Root Knot Research Articles

Solarized IPM Module for Biocontrol of Root-knot Nematode on Tomato at Nursery Level in District G.B Nagar, Uttar Pradesh

Background: The role of soil solarization in suppression of soil borne pathogens and weeds has been established by several researchers around the globe It involves capturing solar radiations when the soil receives the maximum sunlight in May-June using a polythene mulch. Its effectiveness depends on ambient temperature, duration of the treatments and soil moisture. This not only acts as a soil disinfectant but also as soil decontamination. It includes various changes in the soil like physical, chemical and biological properties. Methods: The field to lab and vice-versal based investigations were carried during 2021-2022 at Amity Centre for Biocontrol and Plant Disease Management, Amity University, Uttar Pradesh, Noida and identified tomato nurseries of district G B Nagar where heavy infestation (10-12 J2/cc soil) of root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood was recorded. The treatments comprised of sustainable components viz. deoiled seed cake of neem, a Arbuscular Mycorrhizal fungus Glomus intraradices and indigenous fungal strain of Trichoderma harzianum, (Th7) alone and together applied for evolving IPM module at solarized and unsolarized sets. Under microplot trials, the entire solarized treatments were carried out measuring 3 × 1 sq. meter each in which one set of all the treatments including control covered with clear transparent polythene sheet (400 ì gauge) for solarization. The treatments were replicated thrice in randomized block design. Result: The observations of solarized and unsolarized treatments clearly revealed that the soil solarization in treatments where the sun radiant energy was trapped by 400 µ transparent polysheets significantly reduced the root knot nematode Meloidogyne incognita population both in root and soil in comparison to unsolarized treatments where no solar energy trapping was done. The combined application of locally isolated Trichoderma harzianum (Th7) and VA mycorrhiza, Glomus intraredices enhanced germination and plant growth in nurseries. In the present investigation, the solarized IPM module- 4 comprising of other sustainable components viz. neem oil-seed cake, T. harzianum (Th-7) and Arbuscular Mycorrhizal (AM) fungus G. intraredices is proved to be an ideal one in root-knot nematode pest management in tomato nurseries.

Evaluation of fluopyram for disease and root knot nematode control along with yield response on peanut

Efficacy of in-furrow application of fluopyram + imidacloprid alone or followed by fluopyram + prothioconazole at-pegging and aldicarb for managing peanut root-knot nematode populations, root and pod galling due to nematodes, and yield, along with non-target effects on leaf spot diseases and stem rot were compared on the root-knot susceptible cultivar Georgia-06G over seven years on an irrigated site with an established population of Meloidogyne arenaria race 1. In all years, fungicides were applied to all plots following a Peanut Rx application schedule. Root-knot nematode populations, nematode damage, and yield along with leaf spot severity and stem rot incidence significantly differed among years; except for nematode populations, these measured variables also differed by nematicide treatment. Averaged over years, galling and root damage was significantly reduced with aldicarb compared to the no-nematicide control but not with either of the fluopyram treatments. While similar late-season root-knot nematode populations were noted for all nematicide programs and the non-treated control, pooled over years, significant yield gains were obtained with aldicarb and fluopyram programs with the two-treatment program providing greater yields than the aldicarb treatment. Leaf spot severity, averaged over years, was similar in aldicarb and control treatments; however, both fluopyram treatments had significantly lower leaf spot severity than the aldicarb treatment. Stem rot incidence did not differ among nematicide treatments. In addition, pooled over years, there was a negative relationship between juvenile populations and yield, but this was relatively weak. Weather, particularly extreme rain conditions, impacted yield directly as well as indirectly by affecting leaf spot severity and nematode activity.

Race Composition of Root Knot Nematode (Meloidogyne ) Species Infecting Cucurbitaceous Crops in Terai region of West Bengal

Race Composition of Root Knot Nematode (Meloidogyne ) Species Infecting Cucurbitaceous Crops in Terai region of West Bengal

Effects of allyl isothiocyanate fumigation on medicinal plant root knot disease control, plant survival, and the soil bacterial community

BackgroundAllyl isothiocyanate (AITC) is a natural product with high volatility that is used as a biofumigant to alleviate soil-borne plant diseases, and problems such as root knot nematodes (RKNs) that necessitate continuous cropping. However, little research has assessed the effects of AITC fumigation on medicinal plants.ResultsAITC significantly reduced the population of RKNs in soil (p < 0.0001) and showed an excellent RKN disease control effect within 6 months after sowing Panax notoginseng (p < 0.0001). The seedling survival rate of 2-year-old P. notoginseng was approximately 1.7-fold higher after soil treatment with AITC (p = 0.1008). 16S rRNA sequencing indicated that the AITC treatment affected bacterial richness rather than diversity in consecutively cultivated (CC) soil. Furthermore, biomarkers with statistical differences between AITC-treated and untreated CC soil showed that Pirellulales (order), Pirellulaceae (family), Pseudomonadaceae (family), and Pseudomonas (genus) played important roles in the AITC-treated group. In addition, the microbiome functional phenotypes predicted using the BugBase tool suggested that AITC treatment is more conducive to improving CC soil through changes in the bacterial community structure. Crucially, our research also suggested that AITC soil treatment significantly increases soil organic matter (p = 0.0055), total nitrogen (p = 0.0054), and available potassium (p = 0.0373), which promotes the survival of a succeeding medicinal plant (Polygonatum kingianum).ConclusionAITC is an ecologically friendly soil treatment that affects the top 10 bacterial richness but not diversity. It could also provide a basis for a useful agricultural soil management measure to alleviate soil sickness.

First report of Meloidogyne javanica infecting Bletilla striata in Yunnan, China.

Bletilla striata (Thunb. ex Murray) Rchb. F. (Orchidaceae) is an endangered traditional Chinese medicinal plant and has been traditionally used for hemostasis and detumescence in China (Wang et al. 2022). In March of 2021, during a field survey in Xuanwei city, Yunnan province, China, some B. striata plants with symptoms of plant dwarfing and leaf yellowing were observed. Roots of diseased plants presented numerous galls, typical symptoms of root-knot nematodes (RKNs) infection. The diseased area was approximately 66667 m2, showing a patchy disease distribution pattern. To identify the species of RKNs, females and eggs were isolated from galled tissue, and second-stage juveniles (J2s) were collected from eggs hatched. Nematodes were identified through comprehensive morphological and molecular methods. The perineal pattern of females is round to ovoid with a flat or moderately high dorsal arch and has two conspicuous lateral line striae. Morphological measurements of females (n=20) included body length (L) = 702.9 ± 70.8 (556.2-780.2) μm, body width (BW) = 404.1 ± 48.5 (327.5-470.1) μm, stylet length = 15.5 ± 2.2 (12.3-18.6) μm, distance from base of stylet to dorsal esophageal gland opening (DGO) = 3.7 ± 0.8 (2.1-4.9) μm. The morphometrics of J2s (n=20), L = 438.4 ± 22.6 (354.1-464.8) μm, BW = 17.4 ± 2.0 (12.9-20.8) μm, stylet length = 13.5 ± 0.4 (13.0-14.2) μm, DGO = 3.2 ± 0.6 (2.6-4.7) μm, and hyaline tail terminus = 12.3 ± 1.9 (9.6-15.7) μm. These morphological characteristics were similar to the original descriptions of Meloidogyne javanica (Rammah and Hirschmann 1990). DNA extraction was done 60 times, each from a different single females following the method of Yang et al. (2020). Amplification of ITS1-5.8S-ITS2 region of rDNA and the coxI region of mtDNA was done by using primers 18S/26S (5'-TTGATTACGTCCCTGCCCTTT-3'/5'-TTTCACTCGCCGTTACTAAGG-3') (Vrain et al. 1992) and cox1F/cox1R (5'-TGGTCATCCTGAAGTTTATG-3'/5'-CTACAACATAATAAGTATCATG-3') (Trinh et al. 2019) respectively. The PCR amplification program followed the method described by Yang et al. (2021). The ITS1-5.8S-ITS2 gene sequence (768 bp, GenBank Accession No. OQ091922) showed 99.35-100% identical to the known sequences of M. javanica (GenBank Accession Nos. KX646187, MW672262, KJ739710, KP901063, MK390613). The coxI gene sequence (410 bp, OQ080070) showed 99.75%-100% identical to the known sequences of M. javanica (OP646645, MZ542457, KP202352, KU372169, KU372170). Furthermore, M. javanica species-specific primers Fjav/Rjav (5'-GGTGCGCGATTGAACTGAGC-3'/5'-CAGGCCCTTCAGTGGAACTATAC-3') were used for PCR amplification. An expected fragment of approximately 670 bp was obtained, which was identical to that previously reported for M. javanica (Zijlstra et al. 2000). To verify pathogenicity of this nematode on B. striata, six 1.6-year-old tissue culture seedings of B. striata were maintained in 10-cm-diameter × 9-cm-high plastic pots containing a sterilized mixed soil (humus soil: laterite soil: perlite=3:1:1), and each plant was inoculated with 1000 J2s hatched from eggs of M. javanica. Three non-inoculated B. striata were used as the negative controls. All plants were placed in a greenhouse at approximately 14～26 ℃. After 90 days, the inoculated plants presented symptoms of leaf yellowing, and the roots with root knots identical to those observed in the fields. The root gall rating was 2 according to the 0-5 RKNs rating scale (Anwar and McKenry, 2002) and the reproductive factor (RF= final population/initial population) was 1.6. No symptoms or nematodes were observed on control plants. The nematode was reisolated and identified as M. javanica by morphological and molecular methods as above. To our knowledge, this is the first report of infection of M. javanica on B. striata. The infection of this economically important medicinal plant with M. javanica could pose a great threat to B. striata production in China, and further research will be necessary to develop control strategies.

Evaluation of reference genes for accurate normalization of qPCR data under biotic stresses in mulberry (Morus indica L.)

Biotic stresses adversely affect the leaf quality as well as the yield of mulberry (Morus spp.) which is used to feed mulberry silkworm (Bombyx mori L.). The different biotic stresses which are of economic importance in mulberry are tukra caused by mealybug insect, root knot disease by nematode, powdery mildew, and root rot by fungi. Reverse transcription-quantitative PCR (RT-qPCR) is a preferred technique to assess the transcript abundance of target genes associated with the diseases using a suitable reference gene as a normalizer. However, no study has been conducted to identify suitable reference genes during different biotic stresses in mulberry. In the present work, six candidate reference genes were quantified through qPCR during different biotic stresses in mulberry and their stability was compared using geNorm, NormFinder and RefFinder algorithms. The analysis of data revealed that actin was the preferred gene during root rot and root knot nematode infection for normalizing gene expression. Ubiquitin gene was the best-scoring gene for mealybug infestation resulting in tukra disease. PP2A (Protein phosphatase 2A) and RPL3 (60S ribosomal protein L3) were highly stable expressing genes during powdery mildew fungi infection. In the combined analysis of all tested biotic stresses, actin gene was the most preferred one followed by ubiquitin and PP2A as reference genes. This study identified the best scoring reference genes in various biotic stresses which will contribute for the precise quantification of target genes by RT-qPCR in mulberry as a tool to unravel the disease resistance mechanism.

Uji Efektivitas Serbuk Daun Kipait (Tithonia difersivolia) Terhadap Serangan Nematoda Puru Akar (Meloidogyne Spp) pada Tanaman Tomat

The tomato plant (Lycopersicum esculentum Mill.) is a horticultural plant that is popular with the public because it has good nutritional content, including vitamin A, vitamin B and vitamin C, which have quite high levels which are good for the body to consume. One of the pests that affects tomato plant production, both quality and quantity, is the attack by root knot nematodes (NPA), namely Meloidogyne spp. This research aims to determine the ability of kipahit leaf powder in several doses to suppress attacks by root knot nematodes (Meloidogyne spp.) on tomato plants (Lycopersicum esculentum Mill.). This research was designed using a one-factor Completely Randomized Design (CRD). The factors tested were the administration of kipahit leaf powder at doses of 25 grams, 50 grams, 75 grams and 100 grams with the control treatment not being given kipahit leaf powder as a comparison. This study had 5 treatments and 4 replications. The research results showed that giving 50 grams of kipahit leaf powder was able to reduce the intensity of root knot attacks and could reduce the nematode population around the roots of tomato plants. and had a significant effect on plant height at 46 and 60 days after transplanting.

Assaying the effects of some essential oils on Root-knot Nematode [Meloidogyne javanica (Treub 1885) Chitwood 1949] in the laboratory

Nematodes are man’s faceless enemy whose activities encourage hunger and poverty. This study was conducted to determine the efficacy of selected plant oil extract in the control of root knot Nematode [Meloidogyne javanica] in the laboratory. The experimental design used was Complete Randomized Design (CRD) with fourteen treatments, replicated three times. Egg hatch inhibition test on M. javanica eggs and juvenile mortality test were separately performed by exposing the eggs and juveniles to different dosage of the essential oils. Neem seed oil statistically proved effective in inhibiting egg hatch followed closely by Garlic clove oil and then Moringa seed oil. All the essential oil treatments were more effective than carbofuran treatment. The surfactant Sodium Lauryl Sulphate was shown to have nematicidal properties as it also recorded zero egg hatching at all the doses applied. The second stage juveniles of M. javanica recorded a higher mortality rate (100%), when they were treated with Neem seed oil, closely followed by Garlic clove oil and then Moringa seed oil. All Surfactant treatments caused 100% juveniles’ mortality. The higher the doses of the essential oils, the higher the juvenile mortality rate. Neem seed oil at all the dosage proved effective in controlling Meloidogyne javanica causing high rate of juvenile mortality and suppressing M. javanica egg hatch. The nematicidal characteristics exhibited by the essential oils might be due to the phytochemicals present in the oils.

A southern root-knot nematode (Meloidogyne incognita) first reported on cucumber in Manipur

Root-knot nematode is one of the major pest of vegetable crops that produces root galls in the infected roots, seriously reducing the farmer’s produce. According to statistics, phyto-parasitic nematodes affect 12.3% of the world’s major crops each year, resulting in yield losses. Most common species of root-knot nematodes have been reported to be vulnerable to cucumber and they can reduce productivity by up to 60% in protected commercial farming. Till now, there was no report of root knot nematode affecting cucumber in the state of Manipur (India). In 2021, an extensive investigation was conducted in each block of Kakching district, Manipur to observe for the root-knot nematode (Meloidogyne spp.) infecting the cucumber crop of that area based on morphological characteristic symptoms of the infected plant. The root samples forming galls and soil were collected for confirmatory studies at the laboratory. For the first time, it was discovered during the study that the cucumber crop was infested by the Meloidogyne spp. showing the general symptoms like water and nutrient stress, yellowing of leaves, stunted growth, wilting of infested plants and patchiness of plants in the infested field, together with the typical symptoms of gall formation in the root system. According to morphological investigations, the southern root-knot nematode (M. incognita) was found to be responsible for the infestation of the cucumber plant sample taken from a farmer’s field in the Kakching district of Manipur.

Biocontrol efficacy of endophytic fungus, Acremonium sclerotigenum, against Meloidogyne incognita under in vitro and in vivo conditions

AbstractBiocontrol microorganisms are important tools for the control of root knot nematodes (Meloidogyne spp.). Endophytic fungi have shown great potential as biocontrol agents in such applications. We here isolated an endophytic fungus from tomato root galls infected with M. incognita and identified the isolate as Acremonium sclerotigenum based on morphology and the internal transcribed spacer sequence. The biocontrol potential of this fungus was evaluated both in vitro and in vivo. Specifically, in vitro analyses were conducted to determine the potential of A. sclerotigenum to increase Meloidogyne incognita juvenile (J2 stage) mortality and decrease M. incognita egg hatching rates. The results revealed that A. sclerotigenum culture filtrates caused high J2 mortality rates (up to 95.5%) and significantly inhibited egg hatching (by up to ~ 43%). Furthermore, eggs treated with the culture filtrate were disaggregated and could not develop into nematodes. An in vivo experiment showed that treatment of tomato plants with A. sclerotigenum suppressed root knot nematode populations and significantly reduced the galling index. Both A. sclerotigenum treatment and exposure to the nematicide abamectin had good control effects, with efficacy rates of 55.43% and 70.58%, respectively. In summary, the endophytic fungus A. sclerotigenum here showed excellent potential for biocontrol of M. incognita. Further studies should be conducted to identify the nematicidal compounds produced by this fungus and to establish the molecular mechanism of action associated with the observed biocontrol effects.

Farmer knowledge, management practices and occurrence of tomato root knot nematodes in Kenya

Root-knot nematodes (RKNs) (Meloidogyne spp.) is a major constraint to tomato (Solanum lycopersicum L.) production in sub-Saharan Africa; yet there is low adoption of recommended nematode control measures in regions like east Africa due to inadequate farmer knowledge about the pest and associated diseases. The objective of this study was to assess farmers’ knowledge status, and intensity of damage of root-knot nematodes and their management practices in Kenya. A survey was conducted in Kenya, during February to August 2021; using a semi-structured questionnaire administered to 282 randomly selected household heads of actively growing tomato farmers, at two elevations in three counties. Most farmers (98.9%) could not identify the disease precisely. They mostly attributed its symptoms to moisture stress and nutrient deûciencies. Most farmers (63%) practiced mono-cropping; while only 4.3% of farmers amended soils with manure. Respondents preferred growing RKN susceptible tomato varieties, mainly Rio-Grande, Cal J, Onyx and Kilele FI. A total of 92% expressed willingness to shift to RKNs resistant varieties, if recommended varieties match their desirable characteristics. Majority of the respondents lacked knowledge on nematode characteristics and its associated disease control. A total of 37.9% of the respondents did not use control measures against the RKNs. There was high disease incidence, severity and galling index in the surveyed areas.

Impact of the Interaction between Meloidogyne javanica and Fusarium oxysporum on the Okra Plantation

The development of diseases in cultivated crops depends on the complex interrelationship between the host, pathogen, and prevailing environmental conditions. The interaction between the root knot nematode Meloidogyne javanica and the fungus Fusarium oxysporum was studied for the okra cultivar Pusa Sawani. Sequential and simultaneous inoculation of the nematode and fungus was performed to observe the disease severity in the plants due to the individual and interactive effects of the tested nematode and fungus. The results indicated that plant growth was adversely affected in all cases where the plant was inoculated with M. javanica and F. oxysporum, compared to the uninoculated control. The study clearly showed that nematodes act as predisposing factors in the spread of secondary fungal pathogens.

Characterization of entomotoxic and nematotoxic genes from indigenous Bacillus thuringiensis strains and their biocontrol potential

BackgroundThe gram pod borer (Helicoverpa armigera Hubner), Bihar hairy caterpillar (Spilosoma obliqua Walker), tobacco caterpillar (Spodoptera litura Fabricius) and root knot nematode (Meloidogyne incognita (Kofoid and White) Chitwood) are the major insect pest and nematodes infesting mungbean, urdbean and other legumes. Bacillus thuringiensis (Bt) is a promising biocontrol agent that helps in managing the above pest. Deploying Bt biopesticides instead of chemical pesticides in legume cultivation enhances the soil health substantially. The present study envisages morphological, molecular cum biochemical characterization, entomotoxicity and nematotoxicity potential of four indigenous Bt strains (Ak2.IIPR, F8.IIPR, F5.IIPR and F6.IIPR) along with HD1 (standard check from BGSC).ResultsThe SEM micrograph analysis of above four Bt strains along with F1.IIPR revealed the presence of different combinations of insecticidal crystal proteins, viz. cuboidal crystal (CC), bipyramidal crystal (BC), spherical crystal (SC) and irregularly pointed crystal (IC). This was further confirmed by PCR amplification of Cry1, Cry2Aa, Cry2Ac, VIP3A and chi36 gene-specific primers and their phylogenetic analysis. F8.IIPR and Ak2.IIPR recorded the highest toxicity index against second-instar S. obliqua larvae (292.56 and 174.55), H. armigera (150.00 and 113.65) and S. litura (210.71 and 114.19) based on probit analysis. F5.IIPR (91.67%) and F8.IIPR (89.00%) recorded the highest juvenile mortality against M. incognita, followed by Ak2.IIPR (70.33%). The protein profiling of supernatant of terrific broth inoculated with F8.IIPR indicated the presence of VIP3A and Cry1I.ConclusionThe present study concluded that F8.IIPR and Ak2.IIPR were potential Bt strains isolated from Indo-Gangetic plains which is having both entomocidal and nematicidal properties. Further, these strains were deposited at national repository, ICAR-NBAIM with the following accession no.: NAIMCC-SB-065 and NAIMCC-SB-066, respectively. These strains can be formulated as microbial biopesticide.

Composition and nematicidal activity of the essential oil from Piper longum against root knot nematode

Piper longum L. (Piperaceae family), commonly known as long pepper, is used in traditional medicine and in recognized system of medicine in India for the treatment of inflammation, pain, epilepsy, arthritis, cancer, ulcer, and asthma in addition to pest control activity. Its fruits are rich in essential oil and possess different biological activities, but oil is not much explored against the root-knot nematodes. Thus, the essential oil from the fruits of P. longum was isolated by hydrodistillation method and analyzed by Gas chromatography-Flame ionisation detector and Mass spectrometry. Analysis showed that the oil is a complex mixture of volatile compounds. (Z)-β-Farnesene (25.08%), β-Caryophyllene (13.57%), α-Humulene (13.37%), 8-Heptadecene (9.28%), Heptadecane (7.07%), α-Patchoulene (5.44%), 3-Heptadecene (5.09%), γ-Elemene (4.37%), β-Humulene (3.69%) and Terpinen-4-ol (1.74%) were identified as main compounds in its oil. The essential oil was evaluated for its nematicidal activity against root-knot nematode at 62.5–1000 ppm concentrations in vitro conditions during 2020–21 at ICAR-Indian Agricultural Research Institute, New Delhi. Results showed promising nematicidal activity of the oil and have caused mortality of juvenile (J2), ranging from 2.33–88.0% after 24–96 hours of treatment compared to untreated control. The oil was further evaluated under the pot conditions in tomato (Solanum lycopercicum L.) (var. Pusa Ruby) at 3000 and 2000 ppm. Results showed a significant reduction in the number of galls/root of tomato with better plant growth in the essential oil based treatment as compared to the untreated control. These results suggest that the oil can be used for the development of nematicidal product for the protection of crops from the infestation of M. incognita.

Genetic profiling of locally registered Philippine coffee using molecular markers linked to resistance against diseases and pests

Abstract. Santos NRS, Magat MB, Mondragon MV, Cao EP, Santos DMC. 2023. Genetic profiling of locally registered Philippine coffee using molecular markers linked to resistance against diseases and pests. Biodiversitas 24: 4136-4144. Coffee is a major commodity in the Philippines, but diseases and pests have hampered local production. Natural resistance could help increase production by eradicating infestation or lessening the symptoms of infection and minimizing the need for chemical control. Hence, this study aims to screen local Coffea arabica varieties, whose beans are prized for their superior taste and aroma, using genetic markers. These markers are linked to resistance against Coffee Leaf Rust (CLR, caused by Hemileia vastatrix), Coffee Berry Disease (CBD, caused by Colletotrichum kahawae), and Root Knot Nematode (RKN, Meloidogynespp.). The Arabica samples were obtained from the Bureau of Plant Industry in Baguio City, Benguet, a main distributor of coffee seedlings to farmers. C. canephora and C. liberica trees from Cavite State University, Indang, Cavite, were used as control samples. Results reveal that the registered NSIC-2008-Cf-A-05 (Red Bourbon) Arabica tree contains a unique haplotype in a region of chromosome 3. This region has been linked to the SH3 gene, which confers resistance against CLR, a promising result for infested areas. However, all Arabica samples are inferred to be susceptible to CBD and RKN. Hence, NSIC-2008-Cf-A-05 is a potential source for resistance genes specifically against CLR in future breeding programs.

Phytonematode Diversity in Tomato Crops of Chittoor District, Andhra Pradesh, India: A Comprehensive Survey, Distribution, and Community Analysis

The present study was undertaken to analyze the distribution and community analysis of important plant parasitic nematodes associated with the vegetable crop tomato in Chittoor District of Andhra Pradesh. The study revealed that maximum infestation is observed in somala mandal and least in Chowdepalle mandals of Chittoor District of Andhra Pradesh. Plant parasitic nematodes viz., Meloidogyne incognita, Hoplolaimus spp., and Tylenchorynchus spp. etc. was found to be associated with tomato crops. It has been observed that M. incognita population was found to be maximum in tomato crops at Chittoor Districts of Andhra pradesh. The prominence value was found to be maximum for root knot nematode in tomato crops having 8.76/200 cc. The data also revealed that M. incognita absolute frequency in tomato was 100% and absolute density is around 87.60% while the genera Hoplolaimus showed the least occurrence frequency of 40% and absolute density of 1.56%. From these studies it can be interpreted that M. incognita is most predominant nematode and cause damage substantially to tomato crop grown in Chittoor District of Andhra Pradesh.

Marker assisted early generation identification of root knot disease resistant orange tomato segregants with multiple desirable alleles.

The online version contains supplementary material available at 10.1007/s12298-023-01361-1.

Efektivitas Esktrak Akar Kenikir (Cosmos caudatus Kunth) dan Pepaya (Carica papaya L) dalam Menekan Terbentuknya Puru Akar Nematoda pada Tanaman Seledri (Apium graveolensL)

This study aims to test the effectiveness of root extracts of kenikir and papaya plants in suppressing the rate of root-knots formation, as well as the number of root-knots formed on celery plants. The method used was a factorial experiment in a randomized block design with two factors, namely the type of antagonist plant root and the dosage, with five replications. The results showed that the treatment of papaya root extract (Carica papaya L.) had a significant effect on all parameters, but the HSD test was only significantly different on the number of root knots. The highest average number of root knots in control plants was 67.2 (A1B0), and the lowest was 4.6 (A1B5). The treatment of kenikir root extract (Cosmos caudatus Kunth.) significantly affected all parameters, but the HSD test was only significantly different on plant height and number of root knots. The average plant height in the control was 31.4 cm (A2B0), and in the treatment 40.6 cm (A2B5). The highest average number of root knoots was 50.8 (A2B0), and the lowest was 1.0 (A2B5). Carpain secondary metabolites in papaya root extract, and phenylpropanoids in kenikir root extract played a role in suppressing the growth of root-knot nematodes. Coniferyl alcohol in kenikir root extract is thought to play a role in increasing the height of celery plants. Kenikir root extract was better than papaya root extract in suppressing the growth of root-knot nematodes.

Diversity of bioprotective microbial organisms in Upper Region of Assam and its efficacy against Meloidogyne graminicola.

Meloidogyne graminicola has a well-established negative impact on rice yield in transplanted and direct-seeded rice, resulting in yield losses of up to 20 to 90 percent. Studies were undertaken to isolate potential native strains of bio-control agents to manage the devastating Rice Root Knot Nematode (M. graminicola). Eighteen bacterial strains and eleven fungal strains were isolated from the rhizosphere of crops like rice, okra, ash gourd, chili, beans and cucumber, enveloping diverse soil types from the Upper Brahmaputra Valley region of Assam. Six bacterial strains were gram-positive according to morphological results, while twelve others stained negatively. Fifteen bacteria were rod-shaped, two were coccus and one was diplococcus, and all the bacterial isolates showed signs of movement. All the bacterial strains exhibited positivity for gelatin hydrolysis and catalase test. Seven bacteria showed positive, while eleven showed negative reactions to possess the ability to deduce carbon and energy from citrate. The study of the in vitro efficacy of the twenty-nine bacterial and fungal isolates tested against second-stage juveniles (J2) of Meloidogyne graminicola revealed that all the bacterial and fungal isolates potentially inhibited the test organism and caused significant mortality over sterile water treatment. The promising bacterial and fungal isolates that exhibited mortality above 50% were identified as BSH8, BTS4, BTS5, BJA15, FJB 11 and FSH5. The strain BSH8 exhibited the best result of mortality, with 80.79% mortality against J2 of M. graminicola. The strain BTS4 and BTS5 expressed mortality of 71.29% and 68.75% under in-vitro conditions and were significant. The effective and promising bioagents were identified using the 16 S rRNA sequencing as Bacillis subtilis (BSH8), Bacillus velezensis (BTS4), Alcaligenes faecalis (BTS5), Rhizobium pusense (BJA15), Talaromyces allahabadensis (FSH5) and Trichoderma asperellum (FJB11). These results indicated the microorganism's potential against M. graminicola and its potential for successful biological implementation. Further, the native strains could be tested against various nematode pests of rice in field conditions. Its compatibility with various pesticides and the implication of the potential strains in integrated pest management can be assessed.

Field application of Clethodim herbicide combined with Trichoderma spp. for controlling weeds, root knot nematodes and Rhizoctonia root rot disease in two faba bean cultivars

Field application of Clethodim herbicide combined with Trichoderma spp. for controlling weeds, root knot nematodes and Rhizoctonia root rot disease in two faba bean cultivars