on Crop Productivity,Nutrient Dynamics,and Soil Fertility in Soybean–Wheat–Soybean Crop Sequence in an Acidic Alfisol

A field experiment was conducted in a phosphorus (P)–deficient acidic alfisol of the northwestern Himalayas using three vesicular arbuscular mycorrhizal (VAM) cultures: a local culture developed by CSK Himachal Pradesh Agricultural University, Palampur (Glomus mosseae), VAM culture from Indian Agricultural Research Institute (IARI), New Delhi (Glomus mosseae), and a culture from the Centre for Mycorrhizal Research, The Energy Research Institute (TERI), New Delhi (Glomus intraradices). These were applied alone or in combination with 25 to 75% of recommended P₂O₅ and recommended nitrogen (N) and potassium (K) based on soil-test crop response (STCR) precision model with an absolute control, farmers’ practice, and 100% of recommended P₂O₅ dose based on the STCR model. The results revealed that sole application of either of the three VAM cultures have produced 2.68 to 9.81% and 25.06 to 28.62% greater grain yield than the control in soybean and wheat crops, respectively. Besides greater straw yield, NPK uptake as well as soil nutrient buildup increased. Increase in P fertilization from 25 to 75% of recommended P₂O₅ dose coupled with VAM inoculation with either of the three VAM cultures resulted in consistent and significant improvement in crop productivity (grain and straw yields), NPK uptake, and improved soil nutrient status, though significantly greatest magnitude was obtained with sole application of 100% of the recommended P₂O₅ dose. The targeted grain yields of soybean (25 q ha^?1) and wheat (30 q ha^?1) were achievable with 75% of recommended P₂O₅ dose along with mycorrhizal biofertilizers, thereby indicating that application of efficient VAM fungi with 75% of recommended P₂O₅ dose can economize the STCR precision model fertilizer P dose by about 25% without impairing crop yield targets or soil fertility in a soybean-based cropping system in an acidic alfisol.     

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.     

Improving Phosphorus Use through Co-inoculation of Vesicular Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Bacteria in Maize in an Acidic Alfisol

Performance of three vesicular arbuscular mycorrhizal (VAM) fungi cultures and a phosphate-solubilizing bacteria (PSB) culture alone or in combination with or without 75% of the recommended P₂O₅ dose based on soil-test crop response model was examined in maize in a phosphorus (P)-deficient acidic Alfisol in a glasshouse pot experiment. Sole application of VAM besides co-inoculation with PSB (Pseudomonas striata) and inorganic P stimulated mycorrhizal root colonization. Sole application of PSB, VAM_T (Glomus intraradices), and VAM_I (Glomus mosseae) as well as co-inoculation of VAM with PSB significantly improved crop productivity besides grain protein content, thus indicating a synergistic interaction between VAM and PSB. Application of VAM_T or VAM_I + PSB + 75% P₂O₅ remained at par with sole application of 100% P₂O₅ dose with regard to productivity, nutrient uptake, and soil fertility status (particularly P), thus indicating economization of fertilizer P to the tune of about 25% without compromising crop productivity and soil fertility in an acidic Alfisol.     

Influence of Vesicular Arbuscular Mycorrhizal Fungi and Applied Phosphorus on Root Colonization in Wheat and Plant Nutrient Dynamics in a Phosphorus-Deficient Acid Alfisol of Western Himalayas

Vesicular arbuscular mycorrhizal (VAM) fungi symbiosis confers benefits directly to the host plant's growth and yield through acquisition of phosphorus and other macro- and micronutrients, especially from phosphorus (P)–deficient acidic soils. The inoculation of three VAM cultures [viz., local culture (Glomus mosseae), VAM culture from Indian Agricultural Research Institute (IARI), New Delhi (Glomus mosseae), and a culture from the Centre for Mycorrhizal Research, Energy Research Institute (TERI), New Delhi (Glomus intraradices)] along with P fertilization in wheat in a P-deficient acidic alfisol improved the root colonization by 16–24% while grain and straw yields increased by 12.6–15.7% and 13.4–15.4%, respectively, over the control. Uptake of nitrogen (N), P, potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) was also improved with VAM inoculation over control, but the magnitude of uptake was significantly greater only in the cases of P, Fe, Zn, and Cu. Inoculation of wheat with three VAM cultures in combination with increasing inorganic P application from 50% to 75% of the recommended P₂O₅ dose to wheat through the targeted yield concept following the soil-test crop response (STCR) precision model resulted in consistent and significant improvement in grain and straw yield, macronutrient (NPK) uptake, and micronutrient (Fe, Mn, Zn, Cu) uptake in wheat though root colonization did not improve at P₂O₅ doses beyond 50% of the recommended dose. The VAM cultures alone or in combination with increasing P levels from 50% to 75% P₂O₅ dose resulted in reduction of diethylenetriaminepentaacetic acid (DTPA)–extractable micronutrient (Fe, Mn, Zn, Cu) contents in P-deficient acidic soil over the control and initial fertility status, although micronutrient contents were relatively greater in VAM-supplied plots alone or in combination with 50% to 75% P₂O₅ dose over sole application of 100% P₂O₅ dose, thereby indicating the positive role of VAM in nutrient mobilization and nutrient dynamics in the soil–plant system. There was significant improvement in available N and P status in soil with VAM inoculation coupled with increasing P levels upto 75% P₂O₅ dose, although the greatest P buildup was obtained with sole application of 100% P₂O₅ dose. The TERI VAM culture (Glomus intraradices) showed its superiority over the other two cultures (Glomus mosseae) in terms of crop yield and nutrient uptake in wheat though the differences were nonsignificant among the VAM cultures alone or at each P level. Overall, it was inferred that use of VA-mycorrhizal fungi is beneficial under low soil P or in low input (nutrient)–intensive agroecosystems.     

Fertilizer Economy through Vesicular Arbuscular Mycorrhizae Fungi under Soil-Test Crop Response Targeted Yield Model in Maize–Wheat–Maize Crop Sequence in Himalayan Acid Alfisol

The effect of three vesicular arbuscular mycorrhizae (VAM) cultures with or without inorganic phosphorus (P) was studied in a maize–wheat–maize crop sequence in a P-deficient acidic Alfisol. Application of these three VAM cultures (Glomus mosseae, developed by CSK Himachal Pradesh Agricultural University, Palampur; Glomus intraradices, developed by the Energy and Resources Institute, New Delhi; and Glomus mosseae, developed by the Indian Agricultural Research Institute, New Delhi) alone or with 25% to 75% of recommended P₂O₅ dose based on soil-test crop response (STCR) precision model along with 100% of recommended nitrogen (N) and potassium (K) caused significantly greater grain and straw yield, NPK uptake, and soil nutrient buildup over the control and also increased crop yield and NPK uptake consistently and significantly with increases in applied P from 25% to 75% P₂O₅ dose. Results implied that application of either of the three VAM cultures with 75% P₂O₅ dose can economize the yield-targeted fertilizer P dose to the extent of about one fourth of the P requirement in maize–wheat–maize crop sequence without impairing yield targets and soil fertility in a P-deficient acidic alfisol.     

VAM Fungi Spore Populations in Different Farming Situations and Their Effect on Productivity and Nutrient Dynamics in Maize and Soybean in Himalayan Acid Alfisol

To assess the effect of five vesicular arbuscular mycorrhizae (VAM) isolates of Glomus mosseae screened out from different farming situations, two pot experiments were conducted on maize and soybean in a phosphorus (P)–deficient Himalayan acid Alfisol. There was variation in VAM spore populations of Glomus mosseae isolates screened out from maize harvested fields, soybean fields, vegetable fields, tea orchard, and citrus orchard. Glomus mosseae isolate from vegetable-based cropping system exhibited maximum root colonization at flowering in maize (32%) and soybean (28%), followed by Glomus mosseae isolate from soybean fields, and exhibited the lowest in Glomus mosseae isolate from tea farm. Glomus mosseae isolate from vegetable-dominated fields was at par with Glomus mosseae isolate from soybean-based cropping system, again resulting in significantly high root biomass, nitrogen (N)–P–potassium (K) uptake, and grain and straw productivity both in maize and soybean crops besides the greatest Rhizobium root nodule biomass in soybean. There was a considerable reduction in soil fertility with respect to NPK status over initial status in pot soils inoculated with Glomus mosseae isolate from vegetable-dominated ecosystem, thereby indicating greater nutrient dynamics by this efficient VAM strain in the plant–soil system and greater productivity in a P-deficient acidic Alfisol. Overall, VAM isolates from different cropping systems and farming situations with variable size and composition of VAM mycoflora resulted in differential effects on growth, productivity, and nutrient dynamics in field crops. Overall, Glomus mosseae isolates from vegetable and soybean fields proved to be superiormost in terms of root colonization, growth, and crop productivity as well as nutrient dynamics in above study. Thus, isolation, identification, and selection of efficient VAM strains may prove as a boon in low-input intensive agriculture in P-deficient Himalayan acidic Alfisol.     

Inoculation withGlomus mosseae improves N2 fixation by field-grown soybeans

Summary A field study carried out in a sandy, relatively acid Senegalese soil with a low soluble P content (7 ppm) and low vesicular-arbuscular mycorrhizal (VAM) populations showed that soybean responded toGlomus mosseae inoculation when the soluble P level in the soil had been raised by the addition of 22 kg P ha^–1. In P-fertilized plots, N₂ fixation of soybean, assessed by the A value method, was 109 kg N₂ fixed hat when plants were inoculated withRhizobium alone and it reached 139 kg N₂ fixed ha^–1 when plants were dually inoculated withRhizobium andGlomus mosseae using an alginate bead inoculum. In addition to this N₂ fixation increase (+28%),Glomus mosseae inoculation significantly improved grain yield (+13%) and total N content of grains (+16%). This success was attributed mainly to the low infection potential of the native VAM populations in the experimental site. In treatments without solubleP or with rock phosphate, no effect of VAM inoculation was observed.     

Pre-inoculation with arbuscular mycorrhizal fungi suppresses root knot nematode (<Emphasis Type="Italic">Meloidogyne incognita</Emphasis>) on cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis>)

A pot experiment was conducted to evaluate the influence of pre-inoculation of cucumber plants with each of the three arbuscular mycorrhizal (AM) fungi Glomus intraradices, Glomus mosseae, and Glomus versiforme on reproduction of the root knot nematode Meloidogyne incognita. All three AM fungi tested significantly reduced the root galling index, which is the percentage of total roots forming galls. Numbers of galls per root system were significantly reduced only in the G. intraradices + M. incognita treatment. The number of eggs per root system was significantly decreased by AM fungus inoculation, no significant difference among the three AM fungal isolates. AM inoculation substantially decreased the number of females, the number of eggs g⁻¹ root and of the number of eggs per egg mass. The number of egg masses g⁻¹ root was greatly reduced by inoculation with G. mosseae or G. versiforme. By considering plant growth, nutrient uptake, and the suppression of M. incognita together, G. mosseae and G. versiforme were more effective than G. intraradices.     

Interactive effects of co-inoculation of Bradyrhizobium japonicum strains and mycorrhiza species on soybean growth and nutrient contents in plant

The main objective of this study was to investigate the effects of co-inoculation with different strains of Bradyrhizobium japonicum (i.e. Helinitro, Rizoking, and Nitragin) and arbuscular mycorrhizal fungi (AMF) species (i.e. Glomus fasciculatum, Glomus versiforme, Glomus intraradices, Glomus mosseae, and Glomus etunicatum) on soybean growth, fungal root colonization, and nutrient uptake of nitrogen (N), phosphorus (P), zinc (Zn), iron (Fe), and copper (Cu). Co-inoculation with various AMF species and rhizobia significantly (p<0.01) increased the soybean biomass production as compared to the non-inoculated controls. Furthermore, AMF colonization of roots of soybean plants increased by 79, 70.1, 67, 63, 57.5, and 50.1% in the presence of G. fasciculatum (GF), G. versiforme (GV), G. intraradices (GI), G. mosseae (GM), and G. etunicatum (GE), and Gmix (a mixed culture of fungi), respectively. Higher nutrient contents were observed in plants co-inoculated with Helinitro and GF. More insight into these results will enable optimization of the effective use of AM fungi in combination with their bacterial partners as a tool for increasing soybean yields in Iran; however, its general analytical framework could be applied to other parts of the world.     

Growth response of field-grown Siratro (Macroptilium atropurpureum Urb.) and Aeschynomene american L. to inoculation with selected vesicular-arbuscular mycorrhizal fungi

Summary The effect of inoculation with a selected isolate of Glomus etunicatum Becker and Gerdemann and one of G. intraradices Schenck and Smith on the growth and nutrient content of Macroptilium atropurpureum Urb. cv. Siratro and Aeschynomene americana L., at applied P levels of 10, 30, 60, and 120 kg ha^-1, was studied under field conditions. At all P levels and for all harvests, the shoot dry mass of Siratro and A. americana were greater for the plants inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungi than the control plants. Differences between the VAM fungus-inoculated and the control plants were most marked between 30 and 90 kg ha^-1 of applied P and diminished at 120 kg ha^-1. At the first harvest of Siratro, the plants inoculated with G. etunicatum had a greater shoot dry mass than those inoculated with G. intraradices, for all levels of applied P. However, for subsequent harvest of Siratro and for the one harvest of A. americana the response of shoot dry mass to the two VAM fungi was equivocal. Fungal inoculation gave at least a 30% saving in the amount of P fertilizer required (40 kg ha^-1) for the maximum yield. The plants inoculated with VAM fungi had a greater tissue concentration and total content of P and N than the control plants at low and intermediate levels of applied P. The percentage of root colonized by VAM fungi for the inoculated plants of the two legumes increased linearly with P additions up to 60 kg ha^-1. The conclusion is that under amended (limed and fertilized) soil conditions, inoculation with selected VAM fungi can improve the establishement and growth of forage legumes in fields that contain ineffective populations of native VAM fungi.     

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.     

Effects of ammonium and nitrate on the growth of vesicular-arbuscular mycorrhizalErythrina poeppigiana O.I. Cook seedlings

Erythrina poeppigiana, a woody tropical plant, was inoculated with vesicular-arbuscular mycorrhizal (VAM) fungiGlomus etunicatum Becker and Gerdeman,G. mosseae Nicol. and Gerd. Gerdeman and Trappe, orG. intraradices Schenk and Smith. Growth, N uptake, and nutrition were evaluated in VAM-inoculated plants and controls fertilized with two levels (3 or 6 mM) of either NH _inf4 ^sup+ -N or NO _inf3 ^sup- -N. The response by the mycorrhizal plants to N fertilization, according to N source and/or level differed significantly from that of the control plants. In general, the growth of the mycorrhizal plants was similar to that of the non-mycorrhizal plants when N was provided as NH _inf4 ^sup+ . When the N source was NO _inf3 ^sup- the control plants grew significantly less than the VAM plants. Inoculation with VAM fungi gave yield increases of 255 and 268% forG. etunicatum-colonized plants, 201 and 164% forG. mosseae-colonized plants and 286 and 218% forG. intraradices-colonized plants fertilized with 3 and 6 mM NO _inf3 ^sup- -N, respectively. The increased growth and acquisition of nutrients by plants fertilized with NO _inf3 ^sup- -N and inoculated with VAM shows that VAM mycelium has a capacity for NO _inf3 ^sup- absorption. The results also showed thatE. poeppigiana seedlings preferred NH _inf4 ^sup+ as an N source.G. etunicatum was the most effective endophyte, not only increasing N, P, Ca, Mg, and Zn uptake in the presence of NO _inf3 ^sup- fertilizer but also P and Mg in the presence of NH _inf4 ^sup+ applications. From these results we conclude that VAM symbiosis affects N metabolism inE. poeppigiana plants and that this species can overcome limitations on the use of NO _inf3 ^sup- -N by the mediation of VAM fungi.     

EXPLOITATION OF PHOSPHORUS PATCHES WITH DIFFERENT PHOSPHORUS ENRICHMENT BY THREE ARBUSCULAR MYCORRHIZAL FUNGI

The effect of three arbuscular mycorrhizal (AM) fungi on phosphorus (P) nutrient activation and acquisition by maize from spatially heterogeneous sand was investigated using dual-mesh packages enriched with different P concentrations and compared with non-mycorrhizal cotrols. As would be expected the AM fungi significantly enhanced leaf photosynthetic rate and the biomass and P concentrations in shoots and roots. All three fungi (Glomus intraradices, Glomus mosseae and Glomus etunicatum) displayed the capacity to dissolve inorganic P and promoted P nutrient availability in the packages (P patches). G. etunicatum showed the largest effect comparing with Glomus intraradices and Glomus mosseae, particularly in packages with high concentrations of P. Possible mechanisms involved include the acidification of the P patches by the AM fungi, promotion of the dissolution of the P, and more marked effects of the three fungal isolates with increasing enrichment of P in the patches. Inoculation with G. etunicatum resulted in greater acidification compared to the other two fungi. We conclude that AM fungi can promote P availability by acidifying the soil and consequently exploiting the P in nutrient patches and by facilitating the growth and development of the host plants.     

Selection of efficient vesicular-arbuscular mycorrhizal fungi for wetland rice (Oryza sativa L.)

Summary We tested the response of the wetland rice cultivar Prakash to inoculation with ten vescular-arbucular mycorrhizal (VAM) fungi (three selected from the first screening and seven isolated from local paddy fields) in a pot experiment under flooded conditions in order to select the most efficient mycorrhizal fungi to inoculate the rice nursery. A sandy clay loam soil was used as the substrate, fertilized with the recommended N and K levels (100 kg N ha^–1 as ammonium sulphate and 50 kg K ha^–1 as muriate of potash) and half the recommended level of P (25 kg ha^–1 as super phosphate). The inoculation was made into dry nursery beds and the beds were flooded when the seedlings were about 25 cm high, in 15 days. Twenty-eight-day old seedlings were transferred to pots filled with well puddled soil flooded with 5 cm of standing water. Based on the increase in grain yield and total biomass, Glomus intraradices and Acaulospora sp. were considered efficient and suitable for inoculation into rice nurseries.     

Mycorrhiza inoculation effects on seedling establishment,survival and morphological properties of Ziziphora clinopodioides Lam.

In this paper, the establishment and growth of medicinal species Ziziphora clinopodioides Lam. were studied through inoculation with two mycorrhizal fungi species, Glomus mosseae and Glomus intraradices, in arid/semi-arid Bahar-Kish rangelands, Iran in 2012 and 2013. The root colonization percentage of Ziziphora, as well as their establishment and growth were enhanced in 2013 using G. mosseae. In this year, less rainfall and higher temperature decreased the survival, growth and morphological traits of the studied plants. Growth and establishment of the inoculated plants using G. intraradices improved in 2013, while inoculation with G. mosseae showed more beneficial effects in 2012. In both years, the strain, the growth and establishment percentage of seedlings in inoculated treatments with mycorrhizal species were significantly improved. According to the results, G. intraradices mycorrhizal fungi is recommended as a biological fertilizer in increasing the forage production and the initial establishment of Ziziphora in arid and semi-arid rangelands.     

Pungency of Spring Onion as Affected by Inoculation with Arbuscular Mycorrhizal Fungi and Sulfur Supply

ABSTRACT

The influence of sulfur (S) supply and mycorrhizal colonization on the growth and pungency of spring onion (Allium fistulosum L.) seedlings grown for four months in Perlite and nutrient solution containing three levels of sulfate [0.1, 1.75, and 4 mM sulfate (SO₄ ^2?)] were investigated. Plants were inoculated with Glomus etunicatum, Glomus intraradices, or Glomus mosseae, and uninoculated controls were included. Shoot and root dry weights of mycorrhizal and control plants supplied with 4 mM SO₄ ²⁺ were higher than with 0.1 or 1.75 mM SO₄ ^2?. Enzyme produced pyruvic acid (EPY) and plant sulfur concentrations increased with increasing SO₄ ^2? supply. The EPY and plant S concentrations were usually higher in mycorrhizal plants than controls irrespective of S supply, and shoot total S concentrations and EPY were strongly correlated. Arbuscular mycorrhizal colonization appeared to make a substantial contribution to the sulfur status of spring onion, and may thus have had a strong influence on its flavor characteristics.     

Front Line Demonstration Program: An Effective Technology Transfer Tool for Adoption of Oilseed Production Technology in Himachal Pradesh,India

Oilseed productivity in Himachal Pradesh, India, in northwestern (NW) Himalayas is far less than national averages because of poor crop management. Frontline demonstration (FLD) program is an effective technology transfer tool for better technology adoption that bridges the yield gaps. The technological and extension yield gaps in oilseed crops were studied for 3 years during Kharif 2008 to Rabi 2010–2011 under an FLD program in the Mandi District in Himachal Pradesh, India, revealing that there was a wide yield gap between potential and demonstration yields due to technology and extension yield gaps. Extension yield gaps varied to the extent of 577–905 kg ha^?1 in soybean (Glycine max), 108–195 kg ha^?1 in sesame (Sesamum indicum), 237–350 kg ha^?1 in linseed (Linum usitatissimum), 340–355 kg ha^?1 in toria (Brassica campestris subsp. oleifera var. toria), 448–557 kg ha^?1 in gobhi sarson (Brassica napus var. napus), and 438 kg ha^?1 in brown sarson (Brassica campestris var. brown sarson) during the study period. Improved technology package has also enhanced the profitability of oilseeds in terms of gross and net returns besides additional returns in the range 2445–12838 ha^?1, enhancing incremental benefit–cost ratio (0.96–4.65). Technology indexes in soybean (29.6–52.2%), sesame (52.8–64.7%), linseed (42.3%), toria (45.2–46.4%), gobhi sarson (47.8–51.4%), and brown sarson (29.3%) has implied that demonstrated farm technology in oilseeds is quite feasible under prevailing farming situations in Himachal Pradesh, but it needs to be popularized in an intensive manner to educate hill farmers in NW Himalayas to adopt this technologically sound and economically viable method to enhance oilseed productivity and farm profitability. Improved farm technology, especially improved cultivars and nutrient management technology under these adaptive research trials, has also raised water-use efficiency (WUE) in Kharif (0.28–2.87 kg ha^?1 mm) and Rabi oilseeds (1.79–9.43 kg ha^?1 mm). Overall, it is concluded that demonstrated farm technology has great potential to improve oilseed productivity, profitability, and WUE, thus enabling resource-poor hill farmers to earn better livelihoods in Himachal Pradesh, India, and collateral farming situations in the developing world.     

External phosphorus requirement of mycorrhizal and non-mycorrhizal barley and soybean plants

An experiment was conducted under greenhouse conditions to evaluate the effects of vesicular arbuscular mycorrhizal (VAM) fungi on the external P requirements of barley and soybeans. The plants were grown in pots containing a P-deficient soil. A range of 10 P levels was obtained by adding 0, 20, 30, 40, 50, 60, 70, 110, 160, or 310 mg P kg^-1 as NaH₂PO₄ 2H₂O. Half of the pots were inoculated with the VAM fungus Glomus intraradices. The P concentration in the soil solution was determined using an adsorption isotherm and plotted against the relative yield. Barley did not respond to mycorrhizal inoculation and we concluded that P nutrition was not the limiting factor on the growth of this lowmycotrophic plant. In contrast, mycorrhizal inoculation stimulated the growth of soybeans. The external P requirements were 0.110 g ml^-1 for mycorrhizal and 0.148 g ml^-1 for non-mycorrhizal soybeans to obtain 80% of the maximum yield. In terms of P fertilization this corresponds to a saving of 222 kg P₂O₅ ha^-1. The mycorrhizal dependency of the soybean was highly correlated with the P concentration in the soil solution and it is proposed that both values should be displayed together.     

Effects of microbial inoculations on soil chemical,biochemical and microbial biomass carbon of cassava (Manihot esculenta Crantz) growing Vertisols

Cassava is an important subsidiary food in the tropics. In Tamil Nadu, India, microbial cultures were used to eradicate the tuberous root rot of cassava. Hence, an experiment was conducted for two consecutive years to test the effects of coinoculation of microbes on soil properties. The surface soil from the experimental site was analysed for soil available nutrients, soil enzyme activities and microbial biomass carbon. The treatment of Azospirillum with Trichoderma at the 50% recommended N:P₂O₅:K₂O (NPK) rate (50:25:50 kg ha^?1) significantly increased soil available nitrogen (142.81 kg ha^?1) by 72.66% over uninoculated control. There was a significant increase in available phosphorus in soil by the inoculation of AM (arbuscular mycorrhizal) fungi with Trichoderma at the 50% recommended NPK rate (41.04 kg ha^?1) compared to other treatments. The application of Pseudomonas fluorescens with Trichoderma at the 50% recommended NPK rate significantly increased available iron (19.34 µg g^?1) in soil. The treatment of Azospirillum with Trichoderma increased urease enzyme activity at the recommended NPK rate (816.32 μg urea hydrolyzed g^?1 soil h^?1). Soil application of all cultures at the 50% recommended NPK rate significantly increased dehydrogenase activity (88.63 μg TPF g^?1 soil) and β-glucosidase activity (48.82 μg PNP g^?1 soil) in soil. Inoculation of Trichoderma alone at the 50% recommended NPK rate significantly increased microbial biomass carbon (3748.85 μg g^?1 soil). Thus, the microbial inoculations significantly increased soil available nutrient contents, enzyme activities such as urease, dehydrogenase and β-glucosidase activity and microbial biomass carbon by reducing the amount of the required fertilizer.