Oligotrophic pseudomonads in the rhizosphere: Suppressiveness to Pythium damping-off of cucumber seedlings (Cucumis sativus L.)

Summary Pseudomonads recovered from the cucumber rhizosphere were evaluated for their ability to suppress Pythium ultimum damping-off. Full-strength and 250-fold diluted selective media formulations with King's B medium (KB and KB/250, respectively) as the basal medium were used as the recovery media. Eight per cent of the isolates recovered (11/138) could induce suppression to Pythium damping-off and 45% of these biocontrol agents produced fluorescent pigments. No differences in the ability to induce suppression among the isolates recovered on full-strength and diluted media were detected. The growth rates of the selected isolates indicated that growth in KB broth was faster or equal to that in KB/10. Therefore, no obligate oligotrophs were recovered. Additionally, growth was observed in 15 000-fold diluted KB for 10 of 11 test isolates, which indicated that these isolates were facultative oligotrophs. In general, the faster growing isolates were more likely to induce suppression when used as seed treatments. Finally, the in vitro antifungal properties of test isolates against P. ultimum indicated that 4 of the 11 isolates inhibited P. ultimum.     

库拉索芦荟施肥模型的建立与解析

在云南元江干热河谷气候条件下,采用二次正交旋转组合设计田间小区试验,建立了回归方程并分析了N、P、K、有机肥对库拉索芦荟鲜叶产量、芦荟甙含量和芦荟甙产量的影响。结果表明:P、K肥对提高库拉索芦荟甙含量和芦荟甙产量有显著效果,以K肥的影响最为显著,N肥和有机肥的影响不明显;N、P、K肥施用量与芦荟鲜叶产量的关系符合米氏曲线,有机肥对芦荟鲜叶产量的影响不显著。芦荟鲜叶产量最高时的施肥量为N198kghm-2、P2O5198kghm-2、K2O264kghm-2、鸡粪4125kghm-2。芦荟甙含量和芦荟甙产量最高时的施肥量为N396kghm-2、P2O5396kghm-2、K2O528kghm-2、鸡粪20625kghm-2。     

Comparison of the distribution of mineral nutrients and active substances in dehydration- and salinity-stressed Aloe vera L.

Changes in growth and distribution of inorganic mineral elements and organic active substances in seedlings of A. vera were examined under treatments of ?0.44 and ?0.88 MPa polyethylene glycol 6000 (PEG) and corresponding isosmotic sodium chloride (NaCl). All stress treatments inhibited plant growth, with NaCl severely inhibiting the growth of the seedlings than PEG. However, leaf biomass did not change significantly. The nitrogen concentration under PEG was maintained higher than that under NaCl. Salinity caused more severe ionic imbalance than dehydration. However, when the concentration of NaCl was increased, ion homeostasis was maintained. Stressors induced an increase in aloin concentration in leaves, especially in young leaves. Polysaccharide concentrations in leaves did not change under dehydration. However, the polysaccharide concentration decreased in the middle and base leaves under NaCl. A. vera exhibited high adaptability to suitable osmotic stress, which increases its main active ingredients in leaves.     

一株溶磷细菌的分离、鉴定及其溶磷特性研究

从作物根际土壤样品中筛选到一株溶 P 能力强的菌株 GJT-1,结合生理生化指标和16S rDNA 序列分析鉴定其为假单胞菌(Pseudomonas sp.).菌株 GJT-1 对磷酸三钙、磷酸铝、磷酸铁有一定的溶解能力,28℃培养到第 3 天对磷酸三钙液体培养基的溶 P 量可达 224.51 mg/L.该菌对开阳磷矿粉和宜昌磷矿粉的溶 P 量分别为 194.25 mg/L 和 120.59 mg/L.通过扫描电镜观察到接种活菌处理的磷矿粉表面凹凸且有黏性物质附着,表明菌株 GJT-1 可利用磷矿粉.     

Effect of cations on the growth of fluorescent pseudomonad isolates from spinach roots grown in soils with different salinity levels

Abstract

Effect of Inorganic ion concentrations in culture solution on the growth of Pseudomonas putida and P. fluorescens Isolates from spinach roots grown in soils with high-salinity (H-soil) and low-salinity (L-soil) levels was investigated. Both H- and L-soils were taken from the topsoil of a greenhouse for spinach cultivation and a nearby fallow field, respectively. In the H-soil inorganic ions had accumulated due to the high rates of application of fertilizer. Among the ions, the concentrations of Ca²⁺, NO₃ ^-, and SO₄ ^2- in the H-soil were significantly higher than those in the L-soil. Among the inorganic ions tested (K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^-, NO₃ ^-, and SO₄ ^2-), Ca²⁺ was found to be the most inhibitory on the growth of isolates. In addition, the isolates from the H-soil were more Ca²⁺-tolerant than those from the L-soil.

Consequents the growth tolerance to Ca²⁺ stress of the total 80 isolates, 40 each from the H-soil and L-soil, was compared at 150 mM Ca²⁺. Most isolates from the H-soil showed a significantly higher tolerance. The higher tolerance to Ca²⁺ of the isolates from the H-soil may have been acquired through selection under increasing Ca²⁺ stress in the field. The Ca²⁺ tolerance of the fluorescent pseudomonad strains may account for their survival and root-colonizing activity in soils with Ca²⁺ accumulation.     

Isolation and characterization of phosphate solubilizing bacteria from the rhizosphere of crop plants of Korea

Whole-cell fatty acids methyl ester (FAME) profile and 16S rDNA sequence analysis were employed to isolate and identify the bacterial groups that actively solubilized phosphates in vitro from rhizosphere soil of various crops of Korea. Out of several hundred colonies that grew on Pikovskaya's medium 13 best isolates were selected based on the solubilization of insoluble phosphates in liquid culture and further characterized and identified. They were clustered under the genera Enterobacter, Pantoea and Klebsiella and the sequences of three representative strains were deposited in the GenBank nucleotide sequence data library under the accession numbers AY335552, AY335553, AY335554.     

与黑鹰嘴豆(Vigna mungo L.)共生的VA菌根、解磷细菌及根瘤菌在田间条件下的协同作用

A field experiment was conducted at the G.B.Pant University Research Station,Ujhani(U.P.)in rainy (Kharif) season of the year 1994-1995 to study the effect of Rhizobium,VAM(vesicular arbuscular myc-orrhiza) and PSB(phophate solubilizing bacteria) inoculation,with and without P,on blackgram(Vigna mungo L.) seed yield.Phosphorus application in sol with medium P content(5.4 mg kg^-1) increased nodulation,grain yield,N and P in plant and grain over no phosphorus control.Forty kilograms of P2O5 each hactare recorded an increase of 20.6% in nodule dry weight,significant increases of 0.35 g kg^-1 in N concentration and 1.28 g kg^-1 in P concentration of plant over 20 kg P2O5 ha^-1 ,Similar significan increases of 0.5 g kg^-1 in grain yield and 0.54 and 0.23 g kg^-1 in N and P concentrations of the grain,respectively,over 20 kg P2O5 ha^-1 were also obtained with higher dose.Inoculation of Rhizobium VAM PSB at all the stages of plant growth recorded maximum increaes in all the parameers studied .Dual inoculation of Rhizobium with either VAM or PSB was generally significan in the effect and better than that of VAM PSB,however,P accumulation in plat and grain was more with VAM PSB.A mong single inoculations,Rhizobium gave highest and 21.0% more nodule number,34.7% more nodule dry mass,0.73 g kg^-1 more N in grain and 4.2% higher grain yield over PSB.PSB.however,registered significant increases in P concentration in plant and grain over VAM and Rhizobium.     

芦荟活性多糖保护性分离技术研究

应用自行研制的ACA(Alginate-Chitosan-Alginate)微胶囊技术体系,考察了芦荟液ACA微胶囊成囊过程及微胶囊24h平衡透析过程中芦荟多糖、芦荟蒽醌类化合物渗透分离情况。结果表明,芦荟液微胶囊化过程及微胶囊24h平衡透析后芦荟多糖总渗出率为27.7%,渗出多糖分子量<7600;芦荟蒽醌总渗出率为98.3%。在有利于保持活性的条件下,较好地实现了芦荟多糖和芦荟蒽醌两类不同功效成分的分离。     

Characterization of functional traits of two fluorescent pseudomonads isolated from basidiomes of ectomycorrhizal fungi

Some functional traits of Pseudomonas fluorescens 92 and BBc6, two strains isolated, respectively, from the basidiome of the ectomycorrhizal fungi Suillus grevillei and Laccaria laccata, were evaluated. A rifampicin-resistant mutant of P. fluorescens 92 (P. fluorescens 92R1) showed a significant in vivo plant growth promotion effect on cucumber plants. Quantitative analysis of enzymatic and physiological activities on different substrates showed that P. fluorescens 92 produced about a three times higher level of avicelase than BBc6, while equivalent amounts of β-glucosidase were produced by both strains. Satisfactory levels of neutral phosphomonoesterase and medium levels of acid phosphomonoesterase were produced by both. Only P. fluorescens BBc6 produced a very low amount of phosphodiesterase. Both strains produced high amounts of IAA and siderophores. Both strains showed on an iron deficient medium a very high antagonistic activity against the phytopathogenic fungus Heterobasidion annosum. Purification of fluorescent siderophores by copper-chelate chromatography showed that P. fluorescens 92 produced one pyoverdin (Pf92) and BBc6 two pyoverdins (PfBI and PfBII). A good inhibitory activity against mycelial growth of H. annosum was also observed when using the pyoverdines purified by affinity chromatography. Further purification by reverse phase high pressure liquid chromatography produced multiple fractionation of the three pyoverdins. Analysis of the reverse-phase purified pyoverdines by electronspray ionization mass spectrometry gave for pyoverdin Pf92 the mass value of 1213.8 and for both PfBI and PfBII the mass value of 1305.7. The presence of iron-chelating forms and sodium adducts were also evidenced.     

不同磷效率油菜根际土壤磷活化机理研究

筛选和培育耐低磷植物是缓解磷矿资源缺乏和提高磷肥利用效率的有效途径之一。本研究在前期材料筛选的基础上,通过根箱试验研究不同磷效率油菜根际土壤磷活化机理,其结果如下:在施磷和不施磷处理条件下,磷高效油菜品种B56（HG）的吸磷量和生物量均高于磷低效品种B10（LG）;两油菜品种根际土壤中的NaHCO3-Pi, NaHCO3-Po和 NaOH-Pi,NaOH-Po四种磷素形态均有显著的亏缺现象;磷高效品种（HG）根际土壤上述四种磷素形态亏缺程度大于磷低效品种（LG）,但Resin-P则出现富集,并且HG的富集程度大于LG,这可能与HG具有较高吸磷能力有关。两油菜品种根际土壤HCl-Pi 和 残渣态磷（Residual-P）没有发生明显的亏缺现象。相比较而言,HG能分泌更多的酸性磷酸酶,该酶活性与NaHCO3-Po含量呈显著的负相关,说明酸性磷酸酶对有机磷矿化起着非常重要的作用。     

Preliminary evaluation of eggshells as a source of phosphate on hydroponically grown tomato (Solanum lycopersicum L.) seedlings

Abstract

Phosphorus (Pi) is one of the most limiting factors in plant nutrition as it is the least mobile and available nutrient to plants in most soil conditions. The management of Pi fertilization in agriculture raises ecological, economic, and social issues, since phosphate rock minerals are the only significant global resources of Pi and they will be rapidly depleted. Eggshell waste is a big problem for food companies producing different types of egg products, since the eggshell waste is very often simply discarded and disposed at landfills, with high costs related to their disposal. The aim of this work was the characterization of eggshells as a Pi source for plants, using tomato (Solanum lycopersicum L cv Marmande) as a model species. Plants were grown hydroponically being exposed to adequate and limited Pi availability, with or without eggshell powder. Plant growth performance was characterized by analyzing changes in fresh weight, protein, chlorophyll concentration, carotenoid content, and measuring the plant’s capability to accumulate phosphate. The addition of eggshell powder to the nutrient solution significantly improved plant growth and increased protein and chlorophyll concentration, not only with respect to P-deficient control, but also with P-sufficient ones. Furthermore, eggshell powder significantly increased Pi accumulation in P-deficient plants, suggesting that eggshell waste could be a suitable material as Pi source for tomato plants, thus contributing to the environmentally friendly disposal of this waste.     

通气对几种水培观赏植物生长的影响

采用通气泵对营养液通气以提高营养液中溶解氧量，研究通气对水培小天使、芦荟、金琥、山海带4种植物生长的影响。结果表明：通气会改变植物不同范围直径根在根系中所占的比例，进而增大根总长、根表面积，促进植物对养分和水分的吸收。     

Sugar beet (Beta vulgaris L.) response to diammonium phosphate and potassium sulphate under saline–sodic conditions

Salinity and sodicity are prime threats to land resources resulting in huge economic and associated social consequences in several countries. Nutrient deficiencies reduce crop productivity in salt‐affected regions. Soil fertility has not been sustainably managed in salt‐affected arid regions. Few researchers investigated the crop responses to phosphorus and potassium interactions especially in saline–sodic soils. A research study was carried out to explore the effect of diammonium phosphorus (DAP) and potassium sulphate (K₂SO₄) on sugar beet (Beta vulgaris L.) grown in a saline–sodic field located in Kohat district of Pakistan. The crop was irrigated with ground water with EC_iw value of 2.17–3.0 dS/m. Three levels each of K₂O (0, 75 and 150 kg/ha) as K₂SO₄ and P₂O₅ (0, 60 and 120 kg/ha) as DAP were applied. The application of P significantly affected fresh beet and shoot yield while K fertilizers had significant effect on fresh beet yield and ratio of beet:shoot, while non‐significant effects on the fresh shoot were observed. The application of K₁ and K₂ promoted sugar beet shoot yield by 49.2 and 49.2% at P₁ and 64.4 and 59.7% at P₂, respectively over controls. In comparison with controls, fresh beet yield was increased (%) by 15 and 51, 45 and 84, and 50 and 58 for corresponding K₁ and K₂ at P₀, P₁ and P₂, respectively. Addition of P₁ and P₂ increased beet yield by 37 and 47% over control. The shoot [P] (mmol/kg) were achieved as 55.2, 73.6 and 84.3 at P₀, P₁ and P₂, respectively. The shoot [Mg] and [SO₄] tended to decrease with increasing P levels, while [SO₄] was markedly reduced at P₂. The effect of P on leaf [Na] was non‐significant, but increasing levels of K decreased [Na] substantially at P₀ and P₁, but there was no difference in the effect of K level on [Na] at P₂. Consequently, K application reduced leaf Na:K ratios. Fresh shoot yield was weakly associated with leaf [P] (R² = 0.53). The leaf Na:K ratio showed a negative relationship (R² = 0.90) with leaf [K]. A strongly positive relationship (R² = 0.75) was observed between leaf [K] and fresh beet yield. The addition of K₂SO₄ also enhanced [SO₄] and SO₄:P ratios in leaf tissues. The ratio of Na:K in the shoot decreased with increasing K application. These results demonstrated that interactions of K and P could mitigate the adverse effects of salinity and sodicity in soils. This would contribute to the efficient management of soil fertility system in arid‐climate agriculture.     

通气对几种水培观赏植物生长的影响

采用通气泵对营养液通气以提高营养液中溶解氧量,研究通气对水培小天使、芦荟、金琥、山海带4种植物生长的影响。结果表明:通气会改变植物不同范围直径根在根系中所占的比例,进而增大根总长、根表面积,促进植物对养分和水分的吸收。     

Nematode assemblages in the rhizosphere of spring barley (Hordeum vulgare L.) depended on fertilisation and plant growth phase

Nematodes from rhizosphere soil of barley grown at three fertiliser treatments (control (0), NK and NPK) were studied in a field experiment. Sampling was done twice, during vegetative growth and flowering, respectively, to determine how fertiliser effects on nematode assemblages depended on plant growth phase. At the growth stage the proportion of fungal feeding nematodes (dominated by Aphelenchoides spp. and Aphelenchus sp.) was highest in NK. During flowering, the abundance and proportion of fungal feeders in the 0 and NPK plots had increased and reached a level similar to the NK plot. Overall densities of bacterial feeders (mainly Cephalobidae and Rhabditidae) were similar, but opportunistic bacterial feeders constituted a higher proportion in the fertilised plots compared to the unfertilised. Ectoparasitic plant feeders (Tylenchorhynchus sp.) were more numerous in NK and NPK than in the control at both sampling dates. Endoparasite (Pratylenchus spp.) numbers were lower in the NPK plot at the growth stage. Numbers of Tylenchidae increased between samplings. The classification of Tylenchidae as epidermal cell and root hair feeders as opposed to hyphal feeders is discussed. Results thus indicate that: (i) bacterial and especially fungal feeding nematodes are stimulated by unbalanced fertilisation; (ii) ectoparasitic plant feeders are stimulated by N-fertilisation, while migratory endoparasites are inhibited at high and balanced fertilisation; (iii) nutrient effects diminish after plants reach the flowering stage.     

氮素形态对解磷细菌发酵液解磷效果及小白菜生长和品质的影响

采用盆栽试验,研究了施用硝态氮、铵态氮对解磷细菌发酵液不同组分解磷活性及其对小白菜产量、品质的影响。结果表明,施用相同氮肥时,浇灌解磷细菌原发酵液处理 T3的作用效果明显优于菌体悬浮液T2及菌液上清T1;以硝态氮为底肥时,施用发酵原液的土壤有效态磷含量较高,小白菜产量最高,品质明显优化,即硝态氮含量下降, Vc、可溶性糖、可溶性蛋白、纤维素以及植株磷含量显著增加,且增加变幅均高于以铵态氮为底肥的效果。由此可知,硝态氮与解磷细菌发酵原液配施时, W1菌株解磷效果更好,可能是解磷菌株W1最适的氮源。因此,种植小白菜时直接向其根际施用解磷细菌发酵液并配施硝态氮肥,更有利于提高小白菜的品质及产量。     

Characterization of globulins from common vetch (Vicia sativa L.)

The proteins from Vicia sativa L. (common vetch) seeds were investigated. Protein comprises approximately 11.4% of the seed fresh weight, >50.8% of which is composed by globulins and 43.6% by albumins. The globulins may be fractionated into two main components, which were named alpha-vicinin (comprising 73% of the total globulin fraction, and hence >37% of the total seed protein) and beta-vicinin. Two minor globulin components are also present, gamma-vicinin and delta-vicinin. alpha-Vicinin, the legumin-like globulin, with a sedimentation coefficient of 10.6 S, is a nonglycosylated, disulfide-bond-containing globulin, composed of a group of subunits with molecular masses ranging from 50 to 78 kDa. Upon reduction, each of these subunits releases a heavy polypeptide chain (34-66 kDa) and a light polypeptide chain (21-23 kDa). beta-Vicinin, the vicilin-like globulin, with a sedimentation coefficient of 7.7 S, is a nonglycosylated globulin that contains no disulfide bonds and consists of two major polypeptides with molecular masses of 58 and 66 kDa. gamma-Vicinin is a minor, glycosylated, disulfide-bond-containing globulin. In the reduced form, it comprises six polypeptide chains with molecular masses of 12, 19, 21, 22, 23, and 31 kDa. Finally, delta-vicinin is a minor, highly glycosylated globulin that exhibits hemagglutinating activity. It is composed of a major 47 kDa polypeptide and two minor (33 and 38 kDa) polypeptides. N-terminal sequencing of the delta-vicinin 47 kDa polypeptide revealed no homology to any other known storage protein.     

Effects of phosphorus amended low phosphorus soil on soybean (Glycine max L.) and wheat (Titicum aestivum L.) yield and phosphorus uptake

A major constraint for crop production on disturbed soils is phosphorus (P). A 2-year field study was conducted on a disturbed soil to evaluate broiler litter ash (BLA) as an inexpensive phosphorus fertilizer for soybean. BLA or super phosphate (SP) was applied at four rates and planted with soybean followed by wheat. At soybean growth stage R3, two plants from each plot were removed for tissue analysis. Soybean tissue P concentration distributions were in the order pods?>?leaves?>?stems?>?roots. At maturity, soybean grain and wheat tissue yields were not significantly affected by P source. Except for the high superphosphate rate for the second crop, P concentrations of soybean grain and wheat tissue were not significant between P source. In this study, BLA was as effective as SP for growth of soybean grain and wheat tissue, suggesting that BLA can be used as an inexpensive P fertilizer on low P disturbed soils.