Aisha Sumbul

Dynamic role of organic matter and bioagent for the management of Meloidogyne incognita–Rhizoctonia solani disease complex on tomato in relation to some growth attributes

Abstract 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.

PGPR: Current Vogue in Sustainable Crop Production

Nowadays a large scale of crop produce are pesticide ridden. Heavy application of these hazardous pesticides is not only very costly which leaves financial burden to the farmers but is also harmful to our biodiversity leading to loss of various endangered living species. However, growers are being trained worldwide, and they are progressively switching over their agriculture from chemical or conventional agriculture to organic or sustainable agriculture. Sustainable agriculture reveals crop cultivation with “no chemicals.” But organically cultivated produce are mirage due to their exorbitant prices, at least for the urban dwellers. To resolve this conundrum, the role of plant growth-promoting rhizobacteria (PGPR) has been discussed in the process of plant growth promotion, with their mechanisms and their importance in crop production on sustainable basis. The application of PGPR strain is conducive and creates thrust toward organic farming at every level of farmers, whether it be large landowner or small-scale farmers. However, PGPR strain performance varies from lab to field and even from field to field due to host specificity. Besides, some strains of PGPR have the potential to promote growth of a particular plant, while in another plant they do not respond. There are various ways that promote plant growth such as N2 fixation, P solubilization, siderophore production, phytohormone production, and also the control of phytoparasitic pathogens. In addition to the beneficial role, some important aspects of negativity inducted by the PGPR have also been discussed. Sustainable agriculture, if done in the light of PGPR module, will not only remove the financial burden of the farmers but also prove to be conducive, congenial, and putative. Further studies to commercialize the potent strain of PGPR are stridently needed which will unravel certain yet to be explored mechanisms.

Mycorrhiza: An Alliance for the Nutrient Management in Plants

Mycorrhizal fungi are a wide ranging group of heterogeneous fungal taxa found to be allied with the roots of over 90% of all plant species. Among several types of mycorrhizal associations, two types are of high ecological and economic importance, i.e. arbuscular and ectotrophic mycorrhizal interactions. We have given a brief account on habitat, host specificity, and structural components of these mycorrhizal groups. An elaborated discussion on mineral absorption, different absorption pathways and the mechanisms involved has been presented in this chapter. Besides improving plant uptake of mineral nutrients already present in soil, many mycorrhizal fungi play a significant role in mobilizing nutrients either from organic substrate, mineral particles or rock surface. Mycorrhizal fungi take on several mechanisms to accomplish the function successfully, such as enhanced absorbing area of plant roots, release of biochemicals and consortium with other microorganisms. In addition to mobilizing nutrients, mycorrhizal fungi also serves as an important C sink in the soil, thus having an important influence on the cycling of these elements. The contributions of each partner in a mycorrhizal association are starting to be revealed by the use of molecular and genetic tools, coupled to high-throughput sequencing and advanced microscopy. Signalling pathways between plants and fungi have now been marked out, and the recognition of various novel nutrient transporters has unveiled some of the cellular processes that are fundamental to the mycorrhizal symbiosis. Different transporters, especially proton-coupled phosphate transporters, have been recognized on both the plant and fungal membranes and contribute to delivering phosphate from fungi to plants. Although much work has been previously done on several aspects of such symbioses, the extent to which they are functionally important in agriculture remains unclear. We are in urgent need to focus on the questions, the answers of which will give the new perspectives on mycorrhizal function.

Siderophores: Augmentation of Soil Health and Crop Productivity

Microorganisms harbouring in the soil are extremely important in the sustainable agriculture. They play a very crucial role in the sustenance of ecological services/balance. Siderophore-producing microorganisms have enormous range of application for the sustainable crop production. Application of siderophores has recently caught fire of discussion and being used in the plant disease management, maintenance of healthy soil, plant growth promotion, SAR induction, acceleration of phytohormone production, bioaugmentation of heavy metal (HM), etc. Moreover, nearly all living beings shine their cellular reactions such as electron transportation, different metabolic reactions and organic molecule formations with the help of iron. In iron-deprived environment, siderophores are the chief media by which maximum cellular reactions get completed. However, a wide range of variations among the siderophores has been noticed like bacterial siderophores that have extremely high binding affinities than fungi; however, phytosiderophores have less binding affinities than microbial siderophores. A lot of variations among the microbial siderophores such as algae, bacteria, fungi and actinomycetes have been noticed in significant manner. Additionally, beneficial job of siderophore in other sector of agriculture and allied branch of science may not be ignored. However, there are some hurdles such as lack of infrastructure and communication gap among the concerned researcher which has put such important research on hold. Research on siderophore-producing organisms will provide an arena to formulate bioprocess technology which is indeed needed to maximize the production of microbial siderophores because of its wide range of applicability. Overall, siderophores and siderophore-producing organisms are conducive to human kind as well as in the sustenance of ecological balance. Thus, this article discusses about the present scenario of research pertaining to siderophore applications in agriculture.

Potential role of bio-inoculants and organic matter for the management of root-knot nematode infesting chickpea

Abstract 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.

Diversity of AMF, characterization of soil, spore population in soil and root colonization associated with some commonly cultivated crops at Bhaderwah, Doda District, Jammu and Kashmir, India

An extensive survey was conducted to identify common arbuscular mycorrhizal (AM) fungi present in rhizosphere of some commonly cultivated crops such as Maize, Tomato, Pea, Bean, Chilli, Cauliflower and Brinjal from four different sites viz., Bhaderwah (A), Kotli (B), Bhalla (C) and Malni (D) from Bhaderwah of Doda district, Jammu and Kashmir. A total of nearly 6 AM fungal species were recorded, which included of Glomus Jasciculatum, G. mosseae, G. etunicatum, G. constrictum, G. macrocarpum and Gigaspora gigantea. The frequency of occurrence was recorded in order of Glomus Jasciculatum > G. mosseae > G. etunicatum > G. constrictum > G. macrocarpum > Gigaspora gigantean. Most of the plants are found to be associated with AM fungi in natural ecosystem in this region and showed variation in the extent of infection from plant variety soil nature and climatic surroundings.