MOBILIZATION OF POTASSIUM FROM WASTE MICA BY PLANT GROWTH PROMOTING RHIZOBACTERIA AND ITS ASSIMILATION BY MAIZE (ZEA MAYS) AND WHEAT (TRITICUM AESTIVUM L.): A HYDROPONICS STUDY UNDER PHYTOTRON GROWTH CHAMBER

A hydroponics study was carried out to evaluate the effect of three plant growth promoting rhizobacteria (PGPR) namely, Bacillus mucilaginosus, Azotobacter chroococcum, and Rhizobium spp. on their ability to mobilize potassium from waste mica using maize and wheat as the test crops under a phytotron growth chamber. Results revealed that PGPR significantly improved the assimilation of potassium by both maize and wheat, where waste mica was the sole source of potassium. This was translated into higher biomass accumulation, potassium content and uptake by plants as well as chlorophyll and crude protein content in plant tissue. Among the rhizobacteria, Bacillus mucilaginosus resulted in significantly higher mobilization of potassium than Azotobacter chroococcum and Rhizobium inoculation. Overall, inoculation of maize and wheat plants with these bacteria could be used to mobilize potassium from waste mica, which in turn could be used as a source of potassium for plant growth.     

Effect of biofertilizers application on the growth of Eucalyptus grandis seedlings under greenhouse conditions

Abstract

To investigate the effect of biofertilizers on the growth and yield of Eucalyptus grandis seedlings, greenhouse experiments were performed applying fertilizers based on agricultural byproducts, inoculated with nitrogen-fixing bacteria of the genera Azotobacter spp and Azospirillum spp. For the biofertilizers formulation, a nitrogen-fixing bacteria consortium was inoculated, and the experimental design was a 2?×?2 × 2 factorial arrangement, the factors were nitrogen source (NS: chicken manure), source of carbon (CS: eucalyptus leaf litter) and source of micronutrients (RS: rhizospheric soil) with two dose levels, inoculated with a consortium of Azotobacter spp and Azospirillum spp. The optimal time production of the best biofertilizers was 30?days, with the highest density of Azospirillum (9.23 × 10⁶ CFU·g^?1) and Azotobacter (19.3 × 10⁶ CFU·g^?1), and total nitrogen contents in the range of 2.15-5.64%, released into the biofertilizers with chicken manure and bioaugmented with the bacterium consortium. The treatment with the highest dose of biofertilizer, 500?g, showed the most significant effect on seedling development, increasing growth, stimulating rooting and the highest increase in leaf number. The results show that biofertilizers contributed to Eucalyptus grandis crop yield, and biofertilizers are proposed as an alternative for implementing sustainable soil management in the forest sector.     

Physiological Response of Wheat to Foliar Application of Zinc and Inoculation with some Bacterial Fertilizers

Abstract

In a pot experiment, sterilized sandy soil (irrigated with Long-Ashton nutrient solution containing a half of the recommended dose of ZnSO₄ · 7H₂O) was used to study the effects of zinc (Zn) foliar-application, and soil biofertilization on some physiological traits of wheat (Triticum aestivum cv. Sakha 155) plant grown for 70 days in greenhouse under controlled conditions. The treatments comprised different levels of the foliar applied Zn (0, 25, 50, 100, and 200 mg L^?1) which was added in the form of ZnSO₄ · 7H₂O, and supported by Azotobacter chroococcum (Ar) and/or Azospirillum brasilense (Am) isolates. All test attributes (minerals, photosynthesis, metabolites, and dry matter accumulation) were significantly enhanced by the moderate doses of Zn (25 and 50 mg L^?1), while a contrary trend was observed in case of the higher levels (100 and 200 mg L^?1). Applying the bacterial fertilizers (Ar, Am) to the experimental soil, influenced the most test characters in the direction of improving growth, photosynthesis and dry matter accumulation by the plant. This response was more evident in the case of applying Ar plus Am than Am than Ar, particularly, at the elevated levels of Zn. Zinc application at 50 mg L^?1 supported by the biofertilization with Ar plus Am resulted in the highest shoot contents of nitrogen (N), magnesium (Mg), manganese (Mn), carbohydrate and total-soluble proteins. Superior values of the photosynthetic criteria (Chl a + b concentration and photosystem II activity) as well as shoot concentration of indole-3-acetic acid, and dry matter accumulation by shoots and roots were obtained by the same treatment. The highest phosphorus (P) concentration was achieved at 25 mg L^?1 Zn supported by Ar plus Am. Irrespective of the bacterial inoculum, shoot contents of potassium (K) and Zn showed a positive correlation with the sprayed dose of Zn.     

细菌海藻酸的研究进展

海藻酸是β-D-甘露糖醛酸和α-L-古洛糖醛酸通过1-4糖苷键聚合而成的长链高分子化合物。综述了细菌海藻酸的结构、相关基因和合成过程,讨论了它的发酵生产和研究开发前景。     

Integration of soil solarization and chemical sterilization with beneficial microorganisms for the control of white root rot and growth of nursery apple

White root rot (Dematophora necatrix (Mart.)) is a serious disease of apple (Malus domestica Borkh) in nurseries and orchards in India. In 2002 and 2003, field experiments were conducted to integrate soil solarization with native isolates of Azotobacter chrococcum and vesicular–arbuscular mycorrhizal fungi and observe its effect on the incidence of white root rot and growth of the saplings. Apple seeds coated with two native isolates of A. chrococcum (AZUHF₁ and AZUHF₂) were sown in plots inoculated with 4 native isolates of va-mycorrhiza, i.e. AMUHF₁ (Glomus fesiculatum), AMUHF₂ (Glomus macrocarpum), AMUHF₃ (Glomus mosseae) and AMUHF₄ (Gigaspora sp.) in 14 different combinations and these plots were solarized with transparent polyethylene mulch (25 μm thick) for 40 days in summer months. Soil solarization resulted around 9 °C higher temperature with average maximum temperature of 38–39 °C. Inoculation of saplings with AMUHF₁ isolate of va-mycorrhiza and AZUHF₁ isolate of A. chrococcum and then their planting in solarized soil was found most effective with no incidence of white root rot in comparison to 33.6–35.4% in control accompanied with 78–113% increase in shoot length and 81.6–84.3% increase in root length. Shoot and root length of the saplings was 9.6–10.6 and 9.2–16.0% higher, respectively, in solarized plots in comparison to sterilized plots.     

两种引进菌剂对大豆生长和产量的影响

通过盆栽试验和大田试验,对两种新引进的菌剂对大豆生长和产量的影响进行了研究。结果表明:两种菌剂均有促进生长、增加产量和培肥土壤的效果,与CK相比,出苗早,发苗快,前期株高比CK分别增加7.27%和5.95%,中期株高比CK分别增加8.45%和8.11%,植株干重、根系长度、根系重量和大豆产量增加,土壤全氮、碱解氮、速效磷和速效钾含量增加。大豆专用菌剂处理的植株根部有根瘤形成。     

拉萨长期不同施肥青稞田土壤固氮菌分离鉴定

为寻找拉萨青稞田自生固氮菌,丰富当地固氮菌资源,以减少化肥使用量,降低环境负效应,本研究从6种长期不同施肥模式定位试验的青稞田土壤中进行固氮菌的分离、纯化,观察其菌落形态特征并测定各菌株的固氮酶活性,通过16S rDNA基因测序和构建系统发育树分析了各菌株的分类学地位。结果显示,通过分离和纯化,共得到自生固氮菌50株,其中13株菌具有高效固氮酶活性,分别属于假食酸菌属(Pseudacidovorax)、芽孢杆菌属(Bacillus)、红球菌属(Rhodococcus)、农杆菌属(Agrobacterium)。施用化肥会减少土壤中高效固氮菌种类,不施化肥或施用有机肥能丰富土壤中高效固氮菌种类。     

Interactions of Azotobacter chroococcum, Azospirillum brasilense and Streptomyces mutabilis, in Relation to their Effect on Wheat Development

Single or dual inoculation of wheat seedlings ( Triticum aestivum L. cv. Sakha 69) with Azotobacter chroococcum, Azospirillum brasilense or Streptomyces mutabilis in sterilized soil resulted in significant stimulation of their populations in the rhizosphere, compared with the initial values. Viable counts of Azospirillum and Azotobacter decreased in dual inoculations with Azotobacter or Streptomyces, and contrasted with those of Streptomyces, compared with the results of single inoculation. Single and dual inoculations stimulated plant growth, significantly increased the concentrations of indole-3-acetic acid (IAA), P, Mg, N and total soluble sugars (TSS) in wheat shoots. Soil content of N increased by single inoculation with Azotobacter and all dual inoculations. Soil-IAA significantly increased by all inoculations. Growth of A. brasilense significantly inhibited by filtrates from 7-day-old cultures of S. mutabilis than from A. chroococcum, in vitro. The biosynthesis of antibacterial substance(s) by Azotobacter significantly decreased by supplementing their cultures with metabolic products from A. brasilense, but were stimulated by metabolic products from Streptomyces cultures. All metabolic products significantly decreased the growth of A, chroococcum, A. brasilense and S. mutabilis, nitrogen-fixation and biosynthesis of IAA in A chroococcum, whereas biosynthesis of IAA stimulated in S. mutabilis. Most of the measured parameters after exposure to the tested bacteria or their metabolites were significantly correlated. The significance of IAA, nitrogen fixation and antibacterial substances, produced by such agronomically beneficial bacteria in early wheat growth is discussed.     

一株钾长石分解菌的分离·鉴定及系统发育

[目的]分离、筛选具高效分解钾长石能力的菌株。[方法]从采自湖南省桂东县钾长石矿区的土壤中分离、筛选分解钾长石能力较强的菌株;通过形态观察、生理生化特征检测和基于16SrRNA基因序列的系统发育分析,对分离到的菌株进行初步鉴定。[结果]分离得到一株分解钾长石能力较好的JDM1菌株,初步鉴定为圆褐固氮菌的一个菌株;在温度为30℃、摇瓶转速为200r／min的条件下培养96h后,测得该菌发酵液中钾元素含量高达135．3mg／L。[结论]菌株JDM1是一株具有较高分解钾长石性能的圆褐固氮菌。     

PGPRs affected photosynthetic capacity and nutrient uptake in different Salvia species

Abstract

In order to evaluate the effect of plant growth promoting rhizobacteria (PGPR) on photosynthetic capacity and nutrient uptake of three Salvia officinalis species, an experiment was conducted at the Agricultural Research Center of West Azerbaijan during 2015 and 2016. The experiment was conducted in split factorial based on randomized complete block design with three replications. The main plot included three species of Salvia officinalis (hybrid species), S. Sclarea, and S. nemorosa (both native species). The sub plot included the factorial treatment of nitrogen stabilizing bacteria in three levels (Azosprillium lipoferum, Azotobacter, and control), and phosphate solubilizing bacteria in three levels (Pseudomonas, Enterobacter, and control). Eventually, two years were combined into a compound analysis. The evaluated traits included plant height, leaf area, number of flowering branches, photosynthetic pigments (chlorophyll a, chlorophyll b, and total chlorophyll) and leaf nutrients uptake [(nitrogen (N), phosphorus (P), potassium (K)]. The results indicated a significant effect of the studied traits compared to the year (leaf area, number of flowering branches, chlorophyll a, chlorophyll b), cultivar, N stabilizing bacteria (except chlorophyll b) and phosphate solubilizing bacteria (p?<?0.01). The effect of quadruple interaction showed a significant effect (p?<?0.01) on all studied parameters except of plant height and leaf nutrients. The results indicated that leaf area and number of branches in the second year increased by 24.7 and 28.21%, respectively. The amount of chlorophyll a decreased in the second year, however chlorophyll b increased significantly and total chlorophyll did not change significantly. S. Sclarea produced the highest plant height (102.62?cm) and the highest leaf number (68.16) per plant. Further, the results showed that in all three species, Pseudomonas phosphate solubilizing bacteria had the highest effect on the leaf nutrient uptake and the combination of Pseudomonas with Azotobacter improved the nutrient uptake and the growth status of the plant.