Humic substrates facilitated nitrogen uptake in tea bushes by influencing biochemical and microbiological properties in soil of Northeast India

Abstract

Several groups of microorganisms are involved in converting applied urea into plant-available nitrate nitrogen (N) in soil. The objective of this study was to evaluate efficacy of humic substrates (HS) for maximizing crop yield by enhancing N availability in soil. In this experiment, HS was applied in soil of tea garden in such a way that active substrate was applied at 0, 400, 800, 1,200, 1,600, and 2,000?g ha^?1 in six treatments. Chemical fertilizers were applied in all the treatments (including control) following the recommended doses. This study indicated that applied HS enhanced tea shoot yield and N uptake by tea bushes. Improved biochemical and microbiological properties increased N availability in HS-treated soil and that in turn facilitated N uptake by tea bushes. It was determined that HS substrate application at 1.2?kg ha^?1 could enhance the yield of tea shoots up to 18% higher than control treatment.     

Evaluated Potential of Mica Waste to Release Sufficient Potassium to Support the Growth of Plants in Acidic Tea-Growing Soil in Northeast India

Tea (Camellia sinensis L.) is a nutrient-demanding perennial crop and cultivated in typically acidic soil under sub-tropic humid condition. A large amount of fertilizers, especially urea and muriate of potash (MoP), are applied in the soil to sustain tea productivity. However, high potassium (K)-loss from soil under humid conditions suggests the requirement of an alternative K source for supplementing K in the soil during tea cultivation. The objective was to evaluate the possibility of using K-containing minerals, namely, potassium feldspar (K-spar) and mica waste (WM), as alternative K-source for supplementing K in the soil. In this study, application of WM at the recommended dose increased exchangeable K content in soil compared to control (received no K input); however, the value was lower than that of MoP treatment. The WM-treated plants had better growth and higher K uptake than plants with the MoP treatment. Application of WM at half of the recommended dose increased K content in the soil above no K-treated soil and recorded comparable growth and K accumulation by plants as MoP. MW could be used as K amendment in acidic soil, especially during tea cultivation.     

Chemical Characterization and Stability of Poultry Manure Tea and Its Influence on Phosphorus Sorption Indices of Tropical Soils

This study characterized poultry manure extract (tea) and investigated the effects of integrated use of tea and the sequence of phosphorus (P) application [P added before (PBT), after (TBP), or jointly (PT) with tea] on P-sorption characteristics on acidic, alkaline, and neutral tropical soils. Results indicated that diluted tea contained 400 mg nitrogen, 155.80 mg potassium, and 10.48 mg P L^?1 and the nutrients were greatest after 2 weeks. Soil P sorption conformed to the Freundlich model, indicating that soil P affinity was less than the aqueous solution at low solution P concentration. Freundlich index (k) in neutral soil was 78 and 94% greater than in acidic and alkaline soils, respectively. The lowest P sorption efficiency and greatest phosphate requirement were in acidic soil. Poultry manure tea could enhance P availability and reduce P fixation irrespective of the sequence of application of tea and P.     

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.     

The Effect of Humic Substances and Phosphate Fertilizer on Growth and Nutrient Uptake of the Potato

ABSTRACT

The use of applied phosphorus (P) and the uptake of nutrients from the soil by plants can be improved when the fertilizer is combined with the application of humic substances (HS). However, these beneficial effects are inconsistent and can depend on the type of soil. This study was performed to evaluate the effects of the application of HS (0, 1.25, and 7.50 mL pot^–1), as Humic HF®, and fertilizer-P (10, 50, 100, and 200 mg P dm^–3), as triple superphosphate, on root morphological characteristics, dry matter accumulation, nutrient uptake, and tuber yield of potatoes grown in sandy and clayey soils. Only under low P supply in the sandy soil did the supply of HS, at the rate of 1.25 mL pot^–1, increase the plant growth, yield of tubers, and uptake of macronutrients by the plants, without affecting the efficiency of the P fertilization. In the clayey soil, which had a higher organic matter content, the application of HS did not affect plant growth, tuber yield or nutrient uptake. In both soils, P fertilization increased plant growth, tuber yield, and nutrient uptake. The combined application of HS and P increased the root length of potatoes in sandy soil.     

Improvement of phosphorus uptake, phosphorus use efficiency, and grain yield of upland rice (Oryza sativa L.) in response to phosphate-solubilizing bacteria blended with phosphorus fertilizer

Phosphorus (P) limitation in soil is a major concern for crop productivity. However, the use of chemical fertilizer is hazardous to the environment and costly. Therefore, the use of phosphate-solubilizing bacteria (PSB) is an eco-friendly approach for a sustainable agricultural system. In the present study, a field trial was conducted for two consecutive years to study the effects of three PSB strains isolated, Bacillus licheniformis, Pantoea dispersa, and Staphylococcus sp., with different P fertilizer rates on P uptake, P use efficiency (PUE), and grain yield of rice. The activities of soil enzymes were also studied in relation to PSB treatments. Comparative analysis of the yield and biochemical parameters revealed that inoculation of PSB consortium could reduce almost 50% of the recommended P dose in rice cultivation. Three PSB strains in combination with 50% P dose was most effective and showed the highest increases in P uptake and PUE as compared to the uninoculated control. Moreover, the PSB consortium combined with 50% P dose contributed to 50.58% and 35.64% yield increases compared to the uninoculated control for 2018 and 2019, respectively. Significant increases in the activities of soil dehydrogenase, alkaline phosphatase, and acid phosphatase were also recorded under PSB treatment.     

Growth,phosphorus uptake,and rhizosphere microbial‐community composition of a phosphorus‐efficient wheat cultivar in soils differing in pH

In a pot experiment, the P‐efficient wheat (Triticum aestivum L.) cultivar Goldmark was grown in ten soils from South Australia covering a wide range of pH (four acidic, two neutral, and four alkaline soils) with low to moderate P availability. Phosphorus (100 mg P kg^–1) was supplied as FePO₄ to acidic soils, CaHPO₄ to alkaline, and 1:1 mixture of FePO₄ and CaHPO₄ to neutral soils. Phosphorus uptake was correlated with P availability measured by anion‐exchange resin and microbial biomass P in the rhizosphere. Growth and P uptake were best in the neutral soils, lower in the acidic, and poorest in the alkaline soils. The good growth in the neutral soils could be explained by a combination of extensive soil exploitation by the roots and high phosphatase activity in the rhizosphere, indicating microbial facilitation of organic‐P mineralization. The plant effect (soil exploitation by roots) appeared to dominate in the acidic soils. Alkaline phosphatase and diesterase activities in acidic soils were lower than in neutral soils, but strongly increased in the rhizosphere compared with the bulk soil, suggesting that microorganisms contribute to P uptake in these acidic soils. Shoot and root growth and P uptake per unit root length were lowest in the alkaline soils. Despite high alkaline phosphatase and diesterase activities in the alkaline soils, microbial biomass P was low, suggesting that the enzymes could not mineralize sufficient organic P to meet the demands of plants and microorganisms. Microbial‐community composition, assessed by fatty acid methylester (FAME) analysis, was strongly dependent on soil pH, whereas other soil properties (organic‐C or CaCO₃ content) were less important or not important at all (soil texture).     

Effect Of The Sequential Application Of Liquid Organic Manure And Phosphorus On Maize Agronomic Traits And P Uptake In Some Tropical Soils

Improving phosphorus (P) fertility is challenging in tropical soils because of the fixation of P by soil components. The trial investigated the effect of the sequential application of poultry manure extract (tea) and P fertilizer on maize agronomy and P uptake, through screen house and field experiments. Results indicated that poultry manure tea is rich in nutrients but low in P and could be applied with phosphorus fertilizer to enhance P availability and reduce fixation. Application of P before manure tea produced taller maize plant on the field and the highest P uptake in the screen house and on the field. Manure tea also increased maize dry matter and grain yield. Combined application of poultry manure tea and P fertilizer had positive complementary and synergistic effects. It was concluded that manure tea enhances P availability and reduces P fixation by soil aluminum (Al) and iron (Fe) oxides irrespective of the sequence of application.     

Phosphorus Efficiency of Winter Canola Cultivars and Rhizosphere Properties in Rhizobox Technique

Production of oilseed crops requires balanced fertilization, while environmental problems of applied fertilizers must be considered. We evaluated seven winter canola cultivars (Brassica napus L.) for their relative efficiency to use or acquire phosphorus (P) under deficient and sufficient conditions. Average root mean diameter (RMD), total root length (RL) and root surface area (RA), of plants were measured as well as rhizosphere properties in rhizobox technique. Water-soluble P (WSP) and phosphatase activity of treatments containing plant were higher than control. WSP increased by 2.86 mg kg^?1 soil in Gabriela and 2.63 mg kg^?1 soil in Elvis at P deficient condition, compared to the control soil. The Olsen extractable P of the treatments decreased compared to control. Variations in total dry weights of cultivars were mainly explained by the differences in P solubilizing bacteria (PSB) population, pH, and phosphatase activity. The responsible mechanism for the P efficient (PE) cultivars can be higher P uptake through larger root and changes in rhizosphere properties.     

Influence of phosphorus-solubilizing compounds on soil P and P uptake by perennial ryegrass

Found throughout the world, phosphorus (P)-fixing soils have long been studied for their effect on the availability of P fertilizers for crop production. It is known that organic acids in the rhizosphere affect P solubilization and uptake, although effectiveness has been shown to vary with acid, crop, and soil characteristics. Regardless, commercial products have been developed that include some formulation of organic acids intended to increase P solubility and uptake. Thus, the objective of this research was to evaluate the ability of the commercial P-solubilizing products Avail (maleic-itaconic copolymer) and P Miner (organic acid-based product) to maintain a greater pool of plant-available P for uptake by perennial ryegrass (Lolium perenne L.). Greenhouse experiments were conducted with P fertilization (0, 17, 34, and 50 kg P ha^?1) and P solubilization materials in an incomplete 4?×?5 factorial design. Treatments were added to a soil with a high P-fixing capability and perennial ryegrass planted. Collected data included plant dry matter and P content, and acid (Mehlich-I) and labile (CaCl₂) extractable soil P concentrations. Results are not definitive, but they indicate that both Avail and P Miner have the potential to improve available forms of P in the soil that are available to ryegrass. In these greenhouse trials, the application of P Miner at four times the recommended rate (480 kg ha^?1) resulted in highest labile and acid-extractable P, while application of Avail and P Miner at the recommended rate (120 kg ha^?1) resulted in the highest P uptake.     

Carrier-based and liquid bioinoculants of Azotobacter and PSB saved chemical fertilizers in wheat (Triticum aestivum L.) and enhanced soil biological properties in Mollisols

Abstract

The increasing cost and imbalanced use of chemical fertilizers in wheat (Triticum aestivum L.) stressed the need to explore the potential of bioinoculants of Azotobacter and PSB for saving fertilizer N and P. Field experiments conducted for two years in a Mollisol at Pantnagar revealed maximum plant height, grain and straw yields and nutrient uptake by wheat with application of 100% NP. However, soil application of carrier-based biofertilizer at 10?kg?ha^?1 and liquid-based biofertilizers at 625 and 1250?mL?ha^?1 rates in combination of 75% NP were at par with 100% NP by recording significantly more mean plant height at different intervals, grain yield, by 10.9, 10.5 and 10.8%, and straw yield, by 8.6, 8.2 and 9.1%, over 75% NP, respectively. These treatments also accumulated significantly more N, P and K in plant at different age and; grain and straw. An application of liquid biofertilizer at 1250?mL?ha^?1 with 75% NP gave maximum population of Azotobacter and PSB, microbial biomass C and activities of acid and alkaline phosphatase in soil at different crop age. The carrier and liquid formulations of the biofertilizers were comparable in their performance. Irrespective of formulation and doses, application of biofertilizers in soil was found better than seed treatment for different recorded parameters. An application of 625?mL?ha^?1 liquid biofertilizers in soil with 75% NP was found optimum for the growth, yield and nutrients uptake and soil biological properties.     

Phosphate-solubilization activity of bacterial strains in soil and their effect on soybean growth under greenhouse conditions

The efficiency of 13 phosphate-solubilizing bacteria (PSB; four Burkholderia sp., five Enterobacter sp., and four Bradyrhizobium sp.) was assessed in a soil plate assay by evaluating soil phosphorus (P) availability. A commercial argentine strain, Pseudomonas fluorescens, was used for comparing solubilizing activity. Burkholderia sp. PER2F, Enterobacter sp. PER3G, and Bradyrhizobium sp. PER2H strains solubilized the largest quantities of P in the soil plate assay after 60 days as compared with the other strains, including the commercial one. The effect of PSB inoculation on growth and nutrient uptake of soybean plants was also studied under greenhouse conditions. Plants inoculated with Burkholderia sp. PER2F had the highest aerial height and showed an appropriate N/P ratio. However, none of the PSB increased P uptake by plants. This suggests that PSB inoculation does not necessarily improve P nutrition in soybean, nor was there any relationship between P availability in the soil plate assay and P content in the soybean shoot in the greenhouse. We concluded that the selection of efficient PSB strains as possible inoculation tools for P-deficient soils should focus on the integral interpretation of soil assays, greenhouse experiments, and field trials.     

Microbial and chemical sources of phosphorus supply modulate the yield and chemical composition of essential oil of rose-scented geranium (Pelargonium species) in sodic soils

Rose-scented geranium (Pelargonium sp.) is a highly valued aromatic crop. Its growth is limited by soil salinity and sodicity stress. Arbuscular mycorrhizal (AM) fungus, phosphate-solubilizing bacteria (PSB), and P fertilizers may enhance the growth and secondary metabolism in geranium plants. In this context, a pot experiment was conducted to study the effects of PSB, AM fungi (Glomus intraradices), and P fertilizer on the yield, chemical composition of essential oil, and mineral element acquisition of geranium. The dry matter yield of shoot and essential oil yield, and mineral element (P, K, Ca, Mg, Na, Fe, Cu, and Zn) uptake in shoot tissues of geranium were significantly increased by the inoculation with AM fungi, co-inoculation with AM fungi and PSB, and P fertilization as compared to control. While the co-inoculation of geranium with AM fungi and PSB significantly enhanced the content of the monoterpenes such as citronellol, geraniol, geranial, and a sesquiterpene (10-epi-γ eudesmol), the P fertilization only enhanced the content of a sesquiterpene, 10-epi-γ eudesmol in the volatile oil. We conclude that the co-inoculation of PSB and AM fungi could be the best natural alternative to phosphate fertilizers to enhance the yield and quality of essential oil from geranium plants grown in sodic soils.     

Enhancement of maize plant growth with inoculation of phosphate-solubilizing bacteria and biochar amendment in soil

Maize plant has an absolute requirement of nutrients (N, P, and K) for growth and development. The microbial application can facilitate in addressing limited access to chemical fertilizer concern. Moreover, biochar and phosphorus-solubilizing bacterial (PSB) community can contribute together in nutrient availability. Both have the P-supply potential to the soil, but their interaction has been tested less under semiarid climatic conditions. The purpose of the study was to evaluate the potential of biochemically tested promising PSB strains and biochar for maize plant growth and nutritional status in plant and soil. Therefore, two isolated PSB strains from maize rhizosphere were biochemically tested in vitro and identified by 16S rDNA gene analysis. The experiment was conducted in the greenhouse where the plant growth and nutrient availability to the plants were observed. In this regard, all the treatments such as PSB strain-inoculated plants, biochar-treated plants, and a combination of PSBs + biochar-treated plants were destructively sampled on day 45 (D₄₅) and day 65 (D₆₅) of sowing with four replications at each time. PSB inoculation, biochar incorporation, and their combinations have positive effects on maize plant height and nutrient concentration on D₄₅ and D₆₅. In particular, plants treated with sawdust biochar + Lysinibacillus fusiformis strain 31MZR inoculation increased N (32.8%), P (72.5%), and K (42.1%) against control on D₆₅. Besides that, only L. fusiformis strain 31MZR inoculation enhanced N (23.1%) and P (61.5%) than control which shows the significant interaction of PSB and biochar in nutrient uptake. PSB and biochar have the potential to be used as a promising amendment in improving plant growth and nutrient absorption besides the conventional approaches.     

Isolation of culturable phosphobacteria with both phytate-mineralization and phosphate-solubilization activity from the rhizosphere of plants grown in a volcanic soil

Chilean volcanic soils contain large amounts of total and organic phosphorus, but P availability is low. Phosphobacteria [phytate-mineralizing bacteria (PMB) and phosphate-solubilizing bacteria (PSB)] were isolated from the rhizosphere of perennial ryegrass (Lolium perenne), white clover (Trifolium repens), wheat (Triticum aestivum), oat (Avena sativa), and yellow lupin (Lupinus luteus) growing in volcanic soil. Six phosphobacteria were selected, based on their capacity to utilize both Na-phytate and Ca-phosphate on agar media (denoted as PMPSB), and characterized. The capacity of selected PMPSB to release inorganic P (Pi) from Na-phytate in broth was also assayed. The results showed that from 300 colonies randomly chosen on Luria–Bertani agar, phosphobacteria represented from 44% to 54% in perennial ryegrass, white clover, oat, and wheat rhizospheres. In contrast, phosphobacteria represented only 17% of colonies chosen from yellow lupin rhizosphere. This study also revealed that pasture plants (perennial ryegrass and white clover) have predominantly PMB in their rhizosphere, whereas PSB dominated in the rhizosphere of crops (oat and wheat). Selected PMPSB were genetically characterized as Pseudomonas, Enterobacter, and Pantoea; all showed the production of phosphoric hydrolases (alkaline phosphatase, acid phosphatase, and naphthol phosphohydrolase). Assays with PMPSB resulted in a higher Pi liberation compared with uninoculated controls and revealed also that the addition of glucose influenced the Pi-liberation capacity of some of the PMPSB assayed.     

Growth,P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability

The aim of the present study was to assess the role of soil type on growth, P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability. Two wheat (Goldmark and Janz) and two canola genotypes (Drum and Outback) were grown in a calcareous soil (pH 8.5) at two P levels [no P addition (0P) or addition of 200 mg kg⁻¹ P as Ca₃(PO₄)₂ (200P)] and harvested at flowering or maturity. Shoot and root dry weight, root length and shoot P content were greater in the two canola genotypes than in wheat. There were no consistent differences in available P, microbial P and phosphatase activity in the rhizosphere of the different genotypes. Shoot P content was significantly positively correlated with root length, pH and phosphatase activity in the rhizosphere. The microbial community composition, assessed by fatty acid methylester analysis, of the canola genotypes differed strongly from that of the wheat genotypes. The weight percentage bacterial fatty acids, the bacteria/fungi (b/f) ratio and the diversity of fatty acids were greater in the rhizosphere of the canolas than in the rhizosphere of the wheat genotypes. In contrast to the earlier studies in an acidic soil, only small differences in growth and P uptake between the genotypes of one crop were detected in the alkaline soil used here. The results confirmed the importance of root length for P uptake in soils with low P availability and suggest that the rhizosphere microbial community composition may play a role in the better growth of the canola compared to the wheat genotypes.     

Soil organic carbon and phosphorus availability regulate abundance of culturable phosphate-solubilizing bacteria in paddy fields

Low availability of phosphorus(P) is a major constraint for optimal crop production, as P is mostly present in its insoluble form in soil. Therefore,phosphate-solubilizing bacteria(PSB) from paddy field soils of the Indo-Gangetic Plain, India were isolated, and their abundance was attempted to be correlated with the physicochemical characteristics of the soils. Ninety-four PSB were isolated on Pikovskaya's agar medium, and quantitative phosphate solubilization was evaluated using NBRIP medium. The isolates solubilized P up to a concentration of 1 006 μg mL~(-1) from tricalcium phosphate with the secretion of organic acids. These isolates were identified by 16 S rRNA gene sequence comparison, and they belonged to Gammaproteobacteria(56 isolates),Firmicutes(28 isolates), Actinobacteria(8 isolates), and Alphaproteobacteria(2 isolates). Phylogenetic analysis confirmed the identification by clustering the isolates in the clade of the respective reference organisms. The correlation analysis between PSB abundance and physicochemical characteristics revealed that the PSB population increased with increasing levels of soil organic carbon, insoluble P, K~+, and Mg~(2+). The promising PSB explored in this study can be further evaluated for their biofertilizer potential in the field and for their use as potent bio-inoculants.     

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.     

Inoculation of phosphate-solubilizing bacteria Bacillus thuringiensis B1 increases available phosphorus and growth of peanut in acidic soil

Phosphate-solubilizing microorganisms play an important role in plant nutrition by enhancing phosphorus (P) availability to roots through converting the insoluble phosphates into soluble ions. We isolated phosphate-solubilizing bacteria (PSB) from acidic soil (Ultisols) in the field from the layer of 0–150 mm at a tea garden located at 28°38′26″ N and 116°24′27″ E. The capacity of bacterial isolates to solubilize mineral phosphate was tested on aluminum phosphate (AlPO₄) in liquid medium. Among these PSB, isolate B1 (identified as Bacillus thuringiensis) exhibited the maximum P-solubilizing ability and was particularly efficient at solubilizing AlPO₄ (up to 321 mg L^?1) in vitro. The isolate B1 was inoculated to an acidic soil to study its effect on phosphate solubilization and growth of peanuts (Arachis hypogeae). The Olsen-P in the tested soil increased from 14.7 to 23.4 mg kg^?1, with solubilization of 16.4 mg kg^?1 soil of Occluded-P after 14-day incubation. The inoculation by B1 significantly increased plant height (from 37.7 to 45.7 cm), number of branches (from 34.0 to 52.7 per plant), hundred-seed weight (from 42.1 to 46.9 g) and crude protein content (from 243.5 to 268.2 g kg^?1 dry weight). The phosphate-solubilizing B. thuringiensis strain B1 showed potential as a biological phosphorus fertilizer.     

低磷土壤接种菌根真菌和解磷细菌对大田玉米生长和磷吸收的影响

丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)能与多数陆生植物共生,促进植物吸收养分尤其是磷。解磷细菌(Phosphate-solubilizing bacteria,PSB)可以活化土壤中难溶性无机磷和有机磷。本研究采用苯菌灵对田间低磷土壤中土著AM真菌进行灭菌,并接种外源AM真菌(Glomusversiforme,G.v)和PSB(Pseudomonassp.),研究AM真菌和PSB接种对不同生育期玉米生长、磷养分吸收和产量的影响。结果表明,施用苯菌灵能够有效地抑制土著AM真菌对玉米根系的侵染,未施用苯菌灵处理中土著AM真菌促进了玉米前期和收获期的生长,提高了玉米吸磷量;接种Pseudomonas sp.促进了玉米六叶期根系的生长;接种外源AM真菌G.v促进了玉米六叶期和收获期地上部的生长,但降低了玉米产量。双接种Pseudomonas sp.和G.v对玉米生长、吸磷量和产量未表现出显著的协同效应。