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The present investigation was carried out to evaluate the potential of chitosan alone and in combination with various agricultural wastes for the management of rootknot nematode, Meloidogyne incognita on eggplant cv. ‘BR-112’ under greenhouse conditions. The results showed that chitosan as a single or joint treatment with agricultural wastes significantly (p ≤ 0.05) reduced root-knot indices, and the nematode population in soil. As a result, of this, the growth and growth yielding attributes of eggplant were remarkably augmented. Chitosan as an elicitor induced plant mediated systemic resistance against M. incognita in eggplant. The results of the study demonstrated that maximum reduction in eggmass/root, eggs/eggmasses, nematode population and root-knot indices, was acquired by the treatments: chitosan + onion and chitosan + mentha. It was followed by chitosan + Brassica, chitosan + urad and chitosan + coconut whereas, chitosan combined with corn cob waste was found to be the least effective when compared to the control. The application of chitosan alone was effective but not very satisfactory. Compared to the control applications of all the treatments significantly increased plant growth in terms of length, fresh and dry weights, pollen fertility, yield and biochemical parameters such as chlorophyll, carotenoid content and antioxidant enzymes. This may have been due to the eliciting activity of chitosan, causing systemic resistance in the plant and the release of various toxic chemical compounds during decomposition which have lethal effects against the second stage juveniles of M. incognita and nematode multiplication.

Exploration of nanoparticles (NPs) for various biological and environmental applications has become one of the most important attributes of nanotechnology. Due to remarkable physicochemical properties, silver nanoparticles (AgNPs) are the most explored and used NPs in wide-ranging applications. Also, they have proven to be of high commercial use since they possess great chemical stability, conductivity, catalytic activity, and antimicrobial potential. Though several methods including chemical and physical methods have been devised, biological approaches using organisms such as bacteria, fungi, and plants have emerged as economical, safe, and effective alternatives for the biosynthesis of AgNPs. Recent studies highlight the potential of AgNPs in modern agricultural practices to control the growth and spread of infectious pathogenic microorganisms since the introduction of AgNPs effectively reduces plant diseases caused by a spectrum of bacteria and fungi. In this review, we highlight the biosynthesis of AgNPs and discuss their applications in plant disease management with recent examples. It is proposed that AgNPs are prospective NPs for the successful inhibition of pathogen growth and plant disease management. This review gives a better understanding of new biological approaches for AgNP synthesis and modes of their optimized applications that could contribute to sustainable agriculture. [ABSTRACT FROM AUTHOR]

The current experiment was performed to determine the nematicidal behaviour of aqueous extract of various weed plants viz., Parthenium hysterophorus, Cymbopogon citratus, Eichhornia crassipes, Monstera deliciosa and Tinospora cardifolia against hatching, mortality and penetration rate of Meloidogyne incognita under in vitro condition. The eggs and second stage juveniles were exposed to various concentrations (250, 500, 1000, 1500, 2000 and 2500 µg/ml) for 5 days and 12, 24 and 48 h respectively. During the experiment, all plant extracts displayed nematicidal potential. Comparison of LC50 values of different plant extracts showed that P. hysterophorus was found to be most effective with LC50 664.9 µg/ml, while T. cardifolia was less effective at 48h of LC50 1419.0 µg/ml. Aqueous extracts of P. hysterophorus at 2500 µg/ml was highly effective against hatching and mortality after 5 days and 72h exposure period respectively. Whereas T. cardifolia was found least effective. The macerated leaves of P. hysterophorus applied at 0.3 g/kg sand showed the lowest penetration of M. incognita in brinjal roots while T. cardifolia displayed highest after 3 and 5 days' post inoculation. This study suggests that aqueous extract of the selected plants having nematistatic and nematicidal properties that can be used for the management of M. incognita in an eco-friendly manner and sustainable agriculture. [ABSTRACT FROM AUTHOR]

Root-knot nematodes pose a severe threat to worldwide agricultural development. Due to the high toxicity of chemical nematicides, eco-friendly control strategies against root-knot nematodes need to be established. A pot and in vitro experiment were performed to estimate nematicidal potential of Pochonia chlamydosporia. P. chlamydosporia was used alone or in combination with two botanicals for controlling Meloidogyne incognita in chickpea. The laboratory assessment was performed with four prepared concentrations (S, S/2, S/10, S/25) of fungal inoculum of P. chlamydosporia against egg hatching and second-stage juvenile's mortality of M. incognita. All four concentrations reduced egg hatching and increased mortality of J2s. In pot experiment, P. chlamydosporia was used with chopped leaves of two botanicals viz., Ageratum conyzoides and Eichhornia crassipes against M. incognita in chickpea. All the treatments found significantly suppressed root infestation caused by M. incognita and improved growth and physiological attributes of chickpea. The combined application of P. chlamydosporia + A. conyzoides was found highly effective, and E. crassipes alone was least. Therefore, using P. chlamydosporia with botanicals is a promising sustainable strategy in agriculture against M. incognita infected chickpea. [ABSTRACT FROM AUTHOR]

Root-knot nematode, Meloidogyne incognita (Kofoid and White) is one of most damaging pathogen of vegetables, including carrot (Daucus carota L.). We evaluated nematicidal potential of chitosan in combination with chopped leaves of Argemone mexicana L., Achyranthes aspera L., and Ricinus communis L. against infestation caused by M. incognita on carrot under both in vitro and in vivo. Infectious stage (J2s) and egg masses of M. incognita were exposed to different concentrations (2500, 2000, 1500, 1000, and 500 ppm) of chitosan and botanical extracts separately. Maximum mortality of J2s and the highest inhibition in egg hatching was observed at 2500 ppm of chitosan after 36 h and days incubation period, respectively and minimum found in 500 ppm of A. aspera after 12 h of incubation period. Furthermore, pots treated with 1 g chitosan and 30 g of freshly chopped leaves of all three tested botanicals significantly reduced pathological parameters and improved growth and photosynthetic attributes of carrot. In combination with botanicals, chitosan showed a synergistic effect against M. incognita on carrot as compared to chitosan alone. This study proves that chitosan's bio-efficacy, combined with selected three botanicals, could be utilised to manage M. incognita on the carrot as a potential sustainable treatment. [ABSTRACT FROM AUTHOR]

This review deals with the mechanism of antagonistic action of bacterial and fungal biocontrol agents such as the production of antibiotics, siderophores, enzyme secretion, competition for nutrition, plant growth promotion by rhizosphere microorganism. The utilisation of synthetic pesticides has been the predominant control processor for diseases brought about by phytopathogenic microorganisms. Notwithstanding, their open and improper application in intensive agriculture has realised issues that have prompted ecological contamination, considerable residues in agricultural products and phytopathogen resistance. They are likewise disrupting the quantity of beneficial microorganism which is available in the soil and capable of expanding soil fertility. Along these lines, there is a need to look through the option of synthetic pesticides that are safe, environmental and monetarily feasible to confront this problem. Biocontrol agent's utilisation is the best alternative method to control the different kinds of diseases, such as nematode infestation, fungal pathogen and bacterial pathogen. Nowadays, biocontrol agents assume a significant role in the field of agriculture. It is a financially savvy, environment-friendly and inhibits the advancement of pathogenic microorganism sustainably. This review emphasises the role of biocontrol agents against different pathogenic microorganisms and their significance potentiality to improve plant growth and enhance defence system of plants. [ABSTRACT FROM AUTHOR]

This study was conducted on tomato (Solanum lycopersicum cv. K-21) to investigate the bioprotective nature of Pseudomonas fluorescens and its interactive effects with Meloidogyne incognita in terms of growth biomarkers, changes in biochemical attributes and modulation in antioxidant enzymes of the tomato plant. In this study, we grew tomato plants with M. incognita and P. fluorescens in separate pots, simultaneously and sequentially (15 days prior or post) after 15 days of seed sowing. The sequential inoculation of Mi15→Pf maximally increased the root-knot index and decreased the nematode population. It was also noted that inoculation suppressed the plant growth biomarkers in comparison to control. However, maximum suppression in nematode reproduction and increment in growth and physiological attributes were observed when P. fluorescens was applied 15 days prior to the nematode (Pf15→Mi) as compared to control. All the treatments showed an increase in antioxidant enzymes. Expression of phenol content and defensive enzymes such as peroxidase (POX) and superoxide dismutase (SOD) increased, in contrast to a significant reduction in malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents when compared with the untreated inoculated plants. However, the highest levels of POX and SOD, and a lowest of phenol, MDA and H2O2 were displayed in the treatment Pf15→Mi, followed by Mi+Pf and Mi15→Pf. [ABSTRACT FROM AUTHOR]