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Root-knot nematodes are believed to be amongst the biological constraints causing severe damage and a great reduction in the productivity of okra. The purpose of this study was to apply organic matter and non-symbiotic nitrogen-fixing bacteria to minimize the addition of chemical fertilizers that constantly pollute the environment. Experimental studies were conducted in the field for two summers to determine the effect of inoculations of non-symbiotic nitrogen-fixing bacteria, such as Azotobacter chroococcum and Azospirillum brasilense singly and in combinations, with different recommended doses of inorganic nitrogen as well as organic matter such as neem seed cake on the growth, yield, and organic parameters of the okra crop towards the management of plant-parasitic nematodes. The results show a significant reduction in nematode multiplication through soil application of nitrogen-fixing bacteria and neem seed cake along with different recommended doses of nitrogen inoculated plants. Azotobacter was found to be less effective than Azospirillum in agronomic parameters and nematode control. The most pronounced increases were observed in the yield and growth parameters such as plant height, fresh as well as dry weights, fruit weights/plant, number of total fruits/plant and primary branches, chlorophyll content, and ascorbic acid content when A. chroococcum and A. brasilense were added concomitantly in various combinations. Agronomic parameters such as NPK content in the plant as well as in residual soil increased considerably in almost all the combinations irrespective of these biofertilizers and neem seed cake. In conclusion, the combined application of a 100% recommended dose of nitrogen fertilizer along with Azospirillum and neem seed cake is recommended for better growth and yield of okra with better control of nematodal population.

Experiments were conducted at the University Agricultural Research Farm for the two consecutive years, 2013–2014 and 2014–2015 to study the individual and interactive effects of different plant symbionts (Glomus fasciculatum, Mesorhizobium ciceri), bio-organic waste (Avena sativa straw) and antagonistic fungi, Trichoderma harzianum in all possible combinations for biocontrol of root-knot nematode, Meloidogyne incognita infecting chickpea var. Avrodhi. Biocontrol agents and organic wastes were evaluated for their efficacy in terms of growth characteristics, chlorophyll content, nutrients status, mycorrhization and nematode-related parameters. Combined treatments resulted in higher plant growth, biomass, chlorophyll and nutrient status (N, P and K). Antagonistic fungi, Trichoderma harzianum @ 106 spores plant−1 proved to be most effective of all the plant symbionts (G. fasciculatum, M. ciceri) and organic waste in suppressing the nematode-related parameters in chickpea plants. Of all the treatments, combined inoculation of AM fungus (Glomus fasciculatum @ 800 spores plant−1) + root-nodulating bacteria (Mesorhizobium ciceri @ 1gplant−1) + organic waste (Avena sativa straw @ 10gplant−1) and antagonistic fungi (Trichoderma harzianum @ 106 spores plant−1) was found to be the most efficient in improving the plant growth parameters and decreasing the root-knot development of M. incognita in chickpea plants. Keywords: AM fungi, Chickpea, Interaction, Root-knot nematode, Rhizobium, Trichoderma harzianum

Efficiency of an organic matter like Tagetes erecta and bioinoculants Azotobacter chroococcum and Glomus fasciculatum was investigated in tomato cultivar ‘Pusa Ruby’ when inoculated individually as well as concomitantly for the management of the root-knot nematode, Meloidogyne incognita in terms of growth parameters such as plant length, fresh and dry weights, chlorophyll content, per cent pollen fertility and mycorrhization. Greatest reduction in the numbers of second-stage juveniles in soil, number of root-galls, egg-masses and nematode multiplication was recorded with combined application of T. erecta and bio-inoculants A. chroococcum and G. fasciculatum as compared to untreated control and other treatments. Similarly, the greatest improvement in the plant growth and biomass of tomato was noted in the same treatments. However, individual inoculation of these bio-inoculants and organic fertilizers also showed significant enhancement but was less as compared to combined treatment. A. chroococcum was found most effective against disease incidence followed by G. fasciculatum and T. erecta. Parameters like NP and K contents were significantly enhanced in those plants which received combined treatments of organic matter and bio-inoculants. Azotobacter was found more efficacious against nematodes than Glomus fasciculatum. Organic matter also influenced the activity of bio-inoculants, more with the Azotobacter than G. fasciculatum. DOI: http://dx.doi.org/10.3126/ije.v4i2.12643 International Journal of Environment Vol.4(2) 2015: 206-220

A pot experiment was conducted during 2013–14 to observe the potential role of some organics and bio-organics such as Calotropis procera, Glomus fasciculatum, and Azotobacter chroococcum on some growth attributes of chickpea and subsequently on the root-knot development caused by Meloidogyne incognita. Individual and conjoint treatments significantly enhanced the plant growth parameters as compared to unamended control. Physiological parameter such as chlorophyll content also exhibited significant improvement in all the treatments over non-amended control. The highest improvement in growth parameters of chickpea was observed in combined application of G. fasciculatum and A. chroococcum in pots amended with C. procera. Moreover, combined treatments of both bio-inoculants and C. procera markedly reduced the multiplication and reproduction rate of root-knot nematodes in terms of number of root galls and nematode population. Percent mycorrhization in terms of external and internal colonizations was increased significantly in plant amended with organic and bio-organics conjointly. The regression studies revealed significant relationship between number of galls and some plant growth variables. Present findings may promote organic-based farm products and eco-friendly management of M. incognita as this is a safer and cost-effective option.

Soil application of organics has been explored as an alternative means of organic management of plant-parasitic nematodes. Efficiency of different oil-seed cakes of neem (Azadirachta indica), castor (Ricinus communis), groundnut (Arachis hypogaea), linseed (Linum usitatissimum), sunflower (Helianthus annuus) and soybean (Glycine max) were evaluated in field conditions with association of Pseudomonas fluorescens in relation to growth parameters of chickpea and population of plant-parasitic nematodes. Their efficacious nature was highly effective in reducing the population of these dominant soil nematodes. Significant improvement was observed in plant-growth parameters such as plant weight, percent pollen fertility, pod numbers, root-nodulation and chlorophyll content of chickpea, seemed to be due to reduction in disease incidence and might be due to growth promoting substances secreted by P. fluorescens. The multiplication rate of nematodes was less in the presence of P. fluorescens as compared to its absence. Most effective combination of P. fluorescens was observed with neem cake.

A pot experiment was conducted during winter season of 2009–2010 in the department of Botany, AMU, Aligarh, India, to determine the nematicidal potential of organic matter, neem cake at third level of dose, and bioagent, Glomus fasciculatum in terms of various growth parameters of tomato, when inoculated individually as well as concomitantly with respect to root-knot development. Neem cake and G. fasciculatum showed potential for sustainable management while providing nutrient sources for proper plant growth. Disease intensity of root-knot nematode decreased while increasing the doses of neem cake along with the G. fasciculatum. Chlorophyll contents have been found to be increased in single and combined application as well. There is a progressive increase in growth parameters raised in soil amended with 10, 20, and 30 g neem cake/kg soil and inoculated with G. fasciculatum. Significant improvement in the plant growth was observed when G. fasciculatum and neem cake were inoculated simultaneously. Neem cake plus G. fasciculatum reduced the nematodes’ multiplication and root-galling, and increased the plant growth of tomato as compared to unamended and Meloidogyne incognita-inoculated plants. Mycorrhyzation and agronomic parameters were increased due to application of G. fasciculatum alone, but enhanced further when inoculated with neem cake.

A disease complex involving Meloidogyne incognita–Rhizoctonia solani was studied on tomato (Lycopersicon esculentum var. Pusa Ruby) under glasshouse conditions to determine their concomitant effect on plant growth variables. Biofertilizers Nerium indicum and Trichoderma harzianum were tested against both pathogens individually as well as concomitantly and found its role in minimizing disease severity. Inoculation of M. incognita and R. solani resulted a significant reduction in plant growth variables over control. The plant growth variables reduction was more pronounced by M. incognita as compared to R. solani. However, T. harzianum exhibited their potential against the disease complex but was less effective than N. indicum. A manifold improvement in plant growth parameters was observed when plants were treated with biofertilizers, N. indicum and T. harzianum simultaneously. The present work has revealed that the combined application of N. indicum and T. harzianum may be a better option for the management of disease complex M. incognita–R. solani on tomato. Application of these biofertilizers after field trials may be suitable module of organic farming.

An experiment was conducted to assess the effect of Rhizobium sp., waste tea leaves, eggshell powder, and composted cow dung manure on the root-knot nematode, Meloidogyne incognita, on lentil in Botany department AMU, Aligarh, India. When used alone, composted cow dung was better in reducing galling and nematode multiplication and improving lentil growth followed by eggshell powder, Rhizobium sp., and waste tea leaves. Significant result in the integrated management of M. incognita was obtained when Rhizobium sp. was used in combination with cow dung and eggshell powder (with or without waste tea leaves). Combined application of root nodule bacterium and organic wastes like waste tea leaves, eggshell, and cow dung may be suggested to the farmers/growers or related persons who are having great enthusiasm to establish a lentil production business. Application of these organic materials along with the root nodule bacteria may be helpful to foster soil ecosystem which has been a hot topic in the present scenario.