不同栽培条件下蔬菜塑料大棚土壤尖孢镰刀菌数量的变化

应用尖孢镰刀菌选择性培养基,调查了太湖地区不同蔬菜品种、不同栽培年限、不同栽培方式及不同土壤深度的蔬菜塑料大棚土壤中尖孢镰刀菌数量的变化情况。结果显示,栽种黄瓜的土壤中尖孢镰刀菌数量达1.6×104cfug-1干土,显著大于栽种芹菜和茄子的土壤。随着栽培年限的增加,土壤中尖孢镰刀菌数量有增加的趋势,连作4a土壤中尖孢镰刀菌数量比连作1a土壤增加了22%。与有土栽培相比,基质槽培土壤中尖孢镰刀菌数量较少,仅1.1×104cfug-1干土,基质栽培可能是国内今后蔬菜塑料大棚的发展方向之一。随着土层深度的增加,土壤中尖孢镰刀菌数量逐渐降低,尖孢镰刀菌很少从表层土向下迁移。这些结果为蔬菜塑料大棚土壤的可持续利用提供了一些初步的微生物学依据。     

Effect of integrated management on Fusarium wilt progression and grain yield of chickpea in Syria

Fusarium wilt, caused by Fusarium oxysporum Schlechtend.: f. sp. ciceris (Padwick) Matuo & K. Sato, is a major production problem in many countries. A study was conducted to develop an integrated management of Fusarium wilt of chickpea using genotypes, sowing dates (January as early sowing and March/April as spring sowing) and fungicide seed treatments under natural infested plots in research plots and farmers’ fields 2007–2009 cropping seasons. In most cases, sowing date and fungicides did not affect disease parameters and seed yield. Chickpea genotypes showed significant differences in seed yield but different responses for disease parameters. Averaged over locations and seasons, the rate of disease development was higher in early (0.035 units day^?1) than spring (0.023 units day^?1) sowing. Chickpea genotypes showed different responses in affecting rate of disease development and cumulative wilt incidence in early and late sowing periods. Higher mean seed yield (1.3 t ha^?1) was recorded in early than late sowing (1.0 t ha^?1) of chickpea. The average seed yield reduction due to spring sowing ranged from 9% to 60% and highest yield losses were observed in FLIP-97–706 and Ghab-3. This study showed that integrating January sowing with genotypes having good levels of resistance for Fusarium wilt and Ascochyta blight helps farmers to narrow chickpea yield gaps in Syria.     

Promotion of the seed germination and seedling growth of cabbage by root-colonizing fungi isolated from oat and Eucalyptus roots

(Jpn. J. Soil Sci.Plant Nutr., 77, 265–272, 2006)

We isolated fungi colonizing oat (Avena sativa L.) and eucalyptus (Eucalyptus camaldulensis Dehnh) roots to select the strains that promote the seed germination and seedling growth of cabbage. Twenty-nine strains were inoculated into the soil which grows cabbage seedlings. This inoculation test was repeated three times. From the results of the test, we found that MT0011 and EU0013 strains promoted seed germination. In the first inoculation test, seven strains increased the dry weight of cabbage seedling significantly compared with the control. In the second test with the strains that promoted cabbage growth, MT0008 and EU0013 strains significantly increased the dry weight of seedlings. In the third test, only EU0013 significantly increased seedling growth. The ITS region for DNA (ITS1-5·8SrDNA-ITS2) of 28 isolated strains were sequenced to examine the molecular phylogeny. Isolates were classified into two divisions, Zygomycota and Ascomycota. Nine strains showed the highest similarities with same accession number AF504832 (Uncultured fungus clone D50). MT0011 was clustered with fungi belonging to Drechela sp. from the sequence data on the rDNA ITS region. EU0013 was identified as Penicillium sp. from the morphological feature conidiophore and the sequence of the ITS region.     

Evaluating crude extracts of Monsonia burkeana and Moringa oleifera against Fusarium wilt of tomato

Fusarium wilt is one of the major soil-borne diseases of tomato crop globally. The study aimed to evaluate the efficacy of medicinal plants in the control of Fusarium wilt in tomato. Methanolic extracts of Monsonia burkena and Moringa oleifera were assessed in vitro and under greenhouse conditions. The in vitro experiments evaluated the effect of both extracts on Fusarium oxysporum f. sp lycopersici growth and response to varying concentrations. In greenhouse experiment, tomato seedlings cv. HTX14 were inoculated with conidial suspension of F. oxysporum and transplanted into pasteurised growth media amended with plant extract. Seedlings were treated with aqueous extracts at varying concentrations with an interval of 7 days between applications. Control treatments were treated with sterile distilled water. Both plant extracts significantly reduced pathogen growth in vitro and reduced wilt severity under greenhouse conditions. The highest mycelial growth suppression was observed in Mon. burkeana treatments. Under greenhouse conditions, both plant extracts significantly (P?≤?0.05) reduced Fusarium wilt severity and had a positive effect on plant growth parameters. A significant increase in soil-pH was also recorded in extract treated soil resulting in reduction in disease severity. The results further provide new scientific information on how their effect on soil pH can be beneficial in the control of Fusarium wilt.     

Effects of Arbuscular Mycorrhizal Colonization on Microbial Community in Rhizosphere Soil and Fusarium Wilt Disease in Tomato

Fusarium wilt is caused by soil-borne pathogen Fusarium oxysporum. Tomato (Lycopersicon esculentum Mill.) is susceptible to Fusarium oxysporum f. sp. lycopersici race 1 and was infected with wilt disease. A pot experiment was conducted to investigate effects of inoculating arbuscular mycorrhizal (AM) fungus (Glomus etunicatium) on the microbial community in the rhizosphere soil and Fusarium wilt in tomato (cv. Oogatafukuju). The results indicated that AM fungal inoculation suppressed the Fusarium number in the rhizosphere soil of tomato and decreased the Fusarium wilt disease index. Compared to the control, AM fungal inoculation increased the actinomycete number but increased bacterial number. Bacterial and fungal numbers were high but actinomycetes number was low when tomato basal stems became discolored brown. Fusarium inoculation significantly suppressed development of AM colonization and decreased polyphenol oxidase (PPO) activity in leaves and roots of tomato. Inoculation with AM fungi and Fusarium maintained high PPO activity in leaves and roots. The AM colonization increased root growth of tomato, whereas Fusarium inoculation had no significant effect on tomato growth. These findings suggest that because AM fungal inoculation changes microbial communities and enhances PPO activity, it should suppress occurrence of Fusarium wilt in tomato.     

Effect of soil sterilisation on biological control of Fusarium oxysporum f. sp. lycopersici and Meloidogyne javanica by antagonistic fungi and organic amendment in tomato crop

One of the major challenges in the application of biological control agents into the soil is their inability to withstand competition from natural microflora. In this study a management programme involving fungal biological control agents Trichoderma harzianum (TH) and Purpureocillium lilacinium (PL), and the organic amendment neem was carried out for the control of Meloidogyne javanica and Fusarium oxysporum f. sp. lycopersici (FOL). The experiment was carried out in sterile and non-sterile soil in order to test the efficacy of biological control in natural soil conditions. This experiment was repeated twice. A Wilcoxon's Signed-Rank test indicated there were no significant (P?<?0.05) differences in fusarium wilt control in sterile and non sterile soils in the treatments PL neem and TH neem, but there was significantly (P?<?0.05) higher control of M. javanica in the same treatments in sterile soils compared to non sterile soils. The combinations of fungal antagonists and neem were effective in non sterile as in sterile soils in the control of fusarium wilt, while being less effective in the control of M. javanica. Thus the biological control agents can be very effective in the control of fusarium wilt in natural conditions where the soil is not sterilised, but be less effective in the control of M. javanica in the same conditions. There is therefore potential of integrated management of fusarium wilt and root-knot nematodes (RKN) by these biological control agents in natural soil field conditions as an alternative to using chemicals.     

一株拮抗放线菌的鉴定及其对黄瓜枯萎病的生防效应研究

鉴定从土壤中分离的一株拮抗放线菌(编号CT205),探索其防治植物病害的潜能.通过形态特征、生理生化特征和16S rRNA基因序列分析研究菌株CT205的分类地位,采用平板对峙法测定其抗菌活性,利用连作致病土盆栽试验评价其对黄瓜枯萎病的防治作用.初步鉴定菌株CT205为白刺链霉菌(Streptomyces albospinus),菌株CT205对供试的枯草杆菌、啤酒酵母、小麦纹枯、土豆青枯等植物病原菌均有不同程度的抑制作用,其中对黄瓜枯萎病、西瓜枯萎病、烟草疫霉3种供试病原真菌的抑制作用较强.盆栽试验表明,施用放线菌CT205对黄瓜生长有一定的促生作用,对黄瓜枯萎病防治效果为51.85％,放线菌CT205菌液和有机肥复合制作成生物有机肥,防治效果达81.85％.研究表明,放线菌CT205具有潜在的应用价值.     

根际施用微生物有机肥防治连作西瓜枯萎病研究

为了探讨西瓜专用微生物有机肥料(BOF)对西瓜植株枯萎病的防治效果,采用盆栽试验研究了西瓜专用BOF对连作土壤上西瓜植株生长和枯萎病的防治效果以及西瓜枯萎病致病菌的数量分布的影响。结果表明:1）营养钵育苗和移栽土壤中都施用BOF的处理,未发现西瓜枯萎病植株,而对照植株则完全发病;2）施用BOF处理的致病菌（尖孢镰刀菌西瓜专化型）数量在根际土壤中为0.7×103 cfu/g,在土体土壤中为2.7×103 cfu/g,都控制在104 cfu/g数量级以下,而对照处理的数量分别达到了1.17×105 cfu/g和1.1×105 cfu/g;3）与对照比较,营养钵育苗时施用1%的BOF,西瓜苗期（播种后17 d）生物量都显著增加,根系生物量比地上部生物量提高了16.7个百分点（以鲜重计）和24.8个百分点(以干重计);营养钵育苗和移栽土壤中均施用BOF的处理,西瓜植株（生长67 d）生物量（干重）是对照的1.83倍;在营养钵育苗或移栽时施用BOF的处理,西瓜植株干重两者差异不大,分别是对照的1.28倍和1.27倍。采用营养钵育苗和移栽时都施用BOF的方法种植西瓜,能有效地促进西瓜植株生长,防止西瓜枯萎病发生,克服西瓜连作障碍。     

Control of cotton <Emphasis Type="Italic">Verticillium</Emphasis> wilt and fungal diversity of rhizosphere soils by bio-organic fertilizer

Cotton Verticillium wilt is a destructive soil-borne disease affecting cotton production. In this study, application of bio-organic fertilizer (BIO) at the beginning of nursery growth and/or at the beginning of transplanting was evaluated for its ability to control Verticillium dahliae Kleb. The most efficient control of cotton Verticillium wilt was achieved when the nursery application of BIO was combined with a second application in transplanted soil, resulting in a wilt disease incidence of only 4.4%, compared with 90.0% in the control. Denaturing gradient gel electrophoresis patterns showed that the consecutive applications of BIO at nursery and transplanting stage resulted in the presence of a unique group of fungi not found in any other treatments. Humicola sp., Metarhizium anisopliae, and Chaetomium sp., which were considered to be beneficial fungi, were found in the BIO treatment, whereas some harmful fungi, such as Alternaria alternate, Coniochaeta velutina, and Chaetothyriales sp. were detected in the control. After the consecutive applications of BIO at nursery and transplanting stage, the V. dahliae population in the rhizosphere soil in the budding period, flowering and boll-forming stage, boll-opening stage, and at harvest time were 8.5 × 10², 3.1 × 10², 4.6 × 10², and 1.7 × 10² colony-forming units per gram of soil (cfu g⁻¹), respectively, which were significantly lower than in the control (6.1 × 10³, 3.4 × 10³, 5.2 × 10³, and 7.0 × 10³ cfu g⁻¹, respectively). These results indicate that the suggested application mode of BIO could effectively control cotton Verticillium wilt by significantly changing the fungal community structure and reducing the V. dahliae population in the rhizosphere soil.     

Laboratory Study of Leaching Properties of Mediterranean Forest Species Ashes

For bioremediation of copper-contaminated soils, it is essential to understand copper adsorption and chemical forms in soils related to microbes. In this study, a Penicillium strain, which can tolerate high copper concentrations up to 150 mmol l^?1 Cu²⁺, was isolated from a copper mining area. The objective was to study effects of this fungus on copper adsorptions in solutions and chemical forms in soils. Results from lab experiments showed the maximum biosorptions occurred at 360 min with 6.15 and 15.08 mg g^?1 biomass from the media with Cu²⁺ of 50 and 500 mg l^?1, respectively. The copper was quickly adsorbed by the fungus within the contact time of the first 60 min. To characterize the adsorption process of copper, four types of kinetics models were used to fit the copper adsorption data vs. time. Among the kinetics models, the two-constant equation gave the best results, as indicated by the high coefficients of determination (R ²?=?0.89) and high significance (p?<?0.01). The addition of the fungal strain to autoclaved soil facilitated increases in concentrations of acid-soluble copper, copper bound to oxides, and of copper bound to organic matter (p?<?0.05). However, the inoculation of Penicillium sp. A1 led to a decrease of water-soluble copper in the soil. The results suggested that Penicillium sp. A1 has the potential for bioremediation of copper-contaminated soils.     

Response of soil microbial diversity to land-use conversion of natural forests to plantations in a subtropical mountainous area of southern China

Land-use conversion can affect the soil microbial community diversity, soil organic matter and nutrient cycling. In this study, soils within a representative land-use sequence were sampled in a subtropical region of China, including four natural forests, Altingia gracilipes Hemsl. (ALG), Cinnamomum chekiangense Nakai (CIC), Castanopsis fargesii Franch. (CAF), and Tsoongiodendron odorum Chun (TSO), and two plantations, Cunninghamia lanceolata (Lamb.) Hook. (CUL) and a citrus orchard (Citrus reticulata Blanco). The soil microbial diversity was investigated by phospholipid fatty acid (PLFA) analysis, denaturing gradient gel electrophoresis (DGGE) and real-time quantitative polymerase chain reaction (PCR). Results showed that microbial community diversity exhibited distinct patterns among land-use types. After conversion of natural forests to plantations, the amount of PLFA and the number of bacterial 16?S rRNA gene copies were reduced significantly, as well as the number of DGGE bands. The average quantity of PLFA was lower by 31% in the CUL plantation and 57% in the citrus orchard, respectively, than in natural forests. Simultaneously, the average copy numbers of the bacterial 16?S rRNA gene were significantly decreased from 8.1?×?10^10?g^?1?dry weight (DW) in natural forest to 4.9?×?10^10?g^?1 DW in CUL plantation, and 3.1?×?10^10?g^?1 DW in the citrus orchard. Such negative responses of soil microbes to conversion of natural forests to plantations could mainly result from decreases in soil organic carbon and necessary elements for growth during land-use conversion, as revealed by statistical analysis. Our results suggested that the soil microbial diversity was indirectly in?uenced by land-use types in the mid-subtropical mountainous area of southern China. Changes in the amount of litterfall and the soil nutrient status that resulted from land-use conversion drove these indirect changes. Furthermore, deliberate management brought negative effects on soil microbes, which is not beneficial to the sustainability of the ecosystem.     

Interaction of soil boron application with leaf B concentration,root length density,and canopy size of citrus affected by Huanglongbing

Abstract

Good and balanced citrus nutrition is important for high fruit yields and improved tree performance. A study was conducted for 2?years to investigate the effect of soil application of boron (B) on leaf nutrient content, canopy size, and root length density (RLD). The study was conducted on 10-year-old Candidatus Liberibacter asiaticus (CLas)-infected Vernia sweet orange on Rough Lemon rootstock in a commercial grove east of St. Cloud, FL planted at 375 trees ha^?1 on a traditional soluble dry nutrition and spray programs. Treatments were supplied with various ground-applied controlled-release fertilizer treatments containing B. Boron was applied at 0×, 2×, and 4× current University of Florida recommendation where 1×?=?1.12?kg ha^?1. Data collected included leaf B nutrient content, soil B concentration, trunk diameters, canopy volumes, soil electrical conductivity, and soil pH. The 0×, 2×, and 4× application rates corresponded with leaf nutrient contents ranging from 56?mg kg^?1 and 88?mg kg^?1 in March 2017, 162?mg kg^?1 and 288?mg kg^?1 in September 2017, and 122?mg kg^?1 and 320?mg kg^?1 in May 2018. Temporary, RLD decreased with time from March to September 2017 by 13, 30, and 37% at the 0, 2.24, and 4.48?kg B ha^?1 and increased by 309, 258, and 306% at the 0, 2.24, and 4.48?kg B ha^?1, respectively, from September 2017 to May 2018. No consistent pattern was established between soil B application with canopy size.     

Trichoderma harzianum T-E5 significantly affects cucumber root exudates and fungal community in the cucumber rhizosphere

The Fusarium wilt in cucumbers, caused by the pathogenic fungus Fusarium oxysporum f. sp. cucumerinum, is a serious and destructive disease worldwide. An effort was made to explore the role of Trichoderma harzianum T-E5 in reducing the incidence of Fusarium wilt. Three treatments (Control, T1, and T2) were established in the greenhouse experiment. The effects of T-E5 on the composition of root exudates and fungal community in the cucumber rhizosphere were measured. Compared with the control, the application of a bio-organic fertilizer (BIO) enriched with T-E5 was found to decrease the incidence of Fusarium wilt notably and promote the growth of cucumber plants. Based on real-time PCR, the population of F. oxysporum in the control without T-E5 increased from 10³ to 10⁴ ITS copies g⁻¹ soil, whereas the population decreased from 10³ to 10² ITS copies g⁻¹ soil in the T1 and T2 treatment groups when T-E5 was included. Significant difference in fungal community was also found among the treatment groups. HPLC analysis showed that the detected levels of phenolic compounds in control were significantly higher than the levels in the samples subjected to T1 and T2 treatments. The root exudates from the control group significantly increased the numbers of germinating spores of the pathogen compared with those from the samples treated with T1 and T2. In conclusion, the modification of root exudates and the fungal community by the application of BIO might account for the effective suppression of Fusarium wilt disease in cucumbers.     

茄子与香蕉轮作配施生物有机肥对连作蕉园土壤微生物区系的影响

连作现象在香蕉生产上非常普遍,而长期连作会导致严重的连作障碍。本文针对香蕉连作障碍,选择连作香蕉13年的地块,采用常规方法结合变性梯度凝胶电泳(PCR-DGGE)技术,在田间条件下研究了轮作茄子配施生物有机肥对高发枯萎病连作蕉园土壤可培养微生物数量、土壤化学性状以及土壤细菌群落结构的影响。结果表明:与连作香蕉相比,轮作茄子处理可显著降低可培养尖孢镰刀菌数量,使其数量从种植初的10~4 cfu·g~(-1)(干土)下降到10~3 cfu·g~(-1)(干土),同时提高了土壤p H,增加了土壤有机质、速效钾、碱解氮含量。无论是轮作还是连作种植模式,与配施普通有机肥相比,配施生物有机肥对可培养尖孢镰刀菌、真菌和细菌数量影响均不显著;但在轮作模式下,施用生物有机肥处理的细菌数量与真菌数量比值(B/F,381.2)显著高于配施普通有机肥处理(270.3)。PCR-DGGE分析结果表明,轮作茄子配施生物有机肥显著改变了土壤细菌群落结构,增加了细菌丰度、稳定性和多样性,其中多样性指数(Shannon-Wiener指数,3.22)较连作香蕉配施普通有机肥处理(2.89)显著增加。以上结果表明,茄子与香蕉轮作有利于连作蕉园土壤的微生态环境,同时轮作配施生物有机肥效果更优。     

Stenotrophomonas rhizophila DSM14405T promotes plant growth probably by altering fungal communities in the rhizosphere

Stenotrophomonas rhizophila DSM14405^T is of high biotechnological interest as plant growth stimulator, especially for salinated conditions. The objective of this study was to determine the effect of plant species (cotton, tomato, and sweet pepper) on colonisation and plant growth promotion of this beneficial bacterium in gnotobiotic systems and in non-sterile soil. All plant structures (leaves, stems, and roots) were densely colonised by DSM14405^T reaching up to 10⁹ cells g^?1 fresh weight; under gnotobiotic conditions the abundances were 4–5 orders of magnitude higher than in non-sterile soil. Under non-sterile conditions and ambient humidity, tomato shoots were more densely colonised than shoots of sweet pepper and cotton. S. rhizophila DSM14405^T was shown to grow endophytically and colonise the vicinity of root hairs of tomato. Plant growth promotion was particularly apparent in tomato. In general, the impact of plant species on colonisation and plant growth promotion was more pronounced in soil than under gnotobiotic conditions and likely due to the control of diseases and deleterious microorganisms. S. rhizophila DSM14405^T was shown to control diseases in sweet pepper and in cotton. Molecular profiling via single strand conformation polymorphism of internal transcribed spacers and 16S rRNA genes (PCR-single strand conformational polymorphism (SSCP)) revealed that S. rhizophila DSM14405^T strongly affected fungal, but not bacterial communities in the rhizosphere of tomato and sweet pepper. Major SSCP bands related to uncultured fungi and Candida subhashii, disappeared in tomato rhizosphere after Stenotrophomonas treatment. This suggests an indirect, species-specific plant growth promotion effect of S. rhizophila via the elimination of deleterious rhizosphere organisms.     

Combining ability of yield and yield components among Fusarium oxysporum f.sp. strigae-compatible and Striga-resistant sorghum genotypes

ABSTRACT

Use of sorghum [Sorghum bicolor (L.) Moench] cultivars with partial resistance to Striga spp. and Fusarium oxysporum f.sp. strigae (FOS) represents a novel strategy to control Striga. This study aimed to identify the nature of gene action controlling grain yield and yield components and to select promising sorghum crosses possessing both FOS compatibility and Striga resistance, along with good combining ability effects. One-hundred hybrids, developed from pairwise matings among 10 FOS compatible, high-yielding female lines and 10 Striga-resistant male lines, were evaluated with and without FOS inoculation. The F₁s were field evaluated at three locations in Tanzania known for their severe Striga infestation, using an alpha lattice design with two replications. General (GCA) and specific combining ability (SCA) variances were significant for grain yield per plant, hundred-seed weight, plant height, flowering time and the number of Striga plants. The study demonstrated FOS inoculation to be an effective means of controlling Striga. Families 675?×?672, AS435?×?3993 and 4643?×?AS436 displaying large SCA effects for grain yield, and 4567?×?AS429, 3424?×?AS430 and 3424?×?AS436 with small SCA effects for Striga counts should be useful genetic resources for breeding and integrated Striga management.     

Formulations can affect rhizosphere colonization and biocontrol efficiency of <Emphasis Type="Italic">Trichoderma harzianum</Emphasis> SQR-T037 against Fusarium wilt of cucumbers

Pot experiments were carried out over two growing periods to assay the biocontrol efficacy and rhizosphere colonization of Trichoderma harzianum SQR-T037 (SQR-T037) applied as SQR-T037 conidia suspension (TCS), SQR-T037 conidia suspension blended with organic fertilizer (TBF), or SQR-T037 fermented organic fertilizer (TFF). Each formulation had three T. harzianum numbers. In two experiments, Percent Disease Indexes (PDIs) decreased with the increase of SQR-T037 number added to soils. The TFF treatment consistently exhibited the lowest PDIs at same amendment rate of SQR-T037 and 0–8.9%, 25.6–78.9%, and 4.4–50.0% of PDIs were found in TFF, TCS, and TBF treatment, respectively. Soils treated with TFF showed the highest SQR-T037 population in rhizosphere and bulk soil. Decrease of Fusarium oxysporum population in both bulk and rhizosphere soils occurred in the treatment SQR-T037 at 10⁵ and 10⁶ cfug⁻¹ soil rate. The TFF treatment at the SQR-T037 rate of 10³ cfug⁻¹ soil significantly (p < 0.05) increased SQR-T037 population within the rhizoplane but had no effect on F. oxysporum population when compared to TCS and TBF. Generally, TFF treatments were superior to TCS and TBF treatments on disease control by sustaining colonization of SQR-T037 and decreasing F. oxysporum abundance in the rhizosphere soil. We propose that TFF treatment at SQR-T037 rate of 10⁷ cfug⁻¹ (i.e., 10⁵ cfug⁻¹ soil after applied to soil) was the best formulation for controlling Fusarium wilt of cucumber.     

Fungal N2O production in an arable peat soil in Central Kalimantan,Indonesia

Abstract

To clarify the microbiological factors that explain high N₂O emission in an arable peat soil in Central Kalimantan, Indonesia, a substrate-induced respiration-inhibition experiment was conducted for N₂O production. The N₂O emission rate decreased by 31% with the addition of streptomycin, whereas it decreased by 81% with the addition of cycloheximide, compared with a non-antibiotic-added control. This result revealed a greater contribution of the fungal community than bacterial community to the production of N₂O in the soil. The population density of fungi in the soil, determined using the dilution plate method, was 5.5 log c.f.u. g^?1 soil and 4.9 log c.f.u. g^?1 soil in the non-selective medium (rose bengal) and the selective medium for Fusarium, respectively. The N₂O-producing potential was randomly examined in each of these isolates by inoculation onto Czapek agar medium (pH 4.3) and incubation at 28°C for 14 days. Significant N₂O-producing potential was found in six out of 19 strains and in five out of seven strains isolated from the non-selective and selective media, respectively. Twenty-three out of 26 strains produced more than 20% CO₂ during the 14-day incubation period, suggesting the presence of facultative fungi in the soil. These strains were identified to be Fusarium oxysporum and Neocosmospora vasinfecta based on the sequence of 18S rDNA, irrespective of the N₂O-producing potential and the growth potential in conditions of low O₂ concentration.     

Substitution of mineral fertilizers with biofertilizer: an alternate to improve the growth,yield and functional biochemical properties of strawberry (Fragaria × ananassa Duch.) cv. Camarosa

Abstract

An experiment was conducted to substitute mineral fertilizers with biofertilizers in strawberry to work out the yield, quality of strawberry and soil fertility. A 25% substitution of mineral fertilizer with biofertilizer increased the number of fruits/plant along with improving Juice content (89.55%), Total soluble solids (10.35°B), total sugar (6.69%), ascorbic acid (43.80?mg 100?g^?1), anthocyanin content (81.05?mg 100?g^?1), total phenol (5.97?mg Gallic acid equiv. g^?1), flavonoids (0.12?mg g^?1) and antioxidant capacity (2.13?µmol. Trolox equiv. 100?g^?1). The available N and K content in post-harvest soils were improved significantly with 75% RDF + Azospirillium @ 2?g plant^?1 + PSB @ 2?g plant^?1 + topdressing of 25% K treatments (200.10 and 211.70?kg ha^?1, respectively). Viable count of soil microorganisms (Bacteria, actinomycetes and fungi) was also estimated maximum (4066, 190 and 11.33?×?10⁴ cfu g^?1?dry soil, respectively) with substitution of 25% of mineral fertilizer either with Azotobacter or Azospirillum.     

Seed priming with Pseudomonas putida isolated from rhizosphere triggers innate resistance against Fusarium wilt in tomato through pathogenesis-related protein activation and phenylpropanoid pathway

Pathogenesis-related (PR) proteins are one of the major and preliminary proteins accumulated as a defense against biotic stress. This defense response can be induced by using beneficial rhizobacteria, which has been studied in various host-pathogen interactions. In the present study, eleven Pseudomonas isolates were assessed for their potential to ferment sorbitol, reduce nitrate, and produce mycolytic enzymes, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, phenazine antibiotics, and N-acyl homoserine lactones (AHLs). All isolates were tested against the host-specific pathogen Fusarium oxysporum MTCC1755 in tomato under greenhouse conditions, and shortlisted isolates were tested for their rhizosphere competence. In-vitro test results showed that the isolates were able to produce mycolytic enzymes, including protease, lipase, chitinase, cellulase, and amylase, and the antibiotic phenazine and were negative for pyoluteorin. All the isolates except two were positive for ACC deaminase production. Greenhouse results showed that the isolates M80, M96, and T109 significantly reduced symptoms of Fusarium wilt. Extended greenhouse tests under autoclaved and unautoclaved soil conditions showed that M80, M96, and T109 were excellent rhizosphere competitors and were identified as Pseudomonas putida. In brief, the defense-specific biochemical variations in the host could describe the improved defense against Fusarium wilt occurring in the primed plants. These three Pseudomonas strains could be used as potential biocontrol agents, along with their rhizosphere competence.