Anuradha Jha

Occurrence of arbuscular mycorrhizal fungi in rhizosphere of Jatropha curcas L. in arid and semi arid regions of India.

A study was conducted to identify common arbuscular mycorrhizal (AM) fungi present in rhizosphere of Jatropha curcas L., an important bio-diesel crop, from different arid and semi arid regions of India viz., Jodhpur (Rajasthan), Hissar (Haryana), Jhansi and Lalitpur (Uttar Pradesh) and Hyderabad (Andhra Pradesh). A total of 20 AM species were recorded, which consisted of two species of Acaulospora and 18 species of Glomus. The highest frequency of occurrence was recorded for Glomus intraradix (100%), followed by Acaulospora scrobiculata (83%), G. etunicatum (50%) and Glomus 1 (50%). Maximum species richness was recorded at Jodhpur, followed by Jhansi, Hissar, Hyderabad and Lalitpur. The results seem to suggest that species richness was more in arid regions as compared to semi arid areas.

Effect of arbuscular mycorrhizal inoculations on seedling growth and biomass productivity of two bamboo species.

A study was conducted to identify suitable arbuscular mycorrhizal (AM) fungi for inoculation of Bambusa bambos and Dendrocalamus strictus at nursery stage for increasing growth and productivity. Twelve AM species, isolated from bamboo and other common trees of Bundelkhand were used for inoculations. In B. bambos, total dry weight and phosphorus (P) uptake were significantly increased by all studied fungi and shoot length was increased by eight AM inoculants. Maximum mycorrhizal dependency (MD) was recorded for Acaulospora scrobiculata (44.2%), followed by Glomus cerebriforme (41.6%) and G. intraradix (41.0%). In D. strictus, all tested AM inoculants significantly increased shoot length, dry shoot weight and P uptake, except Glomus 1. Dry root weight was significantly increased by only two inoculants namely, G. cerebriforme and G. etunicatum. Total dry weight was significantly increased by eight AM fungi. Maximum MD was recorded for G. cerebriforme (62.9%), followed by G. diaphanum (55.0%) and G. etunicatum (51.3%). Thus, the results showed that utilization of effective AM fungi can enhance the productivity of bamboo in the region.

Cumulative effects of tree-based intercropping on arbuscular mycorrhizal fungi

In tree-based intercropping system (agroforestry), the role of perennial trees in maintaining active populations and mycelial networks of arbuscular mycorrhizal fungi (AMF) is well documented. Agroforestry positively influences the AMF community, but complete studies regarding mycorrhization in such systems are scarce. The present study was conducted to assess the effect of tree introduction in agriculture fields on mycorrhization. In particular, we investigated the effect of trees on AMF colonization of intercrops and vice versa, the effect of canopy management of trees on their root colonization, and the cross-infectivity of AMF isolated from tree rhizosphere in intercrops and vice versa. The results of the field study suggest that in agroforestry systems, trees acted as AMF inoculum reservoir for intercrops, especially during the rainy season. Intercropping (Phaseolus mungo and Triticum aestivum in the rainy and winter seasons, respectively) increased mycorrhization, i.e., root colonization and spore population in the rhizosphere of Albizia procera and Eucalyptus tereticornis. Canopy management, i.e., shoot pruning, reduces root colonization in A. procera, Anogeissus pendula, Dalbergia sissoo, Hardwickia binata, and Tectona grandis, especially in April 2005 (late spring), but during subsequent periods, differences among the treatments were at par. Results from greenhouse suggest that AMF are nonspecific in their selection of host since species isolated from tree rhizosphere could colonize the roots of crops and vice versa.

Interactions between arbuscular mycorrhizae and Fusarium oxysporum f. sp. ciceris: effects on fungal development, seedling growth and wilt disease suppression in Cicer arietinum L.

The purpose of present study was to develop a management strategy based on a time effective inoculation of arbuscular mycorrhizal fungi (AMF) to mitigate the yield losses of Cicer arietinum L. due to Fusarium oxysporum f. sp. ciceris (Foc). The interactions between AMF (mycorrhizal consortium; Myc) and Foc were studied in three separate experiments in two successive years (2011 and 2012). In particular, we investigated: the effect of Myc on population density of Foc, the effect of Foc on mycorrhisation (root colonisation index and AMF spore density/50 g sand) and the interactive effects of Myc and Foc on growth, phosphorus (P) content and disease severity index of C. arietinum. Results suggested that pre-inoculating plants with AMF (Myc + Foc) considerably reduced Foc population density, while combined (Myc/Foc) and early inoculation of AMF (Myc + Foc) increased mycorrhisation, growth and P content of plants. Combined and early inoculation of AMF reduced disease severity index up to 68 and 89.5%, respectively. Thus, the results suggested that soil pretreated with AMF acted as bioprotectant against the Fusarium. In conclusion, Myc should be inoculated before transplantation of crop seedlings to the fields. However, extrapolation of the results to the real field conditions should be done with caution because of differences in growth conditions and substrate used in present study i.e. net house and sand, respectively.

Indian Bioresource Information Network (IBIN)

The bioresource or biological resource includes all components of biological diversity with actual or potential value for humanity and the sustainability of the living systems. It is generally understood as the biotic component of ecosystems that includes organisms, parts thereof, populations, genetic resources and any other element that are of tangential and non-tangential benefit. Indian sub-continent supports varied bioclimatic regions and biodiversity. Despite several attempts from both the national and international survey organizations, we still have incomplete information about several taxonomic groups (e.g. plants, insects and other lower life forms) on their conservation status. This is because we have not been able to generate the comprehensive data on their distribution and population status. Even more, we hardly have reliable information on the levels of harvesting of these species from the natural habitats, their economic value and ecological significance.

Effects of Arbuscular Mycorrhizal Inoculations and Cotyledon Removal on Early Seedling Growth of Jatropha Curcas L.

A study was conducted to investigate the response of Jatropha curcas L., an important bio-diesel plant species, to arbuscular mycorrhiza (AM) inoculations. AM species, isolated from its rhizosphere could colonize its roots/rhizospheres, indicating that J. curcas does not retard the activities of AM fungi. However, the seedlings did not respond positively to the inoculations and mycorrhizal dependency (MD) for some inoculants was in the negative range. This could be due to the large amount of nutrients stored in cotyledons of big sized J. curcas seeds. Further results showed that the removal of cotyledons (metabolic reserves) immediately after seed germination did not increase MD of J. curcas. Workers from different countries have reported variable results on this aspect and it is generally admitted that different populations, varieties, cultivars or strains of any specific cultivated crop may react differently to different situations such as inoculation with AM fungi. Therefore, it will be worthwhile to test the different populations of J. curcas from various locations under a given set of conditions.