Root Dip Research Articles

Rice Bakanae Disease: Yield Loss and Management Issues in Bangladesh

Fusarium moniliforme, a causal agent of rice Bakanae is a seedborne fungal disease which infects plants through the roots or crowns and it then grows systemically within the plant. From the in-vitro and in-vivo results, it was concluded that Bavistin, Knowin, Haydazim, Topsil plus and Sunphanate @ 0.3% could be effective as seed treating fungicides against bakanae disease. Overnight root dipping of seedlings with Bavistin and Knowin @ 0.3% was effective to control bakanae disease. Seed and seedling treatments with carbendazim fungicides could be used for further dissemination. In field trials, none of the fungicides namely Bavistin, Knowin, Ridomil, Forastin, Sunphanate and Cupravit @ 0.3% were effective against bakanae compared to rogueing when those were sprayed in the standing crop at tillering stage. In seedbed condition, wet seed bed reduced the % of bakanae infected hill (0.31%) in comparison with semi dry (2.18%) and dry (3.45%). In combination with seed bed conditions and seed treatments, wet seed bed with healthy or infected seed but treated with homai @ 0.3% reduced the bakanae incidence (0.21-0.39%). Semi dry seed bed with healthy or infected seed but treated with homai @ 0.3% also control the bakanae disease (0.32-2.68%) compared to dry seed bed (0.82-2.7%).

Evaluation of Mycotoxin Production and Phytopathogenicity of the Entomopathogenic Fungi Fusarium caatingaense and F. pernambucanum from Brazil

Fusarium incarnatum-equiseti species complex (FIESC) is considered as one of the richest insecticolous species. Fusarium species synthesize toxic secondary metabolites that are not fully understood. Mycotoxin production and pathogenicity on germinating seeds, seedlings, and leaves must be carefully studied for the use of Fusarium species in the biological control of insect pests. In this study, we evaluated the mycotoxin production and phytopathogenic potential of entomopathogenic strains of Fusarium sulawesiensis (1), F. pernambucanum (3), and F. caatingaense (23). The phytopathogenicity tests of F. caatingaense (URM 6776, URM 6777, URM 6778, URM 6779, and URM 6782) were performed during the development of bean (Phaseolus vulgaris, Vigna unguiculata, and Phaseolus lunatus), and corn (Zea mays) seedlings, using four treatments (soil infestation with the inoculum, spraying on leaves, root dip, and negative control). The mycotoxins, monoacetyl-deoxynivalenols (AcDON), deoxynivalenol (DON), beauvericin (BEA), fusarenone-X (FUS), T-2 toxin (T2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), were detected in the study; BEA (detected in 25 strains) and FUS (detected in 21 strains) were found to be predominant. None of the strains showed any ability to cause disease or virulence in beans and corn. The FIESC strains showed a highly variable production of mycotoxins without the potential to be used as phytopathogenic agents for the cultures tested.

First report of Mycoleptodiscus terrestris causing root rot of soybean in Indiana.

During the summers in 2019 and 2020, 137 soybean (Glycine max (L.) Merr) seedlings (V1-V3 stage) showing stunting, delayed emergence, and/or crown lesions were collected at Purdue's Agronomy Center for Research and Education in West Lafayette, Indiana. Four seedlings were stunted with reddish-brown girdled lesions along the hypocotyl and crown, rotted tap and lateral roots, and brown discoloration of the cortex and vascular tissues. Four fungal isolates (AC4, AC58, AC96, and AC127) were recovered by plating surface-sterilized symptomatic root tissue onto water agar plates and incubating on the benchtop until mycelia emerged. The growing hyphal tips were transferred to the semi-selective medium DCPA (Andrews and Pitt 1986). On potato dextrose agar, the fungal colonies developed olivaceous green mycelia which melanized into a mat of black microsclerotia with time and no conidia were observed. On 1.5% water agar plates amended with twice autoclaved soybean leaf and root tissue collected from flowering soybean plants, conidia were formed in sporodochia in darkness at 28 οC within one week. Conidia were 1-2 septate, cylindrical with two setae on either end, and measured 20.8 to 26.4 x 4 to 5.6 μm (average 23.9 x 4.7 μm, n=20). The morphological characters matched with the description of Mycoleptodiscus terrestris (Gerd.) Ostaz (Gerdemann 1953). Species identification was further confirmed by sequencing the internal transcribed spacers (ITS) region of rDNA amplified by ITS1 and ITS4 primers (White et al. 1990) and the translation elongation factor 1 alpha (TEF1-α) gene using 983F and 1567R primers with annealing temperature at 53 ○C (Rehner and Buckley 2005). The sequences were deposited in GenBank under the following accession numbers: ITS: MW002684, MT998441, MW010258, and MW010260; and TEF1-α: MW015941-MW015944. The GenBank BLAST searches revealed 100% identity in the ITS region (accession NR_145373.1) and 99.75% identity in the TEF1-α region (MK495977.1) to M. terrestris. Pathogenicity test was conducted on soybean seedlings (cv. Williams) at V1 growth stage using a root dip assay. Isolate AC58 was grown in a modified cotton seed meal broth (CSMB) to produce microsclerotia as inoculum (Gray 1978; Shearer and Jackson 2006). Microsclerotia concentration was measured using a hemocytometer and adjusted to 1.5 x 104 per ml. Five soybean seedlings each were dipped into inoculum or sterile CSMB for 30 minutes then planted individually in vermiculite-filled Styrofoam cups placed on flooded trays in 16-hr photoperiod light racks at room temperature. Seven days after inoculation, all inoculated plants were visibly stunted with root and crown symptoms identical to field symptoms while all controls were healthy. M. terrestris was successfully re-isolated from inoculated plants, but not from the controls, and identified by morphology and sequencing as above. M. terrestris has been previously reported causing root rot of soybean in Illinois (Gray 1978) and Wisconsin (Smith et al. 1998). To our knowledge, this is the first report of M. terrestris infecting soybean in Indiana. Increased geographic distribution of this pathogen warrants more attention for its control. M. terrestris has been proposed as a biological control agent against multiple aquatic weeds (Verma and Charudattan 1993; Shearer and Jackson 2006). Introduction of this fungus into soybean production regions should be avoided.

Effect of Inoculation of Plant Growth Promoting Rhizobacteria (PGPR) Mix I Formulations on Plant Growth, Yield, Disease Incidence and Disease Severity of Rhizoctonia Leaf Blight of Amaranthus (Amaranthus tricolor L.)

Background: Amaranthus is the most popular and commercially cultivated leafy vegetable in the Southern part of India, especially Tamil Nadu and Kerala which is susceptible to a number of diseases. Among the different diseases affecting amaranth, foliar blight caused by Rhizoctonia solani Kuhn, is considered as the most serious disease in Kerala. Methods: A field experiment was taken up at Onattukara Regional Agricultural Research Station (O.R.A.R.S), Kayamkulam, Alappuzha, Kerala during December 2019 to February 2020 to assess the influence of dust and liquid formulations of Plant Growth Promoting Rhizobacteria (PGPR) mix I on growth, yield and disease incidence (Rhizoctonia leaf blight) in amaranthus. Result: The results of the study reveal that maximum number of leaves, number of branches per plant and yield were produced by the plants that were subjected to seedling root dip with 5% talc formulation followed by drenching with 5% talc solution at 30 DAT and 45 DAT. Regardless of talc or liquid formulation of PGPR mix I (2%) seedling dip followed by drenching at 15, 30 and 45 DAT provided the least disease incidence and disease severity in amaranthus at Onattukara condition. Hence use of PGPR mix I is a prerequisite for effective growth, yield and management of leaf blight of amaranthus at Onattukara.

First Report of Fusarium equiseti Causing Seedling Death on Sugar Beet in Minnesota, USA.

In May 2019, sugar beet (Beta vulgaris L.) seedlings with symptoms of wilting and root tip discoloration and necrosis were found in Moorhead (46.5507° N, 96.4208° W), Minnesota, USA. Roots of infected seedlings were surface sterilized with 10% bleach for 15 seconds, rinsed with sterile distilled water and cultured on water agar (MA Mooragar®, Inc, CA) for 3 days at 23 ± 2°C. Isolates were transferred to carnation leaf agar (CLA) and incubated at room temperature (22°C) under fluorescent light for 14 days. Abundant macroconidia were produced in sporodochia. Macroconidia were 5- to 7-septate, slightly curved at the apex, and ranged from 35 to 110 ×1.2 to 3.8 μm. No microconidia were produced. Chlamydospores with thick, roughened walls were observed in chains or in clumps, and were ellipsoidal or subglobose. Single spore was transferred from CLA to potato dextrose agar (HIMEDIA Laboratories, India) produced abundant white mycelium and was pale brown where the colony was in contact with the media. The morphological features of the isolates were consistent with Fusarium equiseti (Corda) Sacc. (Leslie and Summerell 2006, Li et al. 2015). Genomic DNAs (NORGEN BIOTEK CORP, Fungi DNA Isolation Kit #26200) of two representative isolates were used for polymerase chain reaction (PCR). The second largest subunit of RNA polymerase (RPB2) was amplified by PCR with primers 5f2/7cr (O'Donnell et al. 2010). The amplified PCR product was sequenced and deposited in GenBank (accession number MW048778). A BLAST search in Genbank and the Fusarium MLST database showed 100% sequence alignment to F. equiseti with accession MK077037.1 and NRRL 25795, respectively. Pathogenicity testing was done using three sugar beet seedlings (Hilleshög proprietary material, Hilleshög Seed, LLC, Halsey, OR 97348) at cotyledonary stage grown in a pot (4˝×4˝×6˝) with six replicates. Seedlings were inoculated with F. equiseti conidial suspension (104 conidia ml-1 for 8 minutes) by the root dip method (Hanson, 2006). Mock inoculated plants were dipped in sterile water. Inoculated and control plants were placed in the greenhouse at 25 ± 2°C, and 75 to 85% relative humidity. One week later, inoculated seedlings showed root tip tissue discoloration similar to those observed in the field and non-inoculated seedlings were symptomless. This study was repeated. The fungus was re-isolated from diseased roots and confirmed to be F. equiseti based on morphological characters. Fusarium equiseti was reported on freshly harvested and stored beet in Europe but was not found to be pathogenic (Christ et al. 2011). Strausbaugh and Gillen (2009) reported the association of F. equiseti and root rot of sugar beet but did not report pathogenicity. This pathogen is reported in several crops including edible beans that is grown in rotation with sugar beet in several production areas (Jacobs et al. 2018). The most important Fusarium species reported to cause significant economic damage to sugar beet include F. oxysporum and F. secorum (Secor et al. 2014, Webb et. al. 2012). The presence of another pathogenic Fusarium species in sugar beet will require monitoring to determine how widespread it is and whether current commercial cultivars are resistant. To our knowledge, this is the first report of F. equiseti causing disease on sugar beet seedlings in Minnesota, USA.

Evaluation of pathogenicity, systemic colonisation, and host range of

Verticillium wilt of alfalfa (Medicago sativa) is a widespread and destructive disease caused by the soil-borne fungal pathogen Verticillium alfalfae (formerly V. albo-atrum before 2011). Owing to an inadequate understanding of the pathogenicity, systemic colonisation, and host range of V. alfalfae, it has been challenging to develop an effective control measure against this disease. In the present study, seven inoculation methods, including seed inoculation, leaf spraying (LS), fungal plugs placed on leaves (FP), stem injection (SI), root dipping (RD), root injuring and dipping (RI), and watering conidia suspension into soil (WI) were used to analyse the pathogenicity and systemic colonisation of V. alfalfae on alfalfa. The typical verticillium wilt symptoms including V-shaped necrosis of leaves and leaf wilting were observed in alfalfa plants with all inoculation methods. The shortest incubation period (9 days) was observed with stem injection and the longest (40 days) with root dipping. Alfalfa plants inoculated by stem injection showed the highest disease incidence (91%), disease index (65%), and percentage of infected plants (80%), which resulted in the highest shoot biomass loss rate (34%). However, the plants inoculated by fungal plugs showed the lowest disease index (4%), percentage of infected plants (10%), and root biomass loss rate (2%). Further, the stem injection method was used to assess the host range of V. alfalfae on seven non-alfalfa plant species including erect milkvetch, sainfoin, common vetch, sunflower, potato, cotton, and bluish dogbane. The artificial inoculation of V. alfalfae by stem injection successfully infected these plants, with disease incidence ranged from 13 to 100% and disease index ranged from 10 to 69. This indicates that host range of V. alfalfae is not only alfalfa, but also other plant species.

Growth And Yield Response of Okra Under Root Dipping Hydroponic and Conventional Farming System

Growth And Yield Response of Okra Under Root Dipping Hydroponic and Conventional Farming System

Evaluation of IDM modules for tomato leaf curl disease management in Madhya Pradesh

Comparative suitability assessment field trials of fourdifferent IDM modules for the management of leaf curldisease of tomato were conducted at farmer’s field. The trialcites were located in Chorgarhi, Mankesher and Upani villageof district Sidhi, Madhya Pradesh. The trials were conductedduring 2014-15, 2015-16 and 2016-17 as On Farm Trial. Trendof results obtained during past three years of experimentationindicated that all the management modules tested were foundsuperior over predominant farmer’s practice (M1). Themodule M4 having tolerant variety, seed treatment withinsecticide, nursery raising in nylon net cages of 40 mesh,root dip of seedling with systemic insecticide Imidacloprid,as to enable nursery to be transplanted, remain uninfestableby white flies and thrips at least up to 2 weeks aftertransplanting. Further, initial roughing at 3 weeks aftertransplanting and two subsequent sprays of systemicinsecticide before flowering, at 25 and 45 DAT was foundeffective not only in reducing disease incidence butdecreased total number of white fly per plant as well. Thispackage of practice was also able to enhance tomato yieldwith favorable cost benefit ratio. Module 4 was followed bymodule T3, where most of the measures mentioned in module4 were followed except use of nylon net. Therefore, it is verymuch evident that the seed treatment with insecticide andseedling dip measures along with physical intervention todeploy nylon net to prevent assess of vectors to nurseriesinside the cage, hold the great promise to have an almostleaf curl free crop.

Degenerated Virulence and Irregular Development of Fusarium oxysporum f. sp. niveum Induced by Successive Subculture.

Successive cultivation of fungi on artificial media has been reported to cause the sectorization, which leads to degeneration of developmental phenotype, and virulence. Fusarium oxysporum f. sp. niveum (Fon), the causal agent of watermelon Fusarium wilt, forms degenerated sectors after successive cultivation. In the present research, we demonstrated that subculture with aged mycelia increased the incidence of degenerations. To further investigate the differences between the Fon wild type (sporodochial type, ST) and variants (MT: mycelial type and PT: pionnotal type), developmental phenotypes and pathogenicity to watermelon were examined. Results in variants (PT2, PT3, PT11, and MT6) were different from ST with mycelia growth, conidia production and chlamydospore formation. Virulence of degenerated variants on susceptible watermelon Grand Baby (GB) cultivar was determined after inoculation with Fon variants and Fon ST. In root dipping methods, Fon variants showed no significant differences in disease progress compared with ST. Fon variants showed a significant decrease in disease progression compared with ST through infested soil inoculation. The contrasting results of two inoculation methods suggest that the degenerative changes due to repeated successive cultivation may lead to the loss of pathogen virulence-related factors of the early stage of Fon infection process. Therefore, cell wall-degrading enzymes (CWDEs; cellulase, pectinase, and xylanase) activities of different variants were analyzed. All Fon degenerated variants demonstrated significant decreases of CWDEs activities compared with ST. Additionally, transcript levels of 9 virulence-related genes (fmk1, fgb1, pacC, xlnR, pl1, rho1, gas1, wc1, and fow1) were assessed in normal state. The degenerated variants demonstrated a significantly low level of tested virulence-related gene transcripts except for fmk1, xlnR, and fow1. In summary, the degeneration of Fon is triggered with successive subculture through aged mycelia. The degeneration showed significant impacts on virulence to watermelon, which was correlated with the reduction of CWDEs activities and declining expression of a set of virulence-related genes.

Effect of Trichoderma harzianum and Pseudomonas fluorescens on the Enhancement of Drought Tolerance and Plant Growth in Tomato

In the present study, different isolates of Trichoderma harzianum and Pseudomonas fluorescens were evaluated for the induction ofdrought tolerance and growth promotion in tomato plants. Four isolates of Pseudomonas fluorescens viz Pf 2 Pf 4, Pf 6 and Pf 28 and three isolates of Trichoderma harzianum viz. TH 08, IRRI 1 and TH 26 were evaluated by using seed biopriming as well as seedling/transplanted root dip method against drought stress and for their effect onplant growth promotion. Parametersincludingdrought tolerance capacity, water requirement, shoot length, root length, plant height, and chlorophyll content were recorded inall the treatments of different isolates along with the untreated control.Among the two methods of bioinoculation, seed biopriming was found more effective to transplanted root dip in all the treatments of isolates of Trichoderma harzianum and Pseudomonas fluorescens. Among all the isolates, isolate IRRI 1 of Trichoderma harzianum was found highly effective in reducing the water stressbyincreasing thecumulative mean water stresstolerance duration of both methods of inoculation up to 14.83 days after the last irrigation with least mean water requirement of 13.92litres followed by isolate Pf28 of Pseudomonas fluorescens with mean water stress tolerance of 13.66 days and water requirement of 14.25 litres compared to the untreated control plants with least tolerance ofonly 10.66 days and highest water requirement of 16.25litres. Maximum cumulative mean shoot growth, root growth and chlorophyll content ofboth methods of inoculation of 76.25cm, 28.33cm and 41.20 SPAD units respectively were also recorded with IRRI 1 isolate followed by Pf 28 isolate with 67.17cm, 19cm, and 35.46 SPAD units respectively. Treatment with all other isolates of Trichoderma harzianum and Pseudomonas fluorescens also showed better water stress tolerance, less water consumption, increased shoot length, root length and chlorophyll content compared to the untreated control tomato plants.

ON FIELD MANAGEMENT OF ROOT-KNOT INFESTATION IN TOMATO AND BRINJAL THROUGH BIOFORMULATIONS OF PAECILOMYCES LILACINUS AND POCHONIA CHLAMYDOSPORIA

Bioformulations like wettable powder, aqueous liquid and granules of Paecilomyces lilacinus (Nematofree) and Pochonia chlamydosporia (Nematofree+) were evaluated against root-knot infestation in tomato and brinjal at two farmer’s field. The application of the bio-nematicides were carried out at transplanting stage of the crops as root dipping (@ 10gm or ml/ 1L of water) and soil treatment (@5Kg or L/acre incorporated with FYM).The root-knot infestation data was recorded by observing the foliage symptoms of root-knot infestation i.e., stunting, premature wilting, and leaf chlorosis. All the six treatments i.e., T1: Nematofree (WP), T2: Nematofree (Liquid), T3: Nematofree (Granule), T4: Nematofree+ (WP), T5: Nematofree+ (Liquid), T6: Nematofree+(Granule) showed significant reduction in the root-knot nematode infestation in both tomato crop (90 to 96%) and brinjal (75 to 86%). Among all formulation types, the wettable powder formulation of both bio-nematicides provided promising result in reduction of root-knot infestation symptoms. Nematofree+ was found to be more effective than Nematofree in controlling the infestation. Application of both the bionematicides also increased the final yield in case of both tomato and brinjal.

Evaluation of Pseudomonas sp. for its multifarious plant growth promoting potential and its ability to alleviate biotic and abiotic stress in tomato (Solanum lycopersicum) plants

1-Aminocyclopropane-1-carboxylate (ACC) deaminase activity is one of the most beneficial traits of plant growth promoting (PGP) rhizobacteria responsible for protecting the plants from detrimental effects of abiotic and biotic stress. The strain S3 with ACC deaminase activity (724.56 nmol α-ketobutyrate mg−1 protein hr−1) was isolated from rhizospheric soil of turmeric (Curcuma longa), a medicinal plant, growing in Motihari district of Indian state, Bihar. The halotolerant strain S3, exhibited optimum growth at 8% (w/v) NaCl. It also exhibited multiple PGP traits such as indole acetic acid production (37.71 μg mL−1), phosphate solubilization (69.68 mg L−1), siderophore, hydrocyanic acid (HCN) and ammonia production as well as revealed antagonism against Rhizoctonia solani. The potential of isolated strain to alleviate salinity stress in tomato plants was investigated through pots trials by inoculating strain S3 through-seed bacterization, soil drenching, root dipping as well as seed treatment + soil drenching. The strain S3 inoculated through seed treatment and soil drenching method led to improved morphological attributes (root/shoot length, root/shoot fresh weight and root/shoot dry weight), photosynthetic pigment content, increased accumulation of osmolytes (proline and total soluble sugar), enhanced activities of antioxidants (Catalase and Peroxidase) and phenolic content in salt stressed tomato plants. The biochemical characterisation, FAMEs analysis and 16S rRNA gene sequencing revealed that strain S3 belongs to the genus Pseudomonas. The overall findings of the study revealed that Pseudomonas sp. strain S3 can be explored as an effective plant growth promoter which stimulate growth and improve resilience in tomato plants under saline condition.

Role of MgO nanoparticles in the suppression of Meloidogyne incognita, infecting cowpea and improvement in plant growth and physiology

Root-knot disease, caused by Meloidogyne spp., alters histology as well as physiology of the roots thus influencing metabolism of vegetative and reproductive parts leading to huge losses in crop productivity. The experimental plant, Vigna unguiculata L. (cowpea of Fabaceae family) var. Gomti is an economically important pulse crop plant. An experiment was conducted to evaluate the effects of different concentrations (0, 25, 50 or 100 ppm) and various modes of applications (root dip, soil drench or foliar spray) of MgO nanoparticles on cowpea infected with M. incognita. The MgO nanoparticles were synthesized chemically and characterized by transmission and scanning electron microscopy (TEM, SEM), UV–Vis spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The scanning electron microscopy images of second stage juveniles of M. incognita treated with MgO nanoparticles (50 and 100 ppm) exhibited indentations, roughness and distortions in the cuticular surface, in comparison to the control untreated juveniles. MgO nanoparticles, in varying concentrations (50, 100 and 200 ppm), were dispensed into the plants by root dip, soil drench and foliar spray methods and their efficacy was assessed in terms of morphological characteristics, yield parameters and biochemical attributes of M. incognita infected plants. In planta trials revealed that 100 ppm dose of MgO nanoparticles, as root dip application, demonstrated reduced nematode fecundity, decreased number and smaller size of galls; enhanced plant growth, increased chlorophyll, carotenoid, seed protein, and root and shoot nitrogen contents. From these findings it could be inferred that MgO nanoparticles played twin roles, first as a nematicidal agent and the other as growth promotion inducer.

Management of foot rot of finger millet (Eleusine coracana (L.) Gaertan) caused by Sclerotium rolfsii

Seed treatment with T. harzianum @ 5 g kg-1 seed followed by root dipping in T. harzianum solution plus application of Neem cake @ 50 g hill-1 at transplanting recorded the lowest mean per cent disease incidence (3.69) and the maximum average yield for 2 years was 34.54 q ha-1. Seed treatment with thiram @ 3 g kg-1 of seed plus seedling root dipping in solution of T. harzianum at transplanting plus application of neem cake @ 50 g hill-1 at transplanting was at par at 15 DAT, 30 DAT and 60 DAT respectively.

Development of formulation of fluorescent pseudomonads and its evaluation on bio-management of blast of rice

Fluorescent Pseudomonads (Pseudomonas fluorescens and P. putida) were formulated in talc, bentonite, palm oil and coconut oil for the management of blast disease of rice. The formulated products showed promising shelf-value. The formulated products were evaluated by root dipping of rice seedlings and foliar spray followed by inoculation with M. oryzae in pots. All growth parameters, yield parameters, incidence and severity of blast or rice were significantly influenced at every growth stage of rice. Yield contributing parameters were increased significantly giving the highest benefit cost ratio (BCR) compared to untreated control. Among the treatments, T11 (10% BdPf-8 Talc) and T13 (1% BdPf-8 Palm Oil) gave the highest yield 5.18 t/ha and 5.13 t/ha with the highest BCR 2.10 and 2.08, respectively. A negative correlation was observed among vegetative parameters, disease incidence and disease severity. Pseudomonas fluorescens (BdPf-8) can be a potential candidate for commercial production for controlling blast or rice.

Brassinosteroid and hydrogen peroxide improve photosynthetic machinery, stomatal movement, root morphology and cell viability and reduce Cu- triggered oxidative burst in tomato

Brassinosteroids and hydrogen peroxide (H2O2) are extensively used to combat several environmental factors, including heavy metal stress in plants, but their cumulative impact on the maintenance of copper (Cu) homeostasis in plants could not be dissected at elevated level. This study was executed to explore the roles of 24-epibrassinolide (EBL; foliar) and H2O2 (root dipping) in resilience of tomato (Solanum lycopersicum L.) plants to Cu stress. The cumulative effect of EBL and H2O2 in tomato plants grown under Cu stress (10 or 100 mg kg−1 soil) were assessed. Roots of 20 d old plants were submerged in 0.1 mM of H2O2 solution for 4 h and subsequently transplanted in the soil-filled earthen pots and at 30 day after transplantation (DAT), the plants were sprinkled with deionized water (control), and/or 10−8 M EBL and plant performances were evaluated at 40 DAT. High Cu (100 mg kg−1 soil) concentration considerably reduced photosynthetic efficacy, cell viability, and plant growth, and deformed chloroplast ultrastructure and root morphology with altered stomatal behavior, but boosted the activity of antioxidant enzymes, proline content and electrolyte leakage in the leaves of tomato. Moreover, EBL and H2O2 implemented through distinct modes improved photosynthetic efficiency, modified chloroplast ultrastructure, stomatal behavior, root structure, cell viability and production of antioxidants and proline (osmolyte) that augmented resilience of tomato plants to Cu stress. This study revealed the potential of EBL and H2O2 applied through distinct mode could serve as an effective strategy to reduce Cu-toxicity in tomato crop.

Fusarium wilt biocontrol and tomato growth stimulation, using endophytic bacteria naturally associated with Solanum sodomaeum and S. bonariense plants

BackgroundFusarium wilt biocontrol using endophytic microorganisms may represent a potentially attractive and environmentally safe alternative since endophytes could better limit disease incidence and severity through inhibition of the systemic fungus progress.Main body of the abstractTwenty-three endophytic bacterial isolates, naturally associated with Solanum sodomaeum and Solanum bonariense, were evaluated for their ability to control Fusarium wilt of tomato induced by Fusarium oxysporum f. sp. lycopersici (FOL) and to promote plant growth. Selected endophytic isolates were screened in vivo, using the root dipping and the culture substrate drenching methods. The most bioactive isolates were subjected to morphological and biochemical characterization and subsequent identification through 16S rDNA sequencing genes. Seven isolates (Stenotrophomonas maltophilia S23, S24, S26 and S28; Bacillus sp. SV81; Azotobacter chroococcum S11; and Serratia marcescens S14) were found to be the most efficient in reducing disease severity by 82–96% over control. Treatments with these isolates led to a significant enhancement in growth parameters, estimated at 45.5–61 and 24.2–70.5% than the control, in tomato plants infected or not with FOL, respectively. Diffusible and volatile metabolites released from bacterial cultures had significantly limited FOL radial growth. All isolates were positive for indole-3-acetic acid (IAA) production. S. marcescens S14, S. maltophilia S28, and Bacillus sp. SV81 exhibited a positive phosphate solubilization activity. Production of chitinase, protease, pectinase, and hydrogen cyanide were also investigated.Short conclusionThis study clearly demonstrated that endophytic bacteria recovered from these 2 Solanum species can be explored as promising biocontrol agents active against FOL and are able to enhance tomato growth.

Effect of Azotobacter and nitrogen on growth and yield of Tomatocrop (Lycopersicumesculantum) cv. “Pusa Rubby”

The present investigation was carried out at the Horticultural Research farm, Department of Horticulture, Ch. Charan Singh University, Meerut to assess the effect of different treatments of azotobacter culture with different levels of nitrogen on growth and yield parameters. Twenty three days old seedlings were transplanted in experimental field. There were nine treatment combinations consisting two methods of Azotobacter chroococcum application (soil treatment with 2 kg per hectare and Seedling root dip treatment @ 2 kg per 10 liters of water) two levels of nitrogen application 75 kg per hectare and 150 kg per hectare and one control. Result revealed that seedling treatment with Azotobacter performed superior to soil treatment for all growth and yield parameters. The different levels of nitrogen exhibited pronounced effect of improving the various yield contributing traits were recorded maximum at 150 kg. nitrogen in each case. The parameters were recorded maximum under the treatment combination Seedling treatment with Azotobacter culture @ 2 kg+10 liters of water and 150 kg nitrogen/ha. Followed by Soil treatment with Azotobacter @ 2kg / ha. and 150 kg Nitrogen / ha.), Seedling treatment with Azotobacter @ 2 kg +10 liters of water and 75 kg Nitrogen / ha. and Soil treatment with Azotobacter @ 2 kg / ha. and 75 kg Nitrogen/ha.

Establishment of the entomopathogenic fungus Beauveria bassiana as an endophyte in Capsicum annuum and its effects on the aphid pest Myzus persicae (Homoptera: Aphididae)

Introduction: Entomopathogenic fungi have been used as biological control agents of insect pests and have demonstrated a promising ability to colonize as endophytes a wide range of plant species. Objective: The aims of this study were to evaluate, in pepper plants, the most effective Beauveria bassiana inoculation techniques. In order to evaluate the presence of natural endophytes and its interaction with B. bassiana. Also to assess the effect of B. bassiana on the aphid Myzus persicae pepper leaf feeding preference and growth. Methods: Three inoculation techniques were evaluated: leaf spraying, seed immersion and root dipping. The pepper plants were inoculated with a conidia suspension adjusted to 1×108 conidia/ml. The presence of B. bassiana in the seedlings was evaluated at 7, 15 and 28 days after inoculation. Results: We found significant statistical differences between inoculation techniques. Foliar spraying showed the highest B. bassiana colonization frequency. The natural endophytes presented higher presence in the treatments in which B. bassiana had a low presence. This might indicate the occurrence of antifungal activity that interferes with the establishment of the entomopathogen in pepper tissues. We did not find statistical differences between inoculated and control pepper leaves with regard to the mortality and reproduction of the aphid pest M. persicae. However, the inoculation with B. bassiana showed a tendency to increase the mortality of adults and to decrease the offspring (nymphs). We did not find significant differences in the feeding preference between inoculated and control leaves, although there was a higher number of individuals on control leaves compared to those inoculated. Conclusions: The strain B. bassiana LPSC 1067 was established effectively as an endophyte in the pepper tissues. The most effective inoculation technique was leaf spraying. We did not find differences of statistical significance with regard to the mortality and reproduction of the aphid pest M. persicae. However, the inoculation with B. bassiana showed a tendency to increase the mortality of adults and to decrease the offspring (nymphs). Future studies evaluating the indirect effects of endophytic entomopathogens on both plants and herbivorous insects are needed to further explore their potential use in the management of insect pests.

Biomanagement of rice root-knot nematode Meloidogyne graminicola using five indigenous microbial isolates under pot and field trials.

To ascertain the effectiveness of Aspergillus niger, Trichoderma harzianum, Pochonia chlamydosporia, Bacillus subtilis and Pseudomonas fluorescens against rice root-knot nematode, Meloidogyne graminicola, and to optimize their application methods. The relative effectiveness of five indigenous biocontrol agents (BCA) against M. graminicola on rice cv. PS-5 was tested initially in pot culture. The BCAs, A. niger, P. chlamydosporia and P. fluorescens proved more effective, and significantly reduced the nematode disease. It is hypothesized that success of a biocontrol module may vary with the BCA and application methods. Hence, the effectiveness of the above three BCAs as well as seven different treatment schemes were evaluated in naturally infested farmer's fields during 2 consecutive years. In nematode-infested plots without any BCA treatments, terminal galls formed on the roots, and plants suffered a 19-31% decrease in the growth and yield. The treatments with P. chlamydosporia or A. niger through root-dip (RD) plus one soil application (SA) at 15days after planting were found to be highly effective against the nematode. Relatively greater nematode control was achieved with RD plus two SAs (15+30DAP) but statistically the effect was on par with RD+one SA at 15DAP. These treatments significantly reduced galling (22-25%), egg mass production (21-29%) and reproduction factor (63-70%) of M. graminicola, and subsequently increased the grain yield (11-21%). Application methods enhanced the effectiveness of BCAs against M. graminicola. The RD plus one SA at 15DAP proved to be most effective treatment to control root-knot disease in rice. Use of multiple treatments (root dip and SA) appears cumbersome, but in view of effectiveness and limitation of chemical control in rice paddies, farmers may adopt the above module that may lead to 11-21% yield improvement.