Soil Nematode Populations Research Articles

Population of Soil Nematodes in The Treatment of Brassicaceae Plant Waste

Population of Soil Nematodes in The Treatment of Brassicaceae Plant Waste Brassicaceae plants are known to contain glucosinolates which can be hydrolyzed into biofumigant compounds. This research was conducted to examine the effect of biofumigant derived from Brassicaceae plants waste on soil nematode population dynamics. Greenhouse experiment was carried out on 4 types of Brassicaceae plants waste, consisting of leaf waste of radish (Raphanus sativus), broccoli (Brassica oleracea var. italica), cabbage (Brassica oleracea var. capitata), and whole parts kamanilan weed (Roripa indica) in polybags containing 5 L of nematode infested soil. Plant waste was chopped ± 1 cm in size, then as much as 117 g per polybag was mixed in nematode infested soil, doused with water until wet and tightly closed for the biofumigation process for 14 days. At the end of biofumigation step, the polybags were opened for 3-5 days, then 7 day - old cucumber seedlings of var. Roberto 92 were planted and the plants were maintained in greenhouse for up to 8 weeks. Observation of the type and population of soil nematodes was carried out three times, i.e. before treatment, after treatment, and 8 weeks after planting. This experiment was designed in a completely randomized design with 6 treatments and 5 replications. The results of the study showed that the population of free-living nematodes (bacteriovorous nematodes and fungivorous nematodes) was increased in all treatment of Brassicaceae plants waste. On the other hand, there was a significant decrease in the phytonematodes population in the treatment of broccoli leaf waste. All Brassicaceae wastes was able to suppress population of Helicotylenchus sp., Rotylenchulus sp., and Xiphinema sp., significantly. Leaf waste of broccoli leaves showed the highest inhibition value against all phytonematodes genera with inhibition reached 100%.

Nematicidal Properties of Chitosan Nanoformulation.

Chitosan is the second most abundant bio-polymer available in the world, second only to cellulose. It is found in crustaceous shells, e.g., those of crabs, shrimps, prawns, and fungi, as well as insect exoskeletons. The use of nanoformulations for the management of pests and diseases is receiving increased interest with the advancement of nanotechnology. Here, chitosan nanospheres were obtained from chitosan using the ionic gelation technique. The nanoformulations obtained were characterized using a particle size analyzer, Fourier transform infrared spectroscopy, and a transmission electron microscope. The efficacy of chitosan nanospheres in suppressing the root-knot nematode Meloidogyne incognita was studied. The particle size of nanospheres formulated for this study was 380.2 nm, with a polydispersity index (PI) of 0.4 and Zeta potential of 45.7 or 50.9 mV at pH 5.2. The chitosan nanospheres were spherical and the particles did not agglomerate. FTIR spectra of the chitosan nanospheres peaked at 3334 cm-1, thereby indicating the stretching of the OH and NH group. In In-vitro studies, chitosan nanospheres showed significant nematicidal activity against M. incognita. Under pot culture conditions, chitosan nanospheres (1%- active compound chitosan) at 2ml/plant decreased the nematode population in roots or soil. Compared to the control, the number of galls was reduced by 83.68%, the number of egg masses by 83.85%, the number of adult females by 66.56%, and the number of second-stage juveniles by 73.20%. In a field experiment, application of chitosan nanospheres (1%) was followed by a 18.75% increase in fruit yield compared to the non-treated control.

POPULAÇÃO DE NEMATOIDES EM CAFEEIRO ADUBADO COM COMPOSTO ORGÂNICO

INTRODUCTION: The use of organic compost to increase organic matter has been a great ally of the rural producer, since it is a practice of easy access, financially viable and ecologically sustainable. Thus, understanding the influence of organic composts on the incidence of nematodes in the soil, consequently, can help reduce the damage caused by these organisms. OBJECTIVE: Influence of organic compost fertilization on nematode population in soil cultivated with coffee trees. METHODS: A randomized block design was used in the experiment, with five treatments (doses of organic compost, 0, 2.5, 5, 7.5 and 10 t ha-1), divided into four blocks, totaling twenty experimental units. The soils had already been corrected with limestone application at doses of 0, 1, 2, 3, and 4 t ha-1. The dose of organic compost application was inversely proportional to the dose of lime application. RESULTS: The results showed a significant increase in calcium, potassium, base saturation and base sum levels. CONCLUSION: The organic matter content does not interfere in the nematode population.

Integrated application of amendments and chemicals for the management of root-knot nematode (Meloidogyne incognita) in cucumber (Cucumis sativus)

Root-knot nematode is one of the significant plant-parasitic nematodes in cucumber (Cucumis sativus L.). Considering its destructive potential, studies were carried out on effect of organic amendments and their integration with chemicals upon root-knot nematode in cucumber in pots (2016–17) and in infested field (2017–18), at research farm of Punjab Agricultural University, Ludhiana, Punjab. Among the organic amendments, mustard cake treatment (5 t/ha) was found to be most effective with 65.16% nematode infestation reduction in pot experiment and 53.57% nematode infestation reduction in field experiment over control. Integrated treatments were found to be more effective than individual applications. Individually, the maximum reduction in soil nematode population was observed in applying mustard cake (5 t/ha) followed by neem cake (5t/ha). The efficacy of mustard cake was observed to increase in integrated treatments. In integrated treatments, application of mustard cake (2.5 t/ha) + Basamid (20 g/m) was observed to be most effective in reducing nematode infestations in soil and roots of cucumber. Among all the chemicals and amendments evaluated against root-knot nematode, Basamid among chemicals and mustard cake as an amendment in integration were found most effective against root-knot nematode and can be explored further.

A Cost-Benefit Analysis of Soil Disinfestation Methods against Root-Knot Nematodes in Mediterranean Intensive Horticulture.

Losses caused by phytoparasitic nematodes in crops depend directly on their soil densities at the start of the crop, so reducing their populations before planting is the main aim of nematological management. Efficacies in reducing Meloidogyne soil populations of soil disinfestation methods, such as agrochemicals, botanicals, or biosolarization were estimated on multiple field trials conducted over fourteen years in intensive horticultural crops. Soil nematode populations were reduced by 87 to 78% after fumigation with 1,3-dichloropropene + chloropicrin and dimethyl-disulphide, respectively. Non-fumigant nematicides such as azadirachtin, dazomet, fenamiphos, fluopyram, fosthiazate, metam-sodium, and oxamyl showed efficacies ranging from 51 to 64%, whereas the efficacy of natural products, such as abamectin, garlic extracts, or essential oils was 41 to 48%. Biosolarization with chicken manure had an efficacy of 73%. An economic cost-benefit study of nematode management methods was performed for seven vegetable–M. incognita pathosystems. Fumigation with 1,3-dichloropropene + chloropicrin and biosolarization with chicken manure were the only treatments able to reduce RKN populations above 1000 and 750 J2 per 100 cm3 of soil, respectively, to levels below the nematode economic damage threshold, keeping profitability. Fumigation was able to manage RKN soil densities up to 350 J2 per 100 cm3 of soil in most susceptible crops as aubergine or cucumber and up to 1000 J2 per 100 cm3 of soil for more tolerant crops, such as other cucurbits, pepper, or tomato. Other nematicidal treatments were not able to reduce RKN populations above 200–300 J2/100 cm3 of soil below the economic thresholds but were profitable when RKN densities were below the limits of 200–300 J2/100 cm3 of soil.

Biocontrol potential of Pseudomonas rhodesiae GC-7 against the root-knot nematode Meloidogyne graminicola through both antagonistic effects and induced plant resistance

Plant-parasitic nematodes (PPNs) cause serious damage to agricultural production worldwide. Currently, because of a lack of effective and environmental-friendly chemical nematicides, the use of microbial nematicides has been proposed as an eco-friendly management strategy to control PPNs. A nematicidal bacterium GC-7 was originally isolated from the rice rhizosphere, and was identified as Pseudomonas rhodesiae. Treatment with the fermentation supernatant of GC-7 in vitro showed a highly lethal effect on second-stage juveniles of Meloidogyne graminicola, with the mortality rate increasing to 95.82% at 24 h and egg hatching significantly inhibited, with a hatch inhibition rate of 60.65% at 96 h. The bacterium significantly reduced the level of damage caused by M. graminicola infestations to rice (Oryza sativa) in greenhouse and field experiments. Under greenhouse conditions, the GC-7 culture efficiently reduced the gall index and nematode population in rice roots and soils, as well as inhibited nematode development compared to the control. Under field conditions, application of the GC-7 consistently showed a high biocontrol efficacy against M. graminicola (with a control efficiency of 58.85%) and promoted plant growth. In addition, the inoculation of GC-7 in M. graminicola-infested rice plant fields significantly suppressed final nematode populations in soil under natural conditions. Furthermore, activities of plant defense-related enzymes, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase were remarkably increased in plant roots treated with GC-7 compared with roots that were challenge to M. graminicola. Moreover, quantitative real-time PCR analysis showed that GC-7 significantly enhanced the expression of defense genes (PR1a, WRKY45, JaMYB, AOS2, ERF1, and ACS1) related to salicylic acid, jasmonic acid, and ethylene signaling pathways in rice roots after inoculation with GC-7 at different levels. The results indicated that GC-7 could be an effective biological component in the integrated management of M. graminicola infecting rice.

Reducing Pratylenchus Population in Coffee Seedling with Mycorrhizal Fungi and Mycorrhiza Helper Bacteria

The attack of Pratylenchus coffeae nematode on coffee seedlings can limit coffee growth. The use of beneficial microbes as biofertilizer and bioprotectant is suggested to reduce the nematode attack on coffee seedlings and improve growth. A greenhouse experiment was conducted to observe the effect of arbuscular mycorrhizal fungi (AMF) Glomus spp. and mycorrhiza helper bacteria (MHB) P. diminuta and B. subtilis on coffee seedling growth and P. coffeae populations in the soil and roots. The experiment was set up in a randomized block design with five treatments and three replications. The coffee seedlings were grown in potting soil and inoculated with Glomus spp. combined with 20 g or 30 g of MHB solid inoculant. Seedlings were grown in the greenhouse for 10 weeks. The experiment verified that AMF inoculation combined with MHB did not affect the plant height, leaf number, or plant dry weight but decreased the P. coffeae population in the soil and roots of the seedlings. Inoculation of 20 g of MHB solid inoculant with AMF was more effective in reducing nematode population in soil and roots than 30 g of MHB. This experiment verified that Glomus spp., as well as P. diminuta and B. subtilis enable the control of P. coffeae in coffee seedlings.

High-throughput phenotyping of nematode cysts.

The beet cyst nematode Heterodera schachtii is a plant pest responsible for crop loss on a global scale. Here, we introduce a high-throughput system based on computer vision that allows quantifying beet cyst nematode infestation and measuring phenotypic traits of cysts. After recording microscopic images of soil sample extracts in a standardized setting, an instance segmentation algorithm serves to detect nematode cysts in these images. In an evaluation using both ground truth samples with known cyst numbers and manually annotated images, the computer vision approach produced accurate nematode cyst counts, as well as accurate cyst segmentations. Based on such segmentations, cyst features could be computed that served to reveal phenotypical differences between nematode populations in different soils and in populations observed before and after the sugar beet planting period. The computer vision approach enables not only fast and precise cyst counting, but also phenotyping of cyst features under different conditions, providing the basis for high-throughput applications in agriculture and plant breeding research. Source code and annotated image data sets are freely available for scientific use.

Effects of Forest Harvesting Operations on the Recovery of Earthworms and Nematodes in the Hyrcanain Old-Growth Forest: Assessment, Mitigation, and Best Management Practice

The quality and performance of forest soil is closely related to the characteristics of the faunal community in the soil. Focusing on soil organisms can provide good indicators to choose the best soil restoration methods to improve the properties of degraded forest soils. Therefore, the present study aimed to evaluate the effects of the tree litter of different species on the recovery of soil organisms (earthworms and nematodes) from skid trails over a 20-year period after harvest operations. For this purpose, three skid trails with different ages after harvest operations (6, 10, and 20 years), considering three tree litter treatments (beech, beech–hornbeam, and mixed beech) and three traffic intensity classes (low, medium, and high), were identified. The combination of treatments was carried out in the forest with three replications, and a total of 18 sample plots of 0.5 m2 were harvested to measure earthworms and nematodes. The results showed that 20 years after harvest operations, the highest values of earthworm density (5.72 n m−2), earthworm biomass (97.18 mg m−2), and total nematodes (313.65 in 100 g of soil) were obtained in the mixed beech litter treatment compared to other litter treatments. With decreasing traffic intensity from high to low, the activity of soil organisms increased, and the highest values of earthworm density (5.46 n m−2), earthworm biomass (87.21 mg m−2), and soil nematodes (216.33 in 100 g soil) were associated with low traffic intensity. Additionally, in all three litter treatments and traffic intensities, the epigeic ecological species were more abundant than the anecic and endogeic species. Key soil variables including water content, porosity, available nutrients, pH, total organic C, and total N were significantly correlated with earthworm density and biomass and soil nematode population. Litter management and addition to compacted soil can support the functional dynamics and processes of the soil and maintenance of the abundances and activities of the soil fauna.

First Report of the Root-Knot Nematode Meloidogyne enterolobii on Sweet Potato in Guangxi Province, China.

Sweet potato (Ipomoea batatas Lam.) is the seventh most widely cultivated food crop in the world and the sixth most widely cultivated food crop in China. In June 2021, sweet potato plants were found to be displaying nutrient deficiencies with red leaves in a sweet potato field in Hepu County, Beihai City, Guangxi Province (21°37′43.41"N，109°10′58.74"E). Black irregular protuberant scars on tubers and nodular galls on roots were found. Thirty-five sweet potato ‘Variety Guiziweishu No. 1’ tubers were randomly collected and 97% were infected with root-knot nematodes. Females (n = 20) had perineal patterns that were oval, with moderate to high dorsal arches, the lateral field was not obvious or absent. Morphological measurement of females (n = 20) were made from micrographs taken with a microscope (Axio Imager, Z2, ZEISS). Measurements (mean + standard error) were: body length (BL) = 932.8 ± 18.4 μm; maximum body width (BW) = 588.8 ± 22.0 μm; vulval slit length = 19.6 ± 0.6 μm; and, vulval slit to anus distance = 22.3±0.8 μm. Morphological measurements of second-stage juveniles (J2; n = 20) were: BL =512.0± 5.9 μm; BW = 17.4 ± 0.6 μm; Stylet length = 13.4 ± 0.2 μm; dorsal pharyngeal gland orifice to stylet base (DGO) =3.4 ± 0.0 μm; and, hyaline tail length = 17.6 ± 0.5 μm. These morphological characteristics fit those of the original description for Meloidogyne enterolobii (Yang and Eisenback 1983). Molecular analyses were conducted to confirm species identification. Genomic DNA was extracted from 12 single J2 (Luo et al. 2020). The rDNA-internal transcribed spacer (ITS) region was sequenced using primers V5367/26S (5′-TTGATTACGTCCCTGCCCTTT-3′/5′-TTTCACTCGCCGTTACTAAGG-3′) (Vrain et al. 1992), and the D2–D3 fragment of the 28S rRNA genes using primers D2A/D3B (5′-GTACCGTGAGGGAAAGTTG-3′/5′-TCGGAAGGAACCAGCTACTA-3′) (De Ley et al. 1999). The target gene sequences were 733 bp (GenBank accession no. MZ413814) and 733 bp (MZ411468), respectively; they were all 99-100% similar to those of M. enterolobii sequences available in the GenBank. Species identification was also confirmed using PCR to amplify rDNA-IGS2 with M. enterolobii-specific primers Me-F/Me-R (5′-AACTTTTGTGAAAGTGCCGCTG-3′/5′-TCAGTTCAGGCAGGATCAACC-3′). The electrophoresis results showed a bright band (∼200 bp) only in the lane with the M. enterolobii-specific primers, similar in size to that previously reported for M. enterolobii (Long et al. 2006). Therefore, this Meloidogyne sp. population on sweet potato was identified as M. enterolobii based on its morphological and molecular characteristics. To verify the pathogenicity of nematodes, sweet potato ‘Variety Guiziweishu No. 1’ seedlings were individually planted in 18 cm diameter, 11 cm deep plastic pots containing 1000 cm3 autoclaved sandy soil (sand/soil = 3:1). A total of 15 seedlings were inoculated with 10,000 eggs (the population was same with nematode population in soil the field) and 5 seedlings without eggs were used as a control. Plants were maintained at 25-28°C in a greenhouse. After 2 months, root of inoculated plants exhibited elongated swellings similar to symptoms observed in the field. The noninoculated plants did not have any galls or swelling. A reproduction factor (nematode final population density/initial population density) value of 18.6 was obtained. These results confirmed the nematodes’ pathogenicity. To our knowledge, this is the first report of M. enterolobii on a member of the Convolvulaceae in Guangxi Province. In 2014, the nematode on sweet potato was reported in Guangdong Province (Gao et al. 2014). Guangxi Province is the largest producer of sweet potato in south China and is the third top producing region in the whole country. Meloidogyne enterolobii is a potential risk to the production of sweet potato in this region, and control measures are needed to prevent any further spread.

Physiological and bio chemical modification through bio inducer in tube rose infected with root knot nematode (Meloidogyne incognita)

The main aim for this study is to investigate on physiological and bio chemical modification through bio inducer in tube rose infected with root knot nematode, Meloidogyne incognita. Two pot culture experiments was carried out during 2015-2018 for assessment of bio chemicals changes induced by selected bio stimulant in tube rose infected with root knot nematode, M. incognita. In this study bulbs of tuberose var. prajwalwas planted at the rate of 1 bulb/pot with three replications and each replication consist of two pots. The juveniles (1juvinile/g of soil) was inoculated under controlled condition. The pots wastreated with ascorbic acid - corm soaking (24hrs)+ foliar spray (45 and 90 DAP) with various concentration viz.,250 ppm,500 ppm and 1000 ppm, Humic Acid - corm Soaking (24hrs)+ foliar spray (45 and 90 DAP) 1,2 and 3 per cent, salicylic acid - corm soaking (24hrs)+ foliar spray (45 and 90 DAP) 50 ppm, 100ppm and200 ppm, monocrotophos 0.2% - corm soaking (24hrs)+ foliar spray (45 & 90 DAP). Field experiments was conducted at farm of RRS, Paiyur during the period of 2016-2017. The best performed five treatments were callout from pot culture experiments I and II and further experiment was conducted at field conditions in split plot (3mX3m) with three replications. The standard cultural practices were followed as recommended by Tamil Nadu Agricultural University,Coimbatore. The observation viz., Stalk length (Cm), Inflorescences length (cm), Stalk weight (g), Total number of florets, Nematode population in root(5g), Nematode population in soil (200cc), gall index and yield were recorded.

Effect of crop sequences in combination with other ecofriendly practices for management of plant parasitic nematodes infecting jute (Corchorus olitorius L.)

Among the different biotic stress, plant parasitic nematodes are considered to be real menace to successful and profitable cultivation of crops. This tiny microscopic organism can effectively manage by application of chemical pesticides, but frequent use of chemical pesticides may induce residual effect, phytotoxicity, health hazards to human and live stocks including ground water contamination. To overcome these hazards, effort is being made to reduce the nematode infestation by some non chemical methods. Use of proper crop sequences seems to be one of the best methods to counter nematode problem. Incorporation of non host or poor host crop between two susceptible host crops can successfully reduce nematode infestation. In the present study four crop rotation sequences were tested for their efficacy to reduce the incidence of plant parasitic nematodes on jute in a naturally infested field of Biswanth College of Agriculture, Biswanath Chariali, Assam during 2019–20. Other ecofriendly nematode management practices like application of compost and crop residue, soil incorporation of dhaincha as green manure, application of bioagents were also combined with different crop sequence. Among the different crop sequences, Jute-Toria-Dhaincha-Jute was found to be most effective in reducing the final nematode population in soil and increasing the seed yield of jute followed in order of efficacy by the crop sequence Jute-Toria- Fallow- Jute. These crop sequences may be recommended for future record.

Nematicidal Activity of Cyclopiazonic Acid Derived From Penicillium commune Against Root-Knot Nematodes and Optimization of the Culture Fermentation Process.

Among 200 fungal strains isolated from the soil, only one culture filtrate of Aspergillus flavus JCK-4087 showed strong nematicidal activity against Meloidogyne incognita. The nematicidal metabolite isolated from the culture filtrate of JCK-4087 was identified as cyclopiazonic acid (CPA). Because JCK-4087 also produced aflatoxins, six strains of Penicillium commune, which have been reported to be CPA producers, were obtained from the bank and then tested for their CPA productivity. CPA was isolated from the culture filtrate of P. commune KACC 45973. CPA killed the second-stage juveniles of M. incognita, M. hapla, and M. arearia with EC50–3 days 4.50, 18.82, and 60.51 μg mL–1, respectively. CPA also significantly inhibited egg hatch of M. incognita and M. hapla after a total of 28 days of treatment with the concentrations > 25 μg mL–1. The enhancement of CPA production by P. commune KACC 45973 was explored using an optimized medium based on Plackett–Burman design (PBD) and central composite design (CCD). The highest CPA production (381.48 μg mL–1) was obtained from the optimized medium, exhibiting an increase of 7.88 times when compared with that from potato dextrose broth culture. Application of the wettable power-type formulation of the ethyl acetate extract of the culture filtrate of KACC 45973 reduced gall formation and nematode populations in tomato roots and soils under greenhouse conditions. These results suggest that CPA produced by P. commune KACC 45973 can be used as either a biochemical nematicide or a lead molecule for developing chemical nematicides to control root-knot nematodes.

Environmental Sustainability: Bioactivity of Leucaena leucocephala Leaves and Pesticide Residue Analysis in Tomato Fruits

Field studies were conducted on the application of Leucaena leucocephala leaf extracts as an alternative to carbofuran a synthetic nematicide, while possible residues of carbofuran in tomato fruits were also analysed. Acetone, methanol and petroleum ether fractions of the leaves of L. leucocephala were applied at 200 mg/mL in variants of 100 mL, 150 mL and 200 mL to a naturally nematode infested field. Comparison was made with carbofuran a synthetic insecticide and nematicide. Samples of tomato fruits from carbofuran treated and untreated beds were extracted with ethyl acetate for residual pesticide analysis to ascertain the exceedance of the maximum residue limit (MRL). Results revealed that pesticide residue was significantly (p = 0.05) higher in plots treated with carbofuran compared with standard MRL for carbofuran in tomatoes. Crude extracts of L. leucocephala were as effective as carbofuran, while the fraction was however significantly better in producing higher numbers of fruits and reduced nematode population in root and soil of tomato plants.

Paecilomyces formosus MD12, a Biocontrol Agent to Treat Meloidogyne incognita on Brinjal in Green House.

The present study was carried out to analyze the potential of fungi isolated from the rhizosphere of soybean, brinjal, tomato, and potato plants. The density of fungi varied in the pot soil and rhizosphere after Paecilomyces formosus MD12 treatment. The P. formosus MD12 population was 6.3 ± 0.13 × 104 CFU g−1 in the pot planted with brinjal, and the population increased in the rhizosphere (6.72 ± 0.41 × 104 CFU g−1). P. formosus MD12 was cultured in the production medium, and the supernatant was used for egg inhibition studies on a root-knot nematode parasite, Meloidogyne incognita. It was revealed that maximum egg inhibition (94.7 ± 6.2%) was obtained at 100% concentration of extract. The culture supernatant from P. formosus MD12 affected the development of M. incognita juvenile, and the mortality rate was maximum after 96 h (95 ± 6%). Mortality was reduced when treated with 25%, 50%, and 75% supernatant. At 1 × 107 mL−1 of spore suspension, we found reductions of 71.6 ± 3.3% nematode populations in the soil, 60.7 ± 2.2% from the root, and 63.6 ± 2.4% egg mass compared with the control in the pot experiment. The culture supernatant applied at the 10% level showed a maximum mean reduction of the nematode population in roots (72.4 ± 2.2%), soil (77.9 ± 2.5%), and egg masses (73.2 ± 1.5%), respectively. The presence of P. formosus MD12 in a soil environment could antagonize nematode parasites and improve soil amendment. The P. formosus MD12 strain showed good biocontrol ability against the root-knot nematode, M. incognita, under in vitro and green house experimental condition.

Population density of free-living nematodes and their relationships with some soil physicochemical properties in forest and agriculture soils of Gapa Valley Chalt, Gilgit, Pakistan

The present study was conducted in Gapa Valley, Chalt, Gilgit-Baltistan, Pakistan to check the relationship of free-living nematodes in association with soil physicochemical properties. Soil samples from five random sites of pine and potato fields were collected. From each site three composite soil samples were collected, one to determine soil bulk density while two to determine the physicochemical parameters and diversity of free-living nematodes. The nematodes were extracted using modified Baermann’s funnel method and the count showed that the population density of free-living nematodes was generally lower in the pine forest than potato fields. About 156 nematodes belonging to 15 families were recorded in the potato field and 39 nematodes belong to 18 families were recorded in pine forests. Moreover, remarkable differences in physiochemical properties viz., SMC (Soil moisture Content), EC (Electrical conductivity), pH, temperature, soil texture, BD (Bulk density), was found between the pine forest and potato fields. The soil of pine forest was highly acidic with pH 5.90 while the soil of potato fields was near to neutral with pH 6.53. Moreover, temperature, EC and SMC of potato fields were higher than that of pine forests. Additionally, the soil texture of potato fields was silty and sandy loamy soil whereas the soil texture of pine forest was silty but with a high amount of silt content. Finally, Pearson’s correlation showed significant positive and negative correlations between some of the soil physicochemical parameters and nematode population. Keywords: Free-living nematodes; Physiochemical; Population density; Correlation http://dx.doi.org/10.19045/bspab.2021.100050

Relationship between Nematodes and some Soil Properties in the Rhizosphere of Banana Plants

Nematodes are plant-parasitic organisms that cause alterations in the chemical and physical environment of soils. This study investigates the relationship between nematode occurrence and some soil parameters. The results showed that the proportion of nematodes in soil was negatively correlated with soil pH (r2= 0.89); however, it increased with increasing electrical conductivity (EC) (r2 = 0.95), soil moisture (SM) (r2 = 0.60), and organic matter (OM) content (r2= 0.78). A positive correlation was found between the proportion of nematodes in the roots and the amount of coarse sand, while a negative correlation existed between the proportion of nematodes and the amount of fine sand, clay, and silt. The degree of colonization by nematodes increased with increasing coarse sand content (r2= 0.91). Conversely, the soil nematode population decreased with increasing fine sand content (r2= 0.83), clay (r2= 0.80), and silt content (r2= 0.97). The nematode population in banana roots correlated with soil phosphorus (r2 = 0.88), potassium (r2 = 69), calcium (r2 = 0.78), and magnesium levels (r2=0.78). Conversely, a negative correlation was found between nitrogen concentration and the nematode population in banana roots (r2=0.76). Overall, the population of nematodes in soil affects its pH, EC, SM, and OM content.

Relationship between Nematodes and some Soil Properties in the Rhizosphere of Banana Plants

Nematodes are plant-parasitic organisms that cause alterations in the chemical and physical environment of soils. This study investigates the relationship between nematode occurrence and some soil parameters. The results showed that the proportion of nematodes in soil was negatively correlated with soil pH (r2= 0.89); however, it increased with increasing electrical conductivity (EC) (r2 = 0.95), soil moisture (SM) (r2 = 0.60), and organic matter (OM) content (r2= 0.78). A positive correlation was found between the proportion of nematodes in the roots and the amount of coarse sand, while a negative correlation existed between the proportion of nematodes and the amount of fine sand, clay, and silt. The degree of colonization by nematodes increased with increasing coarse sand content (r2= 0.91). Conversely, the soil nematode population decreased with increasing fine sand content (r2= 0.83), clay (r2= 0.80), and silt content (r2= 0.97). The nematode population in banana roots correlated with soil phosphorus (r2 = 0.88), potassium (r2 = 69), calcium (r2 = 0.78), and magnesium levels (r2=0.78). Conversely, a negative correlation was found between nitrogen concentration and the nematode population in banana roots (r2=0.76). Overall, the population of nematodes in soil affects its pH, EC, SM, and OM content.

Effects of Sunn hemp (Crotalaria juncea) and Mexican sunflower (Tithonia diversifolia) soil amendments on yields and quality of two indigenous vegetables grown in a nematode-infested field

Two separate sets of field trials were conducted in 2016 and 2017 to determine the effects of sunn hemp, Crotalaria juncea and Mexican sunflower, Tithonia diversifolia on yields of Amaranthus cruentus and Solanum macrocarpon grown in fields infested with Meloidogyne incognita, Rotylenchulus spp. and Xiphinema spp. Eight week-old seedlings of sunn hemp and Mexican sunflower were incorporated into the soil at 10 and 20 seedlings/plot each four weeks after transplanting. Plots where sunn hemp or Mexican sunflower was not incorporated served as controls. Data were collected on soil nematode populations and yields of the vegetables/plot. The results show that incorporation of sunn hemp and Mexican sunflower each at 10 and 20 seedlings/plot on nematode-infested fields sown to A. cruentus and S. macrocarpon significantly reduced the populations of M. incognita, Rotylenchulus and Xiphinema spp. and increased the yields of the vegetables in comparison with fallow control plots. Incorporation of sunn hemp and Mexican sunflower at 10 or 20 seedlings/plot could provide effective management strategy for plant-parasitic nematodes.

Management of Meloidogyne incognita infecting Eggplant Using Moringa Extracts, Vermicompost, and Two Commercial Bio-products

Two greenhouse pot experiments were conducted to assess the effectiveness of dried leaf powder and extractives (ethanolic, and aqueous extracts) of Moringa(Moringa oleifera) or organic fertilizer (vermicompost) and two commercial products namely BioNematon (Purpureocillium lilacinum) and Abamectin, Gold (Streptomyces avermitilis) on eggplant growth parameters and Meloidogyne incognita infection. In both experiments observed data revealed that combined applications showed better performance than did single ones. Eggplant growth parameters in terms of fresh shoot and root lengths, and shoot and root weights were remarkably improved with single application of Abamectin or BioNematon followed by plant extracts or vermicompost resulting in a significant (P<0.05) suppression in nematode population in soil and root as well as the number of galls and egg masses. However, the potential of bioagent was increased with the addition of Moringa leaf powder and significantly (P<0.05) enhanced eggplant growth and suppressed nematode population, root galling and female fecundity even no significant differences were recorded compared to Oxamyl. Vermicompost derived from municipal wastes showed a low C/N ratio (1:14) with an excess of nitrogen that exhibited nematicidal activity against M.incognita. The addition of vermicompost with such bio-agents showed a synergistic effect upon nematode population, root galling and number of females. Significant differences whether in plant growth or nematode reproduction were not detected compared to Oxamyl. Thus the current study revealed the potential of leaf powder and extractives of Moringa, vermicompost, P.lilacinum and S.avermitilis as safe alternatives to control M.incognita infecting eggplant through an integrated management program and bring sustainability to agriculture.